CA2184481A1

CA2184481A1 - Method and apparatus for monitoring and coordination of multiple geography-altering machines on a work site

Info

Publication number: CA2184481A1
Application number: CA002184481A
Authority: CA
Inventors: Adam J. Gudat; Daniel E. Henderson
Original assignee: Individual
Current assignee: Caterpillar Inc
Priority date: 1994-04-18
Filing date: 1995-04-12
Publication date: 1995-10-26
Also published as: AU2246095A; EP0756653A1; JP3678426B2; US5646844A; EP0756653B1; WO1995028524A1; DE69501401D1; JPH09512072A; DE69501401T2; ZA952853B; AU690979B2

Abstract

An apparatus (40, 50, 60) and method (100, 101, 102, 104, 106, 108, 108a, 109, 110) for directing the operations of multiple geography-altering machines (14) on a common work site (12) relative to one another. Position information from several machines (14) is shared to generate a common, dynamically-updated site database (66) showing the machines' relative positions and site progress in real time. The common site database (66) is used to direct the operation of one machine (14) with respect to another machine or machines (14) for example by generating an operator display (22) of the site (12) showing relative machine position and total machine work on the site (12). The operator can accordingly adjust the machine's operation to avoid interference with other machines (14) or unnecessary overlap of work on the site (12). The information can also be used to coordinate the operations of several machines (14) in complementary fashion Machine position information can be broadcast from the machines (14) to the site database (66) to create a common, dynamically-updated database (66) which is then shared with one or mote of the machines (14). In a particular embodiment each machine (14) is provided with its own dynamically-updated database (66) and operator display (22), and machine position information is shared on a continuous, real-time basis between the machines (14) so that they effectively share a common site database (66).

Description

~; W095/28S24 ~ ' ` ? A t ~ ~ 1 84~81 r~~ C0~
Descri~tion METHOD AND APPARATUS FOR
MONITORING l~ND COORDINATION OF MULTIPLE
GEOGRAPHY-ALTERING M}~CHINES ON A WORK SITE
Technical Field This invention relates to the operation of mobile geography-altering --rh; n~ry on a work site and, more particularly, to the real time monitoring and coordination of two or more ~-rh;noq as they move over and work on the site through the creation of a common database of real time site update and machine pos ition inf ormation .
,3ackqrollnfl Z~rt As used in this patent specif ication the phrase "geography altering ~-rh; nPry~ and various apprn~ -tir~n~ thereof refer to self-propelled mobile --rh;n~c, for example compactors, track-type tractors, road graders, pavers and asphalt layers, which exhibit both ~1) mobility over or through a work site, and (2) the capacity to alter the topography or geography of a work site with a tool or operative portion of the machine such as a, ~ ~rt;nr~ wheel, blade, shovel, bucket, ripper or the like.
Caterpillar Inc., the assignee of this invention, has invented real time methods and systems for precisely detprnl;n;n~r the position of a mobile geography-altering machine as it traverses a work site and f or creating a dynamically updated digital model of the site as it is altered by the machine. These systems improve the ability of an operator or site supervisor to monitor and control the operation of a single machine on the work site.
The Caterpillar systems use a digital data storage, retrieval and process facility which may be W0 95/2NS24 ' " ' ' ~ 8 4 4 8 1 . ~ 4 carried o~ the machine for storing, creating and modifying a digital model of the site as it exists at any given time, as well as a digital model of the desired geography of the site. They further use a 5 mechanism by which the exact position in three-dimensio~al space of the machine, or its operative portion, can be accurately rlPtn~rm; n~-l in real time; i.e., as it traverses and alters the site thereby to update the site model, point by point and in real time. In a preferred implementation a phase differential GPS (global positioning system) receiver system is used which is capable of precisely locating a moving object in three-dimensional space to centimetre accuracy. The digital process facility, 15 e.g. a local r~r~ r, includes a dynamic site database and dif f erencing algorithm which compares the desired site model to the cnn~; nllrusly updated actual site model and generates signals representing the degree of alteration needed at each of a large number 2 0 of coordinates over the site to bring the actual model into conformity with the desired model. The signals are used in one practical application to provide real time displays on the --rh;n~ry to cue the operator as to the machine' s actual position and progress in real 25 time and within a frame of reference which conveys information as to at least a substantial portion of the overall site.
The site, or a practically displayable portion thereof, is subdivided into a rr~nt;nl~r~us 30 matrix of unit areas oi such size that the machine may traverse these unit areas at a rate which is greater than the sampling rate of the GPS receiver and data processing facility. Algorithms are provided which take into account the physical parameters and 35 dimensions of at least an operative portion of the 1~ WOss/28524 ~ t~ '~ 2 1 8 ~ 4 8 1 P~
machine and the relationship thereof to the machine in its path of travel. The unit areas of the display are filled in, coloured, revised or otherwise altered in accordance with progress information derived from the 5 GPS receiver and the digital processing facility. The real time path of the machine relative to the site between position readings i8 f~t~ ;n~d with a dif f erencing algorithm which determines ef f ective parameters of the operative portion of the machine less than or eriual to its actual parameters, and which updates each portion of the site model which the ef f ective parameters traverse .
The present invention addresses the problem of coor~;nAtlng multiple geography-altering r-ch;n-~c as they operate on a common work site.
Di8clo5ure of the Invention According to the invention there is provided apparatus for monitoring and coor~;n~t;n3 the operations of multiple mo~ile geography-altering r~rh;n~ on a work gite, the apparatus comprising:
site database means for storing data representing a site model of representing the geography of the site;
means for generating digital signals representing in real time the inst;~nti~n~ lq three-dimensional site coordinate position of the geography-altering --ch;n~ on a first machine and a second machine as they traverse and alter the site;
means for receiving said signals and for updating said site database means the site model in accordance with the said signals from the first and second -~rh;n.o~ to create a common site database; and w095/28s24 ~ 2 ~ 8 4 4 8 1 ~ 7 ~
~, means for providing control signals for tr;lnPm; RC; nn to said geography-altering ~-rh; n~ in response to updating of said site database means.
The site database can be located remotely S from the --rh;n~g, or on one or both of the ~-rh;n~FI.
The r~~^h~n; r~ for generating position signals asynchronously may broadcast the position signals from each machine to the -h~n; ~r ~or receiving the signals. The asynchronous broadcast means can further broadcast a machine-identification signal with the position signal.
The apparatus may include means for directing the operation of the machine which can comprise an operator display, for exa~ple a display of the site model and the position of the f irst and second r~rh; n~ on the site . The operator display can be located remotely from the ~-~rh;n.~A, or on one or more of the machines.
The apparatus of the present invention can further include means for monitoring the operation of the f irst and seco~d machines relative to one another to prevent interference between them. This can include means for ~lPf;n;n~ a machine interference boundary around a machine to provide a warning signal when the position or boundary of another machine is determined to be within that boundary.
Two mobile geography-altering r-rh; n~oP can each be e~uipped with apparatus to generate signals representing in real time the three-dimensional position of the machine as it traver3es and alters the site. ~ach machine may also provided with digital data storage and retrieval apparatus f or storing a site model representing the geography of the site, and a dynamically updated site database for receiving position signals and for ~updating the site model in ~I W0 951_85A I " ~ ~ o ~ ~ 2 1 8 4 4 8 1 P~I~ 7 _~ _ accordance with the signals. Each machine can further be provided with apparatus for transmitting its position signals to the other machine, and for receiving position signals from the other machine.
5 The site database on each machine is then additionally updated with the position signals from the other machine to create a common site database. Apparatus may be provided f or directing the operation of each machine relative to the other machine working on the site in acrnr-l~nrP with the common site ~t~hZ~
In a further aspect of the invention there is provided a method of monitoring and coordinating the operation of a mobile geography-altering machine on a work site relative to other suc~ --rh;n~
operating on the site.
In a further ~mhQrl;r t of the inventive method, the position signals of each machine are asynchronously broadcast such that only one machine per unit time broadcasts its position signal to the site database.
A machine-identifying signal can be broadcast with the position signal from each machine.
The mixed position/ID signal from a particular machine can be matched with machine parameters to update the site database in accordance with the spPr;f;r characteristics of that machine.
3rief DescriQtion of the Drawinqs Examples of apparatus and methods according to the present invention will now be described with ref erence to the accompanying drawings, in which:
FIG. 1 is a schematic perspective view of a compacting work site with a base reference station and multiple compacting T--rh;nf.q operating on the site;

WOgst28s24 ~ 2184481 ~ 0,.32 FIG. 2 i9 a schematic repres~nt~tinn of a multiple machine conr~n~t;on method according to the present invention;
FIG. 3 i9 a schematic reprpRpnt~;rn of an apparatus which can be used in connection with the receipt and processing of GPS and machine position/ID
signals to carry out the present invention;
FIGS . 4 and ~A are ~rh t ~ r representations of an embodiment of the apparatus of Figure 3 using GPS positioning and two-way radio communication between multiple m~rh;n~
FIG. 5 illustrates an asynchronous machine position broadcasting method;
FIG. 6 is a representative operator display generated by the system of the present invention for a 1 ~n~lf; 11 compacting operation;
FIGS. 6A and 6B are illustrative three-dimensional computer models of a site which can be used with the present invention;
FIGS. 7A-7K are flowchart representations of a dynamic site database w~th multiple machine coordination for a landfill compacting operation according to the present invention;
FIG. 8 is an alternate operator display which can be generated for an earth contouring application of the present invention; and FIG. 9 is a schematic representation of an apparatus z~rrnr~l;ng to the present invention in a system with closed-loop automatic machine controls.
Best Model for r~rr~inq Out the Invention Referring to Figure 1, a landfill compacting site 12 is schematically illustrated with a number of landfill compacting r^~rhinG~ 14 of a known type 35 operating over the site surface to compact it. In the ~, woss/2xs24 ;~ 2 1 ~ 4~ ~ r~

illustrated f.mhnt1; ` each machine 14 is equipped with a three-~l;r^nci~n~l positioning system and a dynamically updated site database for geography-altering operations. The site database includes a digitized site model, for example a two- or three-dimensional topographical map of the site surface subdivided into a number of unit areas in known manner. As the machine positioning system determines and signals the position of machine 14 traversing site 12 in real time, the site database is dynamically updated to reflect the machine position relative to the site and corresponding changes in the site topography, for example by noting elevation changes where the topography is raise~ or lowered by the operation of the machine, or by in~ ; n~ a pass count comprising the number of passes by a machine over a unit area of the site. The dynamic database generates signals reprF~nt;n~ machine position and the updated site model, which signals can be used to direct the operation of the machine, for example with a real time operator display and/or automatic machine controls.
In the illustrated embodiment the r rh;n~
14 are equipped with 3-D position information apparatus 18 using kinematic GPS positioning. Primary position signals are received at 18 from the GPS
satellite constellation orbiting the Earth and a differential/correction signal is received at 58 from base reference station 16. Information on k;n~m:~t;c GPS positioning and a system suitable for use with the present invention can be found, for example, in U.S.
Patent No. 4, 812, 991 issued 14 March 1989 and U S.
Patent No. 4, 963, 889 issued 16 October 1990, both to Hatch. Other 3-D positioning systems are known and can be used, however, for example 3-D laser wo 95l28524 ' A ~ t ~ 2 i 8 4 4 8 1 0 positioning, GPS/laser combinations, or UHF/VHF radio.
Using kinematic GPS or other suitable three-dimensional position signals from an /~t~
reference, the 1rr~tir~n of receiver 18 and each machine 14 can be accurately determined on a point-by-point basis within a few r~hnt; ' ~ 8 ag the ~-rh;nPc traverse site 12. The ~ ,l;nrj rate for coordinate points using the illustrative positioning system is approximately one point per second.
Accordingly, as each machine 14 traverses site 12 and performs its ~l ,~,rt;nj operations, the operator of each machine is provided with accurate, real time machine position and 6ite update information for that machine. Although the illustrated ~ ;r-nt shows a landfill compacting operation, real time machine position and site update systems for geography-alteri~g operations such as earth moving/contouring, grading, paving and the like are within the scope of the invention.
The present invention addresses the need for coor~;n~;nrj the l v~ and work of multiple r-rhlnf~g 14 working on the same site 12. This is achieved by creating a common, dynamically-updated site database reflecting the real time position and site progress of multiple ~-rh; n~c operating on the site, and using that common database to give a machine operator or supervisor accurate, coordinated, real time machine position and site update information for every machine operating on the site.
Real time machine position information is " shared" by each machine with the common databa-ce via suitable transceiver apparatus 68. The site database can then be used to direct the operations of as many machines as desired relative to one another. For example, as in the present example, each machine can ~ W095128514 ",, ,, ~ ~. 2 1 8448 ~ /011~7 g be provided with its own individual site database in an on-board computer 20, that database being ~nn~;nllnusly updated with its own position information and with position information from every other 5 machine, such that each database is essentially jrlPnt;r ;ll to that of every other machine at any point in time. Alternatively, a single database, located on one machine or adjacent the site at base 16, can receive position information from each machine, update 10 the site database locally, and tran6mit signals to each machine to direct their operation, for example for generating an operator display of the dynamically updated site model on each machine.
Ref erring now to ~igure 2, the method of the 15 present invention is shown schematically with - reference to a flowchart. Using a known three-dimensional positioning system as referred to above, machine position coordinates are determined in step 100 as the machine moves over the site. These 20 coordinates are instan~;~n~ol~Rly supplied as a series of discrete points to a differencing algorithm at 102.
The differencing algorithm calculates the machine position and path in real time. Digitized models of the actual and desired site topography/geography are 25 loaded or stored at step 104, in an accessible digital storage and retrieval facility, for example a local digital computer. The differencing algorithm 102 retrieves, manipulates and updates the site model6 from 104 and generates at 106 a dynamic site database 30 of the difference between the actual site and the desired site model, updating the actual site model in real-time as new position information is received from step 100. This dynamically updated site model is then made available to the operator in display step 108, 35 providing real time machine position and site updates Wo 95/28524 ~ .C~ 2i 1 8 4 4 8 ~

in human readable form. Using the information from the display the operator can ef f iciently monitor and direct the manual control of the compacting machine at 109 .
Additionally, or alt~orn~tt~l y, the dynamic update information can be provided to an automatic machine control system at llO, for example an electrohydraulic control system of the type developed by Caterpillar Inc. and used to operate pumps, valves, hydraulic cylinders, motor/ steering r -h~n i I and other controls used in geography-altering r-rh; nt-ry.
The electrohydraulic controls can provide an operator assist to minimize machine work and limit the manual controls if the operator~ s proposed action would, for example, overload the machine. Alternately, the site update information from the dynamic database can be used to provide fully automatic control of one or more machine operating systems.
For the ~ ry compaction embodiment illustrated below, the desired site model is a predetermined desired degree of compaction of material on the site surface. The actual site model is the actual degree of compaction of the site material, ranging between an llnt , rted state and the desired degree of c ll ~ct; on. When the machine traverses the site in a compacting operation, the actual site model is monitored and updated in real time at 106 as the machine bringb the actual site into conformity with the desired site model. For other site operations, for example earth contouring using a blade-ec~uipped tractor, the actual and desired site models may comprise the actual and desired surface contours of the site; the dif f erence between them at any coordinate point is the dif ference in elevation at 35 that point. It will be understo4d that various site ~ Wo 95l285_4 ~ Z 1 8 4 4 8 1 ~"' `" ' "
models for different site operationæ can be used with the present invention. Information on Eite modelling is commercially available.
. Still referring to Figure 2, the method of the present invention may provide for the real time "sharing" of machine position information among multiple machines on the site, guch that the --ch;noR
ef fectively share a common site database of the position of each machine and the site alterations made by each machine. As a result, an unprecedented level of coordination and cooperation between multiple machines working on a single site can be achieved.
For example, the operator~s) of the m~-h;n~R can monitor the relative proximity of ~ h1 n~R to avoid unsafe conditions, and undesirable overlap of machine operations can be reduced or eliminated. Machine operations on the site can also be coordinated in a complementary manner, f or example by tl i rpct; n~ several r~chi n~R to perform succesgive operations on a portion of the site and updating the site database accordingly .
This is achieved in the method of Figure 2 at step 101 where machine position in~ormation, for example 3-D coordinate points in an ~x, y, z) coordinate system, is received from a second machine by a suitable data transmission link. The multiple machine position information from blocks 100 and 101 is delivered to step 102, where the differencing algorithm calculates the position and path of both rs~ch;n~R in real time and updates the site database at 106 accordingly. The resulting database displayed to the operator at 108 shows the positions of both h; n~R on the site ag well as the alterations to the site made by each machine.

W095/28524 ~ 8~1 ~ 2 t 84481 r~ 32 0 .,~

Additionally, the po8ition information received for the first machine at step 100 can be retrieved from step 102 and transmitted at step 101 to an identical dynamic database being used to direct the 5 operations of the second machine. The dynamic database for the second machine is accordingly updated with position information from both the first and second --~h;no~ as described above, and the resulting database displayed to the operator of the second 10 machine. In this manner the two -~rh;n.Q~ effectively share a common, dynamically updated site database.
While the ` ';- o~ Figure 2 illustrates a method where the first and second --rh;n~c receive site update information from their own, separate, 15 commonly-updated site databases, it is possible to omit the transmission of machine position information at step 101 to another database. Instead, the dynamic site updates generated by the database at 106 can be shared directly with the second machine, f or example 20 by transmitting signals to generate an operator display on the second machine as shown in phantom at 108a .
And, while the method of Figure~ 2 is illustrated for coor~;n~;ng two --f-h;n~f:, it will be 25 apparent that the number of ~~o~;nPc which can be coordinated using this method is limited only by the rate at which the machine position information from each machine can be received and processed to update the dynamic database (8~ . For example, at step 101 30 machine position information could be received irom and transmitted to a third machine, a fourth machine, a fifth machine, and so on.
In the illustrated method of Figure 2 the position information ~or the second machine received 35 at step 101 is input directly to the differencing W095128524 . I ?!~ r~ ~ 2 1 ~448 7 r~ 7 algorithm at 102, and the position information for the first machine is retrieved from the differencing algorithm at 102. ~owever, it is possible to input position information from the second machine directly 5 to a system position computer at 100 for subse~uent delivery to the differencing algorithm at 102, and to receive position information for the first machine directly from step 100 for transmission to the second machine .
Referring now to Figure 3, an apparatu~
which can be used in rrnn~rt; rn with the receipt and proc~qqi n~ of GPS signals to carry out the present invention is shown in block diagram form comprising a GPS receiver apparatus 120 with a local reference antenna and a satellite antenna for generating position information for a first machine; a digital radio transmitter/receiver 122 for receiving position information from other -~oh;n~q; a digital processor 124 employing a differencing algorithm, and connected to receive position information from 120 and 122; a digital storage and retrieval facility 126 accessed and updated by processor 124, and an operator display and/or automatic machine controls at 128 receiving signals from processor 124.
GPS receiver system 120 includes a satellite antenna receiving signals from global positioning satellites, and a local reference antenna. The GPS
receiver system 120 uses position _ignals from the satellite antenna and phase differential correction signals from the local reference antenna to generate position coordinate data in three-dimensions to centimetre accuracy for moving objects.
AlterIlatively, raw data from the reference antenna can be transmitted to processor 124, where the differential correction can be locally determined.

W0 95l28s24 ~ 2 ~ 8 4 4 8 1 r~ s.

This po6ition information is supplied to digital processor 124 on a real-time basis a8 the coordinate 8: ,1; n~ rate of the GPS receiver 120 permits. The digital storage facility 126 stores a 5 desired 8ite model, for example a desired degree of compaction of the site according to a predetermined compaction standard, and a second 8ite model, in an illustrative compacting operation the actual degree of compaction of the site, for example lln~ ted as initially surveyed. The actual site model can be accessed and updated in real time by digital processor 124 as it receives new position information from GPS
receiver 12 0 .
Digital processor 124 furt~er generates 15 signals repr~R~nt;n~ the difference between the continuously-updated actual site model and the desired site model. These signals are provided to the operator display and/or automatic machine controls at 128 to direct the operation of the machine over the 20 site to bring the updated actual site model into conformity with the desired site model. The operator display at 128, for example, provides one or more visual representations of the difference between the actual site model and the desired site model to guide 25 the operator in running the machine for the nl~C~RR;~ry operations .
To generate a common site database useful for coordinating multiple ~ hln~R, the apparatus of Figure 3 is provided at 122 with a two-way digital 30. radio capable of receiving position information from other GPS-equipped machines and providing it to the digital processor 124, and transmitting the position coordinates from the GPS receiver system 120 for the f irst machine . Digital processor =124 uses the 35 position information received by radio 122 in the same Wogsl28~24 ~ 2 t 8448 1 manner as the position information received from GPS
system 120 to update the site database. Accordingly, the operator display at 128 will show the site position of each machine for which position information is available, as well as visual representations of the difference between the actual site model and the desired site model as determined or updated by each machine.
With multiple r-rhinPq operating on a site, particularly where the ~ h;n~q are of a different type or size, it is desirable to encode a machine-unique ID signal with the position information from each machine. The ID signal is preferably stored in the database on each machine. T}~e digital processor 124 can then identify each machine from which particular position information is being received. Where the ~~~~hin~q differ in operating parameters or type, machine parameters corresponding to the machine-unique ID signal can be stored in digital storage and retrieval apparatus 126. The machine parameters are retrieved by the digital processor 124 and matched with an incoming position/ID
signal to distinguish the machine on the operator display, to more accurately determine the path of a particular machine and the changes it may have made to the site, and its position.
Referring now to Figure 4, a more detailed schematic of a system like that of Figure 3 is shown using kinematic GPS for position reference signals. A
30 base reference module 40 and a position module 50 together determine the three-dimensional coordinates of a compacting machine relative to the site, while an update/control module 60 converts this position information into real time representations of the site W095128524 ~ S 21 ~ 4 r~ so~ O

which can be used to accurately monitor and control the machine.
sase reference module 40 includes a stationary GPS receiver 16; a computer 42 receiving input from receiver 16; re~erence receiver GPS
sof tware 44, temporarily or permanently stored in the computer 42; a standard computer monitor screen 46;
and a digital transceiver-type radio 48 connected to the computer and capable of transmitting a digital data stream. In the illustrative embodiment base reference receiver 16 ls a high accuracy kinematic GPS
receiver; computer 42 ~or example is a 486DX ~ er with a hard drive, 8 megabyte RAM, two serial communication ports, a printer port, an external monitor port, and an external keyboard port; monitor screen 46 is a passive matrix colour LCD; and radio 48 is a commercially available digital data transceiver.
Position module 50 comprises a matching kinematic GPS receiver 18, a matching computer 52 receiving input from receiver 18, k;r t;c GPS
sof tware 54 stored permanently or temporarily in computer 52, a standard computer monitor screen 56, and a -~tr-h;rg transceiver-type digital radio 58 which receives signals from radio 48 in base reference module 40. In the illustrative ' ~A; - t position module 50 is located on a compacting machine to move with it over the work site.
Update/control module 60, also carried on board the compacting machine in the illustrated e-~ul; ~, includes an additional computer 62 receiving input from position module 50; one or more site models 64 digitally stored or loaded into the computer memory; a dynamic database update module 66, also stored or loaded into the memory o~ computer 62;
and a colour operator display screen 22 connected to _ Wo 9s/28s24 ~ h, ~ 2 1 8 4 4 8 1 ~ 7 the computer.- Instead of, or in addition to, operator - display 22, automatic machine controls 69 can be connected to the computer to receive signals which operate the machine in an automatic or semi-~llto~-t; c 5 manner in known f ashion .
In Figure 4 module 60 further includes a transceiver-type digital radio 68, for example a low level spread spectrum radio, communicating with database computer 62 to supply it with position information received in broadca8ts from other r-l-l~in~:
(not shown). Radio 68 is also capable of transmitting the position information from its own machine position module 50, received through computer 62, to the other machines .
Although update/control module 60 is here shown mounted on the geography-altering machine, some or all portions may be stationed remotely. ~or example, computer 62, site model(s) 64, and dynamic database 66 and radio 68 could be connected by radio data link to position module 50 and operator display 22 or machine control interface 69. Position and site update information can then be broadcast to and from the machine f or display or use by operators or supervisors both on and of f the machine .
Base reference station 40 i8 fixed at a point of known three-dimensional coordinates relative to the work site. Through receiver 16 base reference station 40 receives position information from a GPS
satellite constellation, using the reference GPS
software 44 to derive an inst~nt~n~. us error quantity or correction factor in known manner. This correction factor is broadcast from base station 40 to position station 50 on the compacting machine via radio link 48,58. Alternatively, raw data can be transmitted W09s/28~24 ' 2 ~ B448 1 ~ o from base station 40 to position station 50 via radio link 48, 58, and processed by computer 52 .
Machine-mounted receiver 18 receives position information from the satellite constellation, 5 while the kinematic GPS software 54 combines the signal from receiver-18 and the correction factor from base reference 4~ to determine the position of receiver 18 and the geography-altering machine relative to base reference 40 and the work site within 10 a few centimetres. This position information is three-dimensional (e.g., easting, nording and elevation) and iB available on a point-by-point basis according to the s ~ 1; n~ rate of the GPS system.
Referring to update/control module 60, once 15 the digitized plans or models of the site have been loaded into computer 62, dynamic database 66 generates signals representative of ~the difierence between the actual and desired site models to display this difference graphically on operator display screen 22 20 relative to the site topography. using the position information received from position module 50, the database 66 also generates a graphic icon of the geography-altering machine &uperimposed on the site topography on display 22 rnrresp~n~ll n~ to the actual 25 position and direction of the machine on the site.
Because the sampling rate of the position module 5û results in a time/distance delay between position coordinate points as the compacting machine moves over the site, the dynamic database 66 of the 30 present invention uses a differencing algorithm to determine and update in real - time the path of the machine .
With the knowledge of the geography-altering machine' s exact position relative to the site, the 35 difference between the actual and desired site models, wo 9s/28s24 ~ ? it :~, 2 ~ ~4 4 ~

and the machine's progress relative thereto, the operator can maneuver the ~ t-t; n~ machine over the site to alter it without having to rely on intuitive feel, memory or physical site markers. And, as the operator moves the machine over the site the dynamic databa~e 66 c~nt;n~ to read and manipulate ;n~ ~;n~
position information from module 50 to dynamically update both the machine~ 8 position relative to the site, the path of the machine over the site, and any change to the site (e.g., topography, degree of compaction) affected by the machine' s passage. This updated information is used to generate representations of the site and can be used to direct the operation of the geography-altering machine in real time to bring the actual, updated site model into conformity with the desired site model.
To coordinate the operations of multiple h;n~q on the site with a common, dynamically-updated database, database radio 68 receives position information from other ~ h;n~ on the site which are provided with their own position modules 50 and their own counterparts to radio 68 for broadcasting their position information. Database computer 62 accordingly receives position information from every machine on the site 80 e~uipped. Dynamic database 66 is updated in real time with the position of every machine relative to the site, the path of every machine over the site, and any chan~e in the site effected or ~t~rm;n~ by each machine. The operator is then provided with a display at 22 showing the position and work progress of each machine, and can coordinate their activities accordingly.

w095l28s24 ' ' ~ 2~4481 P~ o~7 ~

In~ ctrial A~licabilitY
Referring to Figure 4A, an illustrative application of the invention is shown srl- 1-; cally in which three compacting r-~h; n~ 14, each provided with a position module 50 and control module 60 as shown in Figure 4, are operating on a common site. The position module 5 0 on each machine determines that machine's pn~i~;nn using reference signals from base reference module 40 and a GPS satellite constellation.
The position information from each module 50 on each machine is delivered to its control module 60 for dynamic updating of the site A~t~h~e. Additionally, a combined position/ID signal from the digital radio 68 associated with each control module 60 is transmitted to a matching radio 68 on the other m__h; n~ such that the dynamic database on each machine is provided with position information corresponding to every machine on the site. The operator of each machine accnr~;ngly knows the exact position of both his own machine and the other machines, and can adjust his operations accordingly.
In this manner each machine effectively shares a common, dynamically-updated database, since each database is updated with the same position information in a nearly simultaneous fashion.
R~fF~rr;n~ now to Figure 5 a method for transmitting the position ;nfnrm-~;nn between m~nh;nf~q is illustrated. Digital radio Ç8 in the illustrated em.bodiment is a low power spread spectrum radio capable of making a general broadcast of a, ;n~r~
position/ID signal to the other m-ch; neR on the site .
To prevent interference between the position/ID
signals from the different m~h;n~ as they are received and proce3sed by the dynamic database, each digital radio 68 is assigned a time slot in which to _ 2 ~ 8 4 4~ l W09~5/28524 .;. ~ , P~ u,,,~.lCI-~7 broadcast its signal, such that one machine broadcasts while all others receive. In the illustrated embodiment the time slots are synchronized with the GPS sampling rate of one coordinate point per second.
In the schematic chart of Figure 5, the one second time interval between a f irst GPS sample coordinate to (xO, yO, zO) and a second GPS sample coordinate tl (x1, Yl, zl) is divided into N broadcast time slots 68a - 68n (in practice, one corr~Rpnn~;n~
to each r~m~ct~n~ machine 14 illustrated in Figure 4A) . At time slot 68a a first machine transmits its position information from sample coordinate time to to the other m~rh;n~R; at broadcast time slot 68b a second machine transmits its positio~ information determined at sample coordinate to i at broadcast time slot 68c the third machine transmits its position information at sample coordinate time to while the other two receive, and 80 on. In this ~ashion machine pos tion/ID signals can be traded in the interval between GPS coordinate samples without interference and in a manner ~n~lhl; nr database computer 62 to update the site database one machine at a time. The number of r-chin~R which can share information to generate a common, dyn;lm; r:ll 1 y-updated site database is accordingly limited only by the speed at which position information can be determined in module 50, transmitted by radio 68, and processed by computer 62.
It will be understood that the invention is not limited to a spread spectrum radio or any particular data tr~nr~;RR;nn link. Virtually any wireless broadcast and receiver system can be used to share the machine position information n~c~RR;Ir,v to generate a common site database for several ~-rh; nl~R, Referring now to Figures 6 and 7A-7I, a w0 95/28s24 t ~ ~ ~ 2 1 8 4 4 8 ~ o ~

further application of the present invention is illustrated for a landfill compacting operation.
In machine compacting, for example of landfills, earth, or freshly laid asphalt, the completion of the compacting operation iB typically a function of the number of passes of the compactor over the surf ace to be compacted . The desired degree of compaction can be determined, for example, by running a compactor over a test area of ~n~ 7Ac~ed material and empirically determining a suitable pass-count standard. By way of illustrative example, in a 1 ~n~lf; 11 compacting operation it is desirable that a machine such as a large, heavy compactor with studded rollers or wheels pass over a portion of the lAn~lf; 11 to compress new refuse to some predetermined degree in accordance with local compaction reg~ At;~nc or sound compacting practices. It is therefore important for the operator of the compactor to know: whether he has been over a given unit area or grid element of the landfill site; how many times the compactor has been over a given grid element on the site; the extent to which the material has been successfully compacted within a grid element on the site; and, whether - ~ted material has been added to a particular grid element since the last compacting pass.
Systems and software are currently available to produce digitized, two- or three-dimensional maps of a geographic or topographic site. For example, a topographic blueprint can be converted into a three-dimensional digitized model of the initially surveyed topogra~hy as shown at 36 in Figure 6A and of a subsequent site topography, for example after a lAn~l~;ll hag been filled in or the original site contour is altered, as shown at 38 in Figure 6B. The site contours can be overlaid with a reference grid of ~ WO 95/285A " ~ r ~ 2 1 8 4 4 8 ~ 7 uniform grid elements 37 in known fashion. Digitized site plans can be superimposed, viewed in two or three dimensions from various angles (e.g., plan or profile), and colour-coded to designate areas in which the site needs to be altered from the actual state to the desired state.
At the start of the, , ct;ng operation, the actual site model may initially comprise a three-dimensional survey or map of the site topography in an l~n~ -rted gtate, for example a digitized three-r~ ; nn~l site model as shown in Figure 6A.
As compacting operations progress, the actual site model more specif ically comprises the actual degree of compaction of the ~ l on the surface of the site, as measured f or example by compaction pass count and/or elevation change. The actual site model is dynamic in that it changes each time new material i9 added or old material is further compacted from its previous state.
The desired site model comprises a pre~ t~rrn;n.o-l, desired degree of compaction for material on the surface of the site. For example, where the desired degree of compaction is predet~rTr;n~d to be a total of five passes of the compactor over a previously llnrr~r~rted area, the desired site model is a pass count of f ive passes over a previously ~ln( ~ ~ct~l area. When that pass count is reached, the desired site model is achieved. The difference between the actual and desired site models at any point on the site comprises the difference between the actual degree of compaction and the desired degree of cl ~-ctinn at that point.
The actual site model accordingly fluctuates between an l1n~ ~ - rted state of the site material and 35 the desired degree of compaction. Whenever new, WO 9S/28524 ~ 8 4 4 8 1 ~ o ~

uncompacted material is detected in a previously compacted area of the site, the actual site model returns or dec: ~, R to an uncompacted state f or that area .
using the method and apparatus of the present invention, all of this infnr~-tinn previously available fo~ a single machine can be ~l~t~rm;n~d and updated in real time for multiple -~nh;nf-R to generate a common, dynamically updated ~lAtAhARe.
Figure 6 shows a sample operator display 22 for a compacting operation according to the present invention . Using a digitized model of the landf ill site with a superimposed set of grid elements, and two compactors equipped with ~osition modules 50 and lS update/control modules 60 as in Figures 4 and 4A, the operator first init;Al;7es the operator display 22, typically upon entering the 1 An~:lf; 1 l site. In landf ill compacting the probable activity f ield ~or a day is typically small, on the order of a few hundred or thmlR~n~ s~auare metres. For purposes of illustration in Figure 6 the site database i8 arbitrarily set at apprn~;r~tf~ly 30 metres by 40 metres. This can be varied depending on the nature of the particular compacting operation. This is smaller than the total area of a typical landfill, but for a single day the compactor operators need a database only for the portion of the lAn~lf;ll in which they will be operating.
In the illustrated ~l n~; t the site is divided into a grid of square ~1 tR of fixed area, e . g ., one square metre .
The operators initialize their displays and are presented on their respective screens 22 with a site database in plan window 70 6uch as that shown in Figure 6, marked of ~ in a grid pattern of ~ tR 71 ~ woss/~8s24 ~ ~"~ 2184481 i_l/U~,_,'O~

initially all one colour; e . g ., black to indicate that no passes have yet been made over that site. A
position coordinate window 72 displays the associated compactor' 6 current position in latitude, longitude, 5 elevation and time. A window 73 displays a colour key for the compaction status of grid elements 71 displayed and updated in plan window 70; in Figure 6 the various colours or qh~fl;ng~ represent a pass count. The position of each compactor is represented by an icon 82, 82 ' with direction indicator 84, 84 ' .
With the exchange of position information between the position modules 60 on the compactors as described in Figures 4 and 4A above, the operator display 22 on each machine shows the real time positions of each compactor relative to the site as illustrated in Figure 6.
As a further feature of the present invention, each compactor icon 82,82' on display screen 22 is provided with a peripheral spacing or boundary icon, in Figure 6 a boundary box 83, to r-int:qin a safe margin between the machines as they operate on the site. For example, if the position or boundary icon 83 of one ~ ~ctor should be determined to touch or overlap that of another compactor on screen 22, the database provides a warning to the operators, for example a visual or audible signal via an indicator or buzzer/beeper associated with screen 22 shown schematically in Figure 6 at 8~. The machine operators can then adjust their operations to avoid work interference or collision.
The size of boundary box 83 for each machine can be varied relative to the machine ~l~p~nrli ng on the machine~s mode of operation. For example, where the machine is operating in a slower mode with a correspondingly greater amount of time to correct for w0 95l28524 ~ 8 4 ~ 8 ~ 7 ~

potential interference between ~-rh;nP~, the boundary defined around the machine i8. set at a first smaller size. When the machine operates in a faster mode, the boundary can be set at a corresprnr~;n~1y greater size 5 to allow suf f icient reaction time once a warning i8 given. Alternately, multiple layers of bn~-n~r; ~,c 83 can be employed, each generating a successively more urgent warning as they are violated by the position or boundary o~ another machine. It will be understood by those skilled in the art that operating parameters other than machine speed can be used as the basis for determininy and setting an appropriate boundary around each machine monitored in this fashion.
Each compactor icon 82, 82 ' on screen 22 is visually distinct 80 that the operator knows which represents his own machine, and which represents the other machine or --rh;n~c. Although in the illustrated embodiment of Figure 6 the di~ference is shown by cross-h~trh;nr~ on an actual display different colours can be used. For different types o~
m-rh;nPc other vigual digtinctions are possible, for example different shapes or outlines.
Prior to the ber,;nn;ng of work on the site, a compaction standard (here a pass count) is set to denote the desired degree=of compaction of the site.
For example, it may be determined that five passes of the compactor over llnromr~rted material on any one grid element are n~rl~cc~ry for that grid element to be ade~auately ~ , ~rtPtl. A8 the compactors traverse the site, each pass of the compactor wheels over a grid element will result in a database update in real-time.
The grid ~ c of the site display can be visually updated i~ a variety of ways to show the difference between the actual and desired degree of compaction, e.g., shading, cross-hatching, colouring or ~painting~

Wo gs/28s24 ~ h '`~ 2 1 8 4 4 8 1 r~ 7 (where a colour display is used~, or in any other known manner to provide an indicator to the operators of the compaction status of the grid elements. In the illustrated: ' a~ of Figure 6, using a colour 5 monitor, the grid changes colour to denote the actual degree of compaction in terms of how many passes have been made; e.g., the darkest to lightest shading of grid ~ c 71 represent black f or no passes, yellow for one pass, green for two passes, red for three 10 passes, blue for four passes, and white indicating satisfactory _-rt;~n at five paggeg. The objective is to make the entire screen white as the operator display is updated in real-time to indicate the number of passes over each grid element. --Since the dyn~mi r~l l y updated database of the present invention is provided with real time position information for both ~ artinJ --rh;n~c 82 , 82 ~, the site model in the site database is updated witll the topography or compaction changes ef f ected by 20 each machine. A8 shown in Figure 6, the operator accordingly has real time information on the position of each machine operating on the site, and the roll~rt;ve site update information indicating the total work of the -~-rh;nf-c on the site. Operators can 25 accordingly avoid machine interference or llnnf~ c,c~ry overlap of work on the site. Or, they can more effectively coordinate their efforts in alterinr, the site from the actual state to the desired state.
As an additional aid to the machine 30 operators, the approximate paths of the rrmr~rt~ r as measured by coordinate samples can be shown on display 22, in Figure 6 denoted by a series of dots 86 where each position reading was taken.
It is n.oc~c~ry to provide some protocol for 35 det~orm;n1n~ when a sufficient portion of a grid W0 95/28s24 ,~ 2 1 8 4 ~ 8 1 , ~~ 7 1 element has been passed over by a compactor wheel to warrant a status update for that grid element and register a compacting pass on the operator display.
For the illustrated compactors with two or more s3?aced 5 compacting wheels, the following illustrative method can be used. The size of each grid element on the digitized site plan is pref erably matched to the width of a compacting wheel; e.g., for one metre wide wheels the grid ~l ~ s should be set to one s~uare metre .
lO Accordingly, if the centre of the wheel crosses a grid element at any point, it is assumed that at least one half of the grid element has been compacted and can be updated on the display. These dimensions and margins can be varied as desired, however.
The coordinates of the ground-contacting surfaces ("footprints'~ of the fixed rear compactor wheels are known relative to the position receiver on the compactor. Each coordinate sampling by the pos tioning system can ~ rnr~ ly be used to 20 determine the precise location of the centre of each wheel at that point. In the illustrated embodiment the positions of the footprints of the rear compactor wheels are tracked.
For site operations other than compacting, 25 it will be understood that the position of virtually any portion of the geography-altering machine can be determined relative to the position receiver on the machine, such that each coordinate sampling by the positioning system can be used to determine the 30 precise location of that portion of the machine. For example, in an earth-contouring operation using a tractor es~uipped with a dozer blade, the position of the tracks or the blade can be determined based on their position relative to the position receiver on the tractor. If possible, it is ~oR; ~ hl e to place ~ wo95l28s24 ~ C~J . 2t~48J r-IIV~

the position receiver close to or on the operative portion of the machine. In a compacting operation the position receiver(s) might preferably be located directly over one or more of the , , - ~ t; n~ wheels .
For earth contouring with a blade-equipped tractor, the position receiver can be mounted directly on the blade. If the portion of the machine being tracked via the position receiver is one which i5 not always in contact with the site, it may be desirable to provide a sensor of known type on the operative portion to indicate when it is contacting the site surface and actually altering the geography/topography .
In the illustrated ~:~ -rtln~ prnhor~;
the time lag between coordinate samplings as the ~ctnr wheels travel over several grid elements must also be taken into consideration to accurately determine the entire real-time path of each compactor.
In a ~ ~ctnr with ~ ~ ct; n~ wheels whose width approximates the width of the site model grid elements, a preferred method shown in the illustrated : ~ ~; t of the present invention uses the well-known Bresenham' s algorithm to produce a rnnt; n~l~Us line apprn~ t; n~ the path of each compactor wheel over the grid elements between coordinate samplings . Then, if the I l; n~ rate only provides a coordinate npoint n every three or f our grid elements, a line approximation is made of the -,tnr wheel paths over those three or four grid elements ~corresponding to the centre of the wheels), and every grid element along that line is given a status update and visual change on the operator display .
Other techniques for measuring the paths of the ~ ninPs~ as they traverse the site are known and WO 95l2xs24 ~ 1 1 S ~ 8 ~ P ./.J~ s c ~ ~ S

may be used, depending on the characteristics of the --rh;n~R, the work, and/or the site. For the illustrative 1 Anrlf; 1 l compacting example, the Bresenham' s line Arrr~Y; r-tion o_ the wheel paths i8 useful.
~f~rr;n~ now to Figures 7A-7I, particularly 7A and 7X-7I, the method of the present invention as applied to a landfill compacting appl irat;r~n i8 schematically shown for receivi~g position information from at least two -~rh;n~R to create a dynamically updated common database. At step 500 in Figure 7A the operator starts from the computer operating system.
At step 502 database memory is allocated and initialized. At step 503 operating ~arameters for each machine which af f ect the manner in which their paths or progress is tracked by the database algorithms are init; A 1 ~ ~erl, f or example in a machine parameter library. At step 504 the various displays are initialized. In step 506 the serial communications between the site database and positioning modules 50 on first and second compactors are init; Al; zed.
For purposes of illustration it will be assumed that one serial port is from a first or ~'home"
compactor on which a position module 50 and control module 60 are located as shown in Figure 4, while the second serial port delivers position information received by a database radio 68 from another machine' s position module 50 broadcast via digital radio link as described above. Xowever, it will be readily understood that the method illustrated in Figures 7A-7I is suitable for a iixed, off-machine database receiving both position inputs by wireless broadcast.
At step 508 the system determines whether there has been an operator request to terminate the -~ Wo gs/28524 ~ 218 4 4 81 r~u~

program, for example from a user interface device such as a computer keyboard. This option is available to the operator at any time, and if the system determines that such a reSIuest to terminate has been received, it proceeds to step 592 and stores the current site database in a file on a suitable memory device, for example a disk. At steps 594, 596 the operator is returned to the computer operating system.
If, however, the system determines at step 508 that there has not been a re~uest to terminate the program, it proceeds to step 510 where a position coordinate is read from the first serial port connection between the f irst rn-~7actnr~ s position module 50 and update/control module 6C of Figure 4, in the illustrated ~mho~; a three-~l; c; nn~l GPS-determined rnnr~in~te point. At step 511 a second position coordinate is read from the second serial port connection delivering the position information f rom other - rtnrS ' timed broadcast . At step 512 the position of the first or "home~ compactor 14 is displayed (Figure 6) in window 72 on operator display screen 22 as three-dimensional coordinates relative to base ref erence 16 .
In steps 514, 515 a subroutine shown in Figures 7s-7c draws the display and icons based on the position information from each compactor. The subroutine determines the orientation of the cn~rartrr and the position of the centres of the "footprints" or ground-rnnt~rt;nr portions of the rear compactor wheels, tracks the path of the rear ~ 7rtnr wheels over the site database, and updates the ' -rtinn status of the grid elements in the path of the compactor. The subroutine runs successively for each compactor in the order its position information is received at steps 510,511.

wo gs/28524 ~ 3, ~ 2 1 ~ 4 ~ 8 ~ 32 Jl Referring to Figure 7B, at step 516 the 6ystem determines whether the first program loop has been ~ r~lt~oA~ If not, the site database and display window coordinate systems are init; ~ l; 7~d and 5 displayed on operator screen 22 at step 518. After the first program loop has been executed and the site database init; ~ l; 7~rl and displayed on the operator screen, the system at step 520 checks whether the a~ Liate icon 82 or 82 ' has already been drawn . If 10 yes, that icon is erased from the display at step 522.
If the icon for that compactor has not yet been drawn, at step 524 the system determines whether the first loop has been executed; if not, the or;~nt~t;on of the compactor is initialized at step 526 and the system completes the overall program loop of Figure 7A. If at step 524 the sy8tem determines that the f irst loop has already been executed, the system proceeds in Figure 7B to step 528 to determine whether the compactor has moved since the last program loop. If the machine has not moved, the system exits the subroutine of Figure 7B and returns to complete the overall program loop of Figure 7A from step 514.
If the machine has moved relative to the site ~t~h~ since the last loop, the sy6tem proceeds to step 53 0 in Figure 7B to calculate the positions of the centres of the footprints of the rear ~ , ~.ct~ r wheels, and from those the orientation of the compactor. At step 532 in Figure 7C the system determines whether the right rear compactor wheel position has moved out of the grid element it occupied during the last position mea~u, ~ t . If it has, at step 534 the path of the right wheel between the previous and current coordinate samplings is determined using the well-known Bresenham' s algorithm to approximate a ~ nt;nllnl~c line path of the right w0 95/28s24 ~ r, ~ 2 ~ 8 1 ~ u~

wheel over the grid elements on the di6play 22. The grid elements of the site database over which the right wheel has passed are then updated to indicate a ~-t i on pa8s, and grid elements are updated on the visual display window 70 with a colour change or other visual indicator.
If at step 532 the right wheel has not moved since the last position mea~lL~ ', or after the v~ t of the right wheel has been tracked and the site database updated at step 534, the process is repeated for the left wheel of the ~ ,-rtrlr at steps 536,538. At step 591 the updated compactor icon is then redrawn on the display to show its current position and direction. The subroutine of step 514 in Figure 7A is then completed f or the f irst ct~m~actor If position information has been received from the second compactor, the subroutine illustrated in Figures 7B and 7C is repeated for the second, -t~t~r at step 515.
When steps 514,515 have been completed for each compactor the system proceeds to step 515a where the interaction between m-~-h;n~c on the site is monitored, and appropriate warning given if operating safety margins are exceeded, according to a subroutine described below in Figure 7I. The system then returns to repeat the program loop of Figure 7A, either proceeding to step 510 for more GPS coordinate samplings, or terminating in response to an operator request .
In Figure 7D a subroutine for the wheel tracking and site llr~tin~ operations of steps 534 and 538 is shown. At step 540 the starting and ending grid cells for the wheel whose path is being determined are defined by the current wheel position 35 mea,~uL. t and the previous wheel position woss/28s24 ~ 21~4i~8~ r~

mea~uL~ taken by the GPS or other positioning aystem. The Bresenham' B algorithm i5 applied to determine the grid cells located along the path between the 8tarting and e~ding grid cells, and the system proceeds to steps 544, 546, 548 to evaluate/update the status of each grid element therebetween, b~ginn;n~ with the first grid element after the starting grid element. At step 542 the system det~ n~q whether the ending grid element has been evaluated; if not, it proceeds to step 544 where the grid element being evaluated is updated according to a subroutine in Figure 7G. Once the ~ ~ ~rt; on status of the current grid element has been updated at step 544, the updated grid element is displayed on the operator screen 22 at step 546, and at step 548 the system is in~ to evaluate the next grid element in the path between the starting and ending grid elements. This loop repeats itself until the ending grid element has been evaluated and updated, at which point the subroutine of Figure 7D is exited and the program returns to step 591 in Figure 7C to draw the updated compactor icon on the display.
In Figure 7X a subroutine for the icon-drawing step 591 in Figure 7C is illustrated for coordinating the display of multiple r-~hln~q on the operator display scree~. At step 591a the system matches the mixed position/ID signal from the machine whose position is currently being evaluated to a set of corresponding machine parameters from an accessible library. The ID ior each machine is preferably stored in the database on each machine, such that the common database effectively has each machine '~tagged" for identification. When a match is found, the icon size and orientatio~ are calculated in the three-dimensional coordinates of the display 70. At ~ Wo ss/28sz4 ~ ~, " .4 ~ C 2 1 8 4 4 8 ~ C _ ~

step 591b the system (lPtPr~; nP~ whether the coordinates match those of icon 82 reprPRPn~; n~ the first or "home" compactor. If yes, the system is set to colour that icon in the ~ u~ iate manner, for 5 example by p~;ntin~ it green, at step 591d. If at step 591b the display window coordinates calculated for the current icon are determined not to represent the f irst compactor icon 82, the system is set to visually distinguish the current icon, for example by colouring it red at step 591c. At step 591e the icon is then drawn on the plan window with the appropriate colour or other visual characteristic distinguishing it from the other icon (8) on the display.
Still referring to Figure 7H, at step 591f the icon currently being evaluated is provided with a boundary box 83 as described above, for example in the illustrated embodiment representing one metre of clearance around the machine. The subroutine of Figure 7~ is repeated for each compactor at step 591 as the system successively evaluates each machine operating on the site. It will be apparent that the subroutine of Figure 7~I is easily PYr~n~lPcl to accommodate more than the two illustrative machines.
Referring now to Figure 7I, a subroutine for step 515a in Figure 7A is illustrated for monitoring a safety margin or interference boundary around each compactor. At step 515b the limits of the currently evaluated or "home" machine boundary box 83 are defined, for example to provide one metre of clearance around the machine. At step 515c the system determines whether the box of the other machine (s) interf eres with the box of the primary machine as defined in step 515b. If yes, the operator is alerted at step 515d, for example with a flashing light and/or audible warning signal such as a beep or buzzer Wo 9SI28524 ~ 3 ' ~ ~ 2 1 ~ 4 4 8 1 P~l/-J,.,~ l l~7 0 indicating the need fQr corrective action. If at step 515c the boxes of the two ~-r~;noC are determined not to interfere with one another, the subroutine proceeds to step 515c to determine whether the other machines 5 on the site have been evaluated for i~terference with the home machine. If no, the next machine on the site is checked at step 515f and the subroutine is repeated. If all -~-r~;nor on the site have been checked, the subroutine terminates and the system returns to step 515a in Figure 7A. In this manner the system checks for interference between each machine operating on the site in the interval between position l; nr c ~rhe risk of ~r~ ; rn or interf erence between machine operations is accordingly reduced or 15 eliminated.
In Figure 7E the subroutine f or the site database update step 544 of Figure 7D is shown.
Referring to Figure 7E, at step 550 the system determines whether the elevation of the cl~rent grid 20 element has been init;~l;70~. If not, the elevation or z-axis coordinate of that grid element is initiali2ed as er~ual to the currently measured compactor wheel elevation at that point. If the grid element elevation has already been init;~l1zo~, the 25 system proceeds to step 554 to compare the currently measured wheel elevation to the previously measured elevation for that grid element. If the currently measured wheel elevation on that grid element is not greater than the previously measured elevation, the 3 0 system determines that no new material has been added and that grid element can be in~L o~ at step 558 to register a compaction pass and increment the pass count for that grid element. If at step 5~4 the currently measured wheel elevation is greater than the 35 previously measured elevation (discounting, for ~ Wo ss/28s24 ' ~ t ~ ~ t ~ 2 ~ 8 4 4 8 1 r ~ s ~

example, minor resilient ~ n~i~n of the material compressed in the last pass, within limits determined by the user) the system determines at step 556 that a new lift of asphalt, earth or waste material has been detected for that grid element, and the pass count status for that grid element is re-zeroed to indicate the need for a complete new gerieg of ~ r~ct;r~n passes. At step 560 the elevation of the current grid element is then set e~ual to the currently measured elevation of the compactor wheel for comparison at step 554 on the next pass of the compactor over that grid element. The subroutine of Figure 7E is then exited for completion of the subroutine loop of Figure 7D .
Referring now to Figures 7F-7G, a subroutine for step 546 of Figure 7D is shown. Once the pass count for the current grid element has been updated at step 544 in Figure 7D using the subroutine of Figure 7E, the system in step 546 enters the subroutine of Figures 7F-7G and at step 562 first determines the location and size of the current grid element f or that compactor on the site database displayed in plan window 70 on the operator screen 22. At step 564, if the pass count for the grid element is zero, the grid element is set, for example, to be coloured black on the display at step 566. If the pass count for that grid element is determined to be one at step 568, the grid element is set, for example, to be coloured yellow on the display at step 570. If the pass count for that grid element is ~-t~rm;n~ at step 572 to be two, the grid element is set, for example, to be coloured green at step 574. If the pass count is determined at step 576 to be three, the grid element is set, for example, to be coloured red at step 578.
If the pass count for that grid element is determined wo5~5n8524 ~ ~ t~ 2 t ~ 8 ~ r~ ....c~

at step 580 to be four, the grid element i5 set, for example, to be coloured blue at step 582. If the pass count is detorm;no~ at step 584 to be five (in the illustrated: '~ ';~ the desired pass count for a 5 completed _-rt;nrJ operation), the grid is set, for example, to be coloured white at step 586. If the pass count for that area is greater than the minimum pass count for a completed compaction operatio~, the grid element is set to be coloured white at step 588.
Once the grid element has been updated according to the current pass count, the grid element is drawn and coloured on the operator display screen 22 at step 590. It will be understood that the grid ol ts can be visually updated on 6creen 22 other 15 than by colouring; e.g., by cross-hatching, shading or other visual indication.
While the tracking and llr~t;ng method of Figures 7A-7I are illustrated for a compactor having two or more spaced compacting wheels whose width 20 approximates the width of the site grid ol- -t~:, the method can also be used for a compactor with a single wheel or roller as will be understood by those skilled in the art. The method of Figures 7A-7I can also be used where the width of the compactor wheel or roller 25 does not match the width of the grid elements of the site model. ~owever, where the width of the compacting wheel or roller is sir,n;~;~r~ntly greater than the width of a single grid element, f or example where it covers several grid elements at one time, an 30 alternate method for tracking the path of a ~ ~ct;n,r wheel or roller may be employed.
This is ~rc l; qho~l by replacing step 530 in Figure 7B with step 530~ from Figure 7J, and the subroutine of Figure 7D with the subroutine of Figure 35 7K. Referring to step 530' in Figure 7J, the system ~ wo9sl28s24 ~ 21~4~ t r~l~u . ,~ ~7 designates "effective" wheel or roller ends inboard from the actual ends. In the illustrated ~
the effective ends are recognized ~y a differencing algorithm as inboard from the actual end a distance 5 approximately one half the width of a grid element.
For example, if the actual wheel width is 1. 5 m ~5 . 0 feet), corrf~Rp~ n~l;n~ to five 0.3m tl.0 foot) x 0.3m ~1. 0 foot) grid ~ , the effective locations of the wheel ends can be calculated, for example, 0.15m ~ft) inboard from each actual end. If the effective ~non-actual) wheel ends of the compactor pass over any portion of a grid element on the digitized site model, that grid element is read and m n; r~ ted by the dif ferencing algorithm as having bee~ compacted, since in actuality at least one half of that grid element was actually passed over by the wheel. Of course, the amount of wheel end of f set can vary depending on the size of the grid elements and the desired margin of error in determining whether the wheel has passed over a grid element.
While the algorithm of step 530 ~ in Figure 7J compensates for the lack of complete correspondence between the width of the compacting wheel or roller and the number of grid elements completely traversed by the wheel or roller, the distance and direction changes which the wheel makes between GPS position readings results in a 1088 of real time update information over a portion of the ~ tor~ 8 travel.
This is particularly acute where compactor travel speed is high relative to the grid elements of the site plan. For example, where the grid elements are one metre s~uare and the sampling rate of the position system is one coordinate sample per second, a machine travelling at 18 km per hour travels approximately five metres or five grid s5~uares between position W09~28524 ~ 21 ~81 ~ co~

samplings. Accordingly, there is no real time information with respect to at least the intermediate three of the f ive grid squares covered by the machine .
To solve this problem a '~fill in the polygon"
algorithm as shown in Figure 7K is used to estimate the path t,av~l~ed by the machine between coordinate E ~ l;nr,R. In Figure 7K the algorithm at step 540' locates a rectangle on the site plan grid surface defined by the effective ends of the compactor wheel at positions (xl, yl) and (x2, y2) and coordinate position (xO , yO ) . At steps 542 ~, 543 ' and 548 ' a search algorithm searches within the rectangle' 8 borders for those grid ~1 em~nt~ within a polygon defined between the two wheel positions; i.e., those grid ~1 t~ traverged by the wheel between it6 ef f ective ends .
The machine path tracking method of~ Figures 7J and 7K is also useful for tracking earth-contouring ~-rh;nf~y, for example a tractor having a dozer blade, by substituting the width of the blade or tool on the earth-contouring machine ior wheel/roller width in step 53 0 ~ .
At steps 544 ' and 546 ~ the database and display are updated as described at steps 544 and 546, respectively, in Figures 7D-7F.
While the illustrated embodiment of a compacting application is a pass-count based system, it will be apparent that other update protocol6 can be employed. For example, the change in amount of compaction per pass over a grid element can be determined by checking the elevation change since the last pass, and when the change in elevation on a particular pass is below a certain value (indicating that the garbage i6 near the desired rr~7~rt 1 on density), that grid element is updated on the screen ~ wogsl28s24 ',~ 2184481 as completed. Another method is to use an absolute compaction standard, registering a particular grid element as f; n; ~h~d when the material thereon has been compacted from an lln~ ~ rted or initial elevation to a predetermined lower elevation.
It will be apparent to those skilled in the art that the principles of the present invention, i.e., multiple machine monitoring and coorrl;n~t;~n via the creation of a common, dynamically-updated site database created with shared machine position information, is not limited in utility to the exemplary l~n~lf;ll compacting operation described above. The inventive method and apparatus can be applied to virtually any earth-moving, contouring or compacting operation in which mobile geography-altering r-rh; n~ry using real time three-dimensional positioning and a dynamically updated site database are operating on a common site.
For example, referring to Figure 8 a display screen can be g~nPr~t~l for an alternate application of the present invention in which multiple earth contouring -^rh;nP~ such as tractors with dozer blades are operating on a site to contour the topography to a desired state . The method and apparatus f or generating a dynamically updated database for such r-rh;nPc~ ig gimilar to the method and apparatus described above for a compacting machine; as noted above, the machine path tracking method of Figures 7J
and 7K can be used f or tracking earth contouring ~-rh;nf-ry simply by substituting blade width for wheel/roller width. While the difference between the actual and desired site models in the illustrated compacting application is determined and displayed as an incremental pass count, for earth-contouring the difference can be determined by comparing the W0 95/28s24 ~ ~ 4 ~ 1 r~

machine' s current elevation coordinate to the desired or target elevation at that point, and the site database updated at that poi~t to indicate whether the actual topography is above, at, or below the target.
5 The sharing of position information to create a common, dynamically-updated database as described above for a particular compacting operation can be r ~ 'i f; ed accordingly by those skilled in the art .
With the general pr;n~ipl~ and a specific application lO of the present invention set forth above, those skilled in the art will be able to carry it out.
For example, referring to Figure 8 an operator display on screen 22 for an earth-contouring application can be generated by ~ ir~in~ two earth-15 contouring l~ hinF~ with the position and updatemodules 50, 60 described above. The display has as a principal, ~n~ a two-~ir R;nnz,l digitized site model in plan window 70 showing the desired final contour or plan of site 12 (or a portion thereof ) 20 relative to the actual topography. On an actual screen display 70 the difference between the actual site topography and the desired site model can be represented by colour coding used to show areas in which earth must be removed, areas in which earth must 25 be added, and areas which have already achieved conformity with the fin;~h~fi site model. The differently shaded or cross-hatched regions on the site displayed in window 70 in Figure 8 graphically represent the varying differences between the actual 30 site topography and desired site topography, updated in real time for each machine on the site.
Operator display screen 22 includes a horizontal coordinate window or display 72 at the top of the screen, showing the position of the "home~
35 machine 82 in three dimensions relative to base WO95128S24 t ~ S 2 1 8448 1 reference 16. Coarse and fine resolution sidebar scales 74, 75 show the elevational or z-axis deviation f rom the target contour elevation, providing an indicator of how much the tractor~ 8 blade should cut or fill at that location. The coarse ;n~;r~tnr 74 on the right shows scaled elevation of 1. 0 f oot in~ c above and below the target elevation; the fine resolution side bar 75 of the left side of the display lists 0.1 foot increments and provides a convenient reference when the operator is within a foot or less of the target contour. using "zoom" or "autoscaling" features in the display software, the scales 74, 75 can be changed to smaller increments as the operator nears the target toE~ography.
A further reference is provided to the machine operator in profile window 76 at the bottom of screen 22. PIofile window 76 shows the elevational difference between the actual site topography 76a and the desired topography 76b in the path of and immediately behind the "home" machine. An elevation scale 78 on the left side of profile display 76 can provide an additional indicator of how deep to make a cut or how much earth to add at a given location, while the horizontal scale 79 at the bottom of prof ile display 76 indicates the distance ahead of the tractor/ blade at which the operator will Pnrnllnt-~r certain actual and desired topography differences. In this manner the operator can simult~n~rllRly monitor the upcoming terrain and the accuracy of the most 30 recent pass in achieving the target contour, and ad~ ust operations accordingly .
The position of two tractors on site 12 is displayed graphically on screen 22 as tractor blade icons 82, 82 ' superimposed on the plan window 70 . Only 35 the "home" machine icon 82 appears in the profile wo95n8s24 j~ r~ 218~48 ~ .C~32 ., window 76, and the appropriate sidebar scale 74, 75 .
In the site plan window 70 icons 82,82' are provided with ~orward-proj ecting direction indicators 84, 84 ~, which serve to identify the terrain a fixed distance ahead of the tractors in their direction of traYel.
The anticipated terrain shown in front of ~home"
tractor icon 82 in prof ile window 76 corresponds to that portion of site 12 covered by direction indicator 84 . While icon 82 in window8 70, 74, 75 moves in response to the current position of the machine relative to the site, the icon 82 in profile window 76 remains centred while the site topography prof iles 76a,76b scroll past it according to machine - v t.
With the detailed position and site update information for both tractors 82,82~ provided to the operator via display 22 the operator has a complete, up-to-date, real-time display of the entire site, both tractors and their progress to date, and their success in achieving the desired topography.
It will be understood by those skilled in the art that the inventive method and apparatus illustrated in Figures 1-7 for compacting operations can be applied to multiple earth-contouring machines as shown in Figure 8, or indeed to any geography-altering machine, with minor variations for the operating characteristics of the machinery and the manner in which the site is being altered to the desired state.
Referring now to Figure 9, an alternative system is schematically shown for closed-loop automatic control of one or more operating systems on a machine. While the ~mhnr~; ~ of Figure 9 is capable of use with or without a supplemental operator di8play as described above, f or purposes of this illustration only ~ ti c machine controls are~

W0 95128524 ~ $ ' r~ 7 2l8448l shown. A suitable digital pro~qq; ng facility, for example a ,-r as described in the f oregoing embn~l1r tq, ~nnt~;nin~ the algorithms of the dynamic database of the invention is shown at 400. The 5 dynamic ~l~t~h~R~ 400 receives 3-D inst~n~n~ous position information from GPS receiver system 410, and the shared position information from other Tn~h;n~q via database radio 411. The desired site model 420 is loaded or stored in the database of computer 400 in any suitable manner, for example on a 8uitable di8k memory. ~llt: t;c machine control module 470 n~mt~;n~
electrohydraulic machine controls 472 connected to operate, for example, steering and drive systems 474,476,478 on the compacting machine. Automatic machine controls 472 are capable of receiving signals from the dynamic database in computer 400 reprl~c~ont;
the difference between the actual site model 430 and the desired site model 420 to operate the steering and drive systems of the compactor to traverse the site in a manner to bring the actual site model into conformity with the desired site model. As the :sllt~ t;c machine controls 472 operate the steering and drive systems of the machine, the compaction of the site and the current position and direction of the compactor are received, read and manipulated by the dynamic database at 400 to update the actual site model. The actual site update information is received by database 400, which corr~qpr~n~;nsly updates the signals delivered to machine controls 472 for 3 0 operation of the steering and drive systems of the compactor as it makes compacting passes over the site to bring the actual site model into conformity with the desired site model.
Additionally, the automatic machine controls g72 can be controlled by signals from the database to W095/28524 2 ~ PCr/US95/04432 ` Q t~ 46- . 8 1 alter the machine' 8 course in the event that interference with another machine i8 detected as described in Figure 7I.
The illustrated ,~ ~ a; t ~ of the present invention are provided to further an understanding of the broad principles of the invention, and to disclose in detail a pref erred application . Many other modifications or applic~ti..-n~ of the invention can be made and still lie within the scope of the appended 10 claims.

Claims

1. Apparatus (40,50,60) for monitoring and coordinating the operations of multiple mobile geography-altering machines (14) on a work site (12), the apparatus (40,50,60) comprising:
site database means (66,126) storing data representing a site model (64) of the geography of the site (12);
means (62,124) for generating signals representing the instantaneous three-dimensional coordinate position of the geography-altering machines (14) on the site (12);
means (62,124) for updating said site database means (66,126) in accordance with said signals; and means (62,124) for providing control signals for transmission to said geography-altering machines (14) in response to updating of said site database means (66, 126).

2. Apparatus (40, 50, 60) as defined in claim 1, further including a plurality of geography-altering machines (14).

3. Apparatus (40,50,60) as defined in claim 2, wherein the site database means (66,126) is located remotely from the machines (14).

4. Apparatus (40, 50, 60) as defined in claim 2, wherein the site database means (66,126) is located on one or more of the machines (14).

5. Apparatus (40, 50, 60) as defined in claim 4, wherein each machine (14) provided with a site database means (66,126) further includes communication means (68,122) to send and receive the position signals to and from the site database means (66, 126) on the other machine or machines (14).

6. Apparatus (40,50,60) as defined in claim 5, wherein the communication means (68,122) comprise asynchronous broadcasting means (68a, 68b, 68c) timed such that only one machine (14) per unit time broadcasts its position signal to the other machine (14).

7. Apparatus (40, 50, 60) as defined in claim 1 or claim 2, wherein the means (68,122) for generating position-representative signals includes means (68a, 68b, 68c) for asynchronously broadcasting the position signals from each machine (14) to the means (62,124) for updating the site database means (16).

8. Apparatus (40,50,60) as defined in claim 7, wherein the broadcasting means (68,122) further include ID signal means (68a, 68b, 68c) to broadcast a machine-identification signal with the position signal.

9. Apparatus (40,50,60) as defined in claim 8, wherein the means (62,124) for updating the site database means (66,126) further includes machine parameter library means (126) to match machine parameters to the ID signal from a machine (14).

10. Apparatus (40,50,60) as defined in any of claims 1 to 9, further including means (60) for directing the operation of the machine comprising operator display means (22).

11. Apparatus (40,50,60) as defined in claim 10, wherein the operator display means (22) include a display of the site model (64) and the position of the machines (14) on the site model (64).

12. Apparatus (40,50,60) as defined in claim 10 or claim 11, wherein the operator display means (22) is located on one of the machines (14).

13. Apparatus (40,50,60) as defined in claim 10 or claim 11, wherein the operator display means (22) is located remotely from the machines (14).

14. Apparatus (40,50,60) as defined in any of claims 1 to 13, further including means (22) for monitoring the operation of the machines (14) relative to one another to prevent interference between them.

15. Apparatus (40,50,60) as defined in claim 14, wherein the means (22) for monitoring the operation of the machines (14) includes means (83,83') for defining a machine interference boundary around a machine (14) and providing a warning signal (85) in response to the position of another machine (14) being determined to be within that boundary.

16. Apparatus (40,50,60) as defined in claim 14, wherein the means (22) for monitoring the operation of the machines (14) include means (83,83') for defining a machine interference boundary around each of the machines (14) and providing a warning signal (85) in response to the boundary of one machine (14) being determined to overlap the boundary of another machine (14).

17. Apparatus (40,50,60) as defined in claim 16, further including means (62,124) for altering the size of the interference boundary (83,83') for a machine (14) in accordance with the machine's mode of operation.

18. Apparatus (40,50,60) as defined in claim 16, wherein further comprising multiple boundaries (83,83') of different size simultaneously defined around a machine (14).

19. Apparatus (40,50,60) as defined in claim 10 and any of claims 15 to 18, wherein the operator display (22) of the site model (64) shows the respective interference boundaries (83,83').

20. Apparatus (40,50,60) as defined in claim 2 or any claim dependent thereon, comprising:
means (68,122) on each machine (14) for transmitting that machine's position signals to another machine (14), and for receiving position signals from another machine (14).

21. A method (100,101,102,104,106,108, 108a,109,110) of monitoring and coordinating the operations of multiple mobile geography-altering machines (14) on a work site (12), the method comprising:

maintaining a site database (66) containing data representing a site model (104,106) of the geography of the site (12);
generating signals representing the instantaneous three-dimensional coordinate position of the geography-altering machines (14) on the site (12);
receiving said signals and updating said site database means (66) in accordance with said signals; and providing control signals for transmission to said geography-altering machines (14) in response to updating of said site database means (66).

22. A method (100,101,102,104,106,108, 108a,109,110) according to claim 21, further comprising:
directing the operation of the machines (14) in accordance with the site database (66).

23. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 21 or claim 22, wherein the site database means (66) is located on each of the machines (14) and further including the step of sharing the position signals of each machine (14) with the site database means (66) on each machine (14), and updating the site database (66) on each machine (14) in accordance with the position signals from each machine (14).

24. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 23, further including the step of asynchronously broadcasting the position signals of each machine (14) such that only one machine (14) per unit time broadcasts its position signal to the site database (66) on another machine (14).

25. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 24, further including the step of storing the machine-identifying signal in the site database (66) on each machine (14), broadcasting the machine-identifying signal with the position signal, and matching the position/ID signal from each machine (14) with machine parameters and updating the site database (66) in accordance therewith.

26. The method (100,101,102,104,106,108, 108a,109,110) as defined in any of claims 21 to 25, including the step of asynchronously broadcasting the position signals from each machine (14) to the site database (66).

27. The method (100,101,102,104,106,108, 108a,109,110) as defined in any of claims 24 to 26, further including the step of broadcasting a machine-identifying signal with the position signal.

28. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 27, further including the step of matching the position/ID signal from a machine (14) with machine parameters and updating the site database (66) in accordance therewith.

29. The method (100,101,102,104,106,108, 108a,109,110) as defined in any of claims 21 to 28, wherein the step of directing the operation of the first machine (14) relative to the second machine (14) includes the step of providing a display (22) of the site database.

30. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 29, wherein the operator display (22) includes a display of the site model (64) and the position of the machines (14) on the site model (64).

31. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 22, wherein the step of directing the operation of the machines (14) includes the step of providing real time control signals to automatic machine controls on the machines (14).

32. The method (100,101,102,104,106,108, 108a,109,110) as defined in any of claims 21 to 31, further including the step of monitoring the operation of the machines (14) relative to one another and providing a warning (85) to prevent interference between them.

33. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 32, wherein the step of monitoring the operation of the machines (14) further includes the step of defining a machine interference boundary (83,83') around a machine (14) and providing a warning signal (85) when the position of another machine (14) is determined to be within that boundary (83,83').

34. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 32, wherein the step of monitoring the operation of the machines (14) further includes the step of defining a machine interference boundary (83,83') around each of the machines (14) and providing a warning signal (85) when the boundary (83) of one machine (14) is determined to overlap the boundary (83') of the other machine (14).

35. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 34, further including the step of altering the size of the interference boundary (83,83') for a machine (14) in accordance with the machine's mode of operation.

36. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 34, further comprising defining multiple boundaries (83,83') of different size simultaneously defined around a machine (14).

37. The method (100,101,102,104,106,108, 108a,109,110) as defined in claim 29 and claims 35 or 36, which includes the step of displaying on the display (22) of the site model (64) the position of the first and second machines (14) on the site model (64) and their respective interference boundaries (83,83').