CA1127304A - Apparatus for determining positional coordinates utilizing the terrestrial magnetism as a directional reference - Google Patents

Abstract

Abstract of the Disclosure Apparatus for determining the positional coordinates of a moving object comprising a plurality of magnetic field vector detecting devices an inclination detecting device for de-tecting the inclination of said magnetic field vector detecting devices a distance detecting device for detecting the distance that the moving object has travelled and arithmetic means which receives output from said magnetic field vector detecting devices as well as from said inclination detecting device calculates the horizontal component force vector of the geomagnetic field by using said output from said magnetic field vector detecting devices and from said inclination detecting device, further calculates the vector in the progress direction of the moving object by referring to said horizontal component force vector, and integrates the product of said vector in the progress di-reaction and the output from said distance detecting device, where-by the positional coordinates is obtained as the output of said operational means which is a computer, and the coordinates which have been set at an arbitrary point is replaced by the newly determined coordinates when turning to the right or left is car-ried out at said arbitrary point as correctly as it is ordered.

Description

z~

Specification Title of the Invention Apparatus For Determining Positional Coordinates Utilizing The Terrestrial Magnetism As A Directional Reference Background of the Invention :
This invention relates to an apparatus for determining positional coordinates utilizing the ter~estrial magnetism as a directional reference. More particularly, the invention relates -~ to an apparatus for determining positional coordinates, which is most suitably designed for installing it on such a small size - moving object as a land vehicle.
In comparatively larger moving objects, for instance, vesseles at sea and aircrafts in flight, there have been adopted - 10 for determining their location at sea or in flight, the method of using gyrocompasses, radio beacon including space satellites, " ~ .
and other instrument for astronomical measurement. Apparatus - and instruments used in such a method, however, have been generally constructed with a large and sophisticated structure, thus resulting in a high cost. Moreover, such a prior art apparatus must have received some restriction in respect of ~he time and place of its use. It is very hard, therefore, to apply them to smaller moving objects such as land vehicles. On one hand, ~here has been the simplest method of determini~g the location of the moving object. That is the method of using a compass which makes use of the earth's magnetic field. When .

, , -- ~lZ73~4L

this method, however, is applied to the small moviny object like a land veh~cle, it has been often experienced that there is introduced into the measurement a large error which is caused by an interferring magnetic field originated from a magnetic body in the vicinity of the compass, or caused by vibration of the moving object itself.
Summary of the Invention It is a principal object of the invention to provide an apparatus for determining positional coordinates, by which the accurate location of the moving object can be determined.
It is another object of the invention to provide an apparatus for determining positional coordinates which is able to be installed on the moving object, has a smaller dimension than the prior art, and also can be manufactured at a low cost.
It is a further object of the invention to provide an apparatus for determining positional coordinates which is substantially independent of the magnetic field from a magnetic body.
It is still a further object to provide an apparatus for determining positional coordinates wherein the horizontal component of the geomagnetic field can be accurately obtained even when the rotary axis of the magnetic field vector - detecting device is inclined.
In accordance with one aspect of the invention, for achieving the objects as mentioned above, there is provided .
an apparatus for determining positional coordinates of a moving object comprising: a plurality of magnetic field vector detecting devices each having a rotary magnetic piece ,~ ' mb/c~ - 2 -~2~
and a fixed coil, the detec-ting devices being disposed in spaced apart fixed relationships to each other; an inclination detecting device for detecting the inclination of the magnetic field vector detecting devices relative to a vertical direction; a distance detecting device for detecting the distance that the moving object has travelled during a particular period of time; and arithmetic means which received output from the magnetic field vector detecting devices as well as from the inclination detecting device, calculates the horizontal component force vector of the geomagnetic ~ield by using the output from the magnetic field vector detecting devices and from the inclination detecting device, further calculates the vector in the progress direction of the moving object referring to the horizontal component force vector, and integrates the product of the vector in the progress direction and the output from the distance detecting device, whereby the positional coordinates are obtained as the output of the arithmetic means, and coordinates which have initially been set at an arbitrary point are replaced by the newly determined coordinates when turning to the right or left is carried out at the arbitrary point correctly as ordered.
- Brief Description of the Drawings Apparatus for determining positional coordinates in accordance with the present invention will now be more fully described, by way of example, wi~h reference to the accompany-ing drawings, in which:
Fig. 1 is a block diagram showing an example of the mb/~,f~ ~ 3 ~

~lZ7;3q34~

apparatu~ for determining positional coordinates e~bodying the present invention;
Fig. 2 is a perspective view of an example of the magnetic field vector detecting device;
Fig. 3 is a diagram for use in explaining about de-tecting error and showing the relationship between the direc-tion of the magnetic field vector detecting device and its output amplitude as well as its phase angle obtained;
Fig. 4 (a) and (b) are diagrams showing equi-magnetic potential distribution lines in the vicinity of the rotary magentic piece of the magnetic field vector detecting device, and lines are drawn in terms of the vertical and horizontal components of the magnetic field vector;
Fig.4A is a diagram showing a modified magnetic field vector device including a partly broken view of the device;
Fig. 5 is a circuit diagram showing an example of the differential arithmetic circuit that is disposed at the output - side of the magnetic field vector detecting device;
Fig. 6 is a schematic diagram for showing an example of the position detector having a rotary magnetic piece as shown in Fig. l;
Fig. 7 is a graph showing the relative output char-acteristics of the position detector against the rotated angle of the magnetic piece;
Fig. 8 is a diagram showing the constitution of the inclination detecting device;

1~73~9~

Fig. 9 is a schematic circuit diagram representing a synchronizin~ circuit as shown in Fig. l;
Fig. 10 is a block diagram showing the principal part of the vector component arithmetic circuit along with the main part of the timing circuit;
Fig. 11 shows wave forms used for explaining the operation of each part shown in Fig. 10;
Fig. 12 is a diagram for use in explaining how the influence of the magnetlc field caused by an external magnetic body i5 eliminated in the apparatus of this invention;
Fig. 13 is a diagram for use in explaining how the measured value is changed by the inclination of the magnetic field vector detecting device;
Fig. 14A through Fig. 14C are flow charts showing an ~15 example of the arithmetic operation by the computer; and Fig. 15 is a diagram schematically showing the con-; stitution of a modified magnetic field vector detecting device.
Explanation of the Preferred Embodiment Fig. 1 shows an apparatus for determining positional coordinates embodying the present invention. In the figure,the apparatus 10 has a magnetic field vector detecting devices 11 (lla, llb and llc) of the class which includes a rotary magnetic piece connected to the rotary axis 13a of a motor 13.
In such magnetic field vecotor detetcing devices lla, llb and

2~ llc, said rotary magnetic piece is formed in S-shape and made to rotate around the axis of a fixed coil. When the S-shaped ~27;3~4 magnetic piece is rotated, magnetic flux passing through the S-shaped magnetic piece varies depending on the direction of an external magnetic ie]d and the rotation angle of the magnetic plece. This varia-tion in the magnetic flux is picked up as a voltage from the fixed coil surrounding said S-shaped magnetic piece. The constitution of the magnetic field vector detecting device as mentioned above is shown in Fig. 12 and will be more detailedly explained later. These magnetic field vector de-tecting devices lla-llc are lined on the axis 13a of the motor 13 keeping an appropriate distance therebetween and arranged to detect geomagnetic field components in the different directions on one plane.
On the rotary axis 13a of said motor 13 there is also provided a rotary position detector 14 which is adapted to detect the rotation of the magnetic piece, and comprises a rotating plate with a slit which is rotated together with said : magnetic piece and the light emitting and receiving elements which are disposed at both sides o said rotating plate. Full explanation on the detector 14 will be made later with reference to Fig. 6.
The apparatus 10 is also provided with an inclination detecting device 17 which detects the inclination of said magnetic field vector detecting devices lla through llc and is capable of transmitting analog signals in correspondence with inclination in all the directions, back and forth as well as right and left. This inclination detecting device will also be cg/(~

l~Z73B4 fully explained later by referring to Fig. 8.
Output from said magnetic field vector detecting devices lla, llb and llc is transmitted to switching means 19 through a differential amplifier circuit 18, which will be fully explained later in connection with ~ig. 5, and then the selected output i5 transmitted to a vector arithmetic circuit 20, which has ability to divide the output amplitude and phase information from the magnetic field vector detecting devices into X and Y vector components by using the output Pl from a ~lO timing circuit 22. The output signal from the magnetic field ; vector detecting device includes second order higher harmonics due to not uniform magnetic field in the neighbour of the detecting device, hlgh order higher harmonics due to the ripple --of the motor torque and the leaked magnetic field, and noise due to mechanical vibration, all of which have to be separated from the basic save component. An analog filter is generally used for such separation. In order to decompose the output signal into the sine and cosine components, there has been adopted the method of measuring phase angle. However, this method often invites error due to phase change in the filter and results in increase of time for calculating. In the present invention, therefore, there is provided a vector component arithmetic circuit 20 which is capable of performing separation and decomposition at a time. Said arithmetic cir-2~ cuit 20 basically comprises memory means 202, multiplying DA
converter 203, and dual slope AD converter 204. The memory 73$~

means 202 is constituted such that the basic sine wave, which is digitally memorized based on the output Pl from the timing circuit 22, is read out as a digital output~ The DA converter 203 receives the analog output from the switching means 19 while it receives the digital output from the memory means 202. The ~D converter 204 is adapted to convert the output from said DA converter 203 based on the output from said timing circuit 22. The output of the arithmetic circuit 20 i.e. the output of AD converter 204 comprises digital sine and cosine signals for use in determining the positional coordinates, and they are transmitted to the computer 25~ The preferred embodi-ment o~ the vector component arithmetic circuit will be more fully described later in connection with Fig. 10.
The computer 25 comprises, as usual, an arithmetic lS unit, a control unit, and a memory unit. The constitution of each unit is well known, so that detailed explanation of them will be refrained from. The computer 25 receives, besides receiving the output from said operation circuit 20/ the output - P3 from said timing circuit 22 as well as the output from a ~o distance detecting device 26, and it calculates the positional coordinates in accordance with the program, as will be later described in detail, and then, transmit its output to display means 27D
- The distance detecting device 26 may comprise means for measuring the revolution number of the propeller shaft of the land vehicle and means for detecting whether the shaft is ~Z~

in normal revolution or in reverse. The output of this device will be transmitted to the computer 25 as the information on the distance that the vehicle has travelled.
The display means 27 may be constituted with appro-priate elements, for instance, LED and is adapted to display the values of X and Y coordinates that the computer 25 has calcualted.
The inclination of the magnetic field vector detecting device is, as mentioned, separately picked up by the inclination 0 detectin~ device 17 in respect of all the directions, back and forth as well as right and left, and then the component picked up separately is transmitted to another switching means 28, which in turn transmits its selected output to another switching ; mçans 29 in compliance with the output P4 from the timing ~5 circuit 22. Then, said switching means 29 selects either output from said switching means 28 or that from AD converter 203 of said arithmetic circuit 20 according to the output P5 from the timing circuit 22. The output selected is then transmitted to said DA converter 204.
0 The timing circuit 22 is adapted to transmit various timing pulses Pl through P5 as mentioned above and also transmit the timing pulse P6 to motor synchronizing circuit 30 in accordance with a reference phase pulse P0 that is the output from the rotary position detector 14 for detecting the rotated position of the S-shaped magnetic piece.
The motor~synchronizing circuit 30 is adapted to keep _ g _ :, ~

~ ~ ~.273~L
the angular velocity of the rotary axis 13a of the motor 13 constant and is constituted as a phase lock loop (PLL) circuit as shown in Fig. 9 in the present invention.
The computer 25 is constituted to perform the following.
The computer memoriæes coordinates corresponding to arbitrary number of objective points at which turning to the right or the left is to be madet and also memorizes orders for making su~h turning. Then, the computer selects one objective point. When $he turning is made at a selected point ~s orderedr the com-puter automatically changes the point initially selected into another point to be next. When the turning is made at a set arbitrary point as ordered, the initial coordinates for the set point is replaced by one newly determined. Further the computer 25 is constituted to indicate, at display 27, information such as three dimensional coordinates (X, Y, Z)~ advancing direction, direction to the objective point, straight distance to the objective point, number or symbol of the objective point, order for turning to the right and left, alarm and so forth.
To put it in the concrete, such computer may be repre-sented by a micro computer 6800, 8 bits, clock 1 MHz of ~otrola of U.S.~.
In the following paragraphs, operation of the respec-tive parts in the apparatus according to the invention will be explained in detail.
Magnetic Field Vector Detectin~ Device These devices lla, llb and llc, as previously mention-

3~

ed, have same construction, so that explanation will be made by taking the device lla. Fig. 2 schematically shows the con-struction of the magnetic field vector detecting device lla which includes the rotary magnetic piece 15 connected to the rotary axis 13a of the motor 13~ The rotary magnetic piece 15 is formed in S-shaped by stacking thin plates made of a mag-netic material such as permalloy, and it has a principal stem 151 which is connected in series to the rotary axis 13a and branches 152 and 153 which are extending from both ends of said 10; principal stem 151 in the direction perpendicular to said stem but in the opposite direction to each other. The detecting device lla also has a fixed ring coil 16, which is formed with a bobbin 161 having flanges at its both ends and a conducting wire coiled on said bobbin as well. With this construction, the magnetic flux ~ of the rotary magnetic piece 15 becomes proportional to the magnetic field vector ~ around said mag-netic piece 15 and takes the value corresponding to the rela-- tive relation-between the mechanical direction of the magne~ic piece and the direction of the magnetic field vector ~. That is, the ~lux I of the rotary magnetic piece is expressed by the following equation.
I = Kl~xy cos ~ ~ K2Hz where, XlK2 ~... constants depending on the material and shape of !5 the magnetic piee 15 Hz .... component o~ the magnetic field vector H in the L273Qi4 direction of the rotary axis r Hxy ........ ..........component of the magnetic field vector in the plane perpendicular to said rotary axis, ~ ........ ..........angle that the direction of the rotary magnetic piece 15 makes to said Hxy component.
; When the rotary axis 13a and the rotary magnetic piece 15 are rotated at a constant angular velocity ~, the angle e becomes w + ~ ~ Thus, there is caused in the rotary magnetic piece 15, a magnetic flux change that is dI/dt = K3Hxy sin (w~
o ~ ~ ), where ~ denotes the angle that is made between the direc-tion of the magnetic piece and said component Hxy at t=O, and K3 is a constant.
Consequently, it is possible to obtain through the fixed coil 16 a sinusoidal output voltage, of which amplitude ; is proportional to said Mxy component while its phase is shift-ed from the direction of the magnetic field vector detecting device lla by an angle y, thus X and Y components of the mag-netic field being obtained therefrom.
In the magnetic field vector detecting device having such a structure as mentio~ed above, a voltage generated by the fixed coil 16 is proportional to the density change in ~he magnetic flux penetrating through the coil. Now, considering such magnetic flux by dividing it into two parts, the magnetic ~lux ~a passing through said rotary magnetic piece 15 and the magnetic flux ~b penetrating through the fixed coil 16, it will be seen that the magnetic flux ~a always penetrates through all ,, ,~ .

273~

the windings regardless of the position of said fixed coil 16.
On the conkrary, the magnetic flux ~b takes different values depending on positional relation between the fixed coil 16 and the magnetic piece 1~. For this reason, if the rotary axis of ~he magnetic piece 15 is not in line with the center of the coil, and if the direction is changed within the rotary plane of the detecting device, the output from the detecting device will vary depending on the directionO
Fig. 3 is a diagram ~or use in explaining a detection error, which shows the relation among the direction of the detecting device, the amplitude of the detecting device output and the phase angle obtained in such a case as mentioned. In the figure, a reference numeral 40 denotes X and Y axes which are taken in the rotary plane of the magnetic piece, 41 the output amplitude of the detector in correspondence with its direction, and 42 vectors of the detector output when the detector directions are o4 and 90 respectively.
As will be apparent from Fig. 3, such a magnetic field vector aetecting device as shown in Fig. 2 has the defect that the rotary axis of the magnetic piece has to be accurately in line with the center of the coil.
This will be more fully explained in the following in conjunction with Fig. 4 whi~h shows equi-magnetic potential dis~ribution lines.
Fig. 4(a) and 4(b) are diagrams copied from the pat-terns displayed on a cathode ray tube, which are equi-magentic ~2~

potential distribution lines made through a computer simulation process with the condition that uniform magnetic fields are applied to the rotary magnetic piece in the direction of its rotary axis as well as in the direction perpendicular thereto.
In the figure, same parts as in Fig. 2 bear same reference numerals. Reference numerals 45 and 45' denote equi-magnetic potential lines while 46 and 46' represents some of lines of magnetic force which perpendicularly intersects equi-magnetic - potential lines. The change in magnetic force lines penetrat-o ing through the coil results in generation of a voltage. In this case, what contributes to voltage generation is each component of magnetic force lines such as 46 and 46' in the direction of the coil axis, and the magnitude of such voltage is inverse to the inclination of the magnetic potential as !5 against the coil axis. Reference numeral 47 and 47' denote lines paralled to the coil axis. Intersecting points between said lines 47, 47' and equi-magnetic potential lines are denoted by reference numerals 48, 49, 48' and 49". From these points, the magnetic field intensity can be quantitatively determined by measuring the distance between points 48 and 49, and points 48' and 49'.
Determining the magnetic field intensity by relying on such a way as mentioned above, it will be understood that in case of ~ig. 4la) there is increased the intensity when there ~S become larger the distance from the branches l52 and 153 of the magnetic piece 15 as well as from the rotary axis 13a, and also L27~

that in Fig. 4(b) the intensity also becomes larger when there becomes larger the distance from said rotary axis but along said branches.

In view of the above, when the coil is located within a certain limited central portion of the rotary axis where the magnetic field intensity is smaller commonly in Figs. 4(a) and

4(b), it becomes possible to decrease to a great extent the quantity of the magnetic flux penetrating through the coil at the place other than the magnetic flux path of the magnetic piece 15.
Flg. 4 shows schematically an example of the modified magnetic field vector detecting device 15 which is constructed in view of the foregoing discussionO The device is chazracter-ized by its fixed coil 16A.

In case ~f preparing and disposing the coil 16A around -~ the stem of the magnetic piece 15r the following requirements must be satisfied. First, the area of the coil cross section taken to include its rotary axis has to be made maximum within the region that is defined, as shown in Fig. 4, by branches 152 2~ and 153 of the rotary magnetic piece 15 and two dotted paral-leled lines A and B. Secondly, the coil has to be disposed around the stem 151 of the magnetic piece 15 in such a way that magnetic flux density of the magnetic piece 15 becomes maximum in respect of magnetic field vector within a plane perpendicular !5 to said rotary axis 13a. Satisfying the requirements above, the coil 16A is made to have a cross section, as shown in Fig. 4, ~3LZ~

like two standing roofs opposing to each other at the both sides of the stem 151 of the rotary magnetic piece. Each slope of those roofs are determined by said two dotted paralleled lines A and B, so that each ridge 164 of the roofs comes to the same

5 level.
Consequently, in the magnetic field vector detecting device as constructed in Fig. 4, no coil is existing at the place where the magnetic flux density largely varies from place to place, so that the quantity of the magnetic flux penetrating ~ 10 through the coil at the place other than the magnetic piece is kept very small almost at all×
: Differential Arithmetic Circuit . Fig. 5 shows with a reference numeral 18, a concrete example of the differential arithmetic circuit, by which the present invention is further characterized. The circuit 18 is ; adapted to correct the deviation in the phase and amplitude of the.output from the detecting devices lla, llb and llc. The deviation is mainly caused by non-uniorm mechanical character-- istics of those detecting devices. The circuit 18 is also 2~ adapted to obtain the output difference among said detecting devices lla~ llb and llc, which is used in eliminating the magnetic field caused by a magnetic body as described later.
In the figure, reference numerals 181, 18~ and 183 den~te amplifiers which have comparatively higher amplification 2~ degree (for instance, 500 times) and receive the output from said detecting device lla, llb and llc. These amplifiers are ~z~
adapted to correct ~he deviation in the phase and amplitude of the output, which results from the mechanical characteristic difference among said detecting devices. The output of an amplifier 183 is transmitted to an adder 184 while the output of an amplifier 181 is inverted and then, sent to said adder 184. The output of an amplifier 182 ls also inverted and then, transmitted to another adder 185. The output of the amplifier 183 is also sent to an input terminal of the switching means 19 through an amplifier 1860 The output from said adder 184 is also transmitted to another input terminal of said switching means 19 through an amplifier 187 while that from said adder 185 is transmitted to another input terminai of said switching means through an amplifier 188. The differential signals obtained from said adders 184 and 185 are small in comparison with the main signal transmitted from said amplifier 181, so that amplifiers 186, 187 and 188 are given weighted amplifica-tion degrees respectively, for instance, twice, 10 times, and 20 times. This weighting is considered in order to decrease the conversion error in A-D converting operation by means of AD
converter 204 in said vector arithmetic circuit 20. Eventually, said error will be corre~ted by using a software of the computer 25 when eliminating the magnetic field originating from a mag-netic body.
otary Position Detector Fig. 6 shows with a reference numeral 14, an embodi-ment of the rotary position detector, which includes a circular ;~

~127~

plate 50 having a slit 50a, light emittig element 51, and light receiving element 52. The circular plate 50 is connected in series to the rotary axis 13a o~ the motor 13, and said slit 50a is formed in the radial direction of the plate 50. Said l'ight emitting and receiving elements 51 and 52 are disposed at the both sides of said circular plate 50 to oppose to each other~ These elements may be LED, for instance. One end of said light receiver 52 is grounded while its output is trans-mitted to an operational amplifier i.e. the level slicer 54 as ~10 well as to an amplifier 55. The output from said amplifier 55 ; receives the detection of its peak value by means of a peak detection circuit 58 which is constituted with a diode 56 and a condenser 57. The output voltage o~ said peak detection circuit is divided by resistors 60 and 51, and then, given to the plus side input of said slicer 54 as a reference voltage .. es- , Since the reference voltage es is determined by the outpu~ of the peak detection circuit, the slice level'is in-creased when the peak value of the light receiver output is 0 increased while it is decreased when said peak value is de- -creased. The slice level to the light receiver output which is - ob~ained from the revolution of the rotary magnetic piece 15 is increased or decreased depending on the increase or decrease of . ~he peak value of said light receiver output. Accordingly, i when the level slice is performed with xeference to said voltage es, tbe time of starting and stopping slicing is kept constant ~Z71~4 :. , regardless of slope angle change in ~he light receiver output.
Thus, it is possible to transmit from the output terminal 62 pulse signals o~ which timing is stabilized at its front and rear end.
One end of said light emitter 51 is connected with a power source ~V while the other end is connected with the out-put terminal of a differential amplifier 65 through a current limiter (a resistor 64). This differential amplifier 65 is an .
operational amplifier, of which minus input terminal receives ~0 ~ the output of said peak detector circuit through an input resistor 66 while plus input terminal is given a control ` voltage Ec. Between the output terminal and said minus input terminal of said amplifier 65 there is connected a nagative feedback registor 67. The input terminal of said amplifier 5S
;15 is connected with said +V source through a re~istor 68 to receive a predetermined biasing voltage.
With the above-mentioned circuit formation, there is provided a feedback loop to the light emitter Sl, which com- -prises the liyht receiver 52, amplifier 55, peak value detec-tion circuit 58, operational amplifier 65, and resistor 64.
~onsequently, when the output voltage of the peak value detector becomes larger than the control voltage Ec, the output level of the differential amplifier 65 is lowered, while it is pushed up when said output of the peak value detector becoms smaller 2~ than Ec. In other woras, the current of the light emitter 51 is aetermined by referring to the control voltage Ec, so that ~12~3~

the current of th~ light emitter 51 is s~abilized regardless of ~luctuation in the power voltage, ambient temperature and other factors.
With the construction as mentioned above, accordingly, i light emitting by the light emitter 51 is stabilized, the peak value of the output from the light receiver 52 is kept constant, the output from the angular position detector is stabilized by setting the re~erence voltage es, and it is possible to obtain from the output terminal 62 the pulse signals produced with precise and constant slicing timing.
- Fig. 7 is a graph showing the characteristic, the magnetic piece rotating angle vs the relative output. A curve "a" represents the output characteristic when all the parts of the detector are normally operated. La denotes the slice level in that condition. When the output of the light receiver 52 is lowered by some causes, for instance, the temperature of the light receiver, its life limit, the power voltage fluctua-tion, or the like, the slice level is lowered by deviation of the peak value from ~he reference value. Thus, the output obtained is able to have same front and rear edges as the ou~put in the normal condition (line a?. When the slice level Gan not be removed up and down, the output i.e. the edge v~ the reference phase pulse is removed from the point Qa to ~he point b~ thus this change causing an error in the directional measurement.
- It should be noted that the angular position detector ~ .
~ - 20 -~' ' .
,, ~ . .

~lZ73~ -as mentioned above is not limited within what is described above and that it can be modified in various ways. For example, the resistors 60 and 61 for use in the voltage divider may be re-placed by variable condensers.
Inclination Detecting Device The inclination detecting device 17 comprises two detecting units which are adapted to detect the inclination in all the directions, back and forth as well as right and left.
Fig~ 8 shows the constitution of the device embodying the pre-sent invention.
In the square, a reference numeral 70 indicates a magnet, 71 a yoke, 72 an arm which is only movable in the direction of the coil axis, 73 a supporting point using a pivot or a spring, 75 a displacement detecting element, 76 a feedback type amplifying system, 78 a force coil, 79 an output terminal, and 80 a resistor. The magnet 70 and force coil 78 are fab-ricated in such a way that the relative position between them is changed when inclination of the device happens. ~urther; -the device is designed to flow an electric current into the D coil 78 when the device is inclined. In this case, the current is flown in the coil in the direction to get back the positional relation between said magnet and coil be~ore occurrence of in-clination.
According to the inclination detecting device as con-; structed above, when the inclination occurs, it is first detected by the displacement detecting device 75. What is detected is ~lZ~73~

transmitted as a displacement signal to the Leedbask type am-plifier 76 and receives amplification there. Then, the current is flown into the force coil 78 in the direction to return the displacement before the inclination happens. In this way, from the output terminal 79 there is obtained analog output which is proportional to the sine oE the displacement angle. According-ly, it becomes possible to obtain vector components of t'ne inclination by arranging two detecting units such that they ~eet at right angles to each other~ -Synchronizing Circuit LO :
Fig. 9 shows the synchronizing circuit 30 embodying the present invention. This circuit is adapted to have the motor 13 synchronizingly operated in accordance with the timing circit 22.
L5 In the figure, a reference numeral 91 denote a pulse motor which is commercial, 92 an input terminal to which the signal for driving the motor is applîed,-and 93 a coil for use in detecting the revolution number of the motor. The motor 13 shown in Fig. 13 is composed of the constituents as mentioned o above The synchronizing circuit 30 has a phase detector 9~
which compares the output from said detecting coil 93 with the input signal P supplied from said terminal 94 and having a reference frequency, and then transmits the output having a pulse width corresponding to the phase difference obtained from said comparison. Furtner, the synchronizing circuit 30 has a ., , 7~

first operational amplifier 97 connected to the plus terminal of the coil 93, a diode 98 for use in rectifying the output of said operational amplifier 97, a condenser 99 connected between the cathode of said diode and the earth, and a connecting mean 100 for use in connecting said cathode with the minus input terminal of said amplifier 97. With constituents as mentioned above there is provided a circuit 101 or detecting a peak value or a mean value. In other words, the circuit 101 has the function capable of detecting a signal having the amplitude in response to the revolution number of the motor 13. Still - -further, the synchronizing circui~ 30 has a second operational amplifier 104 of which the minus input termial is connected with the cathode of said diode 98 through the input resistor 103, and also has a negative feedback resistor 105 between the output of said second operational amplifier 104 and the minus input terminal thereof. T'ne plus input terminal 107 of said operaticnal amplifier 104 receives a reference voltage eRS
which is adapted to set a pull-in center frequency. By the circuit formation as mentioned above, there ;s provided a amplitude control circuit 108 which compares the output from the peak or mean value detecting circuit 101 with the reference voltage eRS applied to the plus terminal of the amplitude and varies it~ output in correspondence with the result of com-parison. Still further, the synchronizing circuit 30 includes transistors 111 and 112. the transistor 111 is a npn transis-tor, of which the collector receives t'ne output of said ampli-i ,,, ' , , ; - 23 -fier 104 through the resistor 110, the emitter receives the output of said phase detector 95 and the base i5 grounded.
Accordigly, it cons~itutes a multiplyer 111 making a product of pulse width by amplitude. On one hand, the other transistor 112 is also npn transistor of which the base receives the collector output of said transistor 111, t'ne collector receives the plus voltage and the emitter transmits the output to the input terminal 92 of said motor 13. Accordingly, it constitutes an amplifier 112 for use in driving the motor.

.
The operation of the synchronizing circit 30 as shown in ~ig. 9 will be explained in the fol1owing.
As the amplitude of the outp~t from the coil 93 ~or detecting motor revolution number is proportional to the revolution number of the motor, the output from the peak or mean value detecting circuit 101 is also proportional to the revolution number of the motor 13. T'ne second amplifier 104 compares the output from said peak or mean value detecting circuit with the reference voltage eRS supplied from tne input terminal 107. The output of this second amplifier 104 is D then varied in response to the comparison result. Namely, when the revolution number of the motor 13 is under the standard, a control is peformed so as to make the output voltage from said second amplifier 1~4 higher while another control is given to lower said output voltage when the motor revolution number is over the standard. When a pulse input is given to said multi-plier 111 from the phase detector 95, there is obtained the ''~ .

~-~z~
pulse signal of which the amplitude is same as that of the output voltage of said second operation amplifier 104 and of which the pulse width is same as that o~ the input pulse. The pulse signal is given to the input terminal 92 for driving t'ne motor through said amplifier 111.
The construction and operation of the phase detector 95 is known well, so that explanation thereabout will be refrained.
The output from the coil 93 proportionally varies correspondig to the revolution number of the motor 91, so that the output from the amplitude control circuit 108 is also varied in correspondence with said motor revolution number.
The phase detector 95 transmits a signal that varies its pulse width in compliance with difference from the reference input signal P6. As a result, the multiplier 111 makes a product by two output, of which one is the amplitude control circuit 108 and the other is from the phase detector 95, and it trans-mits to the input terminal 92 of the motor 13 through ~he amplifier 112, a pulse signal that has the pulse width in correspondence with the motor revolution number. According to the circuit formation as described above, there is prvvided at the output side of the phase detector 95 neither an integral circuit with a large time constant nor a phase compensation circuit which also has a large time constant, thus quick re-2~ sponse characteristic being obtainable. Namely, the responseof the peak or mean value detector is faster than the time 73~

constant of the motor, and said response is transmitted to the motor through the amplitude control circuit 108~ Thus it is possible to provide a simply constructed synchronizing circuit which needs no auxiliary complicated means such as phase com-pensating circuits often used in the prior art and WhiCIl shows a quick synchronizing operat.ion against external disturbance.
Veçtor_Component Arithmetic Circuit And_Timin~ Circuit Fig. lO shows each substantive portion o the vector component arithmetic circuit 20 and t'ne timing circuit 20 according to the present invention, and it is prepared in det~il more than that shown in Fig. l.
As shown in Fig. lO, the arithmetic circut 20 includes an input terminal 201a, which receives the output of the mag-netic field vector detector througb the switch l9, and another input terminal 201b which receives a reference phase pulse Pl from the timing circuit 22. The analog signal received at the input terminal 201a is transmitted to DA convert~r 203 and is used to obtain an analog output proportional to the product of itself and the digital output o~ the memory means 202. Ac-cordingly, wnere voltage-current conversion resistance of the converter 203 is Ro~- current-voltage conversion resistance is Rl, the analog input signal is e, and digital input signals are Al, A2, A3 ..... A8, the ou~put signal of the converter VO is given by the following equation~

VO = e t2 + 4 + 8 ~ 256 ) Ro ~273~

A signal controlling the memory means 202 is the output from a preset couter 221 of the timing circuit 22. In other words, it is such a straight signal that the digital value corresponding to address selection is read out at the output side (i.e. the side o~ D~ converter). The preset counter 221 is counted up with clock input pulses from a preset information setting circuit 222 as well as from a frequency divider 224. The preset counter 221 transmits its output of which polarity is inverted at every one-round of it i.e.
integral gate signal. The preset information setting circuit 222 controls preset values in compliance with a preset infor-mation changing signal Sl inverted at every two rounds, and presets the counter 221 at the time of the reerence phase pulse from the input terminal 225.
The frequency divider 224 transmits various timing signals P3 t'nrough P8 by receiving the output of a master clock pulse generation circuit 226, w'nich is, for instance, a -pulse generator of 100 KHz and of which the output is trans-mitted to said fre~uency divider 224 and also transmitted as the clock output P2, to the AD converter 204, which is a dual integration type converter and performs analog-digital conver-sion by integrating the analog output of the DA converter ~03 or the inclination detecting device 17 over the period that is equal to the integral multiple of the period of the basic sine wave. Namely, the A~ converter receives the output of a switch 29, which is transmitted to a switch 207 through the input ~ - 27 ~

~2~3~

~erminal 206. Said switch is controlled by the integral gate signal P2 from t'ne preset counter 221. When the signal P2 is "0`', an analog signal input terminal 206 is selected, and when it is "1", a reference voltage input terminal 208 is selected. The output of said switch 207 is transmitted to the integrator 212 comprising a resistor 209, a condenser 210 and an amplifier 211. The output of said integrator 212 is trans-mitted to a comparator 213 and compared with zero potential.
The output of said comparator 213 is ~urther transmitted to AN~
gate 214 which makes "and" in respect of said integral signal P2 of the timing circuit 22 and the output of the master clock generating circuit 226 i.e. a clock signal P2,. The output of said AND gate 214 is transmitted to the counter 215 for use in AD conversion. Said counter 215 receives the signal P2 ~rom the timing circuit 22 as a reset pulse and is reset when the signal P2 from the pres~t counter 221 is inverted from "1" to "0". The output of said coun.er 215 is paral1elly picked up and then transmitted to the computer 25.
Fig. 11 shows various wave forms which are used for explaining operation of circuits as shown in Fig. 10. In the figu~e, respective wave forms (a~ through (h~ correspond to a signals as fol1ows. (a) corresponds to the s;gnal that is to be measured and applied to the input terminal 201 of the vector arithmetic circuit 20, (b) the digital signal that is trans mitted rom memory means 204 to DA converter 203, lc) the reference phase pulse appli~d to the input terminal 225 of the - - 2~ _ ~27~4 timing circuit 22, (dJ the analog signal given from DA con-verter 203 to AD converter 204, (e) the integral gate signal P2 ~rom the preset counter 221, (f) the output signal from the integrator 212, (g) the output signal of the comparator 213, and (h) the output signal of AND gate 214.
The operation of the circuits as shown in Fig. 10 will now be described by referring to the wave forms as shown in Fig. 11. As the wave form of a reference signal, there is adopted a sine wave having the frequency f. One period (2 radians) of said reference signal is divided into 2A and `
then, the crest value corresponding to each angle is stored as a D-bit digital signal in the memory 202. By this wayr numbers corresponding to one period are stored in the memory 202. In other words, the memory 202 is a D-bit memory device wherein the address selection information is received from the preset counter 221 by the number of A and signals having t'ne wave form as shown in Fig. 11 is stored as digital values.
The output of the master clock generating circuit 22Z
is divided by the divider 224 to obtain pulse signals with the ~requency 2A x f. When said signals are given to the preset coun~er 221 as 8-phase counting-up clock input, binary digits are provided by tbe number of said input pulse. Said binary digits are received by said memory 202 as address selection information and then, from the output of said memory, there are read out D-bit digital values which represent the crest values of tbe reference sine wave corresponding to each angle that 3~4~

results from said 2A division. By DA converter 203 there are provided signals having the wave form (d) as shown in Fig. 11, which is proportional to the product of the digital signal having the reference sine wave (b) which is read out of the memory 202, and the analog input signal having the wave form (a) that is to be an object of the measurement. This signal with the wave form (d) is then introduced into AD converter 204 in the next stage. Said AD converter 204 which is of double integral type, receives the signal having the wave ~orm (d) Erom said D~ converter 203 through t'ne switch 207, which is controlled by the integral gate signal P2 having the wave form (e), and performs intgration with the integrator 212 to produce the output signal having the wave form (f). The output o~ said integrat~r 212 is introduced into the comparator 213 and compared with the reference voltage. The output of the comparator has'the wave form (g) as shown in Fig. 11. This output signal is then sent to AND gate 214. By said AND gate 214, "AND" is obtained by means of said output from the com-parator 213, the integral gate signal P2 from said preset counter 221 and the clock input signal P2, from the master clock generating circuit 226. From the output of said AND
gate, there is obtained the signal with the wave form (h), which is transmitted to the counter 215 for use in AD converter , to be countedO In this manner, it becomes possible to obtain a direct reading of the preset phase component vector for the input signal out of the output terminal of AD converter 204 ~L~27~

Further, it is possible to read out both sine component and cosine componn~ alternatingly by means of changing the phase of the preset value in the preset information setting circuit from sine to cosine or vice versa by usin~ the preset information changing signal Sl. .
. In the foregoing, for simplifying the explanation, there has been assumed DA converter that is able to produce the product of the input signal and the reference sine wave regard-less of their sign (plus or minus). In general, however, an ordinary DA converter can make a product only when the signals have evenly plus signs. Accordingly~ when working the embodi-ment above actually, it should be noted that the input terminal 201 receiving a signal to be measured as well as the input terminal 206 of AD converter receiving the analo~ input signal has to be provided with a polarity inverting circuit and a switch so as to let both input always be plus. ~t the same time, AD converter 204 should be of the type operable for both plus and minus polarities.
Further, in the foregoing explanation, digital values of the reference sine wave which are stored in the memory 20~ -have to be those for a full period~ but the digi~al values for a half or a quarter period may be usable.
As apparently seen from the explanation above, accord-ing to the circuits as shown in Fig. 10, error due to the selection filter, which has been often observed thus far, .is never introduced and no arithmetic process for coordinated con-~ , , .''.' . , 3 Z73~

version is needed, so that vector components and AD conversion are obtained at the same time.
In the following paragraphs, there will be explained some remarkable functions of the present positional coordinates determining apparatus, which further characterized the present invention.
unction Of Eliminating The Influence Of Ma~netic Field Due To A Magnetic Body Fig. 12 is a three dimensional diagrammatical repre-sentation for explaining the positional relationship among-three magnetic field vector detecting devices and a magnetic body. In the figure, a, b and c represent positions of said 3 'detecting devices (corresponding to lla, llb and llc in Fig.
1), which are lined on Z-axis, and it is assumed that a mag-netic body is existing near the X-Y plane. The magnetic body is considered as a set of a lot of magnetic poles which are distributed in a complicated fashion. In the following discussion, therefore/ the magnetic body is approximated by an equivalent magnetic dipole, of which X-components (in X-Z
~9 plane) are ~mx and mx while Y-components (in Y-Z plane) are fmy and -my, where each component represents a set of magnetic poles and the magnetic field intensity caused at points a, b and c in one direction by one o~ said magnetic poles is entire-ly same as that which is caused by another magnetic pole at same points in the same direction. According to the approxima-tion above, X and ~ components are calculated separately in the ~27;3 ~

same way, so that the discussion hereinafter will be made only is terms of X-component.
Now, as shown in Fig. 12 r when said equivalent magnetic dipole is lined on X-axis such that its X-components ~ mx becomes symmetric with respect to the origin . ~x~ nlX~x and n2X~x represent the distance from points a, b and c to each e~uivalent magnetic pole respectively; h denotes the distance from the origin to the point a, and d indicates the distance rom the orig~n to each equivalent magnetic pole. X-xomponents .
eaX, ebX and eCX of the magnetic field intensity caused by the equivalent magnetic pole are given by the following expres-sions.
eaX = 2~ x d/~x3 ... (1) ~ ebX = 2m x d/nlx3 ~x3 ... ~2) eCx = 2m x d/n2x3 Qx3 -- (3 ~Ixz+h2 n~ (h+Dl) - n2X "~X =~X + (h~D2) where Dl and D2 are the distance ~rom the point a to the point b as well as to the point c.
~0 When Hx is the X-component of the objective magnetic Y' eax+Hx' ebx+Hx' and ecx+~ are measured at meas-uring points a, b and c. Accordingly, the output difference ~ab between detectors a and b, and also the output difference ~ac bétween detectors a and c are given by the following equations.
~ ab = eax ~ ebx = eax (1 - nlx ) ...

~ ac = eac ~ eex ~ eaX (1 - n2X ) ...

"

,.

3~4 The ratio of the above, accordingly, becomes:
~ ac/ ~ ab = (1 - n2X~3 )/(1 - nl~3 ) - (6) nlX and n2X in the riyht side of the equation (6) are generally functions of d, h, Dl and D2. For simpler explanation, ass~ming that Dl and ~2 are adequately smaller than h, the following equa-tion (1) is obtained.
2/ 1 (n2x lj/(nlx - 1) . (7) From equations (6) and (7), it is posslble to determine nlX and n2x' When the X-component o~ the output from the detector a is EaX = eaX + Hx, the X-component Hx f the magnetic field to be measured is obtained from the quation (5) ahove, ~or instance, as follows.
Hx Eax eaX = EaX ~ ~ac/tl - n2 ~3) ... ~8) L5 Accordingly, as shown in ~iys. 1 and 5, when ea, ~ab, and Aac are obtained, the computer 25 becomes ready to calculate the X component ~ o~ the magnetic field to be measured.
As to the Y-component of the magnetic field to be measured, the same way as mentioned above is applicable to o determine it. Accordingly, X and Y components in the plane p~rpendicular to Z-axis are determined without receiving any in1uence from the magnetic body. In other words, according to the apparatus of the present invention, the magnetic field caused by the magnetic body can be eliminated by using the ; output difference between a plurality of magnetic field vector detecting devices as well as the ratio therebetween.

f;

~Z73~1~

In this case, at places other than those near the equator, the vertical component fluctuates with respect to the geomagnetic vector, so that the rotary axis 13a is always required to be hept vertical in order that the X and Y compo-nents obtained are directly measured as bearings of the geomag-netic poles. A moving object such as a land vehicle usually makes pitching and rolling during its runningt so that it hardly possible to satisfy the condition above as far as t'ne measurement is made by using the magnetic vector detecting device fixed on the moving object.
Correction Of Error Due To Inclination Of Magnetic Vector Detecting Device Fig. 13 is a diagram showing the revolut.ion of coor-dinates, which are used ~or obtaining the change o~ the measured value that is ca~sed by inclination of the magnetic field vector detecting device. In the figure, X, Y and Z
represent 3 components of the geomagnetic field vector, and the X-axis represents the direction, along which the moving object runs having a X-Y horizontal detecting plane on it. According-ly, /X~ ~ represents the horizontal component o~ the geomag-netic rorce while Z represents its vertical componen~.
Now, considering two dimensial components X' and Y' of the terrestrial magnetism which are obtained by rotating the coordinates system as shown in Fig. 13 by angles ~ and ~ in the direc~ions of bac~ and fortn as well as of right and left, X' - and Y' are expressed as follows.

1~27:~4 .

X' = X cos ~ ~ Z sin ~ cos ~
X' = Y cos ~ ~ Z cos ~ sin ~ ... (9) Accordingly, inclination angles ~ and ~ of the mag-netic field vector detecting devlce being measured, the horizontal component of the geomagnetic vectors X and Y are obtainable regardless of the inclination of said detecting device.
In the apparatus as shown in Fig. 1, therefore, the error introduced in the detected bearings are corrected by solving the simultaneous equations (9) by the computer 25.
As discussed above, according to the present inven-tion, it is possible to always indicate the positional coor-dinates of the moving object like a land vehicle by using the apparatus havin~ the small and simple mechanism and circuit ,5 constitution. Further, the function o~ the compu~er being fully utilized, the following will be also obtainable.
1) Setting Of An Objective Place The objective place being known rom a map or the like, the coordinates corresponding thereto are memorized.
o - 2) Setting A Running Route A plurality o~ objective places existing and there being characterized points on the designated route, the numbers s assigned to such points and coordinates corresponding thereto - are memorized.
3) Setting Of The Turning Point The numbers assigned to the points a teach o~ which ~; ~ 36 -` ' ' ' ' 1~ 2~0~
turning is to be made, and their corresponding coordinates are memorized. `
4) Calculation of The Error The error to be introduced at running point in cor-rected in response to the running distance from the reference point which includes no error trunning distance error setting value).
5) Calculation Of The Distance To An Objective Place - The linear distance from the running point to the 0 object next in calculated.
) Calculation Of The Anglar Deviation There is calculated the angular deviation between the ;~
running direction and the direction to the objective place. ;
- 7) Determination Of The Present Running Point From the comparison of the value obtained in the item (4) above or a distance limit value as set separately and the resultant of the calculation (5), it is determined whether or ~` not the present running point is within a preset range.
8~ Calculation Of Running Distance, Speed, and Direction ~0 g) Determination ~E Turning ` There is calculated a time differential value with respect to the running distance (this value may be used for ~calculating the acceleration in the right and left directions).
~ Then, the absolute value of said di~ferential value in compared `S with an angular limit as previously set, thereby judging com-pletion of turning. The direction o~ turning, to the right or : ' ' . ' ' . . .

",;' . ' , ' :' ,.: '' ` ~ ~ ' ' :
:, ~, , : . . : . . .,, .
:, - ~ - - . , - - - -left, is ~udged ~rom the sign of the differential value. Fur-ther from comparison with information of the item t3), it is judged whether or not turning made is as requested.
10) Automatic Replacement Of Number Assigned To The Point S In case the running ;s made along the route as set, memorized information as to numbers assigned to points, turning points and the coordinates, is selected according to the planned running course, and the information once usea has to be renewed at the time of every passing the objective places. In this 0 case, the automatic replacement of the number assigned to the point is possible when such a point in limited to a turning point on the route and at the same time the condition or determination in items (7) and (9) are satisfiedO
11) Correckion Of Coordinates In case of performing the automatic replacement as mention in item (10~ above, the coordinates having been set thus far are replaced by the coordinates presently measured~
By this operation, the error invited up to the point measured is obviated, so that the error is less accumulated even in the D long distance running.
1~) Display The ~ollowing information may be displayed through suitable display means. Namely, they are the coordinates (X, Y, Z), the number assigned to the objective point, turning ; point in~ormation, and the resultant of calculation according to items (5), (6) and (8). Display may be made at a time or . --~ .

~' .

:
.
" :

~73~4 separately by means of LED or liquid crystal display means. It is also possible to display the running coordinates and moving direction on the map drawn on a cathode ray tube. Further, it is also possible to plot the position o~ the moving object on a map by using a X-Y plotter.
13) Alarm Alarm i~ made when the running position is out of t'ne set range, or other requirement for alarm happens.
14) Memory Various information, for instance, the traces of the moving object, may be easily memorized by means of either internal memory means or external one, so that it is possible to know both the position and direction of the moving object correctly and dynamically. It hecome also possible to guide the moving object to an unknown objective place with sa~ety and accuracy. Further, it is possible to transmit the positional ; information to a central station, so that centralized control ; of business will be realized at places which require it, for instance, the police station, the hospital for ambulance, the -~29 fire station, the station of transportation and so forth.
Further, it should be note that the position determination by the apparatus of this invention ground but also in the ground as well as in the water.
As enumerated above, the present invention has a very wide range of applic~tion.
For confirming the accuracy of the apparatus according ' ' ' .

, l~Z~

to the present invention, there was performed ~he experiment, in which the coordinates measured through 17 Km running were accurately plotted on the map by means of the X-Y plotter.
As described above, it will be understood that the apparatus according to the present invention is to only appli-cable to the small moving object but also so unique.
In the following paragraphs, it wi]l be described how the computer 25 performs the above-mentioned functions.
Figs. 14A, 14B and 14C are flow charts showing the outline of the program for the computer 25 for calculating the positional coordinates of the moving object such as a land - vehicle.
A~ter co~pletion of initial set~ing, the computer 25 sums up in its memory or registor magnetic field vectors eaX, ~lS eay~ ~abx, ~aby, ~acX~ and ~ acy which are obtained through the magnetic ~ield vector detecting device, and the vector co~-ponents G and T in the pitching and rolling directions of the vehide, which are obtained from the inclinatiGn detedcting device 17 (step 301). The magnetization quantity of the moving object-is calculated in the step 302 by using vector informa- -tion above. Then, through the step 303, correction is made with respect to said magnetization quantity and inclination.
Further, angular deviation is corrected though the step 304.
In the step 305, there is calculated the running distance in a small section by using the output of the distance ~' ~ ~ Z73~

detecting device (26 in Fig. 1). Further, in the st~p 306, the height component in the small section is calculated by using said components o~ inclination. Then, the X and Y components of said moving distance are calculated in the step 308. The positional coordinates are calculated in the step 309. Then, the progressing direction and the linear distance t~ t'ne objec-tive place are calculated through steps 309 and 310 respectively.
The information about said objective place is stored in advance in the memory of the computer. Further, the angle to the ob-ject is calculated by the step 312. The height component from the initial point is obtained through the step 313. The total of moving distance is calculated in the step 314. The saving of the moving distance in the small section is performed through the step 315 to make the correction of inclination as LS against the speed o~ the moving objec... After completion of steps above, the computer 25 transmits its output to the display (27 in Fig. 1) to indicate info~mation, for instance, the distance and angle to the objective place and the positional coordinates at present. Then, it is decided in the step 318 at ~C what degree the directlon is changed with respect to the priox one and also whether or not it is within the predetermined allowable range~ When such directional change is made as demanded, the program is further proceeded to the step 320 ~hrough the step 319. When turning is made within the pre-determined range about the point that is memorized in advance in the memory of the computer as a point where turning is to be ~ 41 -- ~Z7~3~4 made, the program is further proceeded to the step 321, in which it is performed to renew the number assigned to the point and the corresponding coordinates, and also to replace the set value by the newly measured coordinates. Then, the program returns to the portion Q of Fig. 14A and then, same steps are repeated.
Fig. 15 shows a modified embodiment of the magnetic field vector detecting device 11, where there is used a detec-tor of the type in which a magnetic core is excited with the alternating current, and the oùtput of harmonics is detected, thereby the mangetic field vector in the direction of magnetic path length being measured. In the figure, reference numerals 130a and 130b denote detecting coils while 132a and 132b repre-sent exciting coils. These coils are corresponding to fixed coils in ~ig. 1. A combination of the exciting coil 132a and the detecting coil 130a, and the other of the exciting coil 132b and the detecting coil 13~b are respectively constituting transformers, which are disposed to meet at right angles each , ~ .
other thereby X and Y components o~ the terrestrial magnetism ' ~ - being directly and separately obtainable. To each o~ exciting ; ~ coils there is applied an alternating signal. In this case, X
,, .
; and Y components of the output are separately obtained, so that there is no need to change the reference sine wave into sine or ~' cosine, and the same effect heretofore is obtained by keeping it all the time in the same place as the input and letting its frequency be twice the exciting frequency. In the embodiment ~,73~

above, the output from the detecting coils 130a and 130b are connected to the switch 19 suc'n that the output difference among magnetic field vector detecting devices is obtained by calculation after digital conversion. However, it will be possible to make the difference in the state of anolog signals and then, to transmit it to the switch 19.
~ rom the foregoing explanation, it will be ully understood how X and Y components of the horizontal geomagnetic component force is obtained by the apparatus according to the invention. However, the horizontal and vertical geomagnetic component forces are different from place to place, so that upon making the present invention work it is required to cor-rect it. Such correction can be made, as explained in the ; foregoing paragraphs, by means of comparatively simple arith- -metic operation.
When no~malized X and Y components (where Y/X = con-~ stant and X2~Y2 = 1) of the vectors in the direction of the ; moving object progression are calculated through the above-men-tioned procedure, the coordinates of the moving object are at~ained by multiplying said each component by the running distance for a short time which are obtained through the revo-lutisn detecting device. In the same way, the height o~ the moving object can be obtained by using the inclination value in the back and forth direction. Further, the deviation of the inclination detecting device in the direction of gravity accel-eration, which is caused by acceleration, deacceleration or turning of the moving object, may be corrected by calculatiny the change of distance pulse number with respect to the time (acceleration in the back and forth direction) and also calcu-].ating the product oE the speed and the directional change in progression with respect to the time (acceleration in the right and left direction).

,. , ,~.

~;

,.
'; , ; ,...
`

~;

~; .. , - 44 -,

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for determining the positional co-ordinates of a moving object comprising:
a plurality of magnetic field vector detecting devices each having a rotary magnetic piece and a fixed coil, said detecting devices being disposed in spaced apart fixed relationships to each other;
an inclination detecting device for detecting the inclination of said magnetic field vector detecting de-vices relative to a vertical direction;
a distance detecting device for detecting the dis-tance that the moving object has travelled during a par-ticular period of time; and arithmetic means which received output from said mag-netic field vector detecting devices as well as from said inclination detecting device, calculates the horizontal component force vector of the geomagnetic field by using said output from said magnetic field vector detecting de-vices and from said inclination detecting device, further calculates the vector in the progress direction of the moving object referring to said horizontal component force vector,, and integrates the product of said vector in the progress direction and the output from said distance de-tecting device, whereby the positional coordinates are ob-tained as the output of said arithmetic means, and co-ordinates which have initially been set at an arbitrary point are replaced by the newly determined coordinates when turning to the right or left is carried out at said arbitrary point correctly as ordered.

2. Apparatus according to claim 1, wherein each said coil of said magnetic field vector detecting device is disposed around the rotary axis of its corresponding rotary magnetic piece such that the magnetic flux density in the magnetic piece becomes maximum with respect to the magnetic field vector within a plane perpendicular to said rotary axis, and said coil is provided with such a cross section that becomes maximum within the maximum cross section of said magnetic piece but its contour does not extend out of said maximum magnetic piece cross section.

3. Apparatus according to claim 1, wherein the rotary magnetic piece of each magnetic field vector de-tecting device is alinged along the rotary axis of a motor which is synchronizingly rotated by means of a synchronizing circuit comprising signal extracting means for extracting a signal having pulse widths corresponding to the difference between the reference input signal and the rotary phase of the motor, signal detecting means for detecting means for detecting a signal having an amplitude corresponding to the rotational speed of said motor, an amplitude control circuit which varies its output in compliance with the result of comparison between the output of said signal detecting means and a reference voltage, and a multiplying circuit for de-veloping a pulse signal corresponding to the product of the pulse width obtained by said signal extracting means and the amplitude of the output signal developed by said amplitude control circuit, whereby said motor is synchronizingly driven by the pulse signal, the amplitude of which is changed in response to the rotational speed of the motor and the pulse width of which is varied in compliance with the difference between the reference input signal and the rotary phase of the motor.

4. Apparatus according to claim 1, and further comprising a motor for rotating said rotary magnetic pieces, the rotary magnetic pieces of said magnetic field vector detecting devices being disposed in series along the rotary axis of said motor, said apparatus having an angular position detecting device for detecting the rotated position of said rotary magnetic pieces, said angular position detector comprising a rotary plate disposed along the ro-tary axis and having a slit provided therein, light emit-ting and receiving elements which are disposed at both sides of said plate so as to face to each other, a circuit for performing peak detection of the output from said light receiving element, a circuit for generating a reference voltage in response to the output of said peak detection circuit, and a level slice circuit for performing a level slice operation in respect of the output of said peak detection circuit, whereby the output from said level slice circuit is used as the rotated position information of the rotary magnetic piece for determining the positional co-ordinates.

5. Apparatus accordingly to claim 1, wherein there are provided three magnetic field vector detecting devices.

6. Apparatus according to claim 5 wherein a plur-ality of difference signals are developed from the outputs of said plurality of magnetic field vector detecting devices by setting one of said outputs as a common subtrahend or a minuend to the others, and the magnetic field due to the magnetic body is calculated using the ratio of said dif-ference signal and an arbitrary difference signal, thereby eliminating the influence of the magnetic field on said magnetic body.

7. Apparatus according to claim 1, wherein said arithmetic means comprises a DA converter which receives an analog signal from each said magnetic field vector detecting device as well as a digital signal consisting of the digital value for the crest value of a reference since wave and develops an output proportional to the product of said analog and digital input signals; an AD converter which performs AD conversion by means of integrating the output of said DA converter over a period equal to an integer multiple of said reference sine wave period; and a vector component arithmetic circuit which is adapted to obtain the digital value with respect to the preset phase component vector of the input signal from said AD con-verter.

8. Apparatus according to claim 1, wherein said in-clination detecting device is provided with a magnet and a coil arranged so as to be subject to displacement when inclined, and supplies said coil with an electric current having a direction and magnitude sufficient to eliminate said displacement.