WO2016126173A1

WO2016126173A1 - System for positioning of a pointed tool relative to a wall

Info

Publication number: WO2016126173A1
Application number: PCT/SE2015/000005
Authority: WO
Inventors: Anders Rosenqvist
Original assignee: Teknikpatrullen Ab
Priority date: 2015-02-06
Filing date: 2015-02-06
Publication date: 2016-08-11

Abstract

A system for positioning of a tool assembly (131) including a pointed tool (134), where a tip of the pointed tool extends beyond a wall surface (133), relative to a wall (100) has a pushing means (130) and up to three pulling means (141, 142, 143) connected to the tool assembly. A pushing force from the pushing means forces the wall surface of the tool assembly to be parallel to the wall. If the pushing and pulling means are motorized, a control means (150) of the system can adapt to different geometries of the system by using modes to transform (414, 424) directional and corrective commands into suitable motor commands. The control means can choose and/or suggest (410) modes based upon an estimated geometry (406) using information from an angle sensor (170) and from motor command history.

Description

Title

SYSTEM FOR POSITIONING OF A POINTED TOOL RELATIVE TO A WALL

Technical Field

The present invention relates to systems for positioning of pointed tools relative to a wall with spaces for mortar joint as well as to methods for operating the systems.

Background Art

As part of maintenance of a building, brick walls may have to be restored by repointing the external parts of mortar joints. The repointing process includes the removal of old mortar from spaces for mortar joints, called mortar raking, to a specific depth, and replacing it with new brick mortar. The mortar raking is often performed using a raking tool consisting of an angle grinder combined with a special blade or combined with a special rotating rake pin working like a milling cutter. There exist sole plates that are mounted on an angle grinder and that, together with the brick wall, fairly encapsulate the rotating rake pin and allow for mortar dust removal using for example an industrial vacuum cleaner. One example is the "Black Label safety shield" from Danish Tool Productions ApS, Denmark. There also exist rake pins with peripheral holes to an internal axial channel for the mortar dust removal from Armeg Ltd, U.K.

However, operating such a raking tool is still performed by the operator's hands, leading to a noisy, vibrating and/or dusty working environment for the operator, a problem which today has no real solution. In addition, the operator may need a scaffolding or a hydraulic lift to reach all parts of the brick wall. Scaffoldings and lifts mean increased costs, for buying or renting, for transport of the heavy parts to and from building sites and for assembly and disassembly in case of scaffoldings. Further, since scaffoldings and lifts are heavy, the ground at the building site may be damaged. In addition, limited free space next to the wall may make it hard or even impossible to use scaffoldings or lifts in an efficient way.

US5666939A discloses a concrete saw with an extendable handle for manual cutting of grooves in a substantially horizontal concrete surface beyond the physical reach of the operator. The handle is for shoving the saw along the direction of a groove and for retraction of the saw. The handle can, while not locked, pivot around an axis substantially parallel to the rotational axis of the saw blade. The concrete saw may work, with the handle locked, for manual raking of an extended vertical space for mortar joint if not cutting into the bricks above and below. However, an operator will not be able to rake horizontal spaces for mortar joint without a scaffolding or a lift.

It is possible to use some kind of cascade robot, that is a robot where a number of movable parts are connected in cascade like for example in traditional industrial robots, for positioning a raking tool relative to a wall. However, cascade robots are expensive and heavy, leading to problems with costs for buying or renting, transports of heavy machinery and possible damage to the ground at the building site.

Robots using parallel link mechanisms differ from cascade robots by not having cascade connected parts. Thereby parallel link mechanisms can often be made considerably more light weight and with larger tolerances. The larger tolerances can allow for more cost efficient parts and/or for easy disconnecting, transporting in parts and reconnecting.

Patent publications US 5408407A, US5585707A and US6566834B1 each disclose positioning systems based on parallel link mechanisms. However, the systems disclosed in these publications seem to require encoders that give information on the current length of some or all actuators used. Encoders can be expensive, sensitive to mortar dust and/or subject to periodic maintenance and/or cleaning. The systems also require known positions on the fixed ends of the actuators. Determining positions of the fixed ends after each relocation of the system (both between and within building sites) may lead to wasting valuable time of the operator and at the building site in general. In addition, in all these systems at least some fixed ends seem to have to be above the positions that are to be visited, which may require the operator to climb the wall or use a lift anyway. The disclosed positioning systems are neither cost efficient nor easy to install.

Patent publication US 5313854A discloses a three dimensional positioning system to which a so called "robotic wrist" (not disclosed) may be added in order to get a "six degree of freedom robotic manipulator". Six degrees of freedom involves a great number of possible expensive and heavy actuators and also creates the problem of how to observe, by the operator and/or assisted by the positioning system, the raking tool in all six degrees of freedom and to generate appropriate feedback signals. The resulting "robotic manipulator" is neither a cost efficient nor an easy to operate positioning system.

There is thus a remaining need for a cost efficient, easy to operate, easy to transport and install and operator friendly system for a positioning of a raking tool, or some other pointed tool, relative to a wall.

Summary of Invention

It is an object of the present invention to overcome all or at least some of the remaining problems of above. The object is achieved wholly or partly with an arrangement according to claim 1 and its dependent claims.

More specifically the invention relates to a system for positioning of a pointed tool, such as a raking tool, relative to a wall, where the wall has spaces for mortar joint. The positioning system comprises a sole plate with a wall surface, a first connection for fixing a pointed tool to the sole plate, resulting in a tool assembly including the sole plate, the first connection and the pointed tool where at least a tip of the pointed tool extends beyond the wall surface. A joint with at least one degree of freedom connects the tool assembly with one end of a pushing means. When the tip of the pointed tool is situated in an empty space for mortar joint, a pushing force from the pushing means on the tool assembly can force the wall surface of the tool assembly to attain an attitude substantially parallel with the wall at the empty space for mortar joint and the tip of the pointed tool to attain a dependent attitude.

Up to at least three pulling means may be connected to the tool assembly. The other ends of the pushing and pulling means can be connected to fixed reference ends which together with the position of the tool assembly define a geometry. The pushing and pulling means may be motorized. The system may be controlled by an operator and/or a control means. The control means can adapt to different geometries, by using modes that can depend on the geometry and/or the directional commands that are generated by the operator and/or the system. The modes are used to transform both directional and corrective commands into motor commands that are adapted to the current geometry, making the system both easy to operate and efficient to use.

The control means can choose modes based upon estimates of some parameters of the geometry. The control means can in turn estimate these parameters based on information from a cost efficient angle sensor that is robust to mortar dust and from motor command history. The control means does neither need knowledge of the current overall lengths of the pushing/pulling means nor of the positions of the reference ends, making the positioning system cost efficient and easy to install.

The geometry of the tool assembly and its connections may be designed with respect to improved stability and to improving the precision of the parameter estimates. The pushing means can be made light weight and the pulling means can be based upon light weight ropes or wires, further contributing to a system that is cost efficient and easy to transport and install. The positioning system may be combined with a vacuum cleaner for mortar dust removal which improves the working environment for the operator.

Brief Description of Drawings

Fig. 1 shows an overview of a positioning system according to the present invention;

Fig. 2 is a combined mechanics and electronics system overview;

Fig. 3 shows a region of Fig. 1 on a more detailed level;

Fig. 4 is a flow chart of a general method for controlling a positioning system according to the present invention;

Fig. 5 illustrates some angles in a positioning system according to the invention;

Fig. 6 defines some angles in a positioning system according to the invention;

Fig. 7 is a flow chart of an angle estimation method according to the present invention;

Fig. 8 shows a cross-section of a part of a window opening together with some parts of a positioning system according to the invention;

Fig. 9 is a flow chart of another method for controlling a positioning system according to the present invention; and

Fig 10 shows some parts of a positioning system according to the present invention that may be controlled by a method according to Fig. 9.

Description of Embodiments

The invention is described more fully hereinafter with reference to the

accompanying drawings, in which examples of embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. It should also be noted that these embodiments are not mutually exclusive. Thus, components or features from one embodiment may be assumed to be present or used in another embodiment, where such inclusion is suitable.

Fig. 1 shows an overview of a positioning system according to the present invention together with a wall 100 having a door 1 10, a window 120 and some spaces for mortar joint 102, 104, 105, 106 and 108. A Cartesian coordinate system (xyz) is included. Fig. 1 further shows a pushing means 130 acting on a tool assembly (not denoted) via a joint 140. The tool assembly comprises a pointed tool (not denoted), a connection (not shown) which connects the pointed tool to a sole plate 132 and the sole plate. The sole plate and at least a tip of the pointed tool may be in contact with the wall 100. Fig. 1 also shows possible pulling means 141, 142 and 143. The pushing means 130 and the possible pulling means 141, 142, 143 can be used for positioning the tool assembly including the pointed tool and the sole plate 132 as will be described in more detail below. The pushing means can be a motorized telescopic pole. The pulling means can be ropes or wires that are wound around cylinders that are revolved using for example torque limited geared electric motors. The pushing means and pulling means may be connected to reference ends 144, 145, 146 and 147. Connections 161 and 162 are examples of connections between pulling means and the tool assembly. Other possible variants are given below.

The pointed tool can be a raking tool, a nozzle for an industrial vacuum cleaner for cleaning raked spaces for mortar joint, a mouthpiece for watering of raked spaces for mortar joints, a mouthpiece for repointing spaces for mortar joint with fresh mortar or other possible pointed tools. Below, the pointed tool will most often be assumed to be a raking tool. Positioning of the other variants of pointed tools relative to a wall is similar to positioning a raking tool but probably easier due to less tool induced vibrations and smaller forces between tool and wall. Common to the pointed tools are that they comprise a tip that during most phases of the positioning should be positioned inside some already raked space for mortar joint in some wall. The pointed tools are not necessarily delivered together with the rest of the positioning system.

Some possible details of the positioning system have been omitted in Fig. 1 and are instead shown in other figures below. All parts shown in Fig. 1 do not necessarily have to be present in every embodiment of the present invention, as will be described in connection with the embodiments below.

Fig. 2 shows a combined mechanics and electronics system overview.

The tool assembly 131 of Fig. 2 comprises a pointed tool 134 which is shown to be connected to sole plate 132 using connection 160. The tool assembly 131 may further comprise an angle sensor 170, a tilt sensor 172 and a vibration sensor 176. The pointed tool 134 of Fig. 2 comprises a motor 136 and a rake pin 138. Further in Fig. 2, the sole plate 132 is shown to be connected to pulling means 141, 142, 143 using connections 161, 162 and 163 respectively. Still, each of the pulling means can be connected to the tool assembly through the sole plate 132, the pointed tool 134, the joint 140 or the connection 160. Some examples are given below. The pushing means 130 is shown to be connected using the joint 140. The number of pulling means in possible embodiments of the present invention may be between zero and at least three. In addition, Fig. 2 shows optional encoders 180, 181, 182 and 183, that may exist in order to provide the control means 150 with possible additional information on for example the current overall lengths of the pushing and pulling means respectively. An optional slope sensor 174 for providing the control means 150 with possible additional information on the inclination of the pushing means may also exist. Sensors, motors and pushing/pulling means are connected, directly or indirectly, to the control means 150. Additional blocks in the overview in Fig. 2 can be an operator input/output means 152 and optional blocks for external communication and control 154 and vision system 156. Some other sensors 158 may also exist. All parts shown in Fig. 2 do not necessarily have to be present in every embodiment of the present invention, as will be described in connection with the embodiments below.

Pushing means, tool assembly and contact between sole plate and wall

Figures 3A-D show a region of Fig. 1 on a more detailed level. The details shown are not the same through A-D. In Fig. 3B a part of the wall 100 is shown together with the tool assembly (not denoted), joint 140 and pushing means (not denoted) from the left. The tool assembly includes sole plate 132, wall surface (the part of the sole plate in contact with the wall), the motor (not denoted) and rake pin 138 which is a tip of a pointed tool. An example of the center of gravity 139 of the tool assembly and the joint 140 is also shown.

Fig. 3C shows, from above, that the rake pin 138 is situated in a locally empty space 104 for mortar joint which extends to the right of the rake pin. In other words, the mortar joint to the right of the rake pin is free from mortar. It may already have been raked. To the left of the rake pin, there is a space for mortar joint 105 which still contains mortar.

Through Fig. 3 A-D it may be assumed that there is a pushing force from the pushing means 130, acting via joint 140 on the tool assembly. The pushing force can be split in components along x, y and z. If the joint 140 is, for example a ball joint with negligible friction, it cannot transfer torque but force only and in a stationary state that force can then only be directed along pushing means 130. If no torque is transferred, pushing means 130 can be made slender and use a low amount of material and thus be both cost efficient and have low mass. The lack of torque may also make a stability analysis simpler to perform. There may exist other ways of getting a torque free pushing means 130 than requiring the joint 140 to be a ball joint.

Fig. 3B and 3D differ regarding where the joint 140 is situated. In Fig. 3D the joint 140 is situated immediately above the center of gravity of the tool assembly 139. The way the pushing means 130 is directed in Fig 3 A-D, a pushing force along the pushing means can affect the tool assembly with one force component to the left (in the negative x direction), one upwards (in the positive z direction) and one towards the wall (in the positive y direction). In addition there may be forces from the wall via the wall surface of the sole plate 132 and via rake pin 138. There may also be gravity forces.

The positioning system may attain a state of equilibrium with balanced forces and balanced torques where the wall surface of the sole plate 132 attains an attitude substantially parallel with the wall 100 and consequently, where the tip of the pointed tool, i.e. the rake pin 138 in this embodiment, attains an attitude in the locally empty 104 space for mortar joint depending on the design of the connection (not shown) between sole plate and pointed tool.

One possible way of balancing the forces is to combine enough force from the pushing means with a design with angular stability. Angular stability can be achieved by letting the joint 140 be situated along the axis of rake pin 138 and simultaneously letting the center of gravity of the tool assembly be situated a bit off the axis of rake pin 138. The tool assembly will then strive to attain an angle at which the center of gravity is some distance below the axis of rake pin 138. Enough force from the pushing means 130 exists when the upwards component of the pushing force is approximately greater than the total gravity force of the tool assembly and the joint 140. Since friction between the wall 100 and the wall surface as well as forces between rake pin 138 and wall 100 may exist, it is an approximate principle. With the tip of the pointed tool in a locally empty space for mortar joint, the tool assembly is hindered from moving in most of the xz plane and together with the friction between the wall and the wall surface and a suitable direction of the pushing forces from the pushing means, the tool assembly is in a state of balanced forces.

In order to achieve balanced torques, the tool assembly should not tip over the boundary of the sole plate in any direction. The distance from the joint 140 to the wall surface relative to the distance from the center of gravity 139 to the wall surface and the size and shape of the wall surface are some parameters that have an influence on the tipping stability. The direction of the pushing forces from the pushing means is another parameter to consider.

General positioning method

Fig. 4 shows a flow chart of possible steps of a general method 400 for controlling a positioning system according to the present invention. As will be indicated by the description of different embodiments below, each step of the method 400 in Fig. 4 does not necessarily have to be performed in each possible embodiment of a positioning system according the present invention. In addition, the activities of a certain step of the general method 400 may depend on the embodiment.

A simple embodiment

In a really simple preferred embodiment, a human operator may operate a positioning system by holding one end of a pushing means 130 made of a sufficiently long, possibly telescopic, pole and perform steps as follows. At step 402 the tool assembly has already been placed with the rake pin in a locally empty space for mortar joint and the method can start. At step 404 the operator powers up the raking tool, perhaps by flipping an electrical switch on a power cable leading to the raking tool. At step 406 the operator estimates the geometry, which in this embodiment is the geometric relation between the tool assembly and the pushing means, for example by estimating the direction of the pushing means by sight.

At 408 the operator may think of a direction for raking and make that a mental directional command.

Step 410 has no particular meaning in this embodiment, since there is only one means for affecting the tool assembly.

At step 412, the operator may consider quitting.

If so, the raking tool can be powered down at step 416 and the method comes to its end at step 418.

If not, the method proceeds with step 414 where the operator considers how the directional command can be transformed into suitable motor commands to the operator arms and legs etc. In this embodiment the operator has only the pushing means 130 available for motor commands. If the directional command corresponds to going to the left, the operator can assign a force component to the left and at the same time remember to assign force components upwards and towards the wall that are suitable for keeping the wall surface of the sole plate in contact with the wall and for not tipping the sole plate over. If the directional input corresponds to going to the right, the step is similar except from that there should be a force component to the right instead. If the directional input is upwards or downwards, there is no use for any force component to the left or to the right. There should still be a suitable force component towards the wall, while the upwards force component minus the force of gravity of the tool assembly 131 and the joint 140 should be a little positive for going upwards and a little negative for going downwards. Then the operator can transform the assigned force components into a suitable combination of a pushing force along the pushing means and angles that determine the direction of the pushing means.

At step 420 the operator applies the combination of pushing force and direction to the pushing means by means of the operator arms and legs etc.

At step 422 the operator evaluates the result of the current motor commands by estimating any needs for corrective commands. The tool assembly may be on its way in a slightly unwanted direction, on its way of tipping over, a little to low in a horizontal space for mortar joint etc. When the rake pin is raking to the left in a horizontal space for mortar joint, the tool assembly will easily sink relatively to the space for mortar joint. The operator can detect the sinking, by sight or possibly by hearing the rpm or load of the motor change when the rake pin approaches a brick at the lower part of the horizontal space for mortar joint, and react by

extending/raising/pushing the operator end of pushing means 130 upwards.

At step 424 the operator can transform the estimated needed corrective commands to corrective motor commands.

At step 426 the operator can apply the corrective motor commands to the current motor commands.

Step 428 has no particular meaning in this embodiment, since most operators will in principle be watching the tool assembly constantly and thus proceed with step 406. The method will loop until steps 416 and 418 have been performed. While the method is looping, the operator will now and then decide to change the direction of the raking in order to rake all the joints of the wall.

The pushing means only positioning system of this embodiment can improve the working environment with respect to noise, dust and vibrations, but it still uses the muscles of the operator. Also, the operator may stumble and fall while walking around with a powered tool on a long rod. In addition, operation close to a window or a corner of the building may result in the tool assembly falling out of control.

A motorized embodiment

Another preferred embodiment that minimizes the need for moving the lower end of pushing means 130 around and which may improve the stability during operation close to a window, door or corner, will now be described. In this preferred embodiment at least one pulling means, for example in the form of a rope or wire, with an adjustable overall length, has been added.

A possible geometry, which in this embodiment is the geometric relation between the tool assembly, the pushing means and the at least one pulling means, can be like when the pushing means and the pulling means are placed with respect to the tool assembly like in Fig. 1. The pushing means 130 and possible pulling means 141, 142 and 143 each have a reference end, 144, 145, 146 and 147 respectively. The reference ends can be relocated for modifying the geometry but they serve as fixed end points for each means between relocations. The pulling means and pushing means are motorized, where motorization can mean that the overall length, from the reference end to the other end, can be adjusted according to commands from the control means 150.

The reference ends 145 and/or 146 of pulling means 141 and/or 142 are preferred to be close to the wall 100 in the y direction. In the z direction it is advantageous to have the reference ends for pushing and pulling means low, that is lower than all of the desired z positions of the tool assembly. Although an operator may control each motorized pushing and pulling means directly using dedicated controls, a more general control method 400 of Fig. 4 will now be described.

Steps 402 and 404 can be performed like for the previous embodiment.

At step 406 a possible control means 150 may estimate at least some parameters related to the geometry. Fig. 5 illustrates some possible parts of a positioning system in an x-z plane together with some angles in the positioning system. In Fig. 5, the wall 100, the locally empty space for mortar joint 104, the space for mortar joint 105, the pushing means 130, the tool assembly 131, the pulling means 141 and 142 and the reference ends 144, 145 and 146 have been mentioned above. The angles v_p, v_l and v_2 in Fig. 5 are shown in a case when rake pin 138, joint 140 (not denoted) and connections 161 and 162 (not denoted) are all on the same axis along the y direction, which is a special case, which is referred to as the one point approximation below. In addition, the angle sensor reference line 171 (dashed) is identical to the vertical direction (the z direction) in Fig. 5, which is also a special case. More general definitions of v_l and v_2 are given in connection with Fig. 6 below. In Fig. 5 there are dashed lines from reference ends 144, 145 and 146 to a point marked "CPA". At the "CPA" the tool assembly is at its Closest Point of Approach relative to the reference end 144 of the pushing means 130. At the "CPA" in Fig. 5, the angle v_p is zero and the pushing means is at its shortest overall length, for a given height of the joint. At the "CPA" angles v_l and v_2 attain values that may be denoted vl cpa (not denoted) and v2_cpa. These values are also dependent on the height of the joint. Angle sensor 170 is shown to be on top of the tool assembly 131 as an example.

In a motorized positioning system, parameters v_l and/or v_2, defined in Fig. 6A and Fig. 6B respectively, may be estimated automatically, that is without involving the operator, by a control means 150, if present, using an angle estimation method according to the steps of the flow chart of Fig. 7.

At step 700 in Fig. 7 the angle estimation method may start.

At step 702, the estimation is prepared for by putting/having the tool assembly in a position where the rake pin 138 is hindered, by a mortar joint and/or a brick, from moving in a direction in which a pulling means is about to pull. Fig. 6A shows a tool assembly 131 and dashed lines indicating that the rake pin 138 has recently been raking to the left or downwards along the wall. In Fig. 6A the rake pin is hindered from moving towards the reference end 145 by the part of the mortar joint that has not been raked yet. This position is good for estimating v_l . If v_2 is to be estimated, as situation like in Fig. 6B is preferred. It can be advantageous, but not necessary, to temporarily stop the motor of the raking tool in order to minimize the interaction of motor induced torques and/or forces on the sole plate and/or to stop the tool assembly from moving.

At step 704, the inactive pulling means, which is pulling means 142 in case v_l is to be estimated and pulling means 141 in case v_2 is to be estimated, is made loose if not already so.

At step 706, the active pulling means, that is the one of pulling means 141 and 142 that is not the inactive pulling means, is activated in order to line up rake pin 138, the connection 161 or 162 of the active pulling means and the active pulling means itself, like shown in Fig. 6A and 6B respectively.

At step 708, the method may check that the line up of step 706 is in an equilibrium, for example by shaking the sole plate a little using the pushing means 130 in order to overcome the friction between the wall surface and the wall more easily.

At step 710, the method may determine an estimate a est of the angle a (alfa), which is the angular deviation, around the y direction, of the angle sensor reference line 171 from the vertical direction (the z direction). The angular deviation in Fig. 5 is thus zero. The angle a (alfa) is shown in Fig. 6A and 6B and may be estimated by the angle sensor 170 which is shown together with angle sensor reference line 171 in Fig. 5, 6A and 6B. The angle sensor 170 can be based upon an accelerometer. The control means 150 may convert the readings from angle sensor 170 to angles if necessary. At step 712, an estimate of the current value of v_l or v_2 may be computed using the expressions v_lest = w_l - a est or v_2est = w_2- a est respectively. These expressions can be derived from Fig. 6A and 6B respectively. Angles w_l and w_2 are fixed and known by design.

At step 714 the estimation method may end.

Due to the principle of line up used in steps 706-710 and the way the estimates are computed, the estimates of angles v_l and v_2 will, within reasonable limits, not depend on where connections 161 and 162 are situated within the tool assembly. The estimates of v_l and v_2 will behave as if connections 161 and 162 were placed according to the one point approximation defined above. Having the center of gravity of the tool assembly and joint 140 some distance away from an axis through rake pin 138 improves angular stability like described above, but if the distance is too large, the line up may require large pulling forces.

The estimation method of Fig. 7 may perform better when rake pin 138 and joint 140 are on the same axis substantially along the y direction, since it simplifies rotation of the tool assembly and thereby the line up. For a general pointed tool this may correspond to that the joint 140 is located along an axis through the tip of the pointed tool and where the axis is substantially perpendicular to the wall surface around the tip. Since there is probably a hole in the wall surface around the tip, the axis can also be defined to be substantially perpendicular to an imaginary wall in contact with the wall surface. The line up of the estimation method of Fig. 7 further benefits from a joint 140 with at least two degrees of freedom.

It may even be possible to perform some angle estimation or angle supervision during raking, provided that the interaction of motor induced torques and/or forces on the sole plate 132 is small.

The control method 400 may also keep track of whether the tool assembly is to the left or to the right of the "CPA", which can be quite easily performed, since the pushing means attains its minimum length at the "CPA". It is not necessary to have information on the absolute length of the pushing means in order to do this.

At step 408 of method 400 in Fig. 4, a directional command is received by the positioning system from an operator input/output means, from another means of the positioning system and/or from some source external to the positioning system. The directional command may be generated by a vision system. In case an operator uses a joystick with a two dimensional output, the dimension having the command with the currently largest absolute value may be considered as the directional command and the command of the other dimension may be saved as a corrective command for use in a later step. Thereby the operator may not necessarily have to think separately about directional and corrective commands. It may also be possible to use a joystick output as a two dimensional directional command, see step 414 below.

Modes

Having one pushing means and at least one pulling means provides the positioning system with at least two substantially independent means for generating forces on the tool assembly. With two independent means, it is, for many geometries, possible to choose between at least two alternatives, called modes below, when transforming a directional command into motor commands. The operator may prefer to think in up/down (z direction) and left/right (x direction) but, depending on the geometry, the pushing and pulling means seldom act purely along one of the x or z directions. Using modes is a way to make the positioning system easier to use for a human operator. Modes can be used as rules for how to transform directional and corrective commands to motor commands that are optimal or at least suitable with respect to the geometry.

At step 410 a mode may be chosen. The mode can be chosen by the operator, using some switch, lever or input menu of the operator input/output means 152. The mode can even be as simple as the state of a purely electromechanical system of switches that provide connections from a joystick outputs to the drive electronics for the thereby selected motorized pushing and pulling means. The input menu can present possible modes in a preset order or in some order of recommendation based on decisions taken by the control means 150. The mode can be chosen automatically by the control means 150, but perhaps be possible to override by the operator. The control means can base its recommendations and choices on estimates of some or all the angles that are shown in Figure 5, i.e. v_l, v_2, (v lcpa), v2_cpa and/or v_p. Using modes, the operator may, for example, not have to think of which motorized means that currently is the best for forcing the tool assembly to the left in a horizontal space for mortar joint. If the tool assembly 131 is positioned close to the "CPA" like in Fig. 5, that is the tool assembly is close to the reference end of the pushing means 130 in the x direction, there is only a small, or even no, possible pushing force component from the pushing means on the tool assembly along the x direction. However, with the tool assembly still close to the CPA, the pulling means 141 will be able to generate a pulling force in the negative x direction (to the left). Similarly, the pulling means 142 will be able to generate a pulling force in the positive x direction (to the right). The pushing means can still generate a strong pushing force component in the z direction and can therefore be used by corrective motor commands, that is for correcting substantially perpendicular to the direction of raking. For this geometry a mode (called "Horizontal, close to CPA" below), that transforms directional commands left and right into pulling with pulling means 141 and 142 respectively. The thereby inactive pulling means can be ordered to pull with a limited force, low enough for the active means to still be in control of their own overall lengths but high enough to prevent the inactive pulling means from becoming too loose.

As the tool assembly moves further and further to the left of the CPA the direction of the pulling force from the pulling means 141 will change gradually to more and more vertical. When the tool assembly is positioned close to "L" in Fig. 5 in the x direction, there will only be a small, or even no, possible pulling force component from the pulling means 141 on the tool assembly in the x direction. However, meanwhile, the direction of the pushing force from the pushing means will have changed gradually to more and more to the left. During such a move, it may therefore be advantageous to switch mode from the "Horizontal, close to CPA" mode to a mode (called "Left at L" below) that uses the pushing means for generating force to the left when the directional command is left and the pulling means 141 for corrective motor commands. The inactive pulling means can still be handled like above.

The mode "Left at L" may begin to become more suitable than "Horizontal, close to CPA" when the tool assembly comes closer to "L" than to "CPA". This

corresponds, at least approximately, see Fig. 5, to abs(v_p) becoming larger than abs(v l) which is approximately the same as tan(abs(v_l)) divided by

tan(abs(v_lcpa)) becoming lower than 0.5. The latter two expressions may be derived from Fig. 5. The approximations are mainly due to the one point approximation. The expressions may be modified before implementation. In use, estimates of the angles can be plugged into the expressions. It is possible to reuse an estimate of v lcpa from a nearby height and update the estimate at the next CPA passage. However, if the tool assembly has not passed CPA since the last relocation or if the estimate of v lcpa was made at completely different height, reuse may not work well, the raking may progress slower due to suboptimal generation of forces on the tool assembly and the user may want to change mode manually until next time CPA is passed.

I may be good practice to start raking close to the CPA after a relocation and to pass CPA soon. If the operator has relocated parts of the system without alerting the control means, the relocation may still be detected due to sudden changes in estimates of v_l and v_2.

However, raking to the right when being close to "L" may require a mode of its own (called "Right at L") where the pulling means 142 can be used for forcing the tool assembly to the right (according to the directional command) and where the pushing means can be used for corrective motor commands. Going to the right when the tool assembly is far to the left of "L" in Fig. 5. may however result in geometries where large forces are needed from both the pushing means and the pulling means 142 in order to make the tool assembly move to the right. The positioning system may even become unusable or unstable. It may therefore be better to relocate the positioning system than raking far to the left of "L" (and/or far to the right of "R").

Modes like "Right at R", "Left at R" and expressions for when "Right at R" may be more suitable than "Horizontal, close to CPA" can be derived in a similar way, for example by using symmetry and substitution.

For vertical raking upwards it may be useful to have at least two different modes. The pushing means can generate an upwards force on the tool assembly, but at the same time it will generate a force component along the x direction, unless the tool assembly is exactly at the CPA. It may be advantageous to rake the vertical spaces for mortar joint using an upward raking direction, since the mortar dust may thereby fall away faster from the rake pin, which may prolong the life of the rake pin.

One mode (called "Up L" below) may be suitable when the tool assembly is to the left of the CPA. Mode "Up L" can use the pushing means for generation of an upwards force on the tool assembly and use pulling means 142 for correction by balancing a suitable force from pulling means 142 with the force component along the x direction from the pushing means. The pulling means 141 may be inactive and handled accordingly. A mirrored mode (called "Up R" below) may be designed accordingly using symmetry and substitution. If the control means 150 has kept track of whether the tool assembly is to the left or to the right of the CPA, the operator can be assisted in the choice between "Up L" and "Up R" With a cleverly chosen (probably by the operator) geometry of the positioning system, a short horizontal distance ( in an already raked joint) between displaced vertical joints can probably be handled as a correction without necessarily having to temporarily change to another mode.

When raking close to a window, a door, a corner of the wall or the like, it may be harder to prevent the sole plate from tipping over, since parts of the wall surface 133 of the sole plate 132 may not be in contact with the wall 100 and can, accordingly, not support the tool assembly. An extra large sole plate that provides support across a window or a door is a possible solution, but it does not solve the corner situation and it may be impractical.

In Fig. 8 a cross-section of a part of a window opening 120 is shown from above. Raking is performed towards the window and the positioning system may be in mode "Right at L" meaning that pulling means 142 is pulling down/to the right while the pushing means 130 is pushing up/to the left/towards the wall. In Fig. 8 the rake pin 138 is almost at the window and the remaining mortar in the space for mortar joint 105 (not raked yet) is almost non-existent. In order to lower the risk of the tool assembly tipping over around point "T" and into the window, the tool assembly of Fig. 8 has been designed to provide the pushing means with a longer lever around "T" than the lever of pulling means 142 around "T". The relation between these two levers will depend on the geometry and will therefore not only depend on the design of the tool assembly, but one possible way is to design the tool assembly with a distance between the wall surface 133 and joint 140 that is a "lever factor" times the largest of the distances between the wall surface 133 and the connections 161 and 162 respectively. The "lever factor" may be just above one, but since it is possible to put connections 161 and 162 very close to a thin sole plate 132 and since the joint 140, for other reasons, see "supported flight" below, may be quite a distance away from the wall surface 133 anyway, the "lever factor" can easily be two, three or even higher. By distance it is meant the perpendicular distance from a flat wall surface and the perpendicular distance from an imaginary wall in contact with a non-flat wall surface. The distances are meant to be to the geometrical center of joint 140 and connections 161 and 162, i.e. to the points involved in defining the corresponding lever. Thereby, provided that the geometry results in a sufficient pushing force from the pushing means to the left on the joint 140, tool assembly 132 will not tip over around point "T" and the parts of wall surface 133 that are in contact with the wall will prevent the tool assembly, and other parts, from falling into the window. Thus the mode "Right at L" may be used for a situation like in Fig. 8, but it may have an alias name like "Right towards window" and pulling means 141 and 143 may be used as well to prevent the tool assembly from tipping and/or falling into the window. It may be good practice to choose a geometry where the window edge is clearly on the side of the CPA. As an additional feature, choice of the "Right towards window" mode or its "Left towards window" counterpart may also result in the control means 150 supervising the rpm and/or load of the motor 136 and inhibit the pulling force when the supervision indicates that the rake pin 138 has removed all of the remaining mortar from the space for mortar joint 105 (not further described).

Modes for vertical raking downwards can work similarly to "Up L" and "Up R" with a balance between the forces from the pushing means 130 and from at least one of the pulling means 141 or 142. The force of gravity of the tool assembly 131 and the joint 140 is now in the desired raking direction.

Additional modes are possible, for example for mortar joints that are neither horizontal nor vertical. Generally, it is also possible to define modes that use a combination of forces from pulling means 141 and/or 142 and pushing means 130 in order to generate a force according to the directional command and to generate a corrective force by adjusting the proportions in said combination. Also, it is possible to directly use a two dimensional directional command from an operator to determine the combination.

In connection with choice of mode, the control method 400 may, based upon for example the estimated angles, notify the operator that there is no suitable mode and thus that it may be time for relocation of at least some components of the positioning system.

At step 414 the method may transform the directional command to motor commands according to the current mode. For example, if a mode like "Horizontal, close to CPA" has been chosen, directional commands to the left are transformed to motor commands to pulling means 141 while directional commands to the right are transformed to motor commands to pulling means 142. The inactive one of pulling means 141 and 142 is preferred to be handled like inactive pulling means have been handled above. It is also possible to scale the directional command with respect to the geometry when it is transformed to motor commands. For example, the pulling means 141 can generate a pulling force in the x direction on the tool assembly which is proportional to the sine of v_l . Thus, with the tool assembly at CPA in Fig. 5, the control method may scale the motor command to pulling means 141 with a larger factor compared to when the tool assembly is closer to "R".

Some modes, like "Left at L", may only work for directional commands to the left and not respond to motor commands to the right. Like described above, the user or the system may have to use the mode "Right at L" to allow for directional commands to the right, unless there is mode "at L" that uses for example "Left at L" when the directional command is to the left and "Right at L" when the directional command is to the right.

At step 420 the motor commands from step 418 are applied to the pushing and pulling means.

At step 422 a corrective command may be received and/or estimated by the method. The corrective command can, for example, be determined by the operator, estimated by an estimation method using some sensor input and/or received from some source external to the positioning system. The sensors involved may be image sensors, tilt sensors and vibration sensors.

An early indication of the raking pin 138 being a little out of line may be a visual indication like from the operator's vision, from a video camera showing a close up to the operator or from an image analysis (vision) system analyzing a video stream from a camera. However, the view from where the operator is situated may be obstructed by the pointed tool and by other objects in the positioning system. In addition, a video camera may be too expensive and, if it exists, its image quality may be degraded by mortar dust and vibrations from the raking process. These possible early indications may provide information on both the direction and amount of the correction needed. Other early indications may be a change in motor rpm, in motor sound and/or in the vibrations from the motor when the rake pin 138 is deviating from the middle of the space for mortar joint and approaches a brick. If the motor is rpm controlled the controller can be designed to monitor the load, which will increase when the rake pin is approaching a brick. Rpm and/or load supervision may also be used for detecting that the rake pin is worn out and needs replacement and/or that the rake pin is on its way into free air (at a window, door or corner). A vibration sensor 176 may be of the type used for knock detection in turbo engines or the type used for sound pickups in guitars. The frequency spectrum from the vibration sensor 176 can be designed by the choice of sensor and/or by signal processing. Possibly, vibration signals may be extracted from a tilt sensor 172 or an angle sensor 170.

Unfortunately, these other early indications do not give full information on the direction and amount of the correction needed.

However, at least for the "Horizontal, close to CPA" mode, it is possible to make forecasts of the direction of the correction needed. For this mode, when the raking is in the direction towards the CPA the overall length of the pushing means will become too long if not corrected and when the raking is in the direction away from the CPA it will become too short if not corrected. Therefore, at least in this mode, the other early indications can indicate that it is time to correct and the direction of the correction can be chosen according to the forecast. The amount of the corrections can be kept small in order to not correct too much and thereby risk the validity of the forecast of the direction.

For a mode like "Left at L" it may be harder to make valid forecasts of the direction to correct in, since the height of the rake pin in the space for mortar joint may not only depend on the corrections made with pulling means 141 but also on the force of gravity, the geometry and how easily the mortar is removed by the raking tool. If the early indications are not responded to, there may be additional indications later on. At least when raking in horizontal spaces for mortar joint using the

"Horizontal, close to CPA" mode, the tool assembly may begin to tilt around the x direction as an indication of the overall length of the pushing means being too short or too long. The tilt sensor 172 may thus provide a direction of the correction needed. The progress of the raking may also slow down or even stop. Since the signal from a tilt sensor should vary when the tool assembly is following the attitude of a slightly uneven wall, the control method may instead look for sudden changes or obvious trends in the tilt. The control method may assign a limit, determined by the extension of the pointed tool through the wall surface of the sole plate and the size of the wall surface, to the tilt in order to prevent the pointed tool from falling out of the space for mortar joint and simply shut down the operation and/or alert the operator.

It is possible to combine a corrective command from the operator with a corrective command estimated by the control method 400. Thereby, the user may apply supervising and/or fine tuning corrective commands upon the commands of the control method, for example when passing a crossroad of mortar joints.

At step 424 the method may transform the corrective command to corrective motor commands. The transform can result in absolute motor commands for those motorized pushing and pulling means that, according to the current mode, are used for corrective commands only or result in changes (called delta commands below) in motor commands for motorized means that according to the current mode may be used for directional commands as well.

At step 426 the corrective commands are applied to the motorized pushing and pulling means either as absolute commands or delta commands like described for step 424. However, a corrective command may not immediately restore a lowered rpm of the motor 136, since the rake pin may have to force its way through neglected mortar before finding the middle of the space for mortar joint again.

At step 428 the method determines if it is time to (re-)estimate the geometry. A software timer may be used for periodical visits to step 406. The overall length of pushing means 130 may be supervised, and if it attains a minimum, a CPA passage may be declared followed by a visit to step 406. In addition, if parts of the positioning system have been relocated, step 406 should be visited.

Supported flight

The tool assembly can be moved without having the pointed tool in an empty space for mortar joint, using a method, see Fig. 9, that can be called supported flight.

During supported flight, some parts of the sole plate are still in contact with the wall 100 like in Fig. 10, giving stabilization by friction to movements of the tool assembly along the x and z directions. One preferred embodiment for supported flight is shown in Fig. 10. The center of gravity 139 of the tool assembly and the joint 140 is to the right, along the y direction, of the joint 140. Thereby, and provided that joint 140 is flexible enough, the tool assembly, including sole plate 132, strives to tilt around joint 140 allowing the upper part of the sole plate 132 to lean on the wall. However, if the tool assembly is allowed to tilt too much, the center of gravity 139 may come too close to the joint 140 along the y direction and the strive for more tilt may cease. Other mechanical designs that, for example, use springs, limiters or even controlled actuators, to generate the strive for tilt and/or to limit the tilt, are possible. A pulling means 143 is connected using connection 163 with one end in, or close to, joint 140. Thereby the pulling means 143 does not directly affect the tool assembly but only indirectly through movements of joint 140. Connecting pulling means 143 in this way may create stable working conditions for a supported flight control method of Fig. 9, which will now be described.

At step 902 of the method of the flow chart of Fig. 9, supported flight is prepared by removing slack from means 141 and 142 (not shown in Fig. 10) like for other inactive pulling means as described above. Since the rake pin 138 is about to leave the support from the spaces for mortar joint, pulling means 141 and 142 will now have to provide some support along the x direction together with the friction between sole plate and wall.

At step 904 control means 150 estimates the tilt of the tool assembly using information from tilt sensor 172 and compares it to a target value of the tilt. This target value may be a fixed default value for the particular hardware and type of pointed tool and/or adjustable by the user. If the tilt is correct or close enough, the method can proceed at step 908 or else the method will perform step 906 before returning to step 904.

At step 906 the tilt of a tool assembly similar to the one in Fig. 10 may be adjusted by adjusting the position of joint 140 along the y direction, which in turn can be made by adjusting the overall length of pulling means 143.

When the tilt is adjusted, the position of joint 140 and thus the slope of pushing means 130 and the height of joint 140 are affected as well. Therefore there should be some room around rake pin 138 in the vertical direction when adjusting the tilt. "Take off' and "landing" of the supported flight is easiest made in an already raked vertical space for mortar joint and with the tool assembly close to the CPA. At step 908, the control means 150 may receive a command. It can be a go left/right and/or go up/down directional command. It may also be a new target value of the tilt command and/or a quit command. The command can come from an operator, from some other part of the positioning system or from communication with parts external to the positioning system. For example, an image analysis system may provide the command. The command may be unchanged for consecutive laps of the loop in Fig. 9.

At step 910, the control means 150 may adjust pushing means 130, pulling means 141 , 142 and/or 143 according to the command of step 908. If the tool assembly is close to the CPA (recommended) and the command does not involve left/right, it may be sufficient to let the overall lengths of pulling means 141 and 142 passively follow the height of the tool assembly. Such a passive following can be

accomplished by the control means 150 ordering the pulling means 141 and 142 to pull with a limited force, low enough for the pushing means to still be in control of its own overall length but high enough to prevent the pulling means 141 and 142 from being too loose. If the overall length of pushing means 130 is adjusted without any corresponding compensation of the overall length of pulling means 143, the tilt of the tool assembly will for most geometries be affected. The control means may use some forecast of how much the overall length of pulling means 143 should be changed per change of the overall length of pushing means 130 and try to compensate in advance.

Steps 912 and 914 may be implemented similarly to steps 904 and 906. However, if the control means uses a forecast like described at step 910, now may be a good time to adjust the forecast based on the results of steps 912 and 914.

At step 916, the method may quit to step 918 or else it may loop by continuing at step 908. Other methods are possible, which will be obvious to the person skilled in the art of designing positioning systems for pointed tools.

Other embodiments:

Parts of the sole plate 132 that are involved when an operator is observing the progress of the raking can be made thin in order to minimize parallax. The wall surface of the sole plate may partly cover a large area but still have significant holes for observation. The sole plate may have extendable or addable sections in order to increase the supporting area for raking close to windows and doors but still allow for raking in more limited spaces. The sole plate may be prepared for the connection of an industrial vacuum cleaner like some of the sole plates of the prior art. Parts of any encapsulations of the rake pin may be transparent. A camera for a vision system may look through a transparent encapsulation.

A pointed tool for raking may comprise a motor 136 coaxially connected to a rake pin 138, but the connection can also be made through a flexible axle, sprockets or some belt drive.

The first connection 160 may be an integrated part of the sole plate 132 or the pointed tool 134.

There are many possible embodiments of a motorized pushing means 130.

A motorized telescopic pushing means with an overall length that is continuously adjustable over a large span by using a single motor command is one preferred embodiment. Another preferred embodiment is a cascade combination of a motorized continuously adjustable part with a small span like a linear motor or a hydraulic elevator combined with a manually handled extension like a telescopic pole with selectable fixed positions or a mast with extra sections to insert. The overall length can then be coarsely selected by the fixed positions/the number of extra sections (the control means can prompt the operator to act) and continuously adjusted by the motorized part according to motor commands from the control means.

In a preferred embodiment the overall length of the pushing means is fixed between ordered adjustments, that is it is not overly dependent on the force from the tool assembly on the pushing means. Thereby unwanted oscillations of the tool assembly are prevented. However, it is still possible to let the motorized part of the pushing means to strive in the desired direction with a limited force/torque during an ordered adjustment.

In a preferred embodiment the pushing means has bearings at the reference end that allow the slope relative to the z axis and the rotation around the z axis of the pushing mean to easily follow the position of the tool assembly.

There are many possible embodiments of motorized pulling means 141-143 as well. In one preferred embodiment, a pulling means comprises a rope and a motorized spool for winching the rope. The spool can be torque limited, resulting in a force limit on the rope. The torque limit can be adjustable. The rope can run around a trailing wheel on its way from the connection at the tool assembly to the spool. If so, the coordinates of the trailing wheel will determine the geometry and the trailing wheel will act as the reference end. In other embodiments the pulling means can use telescopic poles instead, but rods will probably make the positioning system more complicated and more expensive without adding any obvious advantages. In a preferred embodiment the pulling means has bearings at the reference end that allow the slope relative to the z axis and the rotation around the z axis of the pulling means to easily follow the position of the tool assembly.

The reference end points of the pulling and pushing means can be fixed relative to the ground, to a floor, to a low part of a wall etc. They do not necessarily have to be fixed to something else, the weight of a concrete lump or the water in a ballast tank may do the job. The reference end points may be provided with detectors that can be used by the control means to detect a possible relocation.

The positioning system is dependent on the pushing force from the pushing means, in order prevent the tool assembly from falling off the wall and to the ground.

Therefore it may be important to design a pushing means with built in safety, for example during a potential power failure of the positioning system. However, as long as the tool assembly is pushed against the wall and the pointed tool is supported by a locally empty space for mortar joint, it is probably safe even if a single pulling means breaks or loses power. The control means 150 can be implemented using a microcontroller, an ASIC, an FPGA and/or analog electronics and switches. The microcontroller, the ASIC and/or the FPGA used can be circuit programmable versions.

In addition to geometry estimation methods described above and the sensors that are used for input to these methods, it is possible to also use information from a possible slope sensor 174 and/or a possible encoder 180 in order to estimate more parameters describing the geometry.

By using more information on angles, overall lengths of pushing/pulling means and coordinates of the reference ends, it is possible to design a control means that in its principles of operation resemble the principles used in the prior art. However, determining the coordinates of the reference end points may require valuable operator time. Optional encoders 180, 181, 182 and/or 183 will increase the cost of the equipment and may still be unreliable, for example due to the effect from mortar dust Still, for example if the spaces for mortar joint are not located where expected, the performance of such a system may not be worth the costs.

A camera for a vision system that is mounted on or close to the tool assembly may give parallax free images but result in low image quality due to vibrations and/or mortar dust. A camera may also be mounted a bit away from the wall and allow for less dusty and less vibrated images of larger sections of the wall. The images may be a bit distorted due to the perspective but since the pattern of the spaces for mortar joint may be known to be rectangular shaped the images may be "de-warped" by an image processing algorithm.

The tool assembly may be equipped with a button for manually switching the motor 136 on/off in order to perform manual raking of a first vertical space for mortar joint when the positioning system is relocated.

The positioning system may be transported in parts, for example, the joint 140 and/or connections 161, 162, 163 may allow for the pushing and pulling means to be disconnected from the tool assembly during transport.

It will be appreciated that the foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. As such, the invention is not limited to the specific embodiments provided in the foregoing description and accompanying drawings, but is instead limited only by the following claims and their legal equivalents.

Claims

A system for positioning of a pointed tool (134) relative to a wall (100), the wall having spaces (102, 104, 105, 106, 108) for mortar joint, the positioning system characterized by comprising

a sole plate (132) having a wall surface (133),

a first connection (160) for fixing the pointed tool relative to the sole plate with at least a tip of the pointed tool extending beyond the wall surface resulting in a tool assembly (131) including {the sole plate, the first connection and the pointed tool},

a pushing means (130) and

a joint (140) for joining one end of the pushing means with the tool assembly, the joint having at least one degree of freedom.

A positioning system according to claim 1, wherein the pointed tool comprises a motor (136) and a rake pin (138).

A positioning system according to claim 1, further comprising

at least one pulling means, where each pulling means has one end connected to the tool assembly at connections (161, 162).

A positioning system according to claim 3, wherein the distance between the wall surface and the joint is a lever factor times the largest of the distances between the wall surface and any of the connections (161, 162) and wherein the lever factor is larger than one.

A positioning system according to claim 3, wherein the joint has at least two degrees of freedom and wherein the joint is located along an axis through the tip of the pointed tool with the axis being substantially perpendicular to an imaginary wall in contact with the wall surface.

A positioning system according to claim 3, wherein the pushing means and the at least one pulling means are motorized and each have one reference end.

A positioning system according to claim 6, further comprising a control means 150 that receives (408) a directional command, transforms (414) the directional command to motor commands according to a mode and applies (420) the motor commands to the motorized pushing and pulling means.

8. A positioning system according to claim 7, wherein the directional command is received from an operator input/output means (152).

9. A positioning system according to claim 7, wherein the directional command is received from another means within the positioning system.

10. A positioning system according to claim 7, wherein the directional command is received from an external source (154).

1 1. A positioning system according to claim 7, wherein the control means (150) further receives or estimates (422) a corrective command, transforms (424) the corrective command to corrective motor commands according to the mode and applies (426) the corrective motor commands to the motorized pushing and pulling means.

12. A positioning system according to claim 1 1, wherein the corrective

command is received from a human operator.

13. A positioning system according to claim 1 1, wherein the corrective

command is received from a vision system (156).

14. A positioning system according to claim 1 1, wherein the corrective

command is estimated by the control means (150).

15. A positioning system according to claim 7 or 11, wherein the mode is

received (410) from an operator input/output means (152).

16. A positioning system according to claim 7 or 1 1, wherein the mode is chosen by the control means (150).

17. A positioning system according to claim 1, further comprising a pulling

means (143) with one end connected to the joint using a connection (163).

18. A positioning system according to claim 17, wherein the pushing means and the pulling means are motorized and each have one reference end, further comprising a control means (150) that receives (908) a directional command, adjusts (910) the overall length of the pushing means according to the directional command, checks (912) for correct tilt of the tool assembly and, if not correct, adjusts (914) the tilt using the motorized pulling means.