WO2004106149A1

WO2004106149A1 - Palpation system for insertion of windows in vehicles

Info

Publication number: WO2004106149A1
Application number: PCT/ES2004/000248
Authority: WO
Inventors: José Julio MOYA GARCIA; Albert Redo Sanchez
Original assignee: Asm-Dimatec Ingenieria, S.A.
Priority date: 2003-06-02
Filing date: 2004-05-31
Publication date: 2004-12-09
Also published as: WO2004106149A8

Abstract

The invention relates to a palpation system which can be used to determine precisely the position of the body of a car during an automatic window-mounting process in order to optimise the insertion of said windows. According to the invention, the theoretical position of the edges of the insertion zone is pre-determined. The palpation system employs a mechanical sensing device in order to detect the real position of the window insertion zone, measure the deviation between the edge of the real position and the pre-determined theoretical position, and generate correction instructions such that a robot can insert the window correctly. In addition to the insertion of windows, the inventive system can also be used to perform other processes in the assembly line such as, for example, centring the windows, positioning the cab, seats, hub-caps, etc. The invention can also be used in aeronautical and other assembly lines, and to position parts, examine contours and check components.

Description

PALPATION SYSTEM FOR INSERTING CRYSTALS IN VEHICLES

Object of the invention

The object of the present invention is a palpation system capable of determining the position of the body of a car during the automatic glass bonding process in order to perform an optimal insertion of said crystals, thereby performing the correction in position and orientation with respect to a predetermined reference position.

This position determination is made by a first standard measurement of the position of the edges of the insertion zone through a mechanical system, known as a probe. This probe goes to one or certain positions and measures the deviation of the edge with respect to the position of the standard measurement. According to this deviation, the system is capable of generating a correction so that a robot correctly inserts the glass. So it could be said that this system provides a certain ability to "see" the robot to place the crystals.

The palpation system of the invention can be applied not only to the insertion of crystals but also to other processes within the assembly line such as, for example, the centering of the crystals, cab placement, seats, trim, etc. It can also be used in other markets (for example aeronautics) to position parts, recognize contours and verify components.

Background of the invention.

The increasing automation of assembly processes in the production lines of the automobile industry forces the introduction of increasingly "intelligent" systems. It is no longer only wanted that the process be as reproducible and controlled as possible but also be able to adapt to the deviations of the environment that may arise during the assembly process.

An example of this trend is the control of the position of the car body in the automatic glass bonding process. In this process it is required that the glass be placed on the body frame with errors less than a millimeter. The problem is that the bodywork is not always in the same position due to the tolerances and clearances of the transport line, tolerances and welding defects of the bodywork, errors in the assembly of the bodywork, defective stamped parts, etc. These factors can generate a position deviation of about 10 mm.

With a deviation of this magnitude, the process is not automatable in the classical sense of the word, that is, by programming with a robot a series of repetitive and programmed movements, so the insertion process is still carried out mostly manual or semi automatic. This is because these millimeters of deviation can assume that the glass, which in a classic automatic process would always be placed by the robot, does not sit well within the frame of the body.

An automation capable of correcting these discrepancies would mean a reduction in errors that occur with the manual method and a reduction in costs and manufacturing time. Products and technologies begin to exist that allow the robots to "know" exactly where the body is and thus be able to make the pertinent corrections to insert the crystals in the optimal position, correcting the possible errors of positioning of the line and the tolerance of the welding.

"Smart" solutions based on artificial vision have been proposed that allow the robot to "see" where the car is and assess how much the body has moved relative to its reference position. These solutions based on artificial vision have mainly focused on stereoscopic vision.

Artificial vision with lighting with special spotlights of patterns has the weak point in that it is a system very sensitive to ambient light, since one of the tasks of the cameras is to recognize the pattern of light applied on the body and locate it on the body . This light pattern can be blurred by ambient light, which is very difficult to control since it is formed by natural light, which depends on the weather, the season and the time of day, and general lighting systems such as fluorescent , spotlights, etc., which may or may not be on. The result is that these systems are going well if the ambient lighting conditions they are favorable and controllable, but in another case they are systems that do not give the expected results as far as reliability is concerned.

Other artificial vision systems are based on lighting systems with laser sources, which reduces the problem of interference from ambient light. The problem with these systems is their high cost and their eventual danger to maintenance personnel in the inadequate handling of laser beams.

There are numerous and varied commercial devices capable of detecting displacements with excellent resolution and precision, but they have the limitation of detecting these movements only in a longitudinal direction or in an angular direction.

In short, the systems currently used are not capable of generating a reliable correction when there is a deviation in the body position, which is solved with the present invention, which is based on the use of devices that allow determining the position and orientation of a point in space from the measurement of various points in its measurement plane.

Basic description of the invention.

The objective is to obtain a system that is able to determine the position of insertion of the crystals and make corrections in position and orientation with respect to a reference position. This position determination should be done by measuring the position of the edges of the insertion zone with a mechanical system that will be called a probe. This probe must go to certain positions and measure the deviation of the edge from the position determined as a pattern. According to this deviation, the system must be able to generate a correction so that the robot correctly inserts the glass with a maximum overall error of 0.5mm.

The probes are mounted on the flange of a 6-axis robot. A 6-axis robot is constituted by an articulated mechanical structure with a support base to hold the robot to the ground and a flange at the end on which a tool can be mounted. Each of the 6 joints, or axles, is controlled by a servomotor. The set of servomotors, control input / output signals and Power is controlled by a specific electrical cabinet for each type of robot, in which the control unit for programming it also resides.

Contact positioning systems are widely used for the determination of position in 2 dimensions and angle of rotation in what is known as 2 and a half dimensions correction.

Encoders are used to determine the angle of rotation. An encoder is a device with a rotating shaft that incorporates an electronic system that generates pulses as the shaft rotates. These pulses are counted by a special acquisition card and thus the rotation angle can be determined from the pulses per turn of the probe, which is a parameter of the device. Typically, the pulses per turn of an encoder can range from 500 to 15,000, depending on the required angle resolution.

A probe is a mechanical concept that consists of a two-dimensional measuring device capable of determining the position and orientation of a point in space from the measurement of various points in its measurement plane.

The probe is placed on a mechanical structure attached to a robot that takes it to a predefined position where it comes into contact with the contour of the frame to be positioned. Depending on the deviation of at least three points of the edge of the frame from a standard position, the new position and orientation of the frame can be recalculated. These corrections are transmitted to the robot that performs the insertion taking into account this new position.

Basically, a 3D calculation, control and measurement software is developed, in which 3D edge reconstruction algorithms and correction and position optimization algorithms are incorporated. The algorithms are based on the mathematical theorem according to which any change of reference system can be expressed as the composition of a translation plus a rotation. Now, this theorem must be particularized for the palpation system.

A specific communication protocol with the robot is also developed for the control, which by means of the aforementioned algorithms will generate the appropriate corrections. This protocol includes a terminal that includes a screen and keyboard computer which makes it easy and simple to handle the relevant operations, such as the definition of the insertion tool or "TCPI", the calibration of the measuring tool or "TCPM", the definition of the insertion base, the definition of the measurement path and the definition and correction of the insertion path. All of them will be seen in detail in the preferred description of the invention.

Brief description of the drawings.

FIG. 1 shows the conversion of the positioning of the 6 axes (right) to a Cartesian coordinate system (left) using the control unit (center).

FIG. 2 shows the generation of a reference R 'from points P1, P2 and P3, where P0 is the origin of R'.

FIG. 3 shows the displacement of the reference R 'to position R ". To maintain the same relative position between R' and Z, the latter reference must be moved to position Q.

FIG. 4 schematically shows the definition of the insertion tool or TCPI using the calibration table.

FIG. 5 shows the calibration of the probe as a robot tool, and it shows that the TCPI is linked to the robot's flange but cannot be "touched", it is a virtual tool. The coordinate system associated with the probe can be touched since it is associated with the geometry and directions of movement of the probe. The arrow indicates the movement of the robot from the calibration position, in which the TCPI and the reference base overlap.

FIG. 6 schematically shows the definition of the insertion base

FIG. 7 shows the transformation of the readings of the probes to the coordinate system of the TCPI and from this, through the position and orientation of the point, they are transformed to the coordinate system of the insertion base. FIG. 8 shows a perspective view of the probe assembly, where reference is made to the detector support, the rack axis, the gear shaft, the detection cam, the guide, the arm plate as well as the upper and lower plates and the motherboard of the probe set.

FIG. 9 schematically shows the approach of the probe of the second preferred embodiment, in which the detection movement is intended to be directly associated with the movement of the encoder in order to eliminate hysteresis.

FIG. 10 shows the measurement model of the probe of FIG. 9.

FIG. 11 has two views (front and top) of the probe used in the second preferred embodiment of the present invention in the resting state.

FIG. 12 is a flow chart of the program that runs on the CPU and it shows the measurement process as a succession of more basic processes. The robot takes the initiative and the PC, or is in a waiting state, or responds to the robot's requests confirming it conveniently.

FIG. 13 is a flow chart of the program running on the CPU and it shows the process of selecting a base. If the previous processes are correct, the PC responds to the robot's new requests, otherwise the robot reaches a maximum timing and the general process must be restarted from the beginning.

FIG. 14 is a flow chart of the program running on the CPU and it shows the process of measuring a point. It is necessary to keep in mind if the point that has been measured is the last one or not, since in case of being the last one it is necessary to leave the measurement loop and make the correction request.

FIG. 15 is a flow chart of the program running on the CPU and it shows the request of the correction robot generated by the PC based on the probe readings on the measurement points. Preferred embodiment of the invention.

The palpation system consists of a six-axis robot, probes and specific software that, through algorithms and transformation functions, is able to determine the position of the insertion of the crystals and perform the correction in position and orientation with respect to a previously predetermined reference position.

For a better understanding of the present invention, basic concepts about the movements of a robot will be described below, in which, by means of the control unit, a conversion of the positioning of its 6 axes to a Cartesian coordinate system takes place.

A 6-axis robot is constituted by an articulated mechanical structure with a support base to hold the robot to the ground and a flange at the end on which a tool can be mounted. Each of the 6 joints, or axles, is controlled by a servomotor. The set of servomotors, control input / output signals and power is controlled by a specific electrical cabinet for each type of robot, in which the control unit for programming it also resides.

The movement is done by synchronizing the rotation regime of each of the six axes that make up the robot. These six axes form a set of independent parameters, within the mechanical limitations, that allow to position and orient an object subject to the robot's flange and that correspond to the 6 parameters that determine the orientation (Euler's angles) and position (translation ) in a Cartesian reference system. The robot performs, through the control unit, the conversion between one type of reference and the other. As we can see in FIG. 1 there is a correspondence between the parameters of the robot (A1, A2, A3, A4, A5, A6) and the definition of a point in a Cartesian system with the parameters of position (x, y, z) and rotation (A , B, C).

Basically, the function of a robot is to move a tool attached to it in a defined path by means of specific points referenced with respect to a base. Consequently, the basic elements of a robot, as far as movement parameters are concerned, are bases, tools and points. The bases, tools and points store information about the position and orientation allowing the joint operation of the three elements in the programming of the trajectories.

A base is a Cartesian reference system that, once defined, remains fixed in space regardless of the robot's movements. Basically, every robot has three types of bases:

• Universal coordinate system: it is a fixed and unique coordinate system in one place (it does not move with the movement of the robot), and it serves as a generic coordinate system for an installation (robot, tool for receiving a piece, tool , etc.). In this way, it serves as a common Cartesian coordinate system for both the robot system and also for the peripherals of the installation. This system is also often called the robot world.

• Robot coordinate system: it is a unique coordinate system that is located at the base of the robot and serves as a reference coordinate system for the mechanical structure of the robot. This reference system cannot be redefined and is determined by the manufacturer. Normally this system matches the universal coordinate system.

• Base coordinate system: defined on a fixed workstation in the installation and used as a reference system for the description of the position of the workpiece. The position and orientation parameters of this base are referenced on the universal coordinate system. This makes it possible to associate a trajectory with a base of this type and process several identical pieces to work in different places, with the same program, moving the base to the reference position of the work station of the piece. Several systems of this type can be defined.

The tool coordinate system is a coordinate system that moves with the robot as it is defined fixed to the robot flange. This reference system is also often called TCP (from the English tool center poinf). At least the flange itself is defined, which cannot be changed and is determined at the factory. From it you can define more depending on the number of tools to handle. The position and orientation parameters of the tools that are programmed refer to the TCP of the flange.

The paths are made by interpolation between previously programmed points. This interpolation can be of different types, the most common being the point-to-point, linear and circular interpolation. The information saved by a point is the position and orientation of a particular tool with respect to a specific base, that is, each point has a TCP and a base associated. It does not make sense to define points in the space if it is not specified which tool will be positioned and from which base this position and orientation will be taken.

As stated above, the object of the present invention is to provide a system capable of determining the position of the body of a car during the automatic glass bonding process by performing the correction in position and orientation with respect to a reference position. default

Mathematical algorithms allow these corrections to be made by relating the position of different points in space through formulas since the points in space can be defined in position and rotation with respect to different reference systems.

Mathematically, a reference system with three points that are not aligned can be determined. For this it is necessary to first have an initial reference system on which to reference these points. In FIG. 2 a reference system is determined from three non-aligned points P1, P2 and P3 that we could associate with the above mentioned standard points with respect to an initial reference system Z that we define as the insertion base.

Suppose now, see FIG. 3, which has the orientation and position of a system R 'with respect to Z, or what is the same the standard measurement points with respect to a predetermined reference system that we have called the insertion base. Consider now that each of the three points that determine the R 'system undergoes a displacement that is measured by the system tools or probes, and that they form a new set of three points. These three new points determine another reference R ''. The objective is to determine a new reference Q such that the position and relative orientation of R "is the same as that between R'and Z. The palpation system of the invention will provide the robot with the vector c and the orientation (A, B, C) of Q with respect to Z, so that it can be applied on the insertion base and thus correct the insertion path that had been predetermined in the event that points P1, P2 and P3 did not have displacement.

Once the basic concepts on the movements of a robot have been described, the coordinate systems on which the trajectories of the movements of its flange are referenced and the determination of the reference base according to the deviation of the measurement points, are defined then the parts that make it possible for these measurements to be reliable and fast.

The palpation system of the invention consists of the following parts: • Reference and calibration tool.

• A series of robot adjustment and calibration procedures.

• A probe or mechanical positioning device 2d.

• Control application and communication with the robot.

The reference tool is very important as it allows defining the parameters of the insertion tool (or TCPI) that will be used in a repeatable way. This is necessary in the case where the work tool suffers a collision or breakage and a new one must be installed if the current one cannot be repaired. It is also useful to periodically verify that the tool maintains the geometry since there may be cases of mismatches due to the loosening of screws and fasteners over time. In some way this tool is like a negative mold of what the manipulation, measurement and insertion tool or spider has to be.

As stated, the TCPI is defined to ensure that the insertion is always performed with the same relative position between spider and crystal. For this, a reference base is defined on the calibration table, as shown in FIG. 4, which will always be the same for subsequent recalibrations.

Once this reference base is defined, the calibration process of the insertion tool or TCPI can be started. What is intended is to define position and orientation of the reference base such as the position and orientation of the TCPI when it is calibrated, that is, it will be forced that the position and orientation of the TCPI with respect to the base of the robot or the world is the same as that of the base of reference, or in other words, that the TCPI and the reference base coincide in the reference position. The steps to follow are:

a) The tool is positioned in such a way that the position of its clamping cups is established above the position determined by the calibration table. b) Once the tool is placed in the correct position on the calibration table, the position and orientation of the tool with respect to the reference base will be displayed. c) Once these coordinates are available, the corresponding mathematical equations will be applied to obtain the coordinates of the reference base with respect to the tool, which will define a

"TCP", which we call TCPI.

As you can see in FIG. 5, the TCPI is linked to the robot's flange but cannot be "touched", it is a virtual tool. Unlike the coordinate system associated with the probe, it can be touched since it is associated with the geometry and directions of movement of the probe. The arrow indicates the movement of the robot from the calibration position, in which the TCPI and the reference base overlap.

Once the TCPI is defined, the probe position and orientation are programmed as if it were a robot tool, so the position and orientation parameters will be referenced with respect to the robot flange. The tool may have more than one probe, in which case the position of each one must be calibrated.

A probe is a 2d measuring system, so it is necessary to define very well the orientation of its own XY measurement axes with respect to the robot flange axes as well as a suitable origin. Having the position = (x _p , y _p , z _p ) and the orientation (A _p , B _p , C _p ) of the probe with respect to the robot flange, any displacement reading referenced from the probe to the coordinate system of the flange by expression: ü - t + S Υü 'PP

Being ü 'the probe reading from its own coordinate system, ü that corresponding to the coordinate system of the flange and S is the rotation matrix of the coordinate system of the probe relative to the coordinate system of the flange.

Once the readings are taken from the robot's flange, they can be transformed to readings from the TCPI by the expression: υ tcpí == S t „cpí ^• ( ^β - ^F * _*

W _TCPI and S _TCP I being the position and orientation of the TCPI determined as discussed above.

In this way, all the readings of the same probe (or of the different probes that there might be) can be referred to the same coordinate system: that of the TCPI.

Once the TCPI has been defined and the measurement tool has been calibrated, the insertion base and measurement points must be defined. Although it is not necessary, it is advisable to define a base on the framework to be corrected in order to facilitate the identification of the measurement points and better interpret the corrections provided by the system, which will be given with respect to this base.

The bases are always defined with respect to the world of the robot. To define the insertion base, (it can also be called insertion or zero insertion pattern), the TCPI is referenced with respect to the world and moves to the position that is considered a standard or zero position. The parameters (X, Y, Z) and (A, B, C) obtained must be memorized by the robot and by the calculation application. The program automatically retrieves these parameters from the robot if it is in calibration mode, as shown in FIG. 6. On this basis, at least three measurement points must be defined in order to apply the above and related to FIGS. 2 and 3. More points could be defined to make a better position adjustment by means of optimal adjustment algorithms, but this would be recommended for parts that deviate greatly from the flat geometry.

The position and orientation of these points will be referenced with respect to the insertion base and will correspond to the position and orientation that the TCPl will take in each of them. To program them, the probe must be taken to each of the points to be measured and note the position and orientation of the TCPl with respect to the insertion base.

Once the insertion base and the TCPl have been defined, the measurement process can be carried out, which serves both to define the standard position and for the successive measurements of the deviations from it.

The process is the following:

1. The TCPl is moved to the position and orientation defined by the measurement point / ^' . > 2. The probe reading ü 'referenced with respect to the probe's own coordinate system is obtained.

3. This reading is transformed to the TCPl reference system and it is transformed to that of the insertion base (see FIG. 7) by means of the position and orientation parameters corresponding to the measurement point (as defined in the previous section). Mathematically this is expressed with the following relation: m (, i) m (rj irU ^ tcpl ppt pt) where p _{m (¡)} is the position indicated by the probe reading on the measuring point / ^' with respect to the insertion base , ϊ _{m (i)} and S _{m (i)} the position and orientation of the measuring point with respect to the insertion base and the other parameters have already been defined above.

4. Once you have at least the positions of three points each as described in the previous paragraph, it is possible to apply the above in the points related to FIGS. 2 and 3 and find the reference Z and Q of the standard measurements and insertion measurements respectively. The system corresponding to the zero position measurement is called TCPC

Once the standard position has been determined, it is possible to determine the deviations of the successive positions by taking the probe readings on the measurement points as reference reading and applying the corrections generated on the insertion base.

The insertion path must always be referenced using the corresponding insertion base and the TCPl as a tool. Once this path is defined on this base, it will remain linked to it, so if the base moves, the path will move with it. This is precisely what the correction will do: it will move the base as necessary for the insertion of the crystals to adjust to the new position of the body. For this, what the system will do is follow the position of the TCPC, always measuring on the defined measurement bases.

Once the mathematical fundamentals have been described, and the tool calibration and measurement method, as well as the definition and correction of the insertion path, we will go deeper into the tool or probes used in the present invention to determine the position of The points to measure.

As mentioned earlier, a probe is generically described as a device that is capable of determining a position by physical contact with the object to be positioned. For the system described here it is necessary to determine the position of the edge to be measured in a coordinate system of at least 2 dimensions. This coordinate system must be associated in some way with the geometry of the probe movement.

The first system that can occur to one is an XY system in which the two axes of motion correspond to the coordinate pair. In this XY system, one of the axes slides over the other with a relative rotation of 90 °. Both have a linear movement that determines the measurement range. Each of these axes is associated with one of the XY coordinate axes. The concrete design is as follows: FIG. 8 shows the probe used in a first preferred embodiment where a support plate (1) can be seen where the probe is attached to the robot's flange, the two longitudinal carriages (2, 4) mounting one above the other at 90 ° by the displacement mechanism (3) and the encoder (10) associated with the longitudinal carriage (2) having a cylindrical shape. Although not shown in the figure, because it is hidden, the other longitudinal carriage has another encoder associated. These encoders are rotary and have 2500 pulses per turn, so that linear movements are converted to rotary movements by means of a rack system.

The pulses of the encoder movements are sent to the Control Unit to calculate the position of the point being measured.

The measurement process is initiated by the robot, which, through its flange conveniently attached to the probe, moves the contact cam (6) until it touches the predetermined point. The contact cam (6) is made of plastic so as not to damage the body, but in addition the probe has a damage protection system based on an inductive sensor (11) associated with a stopper tongue (12) and an inductive sensor (7 ) associated with another hidden tab (not shown in the figure). The function of these inductors is to detect metal objects at a certain distance, and if the minimum threshold distance has been reached, the movement is stopped by sending a signal to the control unit.

Once the cam (6) has contacted the body, the robot takes said cam (6) to the standard position of that point since said position is obtained and memorized when the calibration process was performed. This last movement is transmitted from the cam (6) to the aluminum extender (5), and from this to the longitudinal carriages (2) and (4). The movement of the carriage (2) is transmitted by the toothed guide (8) to the axis (9) of the encoder (10) which will send the appropriate impulses to the Control Unit. The movement of the carriage (4) is transmitted by a toothed guide (not shown) to the axis (not shown) of its corresponding encoder (not shown) by sending said encoder the appropriate impulses to the Control Unit.

FIGS. 9 and 10 show a second preferred embodiment of the probe, in which the detection movement is directly associated with the movement of the encoder with the aim of eliminating the hysteresis produced by the zipper of the probe of the first embodiment.

FIG. 9 shows the approach of the second preferred embodiment of the probe As already stated the objective of this design is to eliminate hysteresis of the rack system and also reduce the dependence of the volume on the path. This set consists essentially of:

• A rod of length L that determines the position of point W. This rod revolves around the axis O 'a certain angle Φ with respect to the Y axis of the system. • A rod that determines the angle of point C and T respect the axis OY. This angle is Ψ.

• A reference system O with the X axis aligned with the two rotation axes corresponding to the two positioning rods. These axes are separated a distance D.

FIG. 10 shows the measurement model of this second probe design in which points (Ti) are determined in the plane and the direction of the edges (Wi) with respect to the reference points (Pi). The points W1, W2 and W3 determine a plane π _P and the points Ti belong to said plane and are the points that are located on the edge of the frame to be positioned; therefore, these points will be the ones that will be used to determine the reference to follow. The coordinates of these points must be passed to a common reference for all of them, since the parameters of the probes are given in their own coordinate system. To measure these parameters, the origin O of the probe will be placed on the points Pi.

Mathematically, both the equation of the plane π _P and the equations of the lines that pass through the points Pi and Ti can be calculated. Starting from the fact that the points Ti are at the intersection of said plane with said lines, we will easily have the coordinates of the three points Ti and once these points Ti can be determined the standard reference and the specific reference in a given position of insertion. As stated above, the palpation system of the invention will provide the robot with this data to apply the appropriate corrections on the insertion base and thus correct the insertion path that had been predetermined in the event that the T ^ points T ₂ and T ₃ had no displacement. FIG. 11 shows the front and top views of the probe of the second preferred embodiment that makes measurement possible according to the theory set forth in the preceding paragraphs and related to FIGS. 9 and 10. In it you can see the support plate (21) that serves as a connection with the robot's flange, the contact rod (22), called L in the theoretical explanation of FIG. 9, which moves over the car body by means of a wheel (23) and rotates on the axle (24) to transmit its movement to the encoder (25). You can also see the measuring rod (26), called T in the theoretical explanation of FIG. 9, which has two possible movements, one vertical and the other rotating. The vertical movement of the measuring rod (26) is done so as not to damage the car body by exerting slight pressure with the spring (27), which is held by the head of the spring (28). The rotation movement is done when it reaches the edge of the body and transmits it via the axis (29) to the encoder (30). Like the probe of the first preferred embodiment, the probe of the second preferred embodiment has protective mechanisms such as induction detectors (31) and (32), located in the detector holder (33), and the cams of position (34) and (35) of induction detectors.

The speed with which the measurement and insertion process is carried out is an important factor since productivity depends on it. The measurement data is sent from the robot to a control unit integrated in a PC in which, using specific software, the appropriate corrective calculations are performed. Once these calculations are ready, the PC sends the appropriate commands to the robot to correct the insertion path.

Without going into much detail, the robot-PC communication procedure will be described below. In these processes the robot acts as a master and the slave PC, that is, the robot is the one who takes the initiative and tells the PC what to do. This is done by sending service request messages or SROs which are answered with acknowledgment messages or ACK. The robot waits for this confirmation for a limited time or timing after which it considers that there is an error if no response has been received. The messages involved are: • SRQ: request • ACK: recognition

• STM: start of point measurement or process start.

• BSI: insertion base selection.

• COR: correction request. • NOK: process not OK.

• EOT: end of transmission

The flow chart shown in FIG. 12, shows the general process that includes a series of chained procedures. These procedures will be described in more detail in the following figures. When the robot is above the measurement start point, it sends the request request for measurement (SRQ_STM) to the PC, which is in the waiting state. The PC must answer before a certain time that it has received the measurement start request, responding with the ACK_STM command in which it will include data on the basis and points to be measured; otherwise, if the timing expires, the robot interprets that the PC is busy and must start the process again. If the PC has responded with the above-mentioned ACK_STM command, the robot performs the actions of Base selection, measurement of programmed points and after the measurement of the last programmed point it will request the PC to correct the trajectory. Meanwhile, the PC has been in the waiting state to receive the data from the robot each time one of the sequential operations it performs is completed. If, on the other hand, the PC does not answer before the timing that it has received the measurement start request with the ACK_STM command, an interrupt appears that indicates to the robot that the request has not been answered SRQ_NOK generating a new command to the PC ACK_NOK which puts it on hold.

The flow chart of FIG. 13 shows the process of selecting a base. If the previous processes are correct, the PC responds to the robot's new requests, otherwise if the timing expires, the general process must be restarted from the beginning. The diagram shows that when the PC responds with the recognition command to the request of the measuring start robot, the robot then makes the request for parameters of a certain base B (SRO_BSI), and as we saw before, if the timing does not expire, the PC will send the appropriate parameters with the ACK_STM command so that the robot is positioned at measuring point # 1, and if the timing expires, as we saw before, a interruption that indicates to the robot that the request has not been answered SRQ_NOK generating a new command to the PC ACK_NOK that puts it in a waiting state.

The flow chart of FIG. 14, shows the process of measuring a point P of the base B. Once the PC has responded with the base parameters the robot enters the process of measuring points, for which it sends the command <SRQ_STM to the PC > B / P request for measurement of point P of base B, in which it sends to the PC the reading of the probes made at that point. If the timing does not expire, the PC will send the correct ACK_STM data reception command so that the robot continues with all the programmed points until it reaches the last one, in which case it will request the correction. If during the whole point measurement process the timing expires, the SRQ_NOK command that produces the ACK_NOK command to the PC which puts the PC in standby state and the robot itself in the end of measurement state will be generated as previously seen .

The flow chart of FIG. 15, shows the request process by the robot of the correction generated by the PC based on the readings of the probes on the measuring points. If all the programmed points have been measured without any incident, the robot sends the correction request command <SRO_COR> to the PC, which produces the correction calculation in the PC by applying the appropriate mathematical formulas to the data acquired during the process. Once the PC has calculated the correction, it returns the correction recognition command <ACK_COR>, which includes the parameters for position correction X, Y, Z and rotation correction A, B, C. From here the robot saves the data that it will use in the insertion, generates the command of end of transmission to the PC <SRQ_EOT> and is in the state of end of measurement. On the other hand, the PC when receiving the end of transmission command is in the waiting state. If during the entire correction request process the timing ends, the SRQ_NOK command that produces the ACK_NOK command to the PC which puts the PC in standby state and the robot itself in the end of measurement state will be generated as previously seen .

Having sufficiently described the nature of the present invention, as well as a preferred embodiment thereof, it remains only to add that both its form as the materials and execution of the same, they are susceptible to modifications, as long as they do not substantially affect the characteristics claimed below.

Claims

1.- Palpation system for the insertion of glass in vehicles, which is capable of determining the position of insertion of the crystals on the body structures of automotive vehicles, characterized in that said system is formed by:

- a reference and calibration tool, which determines the parameters of the insertion tool to be used in a repeatable way, allowing the process not to change even if the work tool suffers a collision or breakage and a new one must be installed ;

- a procedure for adjusting and calibrating a robot, which determines the position and orientation of the formerly said probe that is a tool of said robot, whereby the position and orientation parameters of said probe will be referenced with respect to a flange of said robot ; a probe or mechanical positioning device 2d, which measures the position of some standard points on which a standard reference system is defined, as well as the points at which the vehicle body is actually located to define a real reference system; and - a control and communication application with said robot, which receives the measurement data of the probes through said robot and calculates, applying mathematical algorithms, the modification of the pattern insertion path of the crystal, which it sends to said robot so that it makes an exact insertion of the glass even when the vehicle is not in a standard reference position.

2. Palpation system according to claim 1, characterized in that said probe is essentially formed by:

- a support plate (1) that joins the probe to said flange of said robot;

- a first longitudinal carriage (2) and a second longitudinal carriage (4) mounted one above the other at 90 ° by means of a movement mechanism (3), with a first encoder (10) associated to the longitudinal carriage (2) by a first guide toothed (8) and a second encoder associated with the longitudinal carriage (4) by means of a second toothed guide, a contact cam (6) which in conjunction with an aluminum extender (5) transmits the position data to said encoders so that these by means of impulses disclose said position to a control unit; and - a first inductive detector (11) associated with a first stopper tongue (12) and a second inductive detector (7) associated with a second tongue, said detectors and tongues allowing the protection of the bodywork of said automotive vehicles.

3. Palpation system according to claim 1, characterized in that said probe is essentially formed by:

- a support plate (21) that joins said flange of said robot; a contact rod (22), which moves over the car body by means of a wheel (23) that rotates on the axle (24) to transmit its movement to the encoder (25); a measuring rod (26), which has two possible movements, one vertical and the other rotating, the vertical movement of said measuring rod (26) being allowed by the spring (27) which is held by the spring head ( 28), while said rod performs the rotation movement upon reaching the edge of the body by means of the shaft (29) which transmits said movement to the encoder (30), said encoders (25) and (30) transmitting said position by impulses to measure a control unit; Y

- Induction detectors (31) and (32) located in the detector holder (33) that associated with respective position cams (34) and (35) allow the protection of the bodywork of said automotive vehicles.