JP2000176871A - Integrated control system of work support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To comparatively easily match feedback control of a jig for work supporting and control contents of a working means to work on a work with each other. SOLUTION: Respective control contents of a work supporting means 10, a moving means to move the work supporting means, a detection means 12 to detect a current position of the work supporting means, a feedback control means 16 for a work to match a position of the work supporting means with target quantity by outputting a value of a difference between the current position detected by the detection means and the target quantity multiplied by a gain to the moving means, a working means 30 to work on the work supported by the work supporting means, a control means 32 for working to control motion of the working means, a means 14 to detect force working on the work 40 supported by the work supporting means, a means to memorize a position of the work and target quantity of force during the working means works on the work supported by the work supporting means and the feedback control means for the work and the control means 32 for working at the time when the detected position and/or force is different from the target quantity concerning each of them memorized in the above memory means are corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a work station in which a work is supported by a support means such as a work station for performing a welding work on the work, and work such as welding is performed on the supported work. Related to integrated control technology in a system.

[0002]

2. Description of the Related Art Conventionally, when performing a scheduled work for each type of a plurality of types of workpieces, a dedicated work supporting jig is prepared for each type, and the work is carried out using a jig according to the type. After support, I was doing work for that kind, for example welding. Work performed on a work supported by such a work supporting jig is often performed by a robot. When work is performed by a robot, the robot may interfere with the work for some reason. In such a case, if the robot continues to work, a large force is generated between the robot and the work, which may deform the work or destroy the robot. For this reason, there has been a conventional robot provided with a function of issuing a warning to a supervisor when an excessive force acts on the robot for some reason (Japanese Patent Laid-Open No. 7-251394). When such a warning is issued, the conventional control system stops the robot and corrects the control contents of the robot. The reason why the control contents of the robot are corrected when the robot and the work interfere with each other is that it is assumed that the position of the work cannot be shifted using a dedicated support jig.

[0003]

However, in the conventional method in which a dedicated jig is used for each type of work, as the number of types of work increases, more types of jigs for supporting the work are required. In addition to the increased manufacturing cost, the storage space for supporting jigs also increases, which is not efficient. Therefore, a work supporting device capable of supporting a plurality of types of works has been developed. In such a work support device, the work support portion is movable to support works having different shapes by the same device, and the work support portion is moved to a predetermined position according to the type of the work. Work will be supported.

[0004] When a welding gun, for example, approaches a work supported in this way and performs a welding operation, there is a case where a deviation occurs in an approaching position of the welding gun for some reason. In such a case, the welding gun may come into contact with the work at an unintended position, and the work support may be shifted from a predetermined position. The conventional abnormality monitoring technology disclosed in Japanese Patent Application Laid-Open No. 7-251394 uses a phenomenon that an excessive force acts on a robot if an abnormality occurs, assuming that the position of the work does not shift. In a work supporting device in which the work supporting portion is movable so as to be able to support the work, the work supporting portion may move and an excessive force may not act on the robot. Therefore, when trying to apply the conventional robot control system to a work support device in which the work support moves, the rigidity of the work support device itself is increased so that the position of the work does not shift even when an external force acts on the work. There is a need. However, when the rigidity of the work supporting device is increased, the size of the work supporting device itself increases, which causes problems such as an increase in equipment cost and a reduction in the working space of the robot.

[0005] Therefore, as a method of positioning and maintaining a work at a predetermined position without increasing the rigidity of the work support device itself, a position of a work support portion is detected, and based on a deviation between the detected position and a target position, It is conceivable to perform feedback control of an actuator that moves the work support. In such a case, when the work is shifted from the positioning position, the work supporting device pushes the gun back in accordance with the shift, and welding is performed at a position where the force for moving the gun and the force for holding the work in a predetermined position are balanced. Work will be performed. In this case, if the feedback force for holding the work at a fixed position is weak and the force for moving the gun is strong, the work will be performed at a position greatly deviated from the expected position. Conversely, if the force for holding the work in a fixed position is strong and the force for moving the gun is weak, the movement of the gun becomes unstable. If both are strong, a great force is applied to the work, and if both are weak, the work result is not stable. Therefore, considerable man-hours are required to match the feedback force (mechanical impedance) between the work side and the gun side. Also, considerable man-hours are required to harmonize the support position on the work side with the program for executing the work. For example, in the case of a welding operation, if the position of the work is shifted from a predetermined position, the amount of heat to be added may be too large or too small to perform good welding. In this case, a considerable number of man-hours are required to modify the program to make the heat generation amount an appropriate value.

Accordingly, the present invention provides feedback control of a work supporting jig for accurately positioning a work at a predetermined position without increasing the rigidity of the jig itself;
It is an object of the present invention to provide a technique capable of relatively easily matching the control content of a means for performing a work to the work.

[0007]

Means for Solving the Problems In order to solve the above problems, in the first invention of the present application, an integrated control system according to claim 1 is created. In the integrated control system, the integrated control system includes a detection unit that detects an amount related to a current position of the work support unit and a unit that detects an amount related to a force acting on a work supported by the work support unit. Means for storing a target quantity relating to the position and force of the work during the work performed by the work means on the supported workpiece, so that the quantity relating to the detected position and / or the quantity relating to force is stored. Are detected to be different from the respective target amounts stored in the storage means, and when they are different, the control contents of the work feedback control means and the work control means are corrected. That is, since it is detected that the amount relating to the position and / or the amount relating to the force of the work being worked deviates from the target amount, it is first determined that some correction is required. Since the control content of the work means as well as the control content of the work support means is corrected while being detected, the control content of the work support means and the control content of the work means are corrected to match. . Here, the quantity relating to the position means not only the position but also the time differential value (speed) of the position
Or a second derivative of the position. In this case, the work means works satisfactorily while the work moves at an appropriate speed or acceleration. Further, the amount relating to the force may be torque.

In the integrated control system according to the first aspect, the work means is often a moving robot.
For example, when the robot moves the welding gun and performs welding,
The robot is the means of work. In this case, the integrated control system according to claim 2 is particularly useful. In the case of the integrated control system according to claim 2, when it is determined that some correction is necessary based on the amount detected with respect to the position or force of the work, the gain at the time of performing feedback control of the motion of the robot is corrected. Therefore, the impedance of the work means can be corrected so that the position or force of the work does not need to be corrected.

In the integrated control system according to the first aspect, when the work means is a moving robot, the integrated control system according to the third aspect is also useful. In the case of the integrated control system according to claim 3, when it is determined that some correction is necessary from the amount detected with respect to the position or the force of the work, the operation control program for controlling the motion of the robot is corrected. The motion of the robot can be corrected so that no correction is required for the position or force of the work.

The present invention is also useful when the work means does not change its position. For example, when the work means is to add energy to the work, such as when welding with a fixed welding gun,
Inappropriate energy may be detected by a quantity related to the position and / or force of the workpiece.
In the case of the integrated control system according to claim 4, if the occurrence of a state requiring any correction is detected from the quantity relating to the position and / or force of the work, the energy control program is corrected and the position or force of the work is corrected. The energy is corrected so as not to require.

Of course, in these cases described above, it is preferable that the impedance is adjusted by correcting the gain also on the side that performs feedback control of the quantity relating to the position of the work, and the invention of claim 5 is useful. In the case of the integrated control system according to claim 5, since the gain of the work feedback control means is corrected when the detected quantity related to the position and / or the quantity related to the force of the workpiece is different from the respective target quantities. Can be adjusted to an impedance that does not require correction with respect to the position or force.

The invention according to claim 6 is to make the operator perceive occurrence of a situation requiring correction, and warns when the detected quantity relating to the position of the work and / or the quantity relating to the force differs from the respective target quantities. Is added. As a result, the occurrence of a situation requiring correction can be promptly recognized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, according to the present invention, a work support device and a work support device are provided based on the position of a work (the position of a work support means) and the force acting on the work supported by the work support means. This is to correct the control contents of each of the means. The control content to be corrected is the impedance of the work supporting device and / or the work means, and the control program (operation or energy control) of the work means.
In the following embodiment, the impedance is corrected first, and the control program of the work means is corrected when the position of the work and the force acting on the work do not reach the target values by the correction of the impedance alone. And This is because the target value may be obtained only by correcting the impedance without correcting the control program of the work means. However, if the position of the work changes due to thermal expansion due to a large amount of heat input when performing arc welding, for example, the position of the work cannot be corrected even if the impedance of the work means is corrected.
In such a case, the contents of control (energy control program) are corrected without correcting the impedance of the work means.

FIG. 1 shows an embodiment of the present invention.
It will be described based on. FIG. 1 is a drawing showing a system configuration of a work station in which a work supporting device capable of supporting a work at a predetermined position and a work robot are arranged. As shown in FIG. 1, such a work station includes a work support device 10 that positions and supports a work 40 at a predetermined position, and a work robot 30 that works on the work 40 positioned by the work support device 10. Prepare. The work support device 10 and the work robot 30 are respectively a work support device control unit 16 and a work robot control unit 32
Is controlled by Hereinafter, each device will be described in detail.

The schematic structure of the work supporting device 10 will be described with reference to FIG. The work support device 10 includes a work support device control unit 16, an actuator 11 controlled by the work support device control unit 16, a motion transmission mechanism 18 for transmitting the power of the actuator 11, and the power of the motion transmission mechanism 18. And a supporting portion 19 to be transmitted.

The work support device controller 16 has a servo motor controller 13 for controlling the actuator (servo motor) 11 and a correction controller 20 for correcting and controlling the work support device 10 and the work robot 30. The work support device control unit 16 is configured by a general computer, and its configuration is publicly known, so that the description of the specific configuration will be omitted.

In the work supporting apparatus 10 shown in FIG. 2, an electric servo mechanism 17 is constituted by the servo motor 11 and the servo motor control unit 13. However, as such a servo mechanism, a hydraulic servo mechanism using hydraulic pressure or a pneumatic servo mechanism using air can be used. The reason for using the electric servo mechanism in the present embodiment is that there is no need for hydraulic piping or air piping, which is advantageous in simplifying the work supporting device and the like.

The servo motor 11 includes a current sensor 14 for detecting a torque acting on the servo motor 11 based on the current value, and a position sensor 12 for detecting a rotation angle of the servo motor 11. As the position sensor 12, various position sensors such as a potentiometer and an encoder can be used. Here, the torque of the servomotor 11 detected by the current sensor 14 is a force acting on the support 19, that is, a force acting on the work 40. Therefore, the current sensor 14 corresponds to a force detecting means for detecting a force acting on the work. Further, since the position of the support portion 19 is the position of the work 40, the position sensor 12 corresponds to a position detecting means for detecting the position of the work. However, the position detecting means for detecting the position of the work may be a speed sensor such as a tachogenerator. In this case, it is necessary to convert the detected speed into a position by integrating the detected speed.
Alternatively, a load cell or the like can be used as the force detecting means for detecting the force.

The servo motor 11 is controlled by the above-described servo motor control unit 13 so that the support unit 19 is set to the target position based on the value (physical quantity relating to the position) detected by the position sensor 12. Specifically, a command value obtained by multiplying the difference between the position detected by the position sensor 12 and the target position (positioning position) by a certain gain is output from the servo motor control unit 13 to the servo motor 11, and 11 is driven and positioned at the target position. Further, the servo motor 11 converts the position detected by the position sensor 12 into a speed by the servo motor control unit 13 to obtain a difference between the speed and a target speed (a speed 0 at the time of positioning). It is preferable that the motor be driven by a command value obtained by multiplying the difference by a constant gain. The reason why the position is fed back is that when the positioning position is shifted by welding of the work robot 30, the shift cannot be corrected by the open loop control system. Further, it is preferable to feed back the speed in order to give a damping effect to the control system and obtain stability against dynamic input. By adjusting such a gain, the mechanical impedance (rigidity) of the work supporting device can be adjusted.

As the motion transmitting mechanism 18 for transmitting the power of the servomotor 11, a mechanism using gears, a screw nut mechanism, or a mechanism using a belt and a chain can be used. However, the motion transmission mechanism 18 is required to efficiently transmit the power (torque) of the servomotor 11 and have high positioning accuracy. A mechanism using gears has a problem that backlash is large and positioning accuracy is low, and a mechanism using a belt and a chain has a problem in transmission efficiency. Therefore, the work supporting device 11 shown in FIG. 2 uses a screw-nut mechanism. Specifically, a ball screw mechanism is employed. This is because the ball screw mechanism has small backlash and high transmission efficiency.

The support portion 19 is formed with a thread groove which engages with the above-mentioned ball screw (movement transmitting mechanism 19), and is positioned at a predetermined position by rotation of the ball screw. Further, the support unit 19 includes a clamp mechanism that supports the work 40 in a predetermined posture. Examples of such a clamp mechanism include a pin clamp mechanism that inserts a clamp pin into a hole formed in a workpiece and clamps the workpiece, a gauge plate mechanism that clamps the workpiece with a gauge plate that conforms to the shape of the workpiece, and a mechanical hand that clamps the workpiece. Various clamping mechanisms, such as those, can be used.

Next, a schematic configuration of the work robot 30 will be described with reference to FIG. Here, the work robot 30 corresponds to a welding robot for performing spot welding, an assembly robot for assembling a work, a transfer robot for transferring a work, and the like. In a work station that performs spot welding, work transfer, and assembly, the present invention is particularly effective because the work and the work robot come into contact during the work, and an external force acts on the work. Work robot 30
Has a robot main body 31, a tool 34 attached to the tip thereof, and a work robot control unit 32 for controlling the work robot 30. The work robot control unit 32 is configured by a general computer, appropriately calls a program stored in a ROM or the like, and controls the position (posture) of the tool 34 and the like.
It comprises a work robot main body control unit 33 for controlling the movement of the tool and a tool control unit 35 for controlling the movement of the tool. The work robot main body 31 is constituted by an articulated robot whose position and orientation are controlled by a servo mechanism. The servo mechanism includes the work supporting device 10 described above.
Various mechanisms can be used in the same manner as described above. The tool 34 attached to the tip of the work robot main body 31 differs depending on the work to be performed. The tool 34 is a welding torch when performing arc welding, a welding gun when performing spot welding, and a painting gun when performing painting. The tool 34 includes a tool control unit 35
Controls various parameters. For example, in the case of a welding gun that performs spot welding, the amount of heat input (powering time,
The current value), the pressing force and the like are controlled. The work robot control unit 32 and the tool control unit 35 control the physical quantity relating to the current robot position to be fed back, multiplying the difference from the target value by a certain gain, and outputting the result. This is the same as the work supporting device 10.

Next, the operation of the work supporting device 10 and the work robot 30 configured as described above will be described. First, the concept of the control system of the present embodiment will be described with reference to FIG. In FIG. 4, it is assumed that the work robot 30 and the work 40 (work support device 10) are in contact with each other, and a force F is generated therebetween. Here, the mass of the work robot 30 is Ms, the damping coefficient is Ds, the spring constant is Ks, the mass of the work supporting device 10 is Mz, the damping coefficient is Dz, the spring constant is Kz, and the work 40 is
Is defined as Mw. In addition, the target position Yd of the work robot 30 and the target position Xd of the work support device 10 are set, the current position of the work robot 30 is set to Y, and the position of the work support device 10 (the position of the work 40) is set to X. Ideally, the value of the target value Xd of the work supporting device 10 and the work robot 30
The target position Yd is set so that no force acts between the two.
It is assumed that such a deviation has occurred due to the positioning accuracy of the above. The following equations are obtained by formulating the equations of motion for both the jig robot 10 and the work robot 30.

[0024]

(Equation 1)

When this equation is Laplace transformed, the following equation is established.

[0026]

(Equation 2)

As can be seen from this equation, the working robot 3
If the zero and the impedance of the work support device 10 can be adjusted, the position X (S) of the work support device and the force F (S) generated between the work robot 30 and the work 40 (work support device 10) are controlled. be able to. That is, in the control system of the present embodiment, the work supporting device 1
By controlling the impedance of the work robot 30 and the position of the work robot 30, the position of the work support device 10 and the force generated between the work and the work robot 30 are controlled.

The specific operation of the integrated control system of the work supporting device 10 and the work robot 30 according to the present invention will be described below with reference to FIGS. FIG. 5 is a functional block diagram of an integrated control system of the work supporting device 10 and the work robot 30. FIG. 6 is a flowchart showing a procedure of the integrated control system shown in FIG. First, according to the control procedure of FIG.
0 is positioned at a predetermined position, the work robot 30
Performs an operation on the work 40 (S1). At this time, the position of the work support device 10 (work 40) and the force acting on the work support device (work 40) are detected by the position / force detection means 12 and 14 provided in the servo motor 11 (S2). It is determined whether or not the position and force detected by the position / force detection means 12 and 14 have exceeded the set values preset by the evaluation means 21 of the correction control unit 20 (S3). Here, the set value means that the force acts on the work supporting device 10 (work 40) any more, or the work supporting device 10 (work 40)
Is a value that may cause the workpiece support device 10 to break or the workpiece 40 to be deformed, and is input to the evaluation means 21 in advance by the operator. If the detected position or force value exceeds the set value, the warning correction means 23 sends a warning to the servo motor control unit 13 and the work robot control unit 32, and performs servo motor control as described later in detail. The control contents of the unit 13 and the work robot control unit 32 are corrected (S4). That is, the servo motor control unit 1
3 and the work robot control unit 32 stop the operations of the work support device 10 and the work robot 30 based on the warning from the warning correction unit 23. After stopping, the warning correction means 23
As a result, the control contents of the work support device 10 and the work robot 30 are corrected, and the work is started again from the beginning with the corrected control contents. Therefore, the position / force detecting means 12,
Until the position and force detected at 14 fall within the set values, S
Steps 1 to S4 will be repeated.

If the detected position or force value does not exceed the set value, the evaluation means 21 determines whether the detected position or force value is within an allowable value (the amount of deviation from the target value is within an allowable range). Is determined (S5). The permissible value relating to the position (permissible value of the displacement of the work supporting device 10) is previously input to the evaluation means 21 by the operator in accordance with the accuracy required for the work performed by the work robot 30, and the permissible value relating to the force (work The permissible value of the force generated between the work 40 and the work robot 30) is input to the evaluation means 21 in advance by the operator according to the characteristics of the work 40. That is, the permissible value regarding the position is increased in a portion where the work accuracy is not required, and the permissible value regarding the force is reduced when the work 40 is easily deformed, and is increased when the work 40 is not easily deformed. If the detected position and force values exceed the allowable values, the impedance correction means 24 is controlled by the work support device 10 and the work robot 3
The mechanical impedance of 0 is corrected (S6). The method of correcting the mechanical impedance will be described later in detail. The work support device 10 and the work robot 30 continue working based on the corrected mechanical impedance (S
7). In step S5, the detected position,
If the value of the force is within the allowable value, the operation is continued with the same mechanical impedance (S7). Thereafter, it is determined whether or not the work has been completed (S8). If the work has not been completed, the steps S1 to S8 are repeated until the work is completed. When it is determined in S8 that the work has been completed, the control contents such as the mechanical impedance of the work support device 10 and the work robot 30 are taught by the teaching means 22 to the servo motor control unit 13 and the work robot control unit 32 (S8).
9).

Next, the method of correcting the mechanical impedance in S6 and the method of correcting the control contents of the work supporting device 10 and the work robot 30 in S4 in the control flow shown in FIG. 6 will be described in detail. First, the method of correcting the mechanical impedance in S6 will be described using the simplified model shown in FIG. 4 as an example. First, here, it is assumed that the work support device 10 and the work robot 30 are in contact with each other, and the work support device 10 and the work robot 30 are balanced at a position shifted from the target position. A method for correcting the mechanical impedance of the work support device 10 and / or the work robot when correcting the positional deviation of the work support device 10 from this state will be described. Here, the work supporting device 10 and the work robot 30 are assumed to move sufficiently slowly, and are in a state in which speed and acceleration are not considered (static state).
Is assumed. Therefore, the work support device 1 already described
0 and the equation of motion (Equation 1) of the work robot 30 are as follows. Kz (X-Xd) = F Ks (Y-Yd) = F The relationship between the position X and the force F is shown by a solid line in FIG. In FIG.
The horizontal axis is the position X, and the vertical axis is the acting force F. Here, let X0 be the allowable positioning value of the work supporting device 10,
Let Xz be the set value for the position. The allowable value for the force is Fw, and the set value is Fz. In the control system shown in FIG. 5, the acting force F falls within the allowable value Fw and the displacement amount (X-Xd) of the work supporting device 10 falls within the allowable range (X0-Xd). The spring constants Kz and Ks of the work support device 10 and the work robot 30 are corrected. The set values Xz, Fz and the allowable values X0, F
w has been input to the evaluation means 21 of the work support device controller 16 in advance by the operator. However, these values may be appropriately corrected when an abnormality (such as deformation of the work 40) occurs, and it is not necessary to input accurate values from the beginning. In particular, regarding the allowable value Fw of the force acting on the work, since the work station of the present embodiment often handles a plurality of works, it is troublesome to obtain the allowable value Fw of all the works in advance by experiments or the like. Therefore, it is sufficient to input the same value for all the works for the time being, and to correct and learn when an abnormality occurs.

First, F <Fw and X0 <X <X shown in FIG.
The procedure for correcting the mechanical impedance in the case of z will be described. In this case, the force F acting on the work is the allowable value Fw.
As described below, since the position X of the work exceeds the allowable value X0, the spring constant Kz of the work supporting device 10 is corrected so that the position X is within the allowable value X0. In this case, if only the spring constant Kz of the work supporting device 10 is corrected, the force F may exceed the allowable value. Therefore, in the present embodiment, the spring constant of the work robot 30 is also changed so that the force F does not change. Until the force F reaches the allowable value Fw, only the spring constant Kz of the work supporting device may be changed, and after exceeding, the spring constant Ks of the work robot 30 may be changed. That is, the spring constant Kz = F /
(X-Xd), Ks' = F / (Y-Yd) and the corrected spring constant Kz '= F / (X0-Xd), Ks' = F (Y-Yd)
−X + X0).

Next, a description will be given of a procedure for correcting the mechanical impedance when Fw <F and X <X0 shown in FIG. In this case, the value of the force F acting on the work becomes the allowable value Fw.
, The force F acting on the work is reduced to the allowable value Fw.
Must be within. In this case, the spring constants Kz and Ks of the work support device 10 and the work robot 30 are adjusted so that the position X does not change. However, for the same reason as described above, until the position becomes X0, the spring constant Kz of the work supporting device 10 is corrected, and after the position becomes X0, the spring constant of the work supporting device 10 and the working robot 30 is changed. The correction may be made. In order for F to be Fw, the following equation must be satisfied. Kz '(Xd-X) = Fw Ks' (Yd-Y) = Fw Therefore, the corrected spring constant K of the work supporting device 10 is obtained.
Let z 'be Fw / (Xd-X) and the corrected spring constant Ks' of the working robot 30 be Fw / (Yd-Y).

Next, Fw <F <Fz, X0 <shown in FIG.
The procedure for correcting the mechanical impedance when X <Xz will be described. In this case, since both the position X of the work and the value of the force F acting on the work exceed the allowable values X0 and Fw, both must be within the allowable values X0 and Fw. In such a case, first, the force F acting on the work is changed to Fw while keeping the positions of the work robot 30 and the work support device 10 as they are.
To lower. In order for F to be Fw, the following equation must be satisfied. Kz '(X-Xd) = Fw Ks' (Y-Yd) = Fw Therefore, first, the corrected spring constant Kz' of the work supporting device 10 is represented by Fw / (X-Xd), and the corrected spring of the work robot 30 is obtained. Let the constant Ks' be Fw / (Y-Yd). next,
The corrected spring constants of the work support device 10 and the working robot 30 are further corrected so that the position X falls within the allowable value X0. That is, the spring constant Kz "= Fw / (X0-Xd
), Ks "= Fw / (Y-Yd-X + X0).

Next, consider a case where the work robot 30 collides with the work 40 at a constant speed (dynamic problem). What is important in this case is that the force generated at the moment when the work robot 30 collides with the work 40 is applied to the work support device 1.
It is how to control the force F acting on the work 40 by absorbing the impedance by adjusting the impedance of the work robot 30 to zero. This is because after the vibrations have subsided and are in a balanced state, it may be treated as the static problem described above. Therefore, in the control system of the present invention, when the position change is abrupt (for example, when the speed is equal to or higher than a certain value), the spring constant Kz of the work supporting device 10 is reduced, and the spring constant Ks of the work robot 30 is reduced. If the spring constants Kz and Ks of the work support device 10 and the work robot 30 are reduced, vibrations are likely to occur. At the same time, the damping coefficients Dz and Ds are increased.
That is, when the rate of change of the position X of the work 40 with respect to time (the speed of the work 40) is equal to or greater than a certain value, the spring constants Kz and Ks and the damping coefficients Dz and Ds are determined at a constant To change it. Therefore, the force F acting on the work (the force acting on the work support device 10 and the work robot 30) can be reduced, and the deformation of the work 40 and the work support device 10 can be reduced.
In addition, destruction of the work robot 30 can be prevented.
When the change in the position of the work 40 is small, the work support device 1
If the spring constants Kz and Ks of the work robot 30 and the damping coefficients Dz and Ds are kept constant, a static problem occurs after the vibration stops.

Note that, unlike the above-described example, the mechanical impedance may be fixed to a dynamic problem. If the position or the force exceeds the set value, the values of the spring constants Kz, Ks and the damping coefficients Dz, Ds at the time of collision are corrected and optimized by the warning correction means 23 of the work support device control unit 16. is there.

As described above, the impedance correction means 24
Is based on the force acting on the work and the position thereof, so that the position X of the work and the force F acting on the work are within allowable values. To adjust. Therefore, the work 40, the work supporting device 10, the work robot 3
No destruction occurs at 0 and the work is performed with high accuracy. However, the above-described example is merely an example, and the impedance correction processing procedure is not limited to the above.

Next, when the force F acting on the work or the position X of the work exceeds the set values Fz, Xz, the work supporting device 10 and the work robot 30 by the warning correcting means 23 are used.
The modification of the control contents will be described. As a specific example, consider a case where the speed at which the work robot 30 collides with the work 40 is too high. If the rigidity of the work supporting device 10 at the time of collision is too high, the above-described impedance correction may not be performed in time, and the force Fz generated on the work 40 may exceed a set value. Conversely, if the rigidity of the work supporting device 10 at the time of collision is too small, the position X of the work 40 may exceed the set value Xz. In such a case, it is necessary to correct the mechanical impedance at the time of collision between the work support device 10 and the work robot 30, or the control content (target position, speed) of the work support device 10 and the work robot 30. The warning correction unit 23 performs such correction. In such a case, first, the work supporting device 10
And the spring constants Kz and Ks of the working robot 30 and the damping coefficients Dz and Ds are corrected. That is, when the force F acting on the work exceeds, the spring constants Kz, Ks of the work support device 10 and the work robot 30 are reduced based on the excess amount of the applied force from the set value, and the damping coefficients Dz, Ds To increase. When the position X of the work exceeds the set value Xz, the spring constant Kz of the work supporting device 10 is increased and the spring constant Ks of the work robot 30 is decreased. Next, if the adjustment of the mechanical impedance of the work support device 10 and the work robot 30 described above alone exceeds the position of the work or the force acting on the work, for example, both the position of the work and the force acting on the work are set. If the value is exceeded, the control content (target position or speed) of the work support device 10 or the work robot 30 is corrected. In this case, the target value Xd of the work support device 10 is corrected. The target value Yd of the work robot 30 is corrected. The target values Xd and Yd of both the work support device 10 and the work robot are corrected. In the control system of the present embodiment, the target value Yd of the work robot 30 is corrected. This is because the positioning accuracy of the work support device 10 is higher when the work robot 10 and the work robot 30 according to the present embodiment are compared. Therefore, the target position of the work robot 30 is corrected based on the excess amount from the set value of the position or the force. It should be noted that the modified control contents are, as described above, the evaluation means 2
Evaluated and optimized at 1.

Further, for example, when the value of the force Fw that may deform the work is wrong, the work 40 may be deformed during the work. In such a case,
Correct the tolerance Fw. Note that the above-described correction of the allowable value Fw may be automatically performed by the warning correction unit 19 of the work support device control unit 16, or may be configured to be directly input and corrected by the operator. In this case, since the correction is performed based on human experience or the like, optimization can be performed with a small number of learnings.

The above-mentioned correction is repeated until the force acting on the work and the position of the work fall within the allowable range.
Therefore, in the control system of the present embodiment, the control contents such as the target value and the mechanical impedance of the work support device 10 and the work robot 30 are automatically corrected and optimized. Further, when the force acting on the work and the position of the work fall within the allowable range, the control contents of the work support device 10 and the work robot 30 are taught by the teaching means 22 to the work support device 10 and the work robot 30 and stored. You.
Therefore, the work after teaching can be performed with the control contents of the optimized work support device 10 and work robot 30.

In the above-described embodiment, the target value Xd of the work supporting device 10 is used as a reference. However, when the positioning accuracy of the work robot 30 is high, the work robot 30
The spring constants Kz and Ks of the work support device 10 and the work robot 30 may be corrected based on the target position Yd. In the above-described embodiment, the error correction unit 20
Is configured in the work support device control unit 16 of the work support device 10, but is not limited thereto, and may be separately configured as a higher-level control device. However, the error correction unit 2
If 0 is provided as a higher-level control device, it is disadvantageous in that the response is slow.

Next, an embodiment in which the control system of the above-described embodiment is applied to a work station for performing spot welding on an assembly line of a panel part (a front side member) which is a part of an automobile body will be described with reference to FIGS. This will be described with reference to FIG. In a work station for performing spot welding, the control system of the present invention is particularly effective because the work robot and the work come into direct contact with each other, and the position is easily shifted due to a pressing force or the like during spot welding.

First, the configuration of the work station will be described with reference to FIGS. FIG. 10 is a system configuration diagram of a work support device and a work robot arranged in a work station, and FIG. 11 is a layout diagram of a work support device and a work robot arranged in a work station. As shown in FIG. 11, the work station is provided with two work robots 30 that perform work (spot welding) on the work 40 supported by the work support device 50. The work support device 50 is connected to a work support device control unit 52 as shown in FIG. 10, and the two work robots 30 are connected to each work robot control unit 32 as shown in FIG. The work robot control unit 32 is the same as the control system shown in FIG. 1 in that it is connected to the work support device control unit 52. The difference between the control system shown in FIG. 1 and the control system of the work station shown in FIG. 10 is that work type input means 70 for inputting the type of work to be performed in the work station is provided. . This is because the work station of the present invention performs welding work on a plurality of types (vehicle types) of works, and the work positioning position, the welding location, etc. are different for each work type. This is because it is necessary to input to the section 52 and the work robot control section 32. The input type of work is transmitted to the work support device control unit 52 and the work robot control unit 32. The work support device control unit 52 stores processing information on the positioning position of the work for each type of work, and the work robot control unit 32 stores processing information such as a welding point and a pressing force for each type of work. Is stored. Therefore, the work support device control unit 52 and the work robot control unit 32 specify welding conditions such as a positioning position and a welding location based on the type of the work and the processing information. Here, the work type input means 70 may be a keyboard or the like directly input by an operator, or may be a reading device or the like for reading magnetic information stored in a tag attached to the work. The configuration and operation of the work support device control unit 52 are the same as those of the control system shown in FIG.

Further, as the work robot 30 and the work robot control unit 32 provided in the work station, a known welding robot can be used as it is, and its configuration and operation are the same as those of the work robot shown in FIG. The description is omitted because it is the same.

Next, the work supporting device 50 of the present invention disposed at the above-described work station will be described with reference to FIGS. FIG. 12 is a side view of a state where a work is set on the work support device. As shown in FIG. 12, the work supporting device 50 includes a first support 51 supporting the vicinity of the right end of the work 40 and a second support supporting the vicinity of the left end of the work 40. First support part 51
Has two clamp portions 53a and 53b, and the second support portion 51 'has two clamp portions 53c and 53d.

FIGS. 13 to 15 show the first support portion 51.
It will be described based on. FIG. 13 is a perspective view of the first support, FIG. 14 is a view for explaining the axial configuration of the first support, and FIG. 15 is an enlarged view of a clamp mechanism of the first support. . As shown in FIG. 13, the first support portion includes two clamp portions 53a and 53b. As shown in FIG. 14, the clamp portion 53a is movable in two directions, the X direction and the Y direction, by an X direction guide shaft (ball screw) 54a and a Y direction guide shaft (ball screw) 55a.
The clamp 53b is an X-direction guide shaft (ball screw) 54b
And the X direction by the Y direction guide shaft (ball screw) 55b,
It is movable in the Y direction. Each guide shaft (ball screw) 55a, 55b, 55c, 55d is driven by a servomotor (not shown). Each of these servomotors has a position detecting means 12 and a force detecting means 14.
Are attached, and the work support device controller 52 controls each servomotor based on these detected values. Since the two clamp portions 53a and 53b have the same structure, only the clamp portion 53a will be described in the following description.

The clamp portion 53a is mounted on the surface plate 80 and is movable in the X direction.
And a Y-direction slide table 57 mounted on the X-direction slide table 56 and movable in the Y direction. The X-direction slide table 56 is formed with a thread groove that engages with the ball screw 54a, and the X-direction slide table 56 moves in the X direction when the ball screw 54a is rotationally driven by a servomotor. .
The Y direction slide table 57 has a ball screw 5
5a is formed with a screw groove for engaging with the ball screw 5a.
The Y-direction slide table 57 moves in the Y-direction by rotating the 5a by a servomotor.

A column 58 is provided on the Y-direction slide table 57. The support 58 is used to place the work 40 on the surface plate 80.
It has the function of supporting at a predetermined height from. Prop 5
A clamp pin 59 for clamping the work 40 is provided on 8. The clamp pin 59 is inserted into a pin hole 41 formed in the work 40 as shown in FIG. The work 40 is supported by the clamp portion 53a by being sandwiched between the support column 58 and the clamp member 60 while being inserted through the clamp pin 59. In addition, the movement mechanism of the clamp parts 53a and 53b of the first support part 51 used orthogonal two-axis ball screws. The reason for this configuration is that the positioning accuracy of the direct type robot can be higher than that of the case where a mechanism such as an articulated robot such as a manipulator is used.

Next, regarding the structure of the second support portion 51 ',
This will be described with reference to FIGS. 16 is a view for explaining the structure of a portion of the second support portion that clamps the work, FIG. 17 is a view of the rotary shaft 62 shown in FIG. 16 viewed from the axial direction, and FIG. It is a drawing showing a clamp mechanism for clamping. 2nd support part 51 '
Has a rotating shaft 62 supported at both ends by a bearing 61 fixed to a surface plate 80 as shown in FIG. The rotating shaft 62 is driven by a servo motor (not shown). A position detecting means 12 and a force detecting means 14 are attached to a servo motor for driving the rotating shaft 62, and the work supporting device controller 5 is controlled based on these detected values.
2 is controlled. As shown in FIG. 17, the rotating shaft 62 has four protrusions 63 formed at two positions on the rotating shaft 62 at an angle of about 90 ° with each other. This protrusion 6
3 are formed with clamp pins 64a, b, c, and d, respectively. The diameter of each clamp pin 64a, b, c, d is
The diameter is different for each vehicle type according to the type (vehicle type) of the work 40. Therefore, when the type of the work (vehicle type) is input to the work support device control unit 52, the rotating shaft rotates and the clamp pin is selected according to the vehicle type. As shown in FIG. 18, such a clamp pin 64
Is inserted through the pin hole 41. In this state, the clamp member 6
The workpiece 40 is supported by the workpieces 5a and 65b sandwiching the workpiece 40. A clamp pin 64 is formed at the same position on the rotation shaft 62 of the second support portion 52. This is the second
The clamp portion of the support portion 51 'does not change depending on the type of the work, indicating that only the diameter of the clamp pin 64 changes. For this reason, the shaft that must be controlled by the second support portion 51 ′ is also the rotating shaft 62 on which the clamp pin 64 is formed.
Only.

First, the operation of the above-described work station will be described. FIG. 19 shows a work procedure in the work station. First, the work station 40
Is input, the type of the work 40 input by the work type input means 70 is changed to the work support device control unit 52.
And input to the work robot controller 32 (S1). For example, the work stations according to the present embodiment are A, B,
If work is to be performed on a work related to four types of vehicles C and D, the types A, B, C and D are input. Work 4
When the type 0 is input, the positioning position and the work content are determined (S2). That is, the work supporting device control unit 52
Determines the positioning position, and the work robot control unit 32 determines the work content such as the welding location (strike position), the energizing time, the pressing force, and the like. Note that, as described above, the work supporting device 5
Since 0 has five control axes, the positioning position is given to each control axis for each type of work. Table 1 shows work positioning positions for each type of work. The information shown in Table 1 is stored in the work support device control unit 52 in advance.

[0050]

[Table 1]

When the positioning position of each control axis of the work supporting device 50 is determined, the work supporting device control section 52 drives the servomotor to position each axis at a predetermined positioning position (S3). When each axis is positioned at the positioning position, the work 40 is set and supported on the work support device 10 by the operator (S4). When the work 40 is supported by the work support device 50, the work robot 30 starts work (spot welding) on the work 40 (S).
5). At this time, the above-described correction of the mechanical impedance and the like are performed.

The operation of the work support device 50 and the work robot 30 during work will be described. Work support device 50
The allowable value and the set value described above are set in advance for each control axis shown in Table 1 in advance. Work support device controller 5
Step 2 compares the value of the position and force detected by the servo motor of each control axis with the allowable value and set value set for each control axis. If the position and the force are within the allowable values, welding is continued. You. If the position or force does not exceed the set value but exceeds the allowable value, the mechanical impedance of the work supporting device 50 and the work robot 30 is corrected so that the position or force is within the allowable value. The specific correction procedure is the same as the procedure already described, and a description thereof will be omitted. After the mechanical impedance has been corrected, the welding operation is continued. If the position and the force detected by the servo motor exceed the set values, a warning is issued to the work supporting device 50 and the work robot 30, and the control contents and the like are corrected. The control contents to be corrected include the mechanical impedance of the work support device 50 and the work robot 30 and the work robot 30
, The applied pressure, the amount of heat input, etc. The correction of the control contents and the like is repeated until the force acting on each control axis and the displacement are within the allowable values. When it falls within the allowable value, the control content is taught and stored in the work support device control unit 52 and the work robot control unit 32 for each type of work.
Therefore, the work quality (weld quality) of the vehicle type once learned is welded to the work with the optimized control contents (strike position, pressure, energizing time, current value, mechanical impedance). Can be good.

As described above, in the work supporting device 50 according to the embodiment, the number of control axes is four in the first support part 51 and the number of control axes is one in the second support part. The control of each control axis may be performed by independently controlling each control axis.

In the above-described example, the mechanical impedance is corrected by providing an allowable value and a set value for each control axis. However, this is not always necessary. Can be adjusted. For example, such a mechanical impedance may be corrected only for the control axis on which the most force acts during the welding operation.

In the work supporting device 50, the position and the force for each control axis are detected. Therefore, it is possible to analyze the dynamics of the deformation of the workpiece at the time of machining by the finite element method or the like based on the position of each point and the acting force. Then, by feeding back the analysis result to the welding operation, it is possible to determine a welding position in consideration of the deformation of the work, and it is possible to further improve the quality of the welding operation.

Even when the work robot does not directly contact the work, such as arc welding, the work 40 may be thermally deformed by the heat of the arc and the welding position may change. In such a case, the work supporting device 5 described above is used.
According to 0, the dynamics of the deformation of the workpiece at the time of machining can be analyzed by performing the above-described analysis by the finite element method based on the change in the position and the force of each control axis. Then, by feeding back the analysis result to the welding operation, a welding trajectory that takes into account the deformation of the workpiece can be determined, and the quality of arc welding can be improved.

[0057]

As described above in detail, in the integrated control system of the work supporting device according to the present invention, the control contents of the work supporting device and the work means are modified based on the position of the work and the force acting on the work. Therefore, the control contents of the work supporting device and the work means can be relatively easily matched.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a control system of a work supporting device according to the present invention.

FIG. 2 is a drawing for explaining a schematic structure of a work supporting device.

FIG. 3 is a drawing for explaining a schematic structure of a work robot.

FIG. 4 is a view showing a simplified model of the work support device and the work robot in order to explain the concept of correcting the mechanical impedance of the work support device and the work robot shown in FIG. 1;

FIG. 5 is a functional block diagram of the control system shown in FIG. 1;

FIG. 6 is a flowchart showing a control procedure of the control system shown in FIG.

FIG. 7 is a drawing for explaining a procedure for correcting mechanical impedance.

FIG. 8 is a drawing for explaining a procedure for correcting mechanical impedance.

FIG. 9 is a drawing for explaining a procedure for correcting mechanical impedance.

FIG. 10 is a schematic configuration diagram when the control system of the work supporting device according to the present invention is applied to a work station in a welding line of an automobile.

FIG. 11 is a view for explaining an arrangement of a work support device and a work robot of a work station.

FIG. 12 is a drawing for explaining the relationship between the work supporting device and the work.

13 is an enlarged perspective view showing a part of the work supporting device shown in FIG. 12;

14 is a drawing for explaining a shaft configuration of the work supporting device shown in FIG.

FIG. 15 is a view for explaining a clamp portion of the work supporting device shown in FIG. 13;

16 is an enlarged perspective view showing another part of the work supporting device shown in FIG. 13;

17 is an enlarged view showing a part of the work supporting device shown in FIG. 16;

FIG. 18 is a view for explaining a clamp portion of the work supporting device shown in FIG. 16;

FIG. 19 is a flowchart showing a work procedure of the work station.

[Explanation of symbols]

 10. Work support device 12. Position sensor 14. Current sensor 16. Work support device control unit 20 Work robot 22 Work robot control unit 24 Tool 40 Work

Claims (6)

[Claims] 1. A work supporting means for supporting a work, a moving means for moving the work supporting means, a detecting means for detecting an amount related to a current position of the work supporting means, and a current detecting means for detecting a current amount detected by the detecting means. A work feedback control unit that outputs a value obtained by multiplying a difference between the amount related to the position and the target amount related to the position by a gain to the moving unit so that the amount related to the position of the work supporting unit matches the target amount; A work means for performing work on the work supported by the means, a work control means for controlling the operation of the work means, a means for detecting an amount related to a force acting on the work supported by the work support means, Means for storing a target amount relating to the position and force of the work while the work means performs work on the work supported by the work support means; A work support device that corrects the control contents of the work feedback control means and the work control means when the amount relating to the position and / or the amount relating to the force is different from the target amount relating to each stored in the storage means. Integrated control system. 2. The integrated control system for a work supporting apparatus according to claim 1, wherein said work means for performing work on the work is a moving robot, and said work control means detects a current amount related to the movement of said robot. Feedback control means for feedback-controlling the motion of the robot based on an amount obtained by multiplying the difference by a gain by obtaining a difference from the target amount, and the amount related to the detected position and / or the amount related to the force is determined. An integrated control system for a work supporting device, wherein a gain of the robot feedback control means is corrected when the gain is different from a target amount for each stored in the storage device. 3. The integrated control system for a work supporting device according to claim 1, wherein said work means for performing work on the work is a moving robot, and said work control means controls the movement of said robot. Controlling the operation of the robot based on a program, and controlling the operation of the robot when the amount related to the detected position and / or the amount related to the force is different from the target amount related to each stored in the storage device. An integrated control system for a work support device that modifies the program. 4. The integrated control system for a work supporting device according to claim 1, wherein the work means for performing work on the work applies energy to the work, and the work control means controls the applied energy. An integrated control system for a work supporting apparatus, wherein the energy control program is modified when the detected position-related quantity and / or force-related quantity is different from a target quantity stored in the storage device. 5. The integrated control system for a workpiece support device according to claim 1, wherein the amount relating to the detected position and / or the amount relating to force is stored in the storage device. An integrated control system for a work supporting device that corrects the gain of the work feedback control means when the gain is different from the amount. 6. The integrated control system for a work supporting device according to claim 1, wherein the quantity relating to the detected position and / or the quantity relating to the force is stored in the storage device. An integrated control system for a work supporting device to which a means for issuing an alarm when the target amount is different from the target amount is added.