JP2011194497A - Control device of robot, and position correction control method of robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a robot preventing a teaching point correction of a hand tip of a robot body from causing an unintentional motion of a whole arm.SOLUTION: The control device determines a command in a control program in execution at a time of stopping the execution of a teach check mode. This device determines, if the command is an operation command MOVE, with regard to the operation command, and if the command is not the operation command MOVE, with regard to the operation command MOVE executed immediately before, whether or not the hand tip position at the time point matches with the target position of the operation command MOVE (S8, S9). If the hand tip position and the target position do not match with each other (S9: NO), this device performs a correction control of the hand tip position in correspondence with the correction operation by a user to be performed later (S16). If the hand tip position and the target position match with each other (S9: YES), this device performs a correction control with limitation that provides the correction control of the hand tip position to be performed later with a limitation (S10-S12).

Description

  The present invention relates to an automatic operation mode in which an articulated robot body is operated according to a control program, a robot control device capable of executing an operation according to the control program at a lower speed than the automatic operation mode, and a robot position correction control method. About.

  For robots, after teaching (programming) each teaching point, before operating the robot in automatic mode based on the teaching results, a test is performed to check whether teaching has been performed as intended (so-called “teach check”). )) Is generally performed. As a result of the test, it is often necessary to correct some teaching points. In this case, conventionally, it has been necessary to go through a procedure of once ending the test mode, switching to the teaching mode, correcting the teaching point, and switching to the test mode again for testing.

  However, since the operation becomes complicated when the mode is switched many times as described above, there is a demand for making it easier to correct the teaching point. For example, in Patent Document 1, when a teaching point is corrected, the robot is operated in the automatic mode until just before the teaching point to be corrected and then switched to the manual mode, and the hand position of the robot is corrected from there. A technique for teaching by moving to a teaching point is disclosed.

JP 2005-66797 A

However, in the technique of Patent Document 1, the hand of the robot arm can be freely moved in the manual mode, but it is uncertain how the position of the joint (elbow) in the middle of the arm changes accordingly. As a result, even if the position of the hand is corrected, the movement of the arm as a whole may change greatly, and it is assumed that the movement is not predicted by the operator.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a robot control device that can prevent an unintended operation of the entire arm from being corrected by the teaching point of the hand of the robot body. The object is to provide a position correction control method.

  According to the robot control apparatus of the first aspect, the correction control means determines the position determination means when the instruction determination means determines an instruction in the control program being executed when the execution of the test mode is stopped. If the above instruction is an operation command, the operation command is the operation command, and if it is not an operation command, the operation command executed most recently is used to determine whether the hand position at that time matches the target position of the operation command. judge. If the hand position and the target position do not match, the normal control execution means performs correction control of the hand position according to the user's subsequent correction operation, and the hand position and the target position match. In such a case, the restricted control execution means performs restricted correction control that gives a restriction to the correction control of the hand position according to the correction operation performed thereafter.

  In the above-mentioned limited correction control, the maximum value of the rotational speed of the motor that is changed in response to one correction operation is set for each axis of the robot body, and the maximum cumulative displacement allowed in the correction control is set once. The amount of displacement of each axis by the correction operation is limited to the amount of displacement within the operation time until the rotational speed of the motor reaches the maximum value at a constant rotational acceleration. In addition, the position acquired for each axis of the robot body at the time of stop is set as an initial value, and the amount of displacement of each axis is cumulatively added every time a correction operation is performed, and when the added value exceeds the maximum cumulative displacement amount, Limiting the maximum accumulated displacement amount to stop the correction control by the correction operation.

That is, when the user manually corrects the teaching point of the hand of the robot body, the displacement amount of each axis corresponding to one correction operation is limited by (maximum rotational speed) × (operation time) / 2. In addition, the displacement amount of each axis accumulated by performing the operation a plurality of times is also limited by the maximum accumulated displacement amount. Therefore, it is possible to prevent the joint axis of the arm from moving unintentionally by the user as the teaching point of the hand is corrected, and the movement and posture of the arm are within the range that can be easily predicted by the user.
If the hand position at the time when execution of the test mode is stopped does not match the target position of the operation command, it indicates that a new teaching point is added. There is a high probability that it will change significantly. Therefore, the degree of freedom of the correction control can be increased without adding the above-described limitation to the correction control in such a case, and a significant trajectory change of the hand can be easily performed.

  According to the robot control apparatus of the second aspect, the limit amount setting means sets the maximum cumulative displacement amount so that the value corresponding to the axis on the root side of the robot body becomes smaller. In general, the movement of the axis on the base side of the robot body greatly affects the movement of the hand side, so setting the maximum accumulated displacement to be small accordingly prevents the hand position from being displaced greatly. In addition, minute correction of the position can be easily performed.

The flowchart which is one Example and shows the control content of a control apparatus. The flowchart which shows the processing content of step S8 in FIG. The flowchart which shows the processing content of the step S12 The figure which shows an example of a control program list The figure explaining the operation target position of the operation command MOVE described in the control program The figure which shows an example of the limit set about the displacement amount of one correction operation The figure which shows an example of the limit set up about the amount of displacement of each axis The figure which shows the operation example at the time of operating a jog feed operation by designating the third axis when the operation mode is “XY” Top view of teaching pendant Diagram showing the system configuration of a general industrial robot Functional block diagram showing electrical configuration of control device and robot body

Hereinafter, an embodiment will be described with reference to the drawings. FIG. 10 shows a system configuration of a general industrial robot. The robot system 1 includes a robot body 2, a control device (controller) 3 that controls the robot body 2, and a teaching pendant 4 connected to the control device 3. The robot body 2 is configured as, for example, a 6-axis vertical articulated robot. The robot body 2 includes a base 5, a shoulder portion 6 supported by the base 5 so as to be rotatable in the horizontal direction, a lower arm 7 supported by the shoulder portion 6 so as to be rotatable in the vertical direction, and the lower arm 7. The first upper arm 8 is rotatably supported in the vertical direction, the second upper arm 9 is rotatably supported by the first upper arm 8, and the second upper arm 9 is vertically movable. The wrist 10 is supported so as to be rotatable in the direction, and the flange 11 is supported by the wrist 10 so as to be able to be twisted and rotated.
The base 5, the shoulder portion 6, the lower arm 7, the first upper arm 8, the second upper arm 9, the wrist 10 and the flange 11 function as an arm of the robot body 2. Although not shown, an end effector (hand) is attached.

  FIG. 11 is a functional block diagram showing the electrical configuration of the control device 3 and the robot body 2. The control device 3 includes a CPU 12, a drive circuit (inverter) 13 that outputs a drive signal to the robot body 2 based on an operation command from the CPU 12, a RAM 14 that stores an operation program of the robot body 2, and the system of the robot body 2. And a ROM 15 for storing a robot language for creating a program and an operation program. The robot body 2 includes a motor 16 that drives the shoulder portion 6, the arms 7 to 9, the wrist 10, and the flange 11, and an encoder 17 that detects the rotation angle of the motor 16. The motor 16 and the encoder 17 are provided for each link 18 that is a joint mechanism of each axis.

  Based on the encoder angle (encoder value) output by the encoder 17, the CPU 12 rotates the shoulder 6 with respect to the base 5, the lower arm 7 with respect to the shoulder 6, and the first upper arm 8 with respect to the lower arm 7. The angle, the rotation angle of the second upper arm 9 relative to the first upper arm 8, the rotation angle of the wrist 10 relative to the second upper arm 9, and the rotation angle of the flange 11 relative to the wrist 10 are detected, and the position of the robot body 2 ( And posture). Further, the CPU 12 feedback-controls the encoder angle to output a drive signal from the drive circuit 13, and controls the operations of the shoulder unit 6, the arms 7 to 9, the wrist 10 and the flange 11.

  FIG. 9 is a plan view of the teaching pendant 4. Near the center of the teaching pendant 4, a liquid crystal display with backlight (hereinafter referred to as a liquid crystal display) 19 is provided. The liquid crystal display 19 has a function of forming a touch panel that can be operated by an operator on the display surface 19a. A mode changeover switch (mode selector) 20 is provided in the upper left corner.

  The mode changeover switch 20 can be selected from three modes: a manual mode (manual mode), an auto mode (automatic mode), and a teach check mode (test mode). Any one of them can be switched selectively by an operator. The manual mode is a mode for operating the robot body 2 manually, and the auto mode is a mode for operating the robot body 2 automatically. Also, in the teach check mode, prior to operating the robot body 2 in the auto mode, the control program is run at a lower speed than the auto mode in order to check the operating state by the control program and the teaching point of the hand position of the robot body 2. For example, this is a mode for executing the operation while checking the operation step by step.

  An emergency stop switch 21 and a jog dial 22 are provided in the upper right corner. Around the liquid crystal display 19, a motor key 23, lock key 24, robot selection key 25, operation mode key 26, speed key 27, cursor key 28, stop key 29, OK key 30, cancel key 31, and movement of each axis Direction keys 32, shift keys 33, and function keys 34 are provided.

  Next, the operation of this embodiment will be described with reference to FIGS. FIG. 4 shows an example of a control program list executed by the control device 3. In this control program, a command MOVE described in steps 006, 008, and 010 is an operation command for moving the hand position of the robot body 2, and P1, P2, and P3 are movement target positions of the respective commands ( (See FIG. 5 (a)). In this embodiment, the operation is temporarily stopped while the robot main body 2 is operating in the teach check mode, and the user moves the target position P1 in the command MOVE in step 008, for example, as shown in FIG. Will be described in the case of correcting to a new target position P1 ′.

  FIG. 1 is a flowchart showing the control contents of the control device (correction control means) 3. First, when the execution of the control program is started from the top (step S1), the state of the mode change switch 20 of the teaching pendant 4 is identified (step S2), and it is determined whether or not the teaching check mode has been switched (step S2). S3). If the teaching check mode has been switched (YES), the operation mode and the external speed change are set to be prohibited (step S4). Then, the control program is executed at such a low speed that the user can visually confirm the execution state for each step.

In step S3, if the teaching check mode is not switched (NO), step S4 is skipped and the process proceeds to step S5. In this case, the control program is executed in the auto mode.
Note that the “operation mode” indicates “each axis”, “XY”, “tool”, etc., which are designation methods for displacing each axis of the robot body 2 as shown in FIG. . When the operation mode is “each axis”, only the axis designated by the user is displaced, and the other axes are not displaced. Further, when the operation mode is “XY”, when an operation input for displacement in the coordinate system specified by the user is performed, the input is displaced on the XY coordinates (coordinates seen from the base), and the coordinate system Each axis is displaced in accordance with In the case of “tool”, the coordinate system is viewed from the tip (hand) of the arm.

  In the next step S5, the operation of the robot body 2 is started (002: TAKEARM), and processing is performed for each step number (step S6). In the subsequent step S7, it is determined whether or not the stop key (STOP) 29 of the teaching pendant 4 has been turned on. If it has been turned on (YES), the control position is determined (step S8).

  FIG. 2 shows the processing content of step S8. First, the step number of the control program referred to when the stop key 29 is turned on is read (step S21), and the process (command) corresponding to the step number is interpreted (decoded) (step S22). Then, it is determined whether or not the above process is an operation command MOVE (step S23, command determination means). In step S23, when the processing of the step number referred to at the time of stop is the motion command MOVE (YES), the hand position of the robot body 2 is acquired (step S24), and the current position is set as the target position of the motion command MOVE. (Step S25).

  Then, depending on whether or not the current position and the target position are the same (step S26, position determination means), it is determined whether the control position (YES) or not (NO) in step S9 in FIG. In step S23, if the process of the step number is not an operation command MOVE (NO), a backward search of the step number is performed (step S27), and the process returns to step S22.

  A specific example of the above processing will be described. For example, as shown in FIG. 4, it is assumed that the step number of the control program referred to when the stop key 29 is turned on is “012”. In this case, since the process of step number 012 is not the operation command MOVE, if the backward search of the step number is performed, the operation command MOVE of step number 010 is captured. At this time, “YES” is determined in step S23.

  Further, as shown in FIG. 5, for example, when the operation command “MOVE P2” of step number 010 is executed when the hand position of the robot body 2 is at P1, the hand position moves from P1 toward P2. Then, when the hand position reaches the target position P2, the process “I = I + 3” of the next step number 011 is executed. Accordingly, when the process being executed at the time when the stop key 29 is turned on is “MOVE P2,” the hand position of the robot body 2 is between the target positions P1 and P2 and the target position P2. May have reached In order to grasp and distinguish these cases, the process of FIG. 2 is executed.

  Reference is again made to FIG. If it is determined as “YES” in step S9 as a result of executing step S8, the control device 3 sets limit control to execute the limited correction control thereafter (step S10, limited control execution means, limit amount setting). means). If "NO" is determined in the step S9, the limit control is not set, and a normal position correction process (normal correction control) is performed (step S16, normal control execution means). Then, the process proceeds to step S14.

  Here, “setting of limit control” indicates that when the user performs correction control of the hand position of the robot body 2 using the teaching pendant 4, a limit is given to the displacement amount of each axis. For example, when the user operates the movement direction key 32 to perform a so-called “jog feed” operation, the amount of displacement by jog feed by one operation is limited (operation displacement amount limiting means). Further, when the user repeatedly executes the above operation, the maximum cumulative displacement amount from the current position is also limited for each axis (maximum cumulative displacement amount limiting means).

  If the hand position at the time when execution of the test mode is stopped does not coincide with the target position of the operation command MOVE as determined as “NO” in step S9, a new teaching point is added. It is shown that. Therefore, it is highly probable that the subsequent teaching points will be significantly changed. Therefore, in the correction control in such a case, the degree of freedom of the correction control is increased without adding the restriction as in step S10, and the hand is greatly increased. Make trajectory changes easy.

  When the limit is set as described above in step S10, in the subsequent step S11, if the operation mode and external speed setting change from the teaching pendant 4 is permitted, position correction processing with limit control is performed (step S12). Hereinafter, the setting of limit control in step S10 will be described. For example, FIG. 8 shows an operation example when the jog feed operation is performed by designating the third axis (J3) when the operation mode is “XY”. With a single operation input, the displacement angle of the third axis is displaced from 3.62 [deg] to 14.96 [deg], and the angles of the other axes are also slightly displaced accordingly.

FIG. 6 is a diagram for explaining a limit applied to the jog feed operation. As shown in FIGS. 6A and 6B, when the movement direction key 32 is turned on (jog feed operation) and the input is accepted (ON), the motor of the corresponding shaft is rotated at a constant rotational acceleration. However, when the rotational speed of the motor reaches the maximum value max (see (a)), the operation input acceptance is turned off (see (b)). Thereafter, as a second input, an input of a re-on operation of the movement direction key 32 is accepted in a state separated from the first operation (see (c)). Therefore, the axis by one jog feed operation; the displacement amount of the motor is (maximum rotational speed) × (on operation time TON) / 2 = L1 as shown in (a)
(Operation displacement limit). That is, the above-described on operation time TON is limited to the time until the rotational speed reaches the maximum value max, so that the displacement amount is limited to L1.

  FIG. 7 shows an example of the maximum cumulative displacement amount set for each axis. For example, as shown in FIG. 5B, when the target position P1 of the hand is changed to P1 ′, the displacement angle of the first to sixth axes changes from P1 (n) (where n = 1 to 6) to P1 ′. Change to (n). In this case, the maximum displacement allowed is An. In this case, the allowable displacement amount (A1 to A4) of the first axis to the fourth axis is 10 °, and the allowable displacement amount (A5, A6) of the fifth axis and the sixth axis is 30 °. The amount of displacement set for the shaft closer to the root than the shaft is made smaller. This is because the amount of displacement of the axis on the base side in the robot body 2 greatly affects the amount of displacement of the hand.

  Next, details of the position correction processing performed in step S12 will be described with reference to FIG. First, initialization is performed, and when the accumulated angular displacement amount of each axis used in the subsequent calculations is cleared (step S31), a position correction input performed by the user operating the teaching pendant 4 is received (step S32). That is, referring to whether or not the user's operation input (movement direction key 32 on operation) is performed, the current angular displacement amount of each axis is acquired based on the output signal of the encoder 17 and the position correction is performed. Start (step S33).

  In subsequent step S34, it is determined whether or not a limit flag, which will be described later, is set. If the limit flag is not set (NO), it is determined whether or not an interrupt for ending the position correction process has occurred. (Step S35). If the interrupt has not occurred (YES), the position (rotational displacement amount) of each axis is changed according to the user's operation input (step S36), and the displacement amount is calculated (step S37). On the other hand, if the interrupt has occurred (step S35: NO), the position correction process is terminated (step S41), and the process returns to the main routine.

  In step S38, it is determined whether or not the accumulated displacement amount of each axis angle is equal to or less than the maximum accumulated displacement amount (A1 to A6) of each axis shown in FIG. 7 (maximum accumulated displacement amount limiting means). If “YES” is determined here, a displacement amount of each axis is calculated with respect to the user's currently input operation (step S39). If the displacement amount is less than the operation limit amount L1 of the jog feed operation shown in FIG. 6A (step S40, operation displacement amount limiting means: YES), the process returns to step S32 to accept subsequent position correction input. . If “NO” is determined in the step S38, the accumulated displacement amount exceeds the maximum accumulated displacement amount, and therefore, the process proceeds to the step S41 without permitting any further position correction.

  In step S40, when the displacement amount of the jog feed operation by the user's operation input exceeds the operation limit amount L1 (NO), the limit flag is set (step S42), and the process proceeds to step S34. In this case, since the limit flag is set, “YES” is determined in the step S34, and the process waits until the jog feed operation of the user is turned off in a step S43. When the jog feed operation is turned off (YES), the limit flag is cleared (step S44), and the process proceeds to step S32. That is, the next jog feed operation input is accepted.

  Reference is now made to FIG. When the limit control in step S12 is performed as described above, the processing for each step number in the control program is resumed, and the operation mode permitted in step S11 and the external speed change permission are again performed (step S13). Then, it is determined whether or not the operation of the robot is finished, that is, whether or not the operation reaches step 013 in which “GIVEARM” indicating the end of the robot operation is described in the control program (step S14). (NO) Return to step S6.

  If step 013 is reached in step S14 (YES), it is further determined whether or not step 014 in which “END” indicating the end of execution of the program is described is reached (step S15). If step 014 has been reached (YES), the process is terminated. If step 013 is followed backward (NO) and the process proceeds to step 002 in which “TAKEARM” is described (step S17: YES) The process proceeds to step S5. If the process has shifted to a step other than step 002 (NO), the process shifts to step S6, and processing is performed from the transfer destination step.

  As described above, according to the present embodiment, when the control device 3 determines an instruction in the control program that is being executed when execution of the teach check mode is temporarily stopped by the user, the instruction operates. If it is an instruction MOVE, it is determined whether or not the hand position at that time coincides with the target position of the operation instruction MOVE with respect to the operation instruction MOVE that is not the operation instruction MOVE. . If the hand position does not match the target position, the hand position correction control is performed according to the user's subsequent correction operation. If the hand position matches the target position, The limited correction control for giving a limit to the correction of the hand position correction performed in the above is performed.

  In the limited correction control, the maximum value of the rotational speed to be changed according to one correction operation (jog feed operation) is set for each axis of the robot body 2 and the maximum accumulated displacement amount allowed in the correction control is set. Is set, and the amount of displacement of each axis by one correction operation is limited to a value L1 corresponding to the time until the rotational speed reaches the maximum value at a constant rotational acceleration. In addition, when the position acquired for each axis of the robot body 2 at the time of stop is set as an initial value, the amount of displacement of each axis is cumulatively added every time a correction operation is performed, and the added value exceeds the maximum cumulative displacement amount Then, the maximum cumulative displacement amount restriction for stopping the correction control by the correction operation is performed.

That is, when the user corrects the teaching point of the hand of the robot body 2 by the jog feed operation while the execution of the teach check mode is temporarily stopped, the displacement of each axis corresponding to one correction operation The amount is limited to L1, and the displacement amount of each axis accumulated by performing the operation a plurality of times is also restricted by the maximum accumulated displacement amount. Accordingly, it is possible to prevent the joint axis of the arm from moving unintentionally by the user as the teaching point is corrected, and the movement and posture of the arm are within the range that can be easily predicted by the user.
Further, since the control device 3 sets the maximum cumulative displacement so that the value corresponding to the axis on the base side of the robot body 2 becomes smaller, generally, the maximum movement of the axis on the base side of the robot body 2 is maximum. By setting the cumulative displacement amount to be small, it is possible to prevent the hand position from being greatly displaced, and to easily perform minute correction of the position.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible.
You may apply to a horizontal articulated robot.
The displacement limit amount of each axis may be set by changing the numerical value as appropriate. Moreover, the setting of the displacement limit amount of each axis may be set uniformly to the same value, or may be set to a different value for each axis.
The operation performed by the user to correct the position is not limited to the jog feed operation, and any operation input form may be used.

  In the drawing, 2 is a robot body, 3 is a control device (correction control means, command determination means, normal control execution means, limited control execution means, limit setting means, operation displacement limit means, maximum cumulative displacement limit means) Indicates.

Claims (4)

An automatic operation mode for operating an articulated robot body according to a control program, and an operation according to the control program can be executed at a lower speed than the automatic operation mode, and the operation is temporarily stopped according to a user operation. And a test mode capable of executing manual correction control for manually correcting the hand position during the stop,
Correction control means for executing the manual correction control,
Command determining means for determining a command in the control program that was being executed when execution of the test mode was stopped;
If the command being executed is an operation command for moving the hand position to the target position, the operation command is targeted, and if the command being executed is not the operation command, the control program step is retraced. A position determination means for determining whether or not the hand position at that time coincides with a target position of the operation command;
Normal control execution means for performing correction control of the hand position in accordance with a user's correction operation to be performed later when the hand position and the target position do not match;
Limited control execution means for performing limited correction control for giving a limit to correction control of the hand position according to a user's correction operation performed when the hand position matches the target position; Prepared,
The limited control execution means is:
For each axis of the robot body, a limit amount setting means for setting a maximum value of the rotation speed of the motor that is changed according to one correction operation, and setting a maximum cumulative displacement amount allowed in the correction control;
An operation displacement amount limiting means for limiting the amount of displacement of each axis by one correction operation to an amount of displacement until the rotational speed of the motor reaches the maximum value at a constant rotational acceleration;
At the time of stopping, the position acquired for each axis of the robot body is used as an initial value, and the amount of displacement of each axis is cumulatively added every time the correction operation is performed, and the added value exceeds the maximum cumulative displacement amount. In this case, the robot control apparatus includes a maximum cumulative displacement amount limiting unit that stops the correction control by the correction operation.   The robot control apparatus according to claim 1, wherein the limit amount setting unit sets the maximum cumulative displacement amount such that a value corresponding to a base-side axis of the robot body is smaller. An automatic operation mode for operating an articulated robot body according to a control program, and an operation according to the control program can be executed at a lower speed than the automatic operation mode, and the operation is temporarily stopped according to a user operation. In the method of performing the manual correction control, the robot control device having a test mode capable of executing manual correction control for manually correcting the hand position during the stop,
Determining an instruction in the control program that was being executed when execution of the test mode was stopped;
If the command being executed is an operation command for moving the hand position to the target position, the operation command is targeted, and if the command being executed is not the operation command, the control program step is retraced. If the motion command that was executed most recently and the target is the most recently executed, it is determined whether the hand position at that time coincides with the target position of the motion command,
If the hand position and the target position do not match, perform correction control of the hand position according to the user's correction operation performed thereafter,
If the hand position and the target position match, perform a limited correction control to give a limit to the correction control of the hand position according to the user's correction operation performed thereafter,
The limited correction control is:
For each axis of the robot body, set the maximum value of the rotational speed of the motor to be changed according to one correction operation, and set the maximum cumulative displacement amount allowed in the correction control,
An operation displacement amount limit for limiting the amount by which each axis is displaced by a single correction operation to an amount by which the rotation speed of the motor reaches a maximum value at a constant rotational acceleration;
At the time of stopping, the position acquired for each axis of the robot body is used as an initial value, and the amount of displacement of each axis is cumulatively added every time the correction operation is performed, and the added value exceeds the maximum cumulative displacement amount. In this case, the robot position correction control method includes performing a maximum cumulative displacement amount limit for stopping the correction control by the correction operation.   4. The robot position correction control method according to claim 3, wherein the maximum cumulative displacement amount is set so that a value corresponding to a base-side axis of the robot body is smaller.

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