JP6153316B2 - Robot system and control method of robot system - Google Patents

Description

  The present invention relates to a robot system using a multi-joint arm that is driven by controlling a plurality of joints, and a control method of the robot system.

  Conventionally, in order to cause a robot having a vertical articulated arm and an end effector (for example, a hand) to perform a desired operation, the robot stores in advance teaching points at which the robot has a desired position and orientation, and in accordance with the stored teaching data. The robot is operated. To move the workpiece to the target position and orientation using this type of robot, measure the position and orientation of the target workpiece with a sensor such as a camera, and correct the position and orientation of the workpiece as appropriate until the workpiece is moved to the target position and orientation. It is desirable to do.

  However, since this type of robot generally has a structure in which joints are connected in series, it is necessary to calculate kinematics in order to calculate the position and orientation of the hand. On the other hand, in order to cause the hand to take a desired position and orientation, it is necessary to calculate inverse kinematics and calculate command values for each joint of the arm. In order to calculate the command value for each joint, trajectory calculation is required, and this trajectory calculation takes a long time.

  In order to reduce the increase in operation time due to the trajectory calculation of the robot, the robot (10) is started to move toward the approximate position, and then the sensor is measured at any time and the command value is corrected in real time. A control device (50) has been developed (Patent Document 1). According to this robot control device (50), since it is not necessary to measure and correct the position error when the robot has completed the movement, an increase in operation time can be reduced.

JP 7-14115 A

  However, in the robot control device (50) described in Patent Document 1, since the command value is corrected after the operation of the robot (10) is started, the trajectory calculation is necessary, and the trajectory calculation cannot be eliminated. Moreover, the operation | movement accompanying correction of command value will occur at any time. For these reasons, the robot control device (50) has a problem in that the increase in operating time is not sufficiently suppressed.

  It is an object of the present invention to provide a robot system and a robot system control method that can suppress an increase in operation time due to correction when correcting the position and orientation of a workpiece based on the measurement result of a sensor.

The present invention relates to a multi-joint arm, an end effector supported by the multi-joint arm, the position and posture of which are adjusted by the operation of the multi-joint arm and having a holding part capable of gripping a work, and the position of the work And a sensor that measures at least one degree of freedom of the posture, and is disposed between the most advanced joint of the multi-joint arm and the holding unit of the end effector, and the position of the holding unit with respect to the multi-joint arm; A holding unit adjustment mechanism capable of adjusting at least one degree of freedom of posture, and at least the articulated arm, the end effector, and the holding unit adjustment mechanism are controlled, and the position and posture of the workpiece are determined from measurement data acquired from the sensor. and a control device for calculating at least one degree of freedom, said control device, teaching placed so that the reference phase to the gripping position The workpiece is gripped by the end effector and then moved to the target position. Based on the motion data of the articulated arm during that time, a command value to the articulated arm is calculated in advance and placed at the gripping position. After the sensor measures the phase of the workpiece, the articulated arm is operated according to the command value, and the workpiece is gripped at the gripping position and then moved to the target position. While operating the articulated arm, at least a part of the calculation of the difference between the phase of the workpiece measured by the sensor and the reference phase and the correction operation of the holding unit adjustment mechanism based on the difference are performed. It is characterized by.

The present invention also provides an articulated arm, an end effector supported by the articulated arm, the position and posture of which are adjusted by the operation of the articulated arm, and a holding part capable of gripping the work, and the work A sensor that measures at least one degree of freedom of the position and posture of the multi-joint arm, the most advanced joint of the multi-joint arm and the holding unit of the end effector, and the holding unit with respect to the multi-joint arm. A holding unit adjusting mechanism capable of adjusting at least one degree of freedom of position and posture; and controlling at least the multi-joint arm, the end effector, and the holding unit adjusting mechanism; a control device for calculating at least one degree of freedom of posture, the control method of a robot system provided with a reference phase to the gripping position The teaching work placed so as to be gripped by the end effector and then moved to the target position, and based on the operation data of the articulated arm during that time, the command value to the articulated arm is sent to the control device. A pre-calculation teaching step, a measuring step of measuring the phase of the workpiece placed at the gripping position by the sensor, and operating the articulated arm according to the command value to grip the workpiece at the gripping position. A multi-joint arm moving step for moving to a target position, and a correction step for calculating a difference between the phase of the workpiece measured in the measuring step and the reference phase, and operating the holding unit adjusting mechanism based on the difference And at least a part of the correction step is performed during the execution of the articulated arm movement step .

  According to the present invention, at least a part of the calculation of the workpiece error and the correction of the error by the holding unit adjusting mechanism is performed simultaneously with the movement of the articulated arm. In comparison, an increase in the correction operation time can be suppressed.

It is explanatory drawing which shows schematic structure of the robot system which concerns on 1st Embodiment of this invention. 1 is a block diagram showing a schematic configuration of a robot system according to a first embodiment of the present invention. It is a flowchart which shows the operation | movement at the time of the operation preparation of the robot system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the operation | movement at the time of operation | movement of the robot system which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the positional relationship of the camera which concerns on 1st Embodiment of this invention, and a workpiece | work supply position. It is a figure which shows the image which image | photographed the teaching jig | tool with the camera in FIG. It is a side view which shows the movement of the hand which concerns on 1st Embodiment of this invention, (a) is the state which hold | gripped the movement side cylindrical member, (b) is the middle of moving the movement side cylindrical member to a target teaching point. (C) is a state where the moving side cylindrical member is moved to the target teaching point. It is explanatory drawing which shows schematic structure of the robot system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement at the time of the operation preparation of the robot system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement at the time of operation | movement of the robot system which concerns on 2nd Embodiment of this invention. It is a side view which shows the movement of the hand which concerns on 2nd Embodiment of this invention, (a) is the state which moved the screw hole teaching jig to the target teaching point, (b) is a measurement teaching of the screw hole teaching jig It is the state moved to the point. It is a figure which shows the image which image | photographed the teaching jig | tool with the camera in FIG.11 (b). It is a flowchart which shows the operation | movement at the time of the operation preparation of the robot system which concerns on a reference form. It is a flowchart which shows the operation | movement at the time of operation | movement of the robot system which concerns on a reference form. It is explanatory drawing which shows the positional relationship of the camera which concerns on a reference form, and a measurement teaching point. It is a figure which shows the image which image | photographed the teaching jig | tool with the camera in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
As shown in FIGS. 1 and 2, the robot system 1 includes a robot 2, a control device 3 that controls the robot 2, and a camera 7 as a sensor.

  The robot 2 includes a 6-axis vertical articulated arm (hereinafter referred to as an arm) 20 and a hand 21 as an end effector. In the present embodiment, a six-axis vertical articulated arm is applied as the arm 20, but the number of axes may be changed as appropriate according to the application and purpose. In the present embodiment, the hand 21 is applied as an end effector. However, the present invention is not limited to this, and any material may be used as long as it can hold and release the workpiece by some method such as adsorption by magnetic force or negative pressure.

  The arm 20 includes seven links 61 to 67 and six joints 71 to 76 that connect the links 61 to 67 so as to swing or rotate. The distal end link 67 on the most distal end side is substantially L-shaped. As each of the links 61 to 67, one having a fixed length is adopted. However, for example, a link that can be expanded and contracted by a linear actuator may be employed.

  Each of the joints 71 to 76 is provided with a motor that drives each of the joints 71 to 76, or a linear motion actuator as necessary, as the output device 20b. Each joint 71 to 76 includes an encoder that detects the rotation angle of the motor, a current sensor that detects a current supplied to each motor, and a torque sensor that detects the torque of each joint 71 to 76 as the input device 20a. Is provided.

  The hand 21 is supported by the arm 20, and at least one degree of freedom of position and posture is adjusted by the operation of the arm 20, and includes a holding unit 22 and a holding unit adjustment mechanism 23. The holding unit 22 is attached to the distal end link 67 of the arm 20 via the holding unit adjusting mechanism 23 and can work on the workpiece. In the present embodiment, since the hand 21 is employed as the end effector, the holding unit 22 is configured by a plurality of fingers such as three fingers that can grip the workpiece. The hand 21 includes a motor for operating the holding unit 22 as an output device 22b, and an encoder for detecting the rotation angle of the motor as an input device 22a.

  As shown in FIG. 2, the control device 3 is configured by a computer and controls the robot 2. A computer constituting the control device 3 includes, for example, a CPU 30, a ROM 31 that stores a program for controlling each unit, a RAM 32 that temporarily stores data, an input interface circuit 33, and an output interface circuit 34. Yes.

  The CPU 30 includes an arm control unit 80, a holding unit control unit 81, a holding unit adjustment mechanism control unit 82, an operation data acquisition unit 83, a trajectory calculation unit 84, a reproduction unit 85, and an image processing unit 86. I have.

  The arm control unit 80 is configured to control the arm 20 by calculating a command value to the arm 20 by arm control software stored in the ROM 31 and performing data communication with the arm 20.

  The holding unit control unit 81 calculates a command value to the holding unit 22 by the holding unit control software stored in the ROM 31 based on the position and orientation of the arm 20, and performs data communication with the holding unit 22. The holding unit 22 is controlled.

  The image processing unit 86 performs image processing on a workpiece image (measurement data) acquired by a camera 7 to be described later and calculates at least one degree of freedom of the position and orientation of the workpiece.

  The input interface circuit 33 and the output interface circuit 34 are configured by, for example, CAN communication means or RS-232C communication means. In the present embodiment, the arm control unit 80 and the holding unit control unit 81 communicate with each other using a CAN communication unit, and a holding unit adjustment mechanism control unit 82 described later performs communication using an RS-232C communication unit. Yes.

  As shown in FIG. 5, the camera 7 is supported downward by appropriate support means above a workpiece supply position 6 a provided on a table 6 as a fixing member. Thereby, the work placed at the work supply position 6a is photographed by the camera 7. The camera 7 is connected to the input interface circuit 33 and the output interface circuit 34, captures an image in response to a command from the image processing unit 86, and transmits captured image data obtained by the imaging to the image processing unit 86. Yes.

  As shown in FIG. 2, a teaching pendant 4 for teaching the robot 2 can be connected to the control device 3. The teaching pendant 4 is connected to the input interface circuit 33 and the output interface circuit 34, and when the operator operates the teaching pendant 4, the robot 2 is operated and taught.

  Next, characteristic parts of the robot system 1 according to the present embodiment will be described in detail.

  As shown in FIG. 1, the holding unit adjusting mechanism 23 is disposed between the sixth joint 76 as the most advanced joint of the arm 20 and the holding unit 22, and includes a Z-axis rotating mechanism 92. In the present embodiment, the holding unit adjusting mechanism 23 is provided as a part of the hand 21.

  The Z-axis rotation mechanism 92 is a rotation drive mechanism that rotates around the Z-axis that is perpendicular to the flange surface of the tip link 67. The Z-axis rotation mechanism 92 has a single-rotation configuration that uses a precise worm gear (reduction gear) and is driven by being rotated by a stepping motor. In addition to the Z axis, the coordinate axis of the holding portion adjusting mechanism 23 is set to an X axis and a Y axis that are orthogonal to each other on a plane parallel to the flange surface of the tip link 67.

  When the Z-axis rotation mechanism 92 rotates, the rotation center of the holding unit 22 that grips the workpiece does not fluctuate in the X-axis direction and the Y-axis direction, so that the center position of the workpiece gripped by the holding unit 22 does not fluctuate. Adjustment is made so that the rotation center of the shaft rotation mechanism 92 is concentric. The deviation between the rotation center of the Z-axis rotation mechanism 92 and the rotation center of the holding unit 22 is assumed to be smaller than the allowable assembly tolerance. However, the X-axis direction and the Y-axis can be considered in consideration of the shift in the X-axis direction and the Y-axis direction due to the rotation correction by identifying the position shift between the centers in advance without performing such adjustment. A direction correction amount may be calculated.

  The holding unit adjusting mechanism 23 may be a mechanism capable of adjusting at least one degree of freedom of the position and posture of the holding unit 22 with respect to the arm 20, but in the present embodiment, the holding unit adjusting mechanism 23 is a mechanism having a single rotation axis. It has become. This is effective, for example, when the rotation angle (phase) of the supplied cylindrical workpiece is adjusted and moved to the next position and orientation (see FIG. 7).

  As shown in FIG. 2, the holding unit adjustment mechanism control unit 82 of the CPU 30 calculates a command value to the holding unit adjustment mechanism 23 by the holding unit adjustment mechanism control software stored in the ROM 31 based on the position and orientation of the arm 20. It is like that. The holding unit adjustment mechanism control unit 82 controls the holding unit adjustment mechanism 23 by performing data communication with the holding unit adjustment mechanism 23.

  The operation data acquisition unit 83 of the CPU 30 acquires each operation data when the arm 20 and the holding unit adjustment mechanism 23 are taught, and stores them in the RAM 32.

  The arm 20 and the holding unit adjusting mechanism 23 are configured so that the holding unit 22 moves from the holding teaching point as the first position and posture to the target teaching point as the second position and posture by the operation of the teaching pendant 4 by the operator. To be taught. At this time, the operation data acquisition unit 83 acquires the encoder values and the like of the arm 20 and the holding unit adjustment mechanism 23 as operation data and stores them in the RAM 32.

  Here, the holding teaching point of the holding unit 22 is a point at which the workpiece placed at the workpiece supply position 6 a is gripped, that is, a position and orientation at which the holding unit 22 holds the workpiece measured by the camera 7. The target teaching point of the holding unit 22 is a position and orientation at which the holding unit 22 holds a workpiece positioned at the target position of movement. For example, the work held by the holding unit 22 is subjected to operations such as assembly and processing. It can be set as a point or a passing point for avoiding other devices.

  The trajectory calculation unit 84 calculates a trajectory from the holding teaching point of the arm 20 to the target teaching point based on the motion data about the arm 20 obtained by the motion data acquisition unit 83, and calculates a command value to the arm 20. It is supposed to be.

  The reproduction unit 85 of the CPU 30 reproduces the arm 20 and the holding unit adjustment mechanism 23 based on the operation data. The holding unit 22 is moved from the holding teaching point to the target teaching point by the operation of the arm 20 and the holding unit adjusting mechanism 23.

  The operation at the time of preparing the operation until the robot system 1 teaches the robot 2 and obtains the command value will be described with reference to the flowchart shown in FIG.

  First, the moving side cylindrical member 52 which is a part of the teaching jig 5 described later is placed on the workpiece supply position 6a by the operator (step S1). As shown in FIG. 5, the moving-side columnar member 52 is provided with a D-cut surface 52a on the outer periphery at one end, and the end surface on which the D-cut surface 52a is formed is placed downward. As shown in FIG. 6, a mark 52 b to be photographed by the camera 7 is attached to the end surface opposite to the end surface where the D-cut surface 52 a of the moving side cylindrical member 52 is formed. The mark 52b indicates the direction in which the D-cut surface 52a is formed with respect to the rotation center 52c of the moving-side cylindrical member 52.

  Then, the direction of the D-cut surface 52a is set and placed so that the direction of the moving-side cylindrical member 52 here becomes the reference phase. That is, the reference phase is a measured value when the placed work is in an ideal phase. In actual operation, the difference between the reference phase and the phase when actually measuring the work is used. Then, it is corrected by the holding unit adjusting mechanism 23.

  In addition, the mark 52b has the same positional relationship as the characteristic portion that specifies the phase of the workpiece when actually measuring. That is, when the moving-side cylindrical member 52 and the actual workpiece are placed in the same phase, the measured phase is also set to the same angle. Thereby, the phase to be corrected can be acquired only by calculating the difference between the reference phase and the measured phase. However, the mark 52b to be applied to the moving-side cylindrical member 52 and the characteristic part for specifying the phase of the workpiece are not limited to being formed at the same position, and the phase difference between the mark 52b and the characteristic part of the workpiece is not limited. On the other hand, an angle obtained by subtracting the offset can be used as a phase correction amount.

  Further, when the holding unit 22 grips the moving-side columnar member 52, the holding unit 22 grips the rotating shaft of the moving-side columnar member 52 and the rotating shaft of the Z-axis rotating mechanism 92 in parallel. The parallelism required here is set from the accuracy with which the workpiece is positioned at the target teaching point. By gripping in parallel in this way, when the Z-axis rotation mechanism 92 rotates the holding portion 22, the movement-side columnar member 52 rotates in the X-axis direction and the Y-axis direction, that is, tilts with respect to the Z-axis. Can be suppressed. Note that when the holding unit 22 grips the actual workpiece, the rotation axis of the workpiece and the rotation axis of the Z-axis rotation mechanism 92 are parallel to each other, as in the case of gripping the moving columnar member 52. Of course, it is made to grasp.

  Then, the image processing unit 86 issues an imaging command to the camera 7, and the camera 7 images the moving columnar member 52 from above (step S2). The camera 7 transmits imaging data to the image processing unit 86, and the image processing unit 86 performs image processing. Here, as shown in FIG. 6, the outline of the moving-side cylindrical member 52 is extracted from the image 14, and the rotation center 52c is calculated. Then, an angle θ formed by the straight line connecting the rotation center 52c and the mark 52b in the camera coordinates is calculated, set as a reference phase, and stored in the RAM 32 (step S3).

  Then, the arm 20 is operated by operating the teaching pendant 4, and as shown in FIG. 7A, the moving side cylindrical member 52 placed at the workpiece supply position 6a is gripped by the holding portion 22 (step S4). . The motion data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 23 at that time as holding teaching points and stores them in the RAM 32 (step S5).

  By operating the teaching pendant 4, the arm 20 and the holding unit adjustment mechanism 23 are moved to the target teaching point, and the operation data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 23 as the target teaching point and stores them in the RAM 32. Store (step S6). Here, the teaching jig 5 is used for teaching as follows.

  As shown in FIGS. 7B and 7C, as the teaching jig 5 of the robot 2, for example, a cylindrical member 50, a fixed side cylindrical member 51, and a moving side cylindrical member 52 are used. The cylindrical member 50 includes a through hole having a D-shaped cross section 50a and a substantially D-shaped cross section. The fixed-side columnar member 51 has a D-cut surface 51a on the outer periphery, and is formed in a thickness that cannot penetrate the cylindrical member 50 without being rotatable. The moving-side columnar member 52 is formed in a thickness that can be inserted into the cylindrical member 50 without being rotatable at the portion where the D-cut surface 52a is formed.

  The fixed-side columnar member 51 is placed at the target position 6 b of the table 6. The cylindrical member 50 is provided so as to be movable up and down around the fixed-side columnar member 51. The position at which the fixed-side cylindrical member 51 is placed and the angle (phase) at the vertical axis (the dashed line in the figure) are set by the position and orientation of the target teaching point of the holding unit 22. Specifically, as shown in FIG. 7C, when the cylindrical member 50 becomes movable from the periphery of the fixed-side cylindrical member 51 to the periphery of the moving-side cylindrical member 52, the moving-side cylindrical member 52 is set so that the holding unit 22 that holds 52 is positioned at the target teaching point.

  That is, the X-axis of the holding part 22 is obtained by matching the moving-side cylindrical member 52 in the vertical direction and abutting the front end surface of the moving-side cylindrical member 52 with the upper surface of the fixed-side cylindrical member 51 in the center. The direction coordinate and the Y-axis direction coordinate coincide with the X-axis direction coordinate and the Y-axis direction coordinate of the target teaching point. Further, the phases of the movable side cylindrical member 52 and the stationary side cylindrical member 51 are matched so that the D cut surfaces 52a and 51a of the movable side cylindrical member 52 and the stationary side cylindrical member 51 are on the same plane. Thus, the Z-axis rotation direction coordinate of the holding unit 22 matches the Z-axis rotation direction coordinate of the target teaching point. At this time, the phase of the moving-side cylindrical member 52 relative to the holding unit 22 and the fixed-side cylindrical member 51 are placed so that the holding unit 22 that holds the moving-side cylindrical member 52 is positioned at the target teaching point. Set the position and phase.

  Prior to teaching, as shown in FIG. 7B, a fixed-side columnar member 51 is installed at the target position 6b, and a cylindrical member 50 is provided around it. Then, at the time of teaching, the teaching pendant 4 is used to abut the lower surface of the moving-side cylindrical member 52 with the upper surface of the fixed-side cylindrical member 51 so that the center coincides with each other, as shown in FIG. And the holding unit 22 is moved to the target teaching point. When the operator determines that the cylindrical member 50 can move from the periphery of the fixed-side cylindrical member 51 to the periphery of the moving-side cylindrical member 52, the operator determines that the holding unit 22 has reached the target teaching point.

  Here, the operator positions the target teaching point in the X-axis direction, the Y-axis direction, and the Z-axis direction with the arm 20, and then adjusts the Z-axis rotation direction with the holding unit adjusting mechanism 23 to move to the moving side columnar shape. The phases of the member 52 and the fixed-side cylindrical member 51 are matched. The motion data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 23 as target teaching points and stores them in the RAM 32.

  Next, the trajectory calculation unit 84 performs trajectory calculation from the held teaching point to the target teaching point with respect to the arm 20, and calculates a command value to the arm 20 (step S7, trajectory calculation step). This trajectory calculation needs to take into account avoidance of interference with surrounding jigs as necessary. The pre-operation preparation is completed by calculating the command value. Therefore, since the trajectory calculation of the arm 20 is completed in the pre-operation preparation, it is not necessary to execute the trajectory calculation during the actual operation of the robot 2, and an increase in operating time can be suppressed even if correction is necessary.

  Next, the operation when the robot 2 is actually operated by the robot system 1 described above will be described with reference to the flowchart shown in FIG.

  It is assumed that the workpiece is placed at the workpiece supply position 6a. The arm 20 and the holding unit adjusting mechanism 23 move to the holding teaching point in order to hold the workpiece (step S10). When the robot 2 moves to the holding teaching point, the holding unit 22 grips the workpiece (step S11). Further, the arm 20 is operated by the arm control unit 80 based on the command value obtained by the trajectory calculation, and moves from the held teaching point to the target teaching point (step S12, arm moving process).

  On the other hand, at the same time that the robot 2 moves to the holding teaching point to grip the workpiece, the image processing unit 86 instructs the camera 7 to photograph the workpiece to be grasped, and the camera 7 photographs the workpiece ( Step S13, workpiece measurement step). The image processing unit 86 acquires imaging data from the camera 7, performs image processing, and calculates the phase of the workpiece placed at the workpiece supply position 6a with respect to the camera coordinates (step S14).

  Here, after the camera 7 has photographed the workpiece, the error with respect to the reference position and orientation is calculated for the workpiece, and the error is corrected by the holding unit adjusting mechanism 23 based on the calculation result (steps S15 to S17, correction work process).

  First, the image processing unit 86 calculates the difference between the reference phase and the actual workpiece phase to obtain a phase error (step S15, error calculation step). Then, the reproducing unit 85 calculates the correction amount of the holding unit adjusting mechanism 23 from the phase error (step S16, correction calculation step). In this case, since the phase error becomes the correction amount of the holding unit adjusting mechanism 23 as it is, the calculation load can be suppressed extremely small. The reproducing unit 85 reflects the obtained correction amount of the holding unit adjustment mechanism 23 in the operation data of the holding unit adjustment mechanism 23, calculates a command value of the holding unit adjustment mechanism 23, and instructs the holding unit adjustment mechanism 23 to target teaching The point is moved (step S17, correction operation step). That is, the holding unit adjusting mechanism 23 moves to the target teaching point while correcting the phase.

As a result, the arm 20 and the holding unit adjustment mechanism 23 move to the target teaching point, and the phase error of the workpiece is corrected by the holding unit adjustment mechanism 23, so that the workpiece moves to the target teaching point at a desired position and orientation ( Step S18). Here, arm 20 has a have been corrected.

  Here, after photographing the workpiece, an error with respect to the preset reference position and orientation is calculated for the workpiece in parallel with at least a part of the movement of the arm 20, and the error is corrected by the holding unit adjusting mechanism 23 (step). S15 to S17, correction work process). For this reason, simultaneously with the movement of the arm 20, at least a part of the calculation of the phase error (step S15), the calculation of the correction amount of the holding unit adjustment mechanism 23 (step S16), and the movement of the holding unit adjustment mechanism 23 (step S17). Running.

  As described above, according to the robot system 1 of the present embodiment, at the same time as the arm 20 is moving, at least a part of error calculation, correction calculation, and correction operation can be executed. Thereby, in addition to the movement time of the arm 20, a necessary time can be suppressed, and an increase in operation time due to the correction of the position and orientation of the workpiece can be suppressed.

  Further, according to the robot system 1 of the present embodiment, the trajectory calculation of the arm 20 is executed prior to any of error calculation, correction calculation, and correction operation, so the trajectory calculation of the arm 20 is completed at the time of operation preparation. Will do. Thereby, since it is not necessary to execute the trajectory calculation of the arm 20 at the time of actual operation, an increase in the operation time due to the correction can be suppressed as compared with the case where the trajectory calculation is executed during the operation of the arm 20.

  Further, according to the robot system 1 of the present embodiment, the holding unit adjusting mechanism 23 has one degree of freedom of one rotation axis, so that, for example, when determining the phase of a cylindrical workpiece, highly accurate positioning is performed. Can be realized.

Further, according to the robot system 1 of the present embodiment, since the holding unit adjusting mechanism 23 is provided in a part of the hand 21, the holding unit adjusting mechanism 23 is provided with a different configuration depending on the type of the end effector. You can also . For example, when the end effector needs to be adjusted only in the X-axis direction and the Y-axis direction, the holding unit adjusting mechanism 23 can be provided with an X-axis translation mechanism and a Y-axis translation mechanism. Therefore, the holding unit adjusting mechanism 23 can be selected according to the type of the end effector, and optimal control of the end effector can be realized.

  In the robot system 1 according to the present embodiment described above, as an example of the actual movement of the workpiece, it is assumed that the phase is determined and the cylinder is assembled to the column. Therefore, the holding unit adjusting mechanism 23 has one degree of freedom of one rotation axis. It was. However, the robot system according to the present invention is not limited to this. For example, even in the step of assembling the cylinder to the cylinder, the phase adjustment is not necessary and the two-degree-of-freedom alignment of the center in the horizontal direction is sufficient. 23 can have only two translational axes. Or you may make it the mechanism in which the holding | maintenance part adjustment mechanism 23 can set the freedom degree more than 4 degrees of freedom. As described above, the degree of freedom required for the holding unit adjusting mechanism 23 can be appropriately changed according to the actual work process.

[Second Embodiment]
Next, a robot system 101 according to the second embodiment of the present invention will be described.

  Compared with the first embodiment, the second embodiment has a hardware configuration in which the holding unit adjusting mechanism 123 of the hand 121 of the robot 102 does not have the Z-axis rotation mechanism 92 as shown in FIG. The configuration is different in that a translation mechanism 90 and a Y-axis translation mechanism 91 are provided. Further, the distal end link 67 of the arm 20 has a substantially linear shape. Other configurations are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

  In the present embodiment, it is assumed that a screw tightening process is performed on the work gripped by the holding unit 22 (see FIG. 11A). That is, the screw hole position in the gripped workpiece is acquired by the camera 7 and the image processing unit 86, and the position error in the X-axis direction and the Y-axis direction of the screw hole position is corrected, so that the screw tightening can be performed accurately. Objective. Therefore, since it is necessary to correct the position of one point at the center of the screw hole, the translational two axes are appropriate for the holding portion adjusting mechanism 123.

  As shown in FIG. 8, the holding part adjusting mechanism 123 includes an X-axis translation mechanism 90 provided on the distal end link 67 side, and a Y-axis translation mechanism 91 provided on the holding part 22 side. The X-axis translation mechanism 90 and the Y-axis translation mechanism 91 are translational movement mechanisms that operate in the X-axis direction and the Y-axis direction orthogonal to each other on a plane parallel to the flange surface of the tip link 67 of the arm 20. The X-axis translation mechanism 90 and the Y-axis translation mechanism 91 use a precise guide and a ball screw, and have a translational biaxial configuration that is driven by rotating the ball screw by a stepping motor. The orthogonality of the two axes is calibrated in advance. Try to keep it.

  Since the holding unit adjusting mechanism 123 corrects the position error when the arm 20 moves to the target teaching point, the movable range is small, and for example, a position error of about 2 to 3 mm is 10 to 20 μm. The movable range can be adjusted to adjust the degree of error. Further, since the movement of the holding unit adjusting mechanism 123 may be performed in parallel with the movement of the arm 20, a high speed is not necessary, and the load resistance only needs to correspond to the weight of the hand 21 and the workpiece. Thus, since the holding part adjustment mechanism 123 has few functional restrictions and a wave gear reducer is unnecessary, a mechanism with a small hysteresis loss etc. can be employ | adopted. Therefore, the holding unit adjusting mechanism 123 is a mechanism having a smaller hysteresis loss or the like than the joints 71 to 76 of the arm 20. As a mechanism having a small hysteresis loss, for example, there is a mechanism using a piezoelectric element in addition to the configuration of the present embodiment.

  As shown in FIG. 11 (b), the camera 7 is supported above an appropriate workpiece photographing position 15 and facing downward by appropriate support means. As a result, the work positioned by the robot 102 at the work shooting position 15 is shot by the camera 7. Further, when the work held by the holding unit 22 is brought into a state where it can be photographed by the camera 7, the positions and orientations of the arm 20 and the holding unit adjusting mechanism 123 at that time are set as measurement teaching points.

  The operation at the time of preparing the operation until the robot system 101 teaches the robot 102 and obtains the command value will be described with reference to the flowchart shown in FIG.

  The holding part 22 holds a screw hole teaching jig 150 described later. First, the arm 20 is operated by operating the teaching pendant 4, and the holding unit 22 is positioned at the work photographing position 15 below the camera 7. The motion data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 123 at that time as measurement teaching points (first position and orientation), and stores them in the RAM 32 (step S20).

  Here, two orthogonal axes (hereinafter referred to as Xt and Yt) on which the holding unit adjusting mechanism 123 operates and two axes (hereinafter referred to as Xv and Yv) on which the camera 7 and the image processing unit 86 perform measurement are referred to. Since the directions do not match, calibration is required. For this reason, the holding unit 22 grips the calibration jig and operates the holding unit adjusting mechanism 123, and the position of the calibration jig at that time is detected by the camera 7 and the image processing unit 86. Assuming that the position change caused by operating the holding unit adjusting mechanism 123 is (ΔXtn, ΔYtn) and the position change measured by the camera 7 and the image processing unit 86 is (ΔXvn, ΔYvn), Formula 1 is established. N may be any number as long as it is 2 or more.

  The CPU 30 calculates the transformation matrix using the pseudo inverse matrix calculation, so that the movement value (ΔXv, ΔYv) of the object measured by the camera 7 is converted into the biaxial movement value (ΔXt, ΔYt) of the holding unit adjustment mechanism 123. A coordinate transformation matrix H to be transformed is calculated (step S21). As a result, calibration between the two axes of the holding unit adjusting mechanism 123 and the measurement coordinates of the camera 7 becomes possible.

  Next, by operating the teaching pendant 4, the arm 20 and the holding unit adjustment mechanism 123 are moved to the target teaching point, and the operation data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 123 as the target teaching point. And stored in the RAM 32 (step S22). Here, the teaching jig 105 is used for teaching as follows. Here, teaching is performed using the teaching jig 105, but teaching may be performed using an actual workpiece.

  As shown in FIG. 11A, a screw fastening machine 8 is provided at the target teaching point. The screw fastening machine 8 includes a main body 8a, a driver 8b that can rotate downward, and a cylindrical sleeve 8c that covers the periphery of the driver 8b. The sleeve 8c can be moved in and out of the main body 8a, and the driver 8b can be used by being pulled closer to the main body 8a than the front end of the driver 8b. Is supposed to protect.

  As shown in FIGS. 11A and 12, the teaching jig 105 includes a screw hole teaching jig 150 and a driver teaching jig 151. The screw hole teaching jig 150 has a cylindrical shape, and a screw hole 150a is formed in a part of one end surface. The holding part 22 grips the screw tightening teaching jig 150 with the end surface side where the screw hole 150a is formed as the front end side. The driver teaching jig 151 is provided at the tip of the sleeve 8c of the screw fastening machine 8 by fitting, and has a rod-shaped protrusion 151a having the same diameter as the driver 8b.

  Then, by operating the teaching pendant 4, the arm 20 and the holding unit adjusting mechanism 123 are moved to the target teaching point, and the screw hole 150 a of the screw hole teaching jig 150 is moved to the driver teaching jig 151 as shown in FIG. It adjusts so that it may fit in the protrusion 151a. Here, the operator is positioned in the vicinity of the target teaching point by a large movement of the arm 20, and then adjusted in the X-axis direction and the Y-axis direction by the fine operation of the holding unit adjusting mechanism 123 to be positioned at the target teaching point. Let Then, the motion data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 123 as target teaching points and stores them in the RAM 32.

  After teaching the target teaching point, as shown in FIG. 11B, the holding unit 22 moves to the measurement teaching point taught in step S <b> 20 while holding the screw hole teaching jig 150. The upper surface of the screw hole teaching jig 150 is photographed (step S23, workpiece measuring step). The camera 7 transmits imaging data to the image processing unit 86, the image processing unit 86 performs image processing of the image 14, sets the coordinates of the obtained screw hole 150a in the camera coordinates as the reference position (Xvd, Yvd), It memorize | stores in RAM32 (step S24).

  Next, the trajectory calculation unit 84 performs trajectory calculation from the measurement teaching point to the target teaching point with respect to the arm 20, and calculates a command value to the arm 20 (step S25, trajectory calculation step). This trajectory calculation needs to take into account avoidance of interference with surrounding jigs as necessary. The pre-operation preparation is completed by calculating the command value. Accordingly, since the trajectory calculation of the arm 20 is completed in the pre-operation preparation, it is not necessary to execute the trajectory calculation during the actual operation of the robot 102, and an increase in operating time can be suppressed even if correction is necessary. If necessary, the trajectory may be calculated in consideration of another process such as applying grease.

  Next, the operation when the robot 102 is actually operated by the robot system 101 described above will be described with reference to the flowchart shown in FIG.

  First, the robot 102 grips a workpiece with the holding unit 22 (step S30). Then, the robot 102 moves to the measurement teaching point in order to photograph the gripped work (step S31). The image processing unit 86 instructs the camera 7 to photograph a workpiece to be grasped, and the camera 7 photographs the workpiece (step S32). The image processing unit 86 acquires imaging data from the camera 7, performs image processing, and calculates the position (Xv, Yv) of the workpiece in the camera coordinates (step S33). The arm 20 is operated by the reproducing unit 85 based on the command value obtained by the trajectory calculation, and moves from the measurement teaching point to the target teaching point (step S34, arm moving step).

  On the other hand, after the camera 7 has photographed the workpiece, the arm 20 moves, and at the same time, an error with respect to the reference position and orientation is calculated for the workpiece, and the error is corrected by the holding unit adjusting mechanism 23 based on the calculation result (Steps S35 to S37, Correction work process).

  First, the image processing unit 86 calculates a difference between the reference position (Xvd, Yvd) and the actual work position (Xv, Yv), and obtains a position error (ΔXv, ΔYv) (step S35, error calculation step). ). Then, the reproducing unit 85 calculates the correction amount of the holding unit adjustment mechanism 123 from the position error (step S36, correction calculation step). Here, the correction value (ΔXt, ΔYt) for the holding unit adjusting mechanism 123 is calculated by adding the coordinate transformation matrix H obtained by coordinate calibration to the position error (ΔXv, ΔYv). The reproduction unit 85 reflects the obtained correction amount of the holding unit adjustment mechanism 123 in the operation data of the holding unit adjustment mechanism 123, calculates a command value of the holding unit adjustment mechanism 123, and instructs the holding unit adjustment mechanism 123 to target teaching The point is moved (step S37, correction operation step). That is, the holding unit adjusting mechanism 123 moves to the target teaching point while correcting the position.

  As a result, the arm 20 and the holding unit adjusting mechanism 123 move to the target teaching point, and the holding unit adjusting mechanism 123 corrects the position error of the workpiece, so that the workpiece moves to the target teaching point in a desired position and orientation ( Step S38). Accordingly, the screw tightening can be performed by the screw tightening machine 8 after correcting the position error of the screw hole of the workpiece.

  Here, after photographing the workpiece, the position error with respect to the preset reference position and orientation is calculated for the workpiece in parallel with at least a part of the movement of the arm 20, and the position error is corrected by the holding unit adjusting mechanism 123. (Steps S35 to S37, correction work process). Therefore, at the same time as the movement of the arm 20, at least a part of the calculation of the position error (step S35), the calculation of the correction amount of the holding unit adjustment mechanism 123 (step S36), and the movement of the holding unit adjustment mechanism 123 (step S37). Running.

  As described above, according to the robot system 1 of the present embodiment, at the same time as the arm 20 is moving, at least a part of error calculation, correction calculation, and correction operation can be executed. Thereby, in addition to the movement time of the arm 20, a necessary time can be suppressed, and an increase in the operation time due to the correction of the position and orientation of the workpiece can be suppressed. Further, since the trajectory calculation of the arm 20 is executed prior to any of error calculation, correction calculation, and correction operation, an increase in operation time due to correction of the position and orientation of the workpiece can be suppressed.

  Here, in order to operate the holding unit 22 by (ΔXt, ΔYt), a conventional robot that does not have the holding unit adjustment mechanism 123 must calculate the command value of the robot 2 by solving the inverse kinematics of the robot 2. In other words, the operation time becomes long. On the other hand, according to the robot system 101 of the present embodiment, the coordinate transformation matrix H calculated by Equation 1 is integrated and (ΔXt, ΔYt) obtained before the operation is only added to the command value of the holding unit adjustment mechanism 123. Can be corrected. For this reason, since the calculation time can be shortened, the operation time of the robot 2 can be shortened.

  Further, according to the robot system 1 of the present embodiment, the holding unit adjustment mechanism 123 is configured using a coordinate transformation matrix obtained by calibrating the measurement coordinate system of the camera 7 and the operation coordinate system of the holding unit adjustment mechanism 123. The correction amount can be calculated to correct the workpiece position error. Thereby, when correcting the position and orientation of the workpiece using the measurement result by the camera 7, even if the arm 20 operates nonlinearly, the coordinate calibration error and the movement error are caused by the highly linear holding unit adjustment mechanism 123. Both of these can be suppressed and corrected with high accuracy. Further, since it is not necessary to use the arm 20 to correct the position error of the workpiece, for example, the arm 20 can only be moved between predetermined teaching points, and even if the arm 20 operates non-linearly. The effect can be minimized.

  That is, when correction is performed by a conventional robot that does not have the holding unit adjusting mechanism 123, an error in coordinate change due to nonlinearity of the arm 20 or a movement error of the arm 20 becomes large. On the other hand, since the holding unit adjusting mechanism 123 can be operated with orthogonal linear coordinates, it is possible to make the error and the movement error due to the coordinate conversion minute by performing correction using this. . Accordingly, the correction can be performed with high accuracy regardless of the nonlinear operation of the arm 20.

[ Reference form]
Next, the robot system 201 according to the reference embodiment will be described. The reference form has the same hardware configuration as the second embodiment shown in FIG. Accordingly, the same reference numerals as those in the second embodiment are given and the description thereof is omitted. The teaching method for the workpiece and the robot 102 handled by the robot system 201 of the reference embodiment is the first implementation in that an error is caused in the position in the X-axis direction and the Y-axis direction of the workpiece held by the holding unit 22. Although it differs from a form, it is the same as that of 1st Embodiment in other than that point.

In this reference embodiment, a process of assembling a cylindrical part to a columnar part with matching the center position and phase will be described as an example. Since the correction is performed with a total of three degrees of freedom, ie, two degrees of freedom of the position and one degree of freedom of the phase, the holding unit adjusting mechanism 123 has three degrees of freedom of the translation mechanism of two degrees of freedom and the rotation mechanism of one degree of freedom. It is preferable to have. However, since restrictions such as the need to slow down the operation of the robot 102 increase when the tip of the robot 102 becomes heavy, a translation mechanism having only two degrees of freedom is used here as in the second embodiment.

  That is, the number of degrees of freedom necessary for error correction is 3. On the other hand, since the degree of freedom of the holding portion adjusting mechanism 23 is 2, for the 1 degree of freedom obtained by subtracting 2 degrees of freedom from the 3 degrees of freedom, the same number of sixth joints 76 of the arms 20 as the degree of freedom are used. . For this reason, in the design and selection of the reducer of the sixth joint 76, it is preferable to select one that reduces hysteresis loss and the like. Even with a vertical articulated arm, such a selection is possible because there are few restrictions on the load resistance and speed as long as the axis is close to the tip.

Further, in the present reference embodiment, the plane of rotation of the robot 102 work phase changes to gripping, so that substantially parallel to the plane of rotation of the sixth joint 76 of the arm 20, to adjust the time of holding the workpiece. This parallelism can be designed based on the measurement accuracy of the camera 7 and the accuracy required at the target teaching point of the workpiece. As a result, the amount by which the phase of the workpiece is changed and the amount by which the sixth joint 76 is turned can be made substantially the same, and the change in the posture of the workpiece at that time can also be almost eliminated. In this reference embodiment, the error between the rotation center of the sixth joint 76 and the center of the workpiece is assumed to be smaller than the allowable assembly tolerance.

  The operation at the time of preparing the operation until the robot system 201 teaches the robot 102 and obtains the command value will be described with reference to the flowchart shown in FIG.

  The holding unit 22 holds the moving side columnar member 52. First, the arm 20 and the holding unit adjusting mechanism 123 are operated by operating the teaching pendant 4, and the holding unit 22 is positioned at the workpiece photographing position 15 below the camera 7. The motion data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 123 at that time as measurement teaching points (first position and orientation) and stores them in the RAM 32 (step S40).

  Here, the two orthogonal axes in the X-axis direction and the Y-axis direction in which the holding unit adjusting mechanism 123 operates and the two orthogonal axes in the X-axis direction and the Y-axis direction in which the camera 7 performs measurement are calibrated. The coordinate transformation matrix H is calculated by the same method as (Step S41).

  Next, by operating the teaching pendant 4, the arm 20 and the holding unit adjustment mechanism 123 are moved to the target teaching point, and the operation data acquisition unit 83 acquires the position and orientation of the arm 20 and the holding unit adjustment mechanism 123 as the target teaching point. And stored in the RAM 32 (step S42). Here, teaching is performed in the same manner as in the first embodiment.

  After teaching the target teaching point, as shown in FIG. 15, the holding unit 22 moves to the measurement teaching point taught in step S <b> 40 while holding the moving columnar member 52, and the camera 7 moves the moving side circle. The upper surface of the columnar member 52 is photographed (step S43). The camera 7 transmits the imaging data to the image processing unit 86, and the image processing unit 86 performs image processing. As shown in FIG. 16, the contour of the moving-side cylindrical member 52 is extracted from the image 14 to obtain the rotation center 52c. calculate. The image processing unit 86 sets the coordinates of the rotation center 52c as the reference position (Xvd, Yvd), sets the direction of the D-cut surface 52a as the reference phase θd, and stores it in the RAM 32 (step S44).

  Next, the trajectory calculation unit 84 performs trajectory calculation from the measurement teaching point to the target teaching point with respect to the arm 20, and calculates a command value to the arm 20 (step S45, trajectory calculation step).

  Next, an operation when the robot 102 is actually operated by the robot system 201 described above will be described with reference to a flowchart shown in FIG.

  First, the robot 102 grips a workpiece with the holding unit 22 (step S50). Then, the arm 20 and the holding unit adjusting mechanism 123 move to the measurement teaching point in order to photograph the gripped work (step S51). The image processing unit 86 instructs the camera 7 to photograph a workpiece to be grasped, and the camera 7 photographs the workpiece (step S52, workpiece measurement process). The image processing unit 86 acquires imaging data from the camera 7, performs image processing, and calculates the position (Xv, Yv) and phase θ of the workpiece in the camera coordinates (step S53). The image processor 86 calculates the difference between the reference position (Xvd, Yvd) and reference phase θd and the actual workpiece position (Xv, Yv) and phase θ, and calculates the position error (ΔXv, ΔYv) and phase error Δθ. Obtain (Step S54, error calculation step).

  Then, the reproducing unit 85 calculates the correction amount of the sixth joint 76 from the phase error Δθ (step S55). Here, the phase error Δθ is set as the correction amount of the sixth joint 76. The reproducing unit 85 reflects the obtained correction amount of the sixth joint 76 in the operation data of the sixth joint 76, corrects the command value of the arm 20, and moves the arm 20 from the measurement teaching point to the target teaching point. (Step S56, arm moving step). That is, the arm 20 moves to the target teaching point while correcting the phase.

  On the other hand, after the camera 7 has photographed the workpiece, the reproducing unit 85 calculates the correction amount of the sixth joint 76, and at the same time, calculates the correction amount of the holding unit adjusting mechanism 123 from the position error (step S57, correction calculation step). ). Here, since the holding part adjusting mechanism 123 is located on the tip side with respect to the sixth joint 76, the operation coordinate system of the holding part adjusting mechanism 123 is rotated by the phase rotation correction by the sixth joint 76. For this reason, the correction value (ΔXt, ΔYt) to the holding unit adjusting mechanism 123 is accumulated by rotating the coordinate transformation matrix H obtained by coordinate calibration by the correction amount Δθv in the rotation direction and integrating the position error (ΔXv, ΔYv). ) Is calculated.

  The reproduction unit 85 reflects the obtained correction amount of the holding unit adjustment mechanism 123 in the operation data of the holding unit adjustment mechanism 123, calculates a command value of the holding unit adjustment mechanism 123, and instructs the holding unit adjustment mechanism 123 to target teaching The point is moved (step S58, correction operation step). That is, the holding unit adjusting mechanism 123 moves to the target teaching point while correcting the position.

  As a result, the arm 20 and the holding unit adjustment mechanism 123 move to the target teaching point, the work phase error is corrected by the arm 20, and the work position error is corrected by the holding unit adjustment mechanism 123. Accordingly, the workpiece moves to the target teaching point at a desired position and orientation (step S59).

  Here, after photographing the workpiece, an error with respect to the preset reference position and orientation is calculated for the workpiece in parallel with at least a part of the movement of the arm 20, and the error is corrected by the holding unit adjusting mechanism 23 (step). S54, S57 to S58, correction work process). Therefore, at the same time as the movement of the arm 20, at least a part of the calculation of the correction amount of the holding unit adjustment mechanism 123 (step S57) and the movement of the holding unit adjustment mechanism 123 (step S58) is executed.

According to the robot system 201 of this reference embodiment, as described above, at the same time as the arm 20 is moving, it is possible to perform at least some of the correction calculation and correction operations. Thereby, in addition to the movement time of the arm 20, a necessary time can be suppressed, and an increase in the operation time due to the correction of the position and orientation of the workpiece can be suppressed. Further, since the trajectory calculation of the arm 20 is executed prior to any of error calculation, correction calculation, and correction operation, an increase in operation time due to correction of the position and orientation of the workpiece can be suppressed.

The present according to the reference embodiment of the robotic system 201, the robot operation due to phase correction is only adding the correction value to the command value of the sixth joint 76, etc or the trajectory calculation or solving inverse kinematics The processing which requires a long time is not required. Thereby, it can suppress that operating time becomes long. Accordingly, since the degree of freedom of the holding portion adjusting mechanism 123 can be less than the degree of freedom to be corrected, the weight and cost can be reduced, and the distance from the flange surface of the tip link 67 to the operating point of the holding portion 22 can be reduced. Is possible.

In the robot system 201 of the present reference embodiment, the rotation center of the sixth joint 76, since the center of the work was assumed to be almost the same, the phase correction and position correction could be carried out simultaneously. However, these centers are not limited to match, and even if these centers do not match, after phase correction is performed, it is divided into two stages to perform measurement and position correction, or accompanied by phase correction. The same correction can be performed by calculating the position error and adding it to the position correction value.

In the robot systems 1, 101, 201 of the first embodiment to the second embodiment described above, the holding unit adjusting mechanisms 23, 123 are configured to be provided in a part of the hands 21, 121. However, in the robot system according to the present invention, the present invention is not limited to this, and the holding unit adjusting mechanisms 23 and 123 are located between the sixth joint 76 of the arm 20 and the holding unit 22 and the position of the holding unit 22 with respect to the arm 20. Any device that can adjust its posture is acceptable. For this reason, as the holding part adjusting mechanisms 23 and 123, for example, an independent separate mechanism interposed between the arm 20 and the hands 21 and 121, or a part of the tip link 67 of the arm 20 is provided. May be.

  When the holding portion adjusting mechanisms 23 and 123 are provided in a part of the distal end link 67, the holding portion adjusting mechanisms 23 and 123 can be shared to suppress an increase in cost and a conventional end effector. Can be used as is.

In the robot systems 1, 101, and 201 of the first to second embodiments described above, the case where the camera 7 is used as a sensor has been described. However, the robot system according to the present invention is not limited to this, and other sensors such as a laser displacement meter may be used.

In the robot systems 1, 101, and 201 of the first embodiment to the second embodiment, the case where each teaching is performed by operating the teaching pendant 4 by the operator and using the teaching jigs 5 and 105 has been described. However, the robot system according to the present invention is not limited to this. For example, by using the camera 7 and the image processing unit 86, the robot 2 is automatically taught without manual operation by the operator. May be.

In the robot systems 1, 101, and 201 of the first embodiment to the second embodiment, the case where the motion data acquisition unit 83 acquires motion data by teaching has been described. However, the robot system according to the present invention is not limited to this. For example, the operation data may be obtained by downloading from an existing database, or the operation data may be obtained by calculation.

Further, in the robot systems 1, 101, 201 of the first embodiment to the second embodiment, the case where the teaching to the arm 20 and the holding unit adjusting mechanisms 23, 123 is performed simultaneously or continuously without particular separation has been described. . However, the robot system according to the present invention is not limited to this. For example, the first teaching is performed on the arm 20 at a speed slower than the actual reproduction speed, the arm 20 is reproduced at the actual reproduction speed, and the holding unit adjusting mechanism 23 having less hysteresis loss or the like than the arm 20 from the position after the reproduction. , 123 may be subjected to the second teaching.

  In this case, at the time of reproduction, the arm 20 is reproduced by the first teaching data, and the holding unit adjusting mechanisms 23 and 123 are reproduced by the second teaching data. As a result, even if a position error occurs due to hysteresis loss or the like in the arm 20, the holding unit adjusting mechanisms 23 and 123 can correct the position error, and the accuracy of movement of the workpiece by the robot 2 can be improved. It is possible to improve the accuracy of assembling the parts.

The processing operations of the first to second embodiments described above are specifically executed by the control device 3. Therefore, it may be achieved by supplying a recording medium recording a software program for realizing the above-described functions to the control device 3, and reading and executing the program stored in the recording medium by the CPU 30 of the control device 3. . In this case, the program itself read from the recording medium realizes the functions of the above-described embodiments, and the program itself and the recording medium on which the program is recorded constitute the present invention.

  In each embodiment, the case where the computer-readable recording medium is the ROM 31 and the program is stored in the ROM 31 has been described. However, the present invention is not limited to this. The program may be recorded on any recording medium as long as it is a computer-readable recording medium. For example, an HDD, an external storage device, a recording disk, or the like may be used as a recording medium for supplying the program.

DESCRIPTION OF SYMBOLS 1 ... Robot system, 2 ... Robot, 3 ... Control apparatus, 6 ... Table (fixing member), 7 ... Sensor (camera), 20 ... Articulated arm (arm), 21 ... End effector (hand), 22 ... Holding part , 23 ... holding part adjustment mechanism, 76 ... state-of-the-art joint (sixth joint), 101 ... robot system, 102 ... robot, 123 ... holding part adjustment mechanism, 201 ... robot system

Claims (10)

An articulated arm,
An end effector that is supported by the articulated arm, the position and posture of which are adjusted by the operation of the articulated arm, and a holding unit capable of gripping a workpiece;
A sensor for measuring at least one degree of freedom of the position and posture of the workpiece;
A holding part adjustment that is arranged between the most advanced joint of the multi-joint arm and the holding part of the end effector and that can adjust at least one degree of freedom of the position and posture of the holding part with respect to the multi-joint arm Mechanism,
A control device that controls at least the articulated arm, the end effector, and the holding unit adjustment mechanism, and calculates at least one degree of freedom of the position and orientation of the workpiece from measurement data acquired from the sensor;
The controller is
A teaching work placed so as to have a reference phase at a gripping position is gripped by the end effector and then moved to a target position. Based on the motion data of the articulated arm during that time, Calculate the command value in advance,
After causing the sensor to measure the phase of the workpiece placed at the gripping position, the articulated arm is operated according to the command value, and the workpiece is gripped at the gripping position and then moved to the target position. ,
At least the calculation of the difference between the phase of the workpiece measured by the sensor and the reference phase while operating the articulated arm according to the command value, and the correction operation of the holding unit adjustment mechanism based on the difference Do some,
A robot system characterized by this. The sensor is a camera that photographs the workpiece.
The robot system according to claim 1 . The sensor measures the workpiece in a state of being placed on a fixed member;
The robot system according to claim 1 or 2 , characterized in that The robot system according to any one of claims 1 to 3 , wherein the sensor measures the workpiece in a state of being held by the holding unit. An articulated arm,
An end effector that is supported by the articulated arm, the position and posture of which are adjusted by the operation of the articulated arm, and a holding unit capable of gripping a workpiece;
A sensor for measuring at least one degree of freedom of the position and posture of the workpiece;
A holding part adjustment that is arranged between the most advanced joint of the multi-joint arm and the holding part of the end effector and that can adjust at least one degree of freedom of the position and posture of the holding part with respect to the multi-joint arm Mechanism,
A robot system comprising: a control device that controls at least the articulated arm, the end effector, and the holding unit adjustment mechanism, and calculates at least one degree of freedom of the position and posture of the workpiece from measurement data acquired from the sensor; In the control method of
A teaching work placed so as to have a reference phase at a gripping position is gripped by the end effector and then moved to a target position. Based on the motion data of the articulated arm during that time, A teaching step for causing the control device to calculate a command value in advance;
A measuring step of measuring the phase of the workpiece placed at the gripping position by the sensor;
An articulated arm moving step of operating the articulated arm in accordance with the command value and gripping the workpiece at a gripping position and then moving the workpiece to a target position;
A step of calculating a difference between the phase of the workpiece measured in the measurement step and the reference phase, and operating the holding unit adjustment mechanism based on the difference, and
Performing at least a part of the correction step during the execution of the articulated arm movement step;
A control method of a robot system characterized by the above. The sensor is a camera that photographs the workpiece.
The robot system control method according to claim 5 , wherein: The sensor measures the workpiece in a state of being placed on a fixed member;
The robot system control method according to claim 5, wherein the robot system is a control method. The robot system control method according to any one of claims 5 to 7 , wherein the sensor measures the workpiece held in the holding unit. The program for making a computer perform each process of the control method of the robot system of any one of Claims 5 thru | or 8 . A computer-readable recording medium in which a program for causing a computer to execute each step of the robot system control method according to claim 9 is recorded.

Images