JP7295302B2 - Robot control device and teaching operation panel for calibrating mechanism error parameters for controlling robot - Google Patents

Description

The present invention relates to a robot controller and a teaching operation panel for calibrating mechanism error parameters for controlling a robot.

It is known in the prior art to perform various tasks by driving robots with working tools attached thereto. The robot moves the work tool to a predetermined position and orientation based on the motion program. The position and orientation of the robot preferably match those specified in the motion program. However, the position and orientation of the robot may deviate slightly from the position and orientation specified in the motion program due to manufacturing errors in the components when manufacturing the robot and the effects of gravity when driving the robot. .

In the prior art, control is known in which a three-dimensional position detection device is arranged at a location away from the robot to correct the motion of the robot (see, for example, Japanese Unexamined Patent Application Publication No. 11-90868). A three-dimensional position detection device can detect the actual position and posture of the robot. The actual position and orientation of the robot are different from those specified in the motion program. The control device calculates a correction matrix based on the position and orientation of the robot detected by the three-dimensional position detection device and the position and orientation of the robot designated by the motion program. The controller can use this correction matrix to modify the motion of the robot.

Errors in a plurality of items are conceivable as the cause of deviation of the actual position of the robot from the position designated by the motion program. For example, the actual position of the robot deviates from the position designated by the motion program due to an error in the length of the arm between the drive shafts or an error in the gear ratio of the speed reducer. In the prior art, a method of setting a plurality of such items as mechanism error parameters and setting values for each mechanism error parameter is known (for example, Japanese Patent Application Laid-Open No. 2008-12604, and Japanese Patent Laid-Open No. 2008-12604, and See JP-A-2012-196716).

JP-A-11-90868 Japanese Unexamined Patent Application Publication No. 2008-12604 JP 2012-196716 A

The controller of the robot can adjust the rotation angles of the drive motors that drive each component based on the mechanism error parameter. By accurately setting the mechanical parameters corresponding to the robot, the actual position and orientation of the robot can be brought closer to the position and orientation specified by the motion program.

For example, it is necessary to calibrate the mechanism error parameters when replacing the parts that make up the robot. That is, it is necessary to reset the mechanism error parameters. In the prior art, when calibrating the mechanical error parameters, control was performed to calculate all the mechanical error parameters. When calculating the mechanism error parameters, the actual position of the robot is detected by attaching a camera to the wrist of the robot or placing a three-dimensional measuring device at a position away from the robot. The actual position of the robot is measured a number of times by driving the robot to change its position. Then, a mechanism error parameter is calculated based on the actual position of the robot.

However, many mechanism error parameters are set in the robot controller. For this reason, it is necessary to drive the robot to a large number of positions in order to calculate all the mechanism error parameters. Alternatively, if all mechanism error parameters are to be calibrated, it is necessary to drive the robot over its entire range of motion. However, a robot installed in a factory or the like may have a limited driving range. For example, there are cases in which fences or devices other than the robot are placed around the robot so that the range in which the robot can be driven is small. Even if the robot is driven and the actual position of the robot is measured within such a small range, accurate mechanism error parameters may not be calculated. As a result, the accuracy of robot control may not be sufficiently improved.

In addition, since many mechanical error parameters are set in the robot controller, it is necessary to drive the robot to many positions and measure the actual position of the robot. For this reason, even when some parts are replaced, a long working time is required for calibration of the mechanism error parameters. As a result, there is a problem that the robot device cannot be used for a long time and the productivity of the factory deteriorates.

A controller for a robot including a plurality of drive axes according to one aspect of the present disclosure includes at least one memory that stores a plurality of mechanism error parameters including a first mechanism error parameter and a second mechanism error parameter; a processor; A first machine error parameter is set for one drive axis of the robot and a second machine error parameter is set for the remaining drive axis of the robot. At least one processor drives the robot to a plurality of positions and poses based on the second mechanism error parameter to obtain measured positions of the robot and information regarding the state of the robot. At least one processor calculates a third mechanism error parameter by correcting the value of the first mechanism error parameter based on the measured position of the robot and the information about the state of the robot. At least one processor controls the robot based on a plurality of mechanism error parameters including a second mechanism error parameter and a third mechanism error parameter.
A teaching operation panel according to another aspect of the present disclosure is connectable to a robot controller that controls the robot based on a plurality of mechanism error parameters. The teaching operation panel has a display unit capable of displaying information about the robot, and at least one of information about the replaced component parts of the robot and information about the reason for calibrating the robot based on the information about the robot displayed on the display unit. and an input unit that receives input of information from. The teaching operation panel causes the controller of the robot to change a first mechanical error parameter selected from a plurality of mechanical error parameters set for the robot based on the information received by the input unit.

The robot control device and the teaching operation panel according to one aspect of the present disclosure can calibrate the mechanism error parameters in a short period of time.

1 is a schematic diagram of a robot device according to an embodiment; FIG. 1 is a block diagram of a robot device; FIG. 1 is a side view of a three-dimensional measuring instrument according to an embodiment; FIG. Fig. 4 is an enlarged perspective view of the flange of the wrist in the embodiment; 4 is a flow chart of control of the robot apparatus;

A calibration device according to an embodiment will be described with reference to FIGS. 1 to 5. FIG. The calibrating device of this embodiment is arranged in a robotic device comprising a robot. A calibration device calibrates mechanism error parameters for adjusting control of the robot.

FIG. 1 is a schematic diagram of a robot apparatus according to this embodiment. The robot device 5 includes a hand 2 as a work tool and a robot 1 that moves the hand 2 . The robot 1 of this embodiment is an articulated robot including a plurality of joints 18a, 18b, and 18c. The robot 1 includes a plurality of moveable components. Each component of robot 1 is configured to rotate about drive axes J1-J6.

The robot 1 includes a base portion 14 fixed to an installation surface 79 and a swivel base 13 supported by the base portion 14 . The swivel base 13 rotates around the drive axis J1 with respect to the base portion 14 . Robot 1 includes upper arm 11 and lower arm 12 . The lower arm 12 is supported to rotate about the drive shaft J2 with respect to the swivel base 13 . The upper arm 11 is supported to rotate about the drive axis J3 with respect to the lower arm 12 . Further, the upper arm 11 rotates around the drive axis J4. Robot 1 includes a wrist 15 supported by upper arm 11 . Wrist 15 rotates around drive axis J5. Wrist 15 also includes a flange 16 that rotates about drive axis J6. A hand 2 is fixed to the flange 16 .

Although the robot of this embodiment has six drive shafts, it is not limited to this form. A robot that changes its position and orientation with any mechanism can be employed. Moreover, although the work tool of the present embodiment is a hand that grips a work, it is not limited to this form. A worker can select a work tool according to the work to be performed by the robot device. For example, a work tool for welding or a work tool for applying adhesive can be employed.

A reference coordinate system 71 is set in the robot device 5 of the present embodiment. In the example shown in FIG. 1, the origin of the reference coordinate system 71 is arranged on the base portion 14 of the robot 1 . The reference coordinate system 71 is also called a world coordinate system. The reference coordinate system 71 is a coordinate system in which the position of the origin is fixed and the directions of the coordinate axes are fixed. Even if the position and orientation of the robot 1 change, the position and orientation of the reference coordinate system 71 do not change. The reference coordinate system 71 has, as coordinate axes, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. Also, the W axis is set as a coordinate axis around the X axis. A P-axis is set as a coordinate axis around the Y-axis. An R-axis is set as a coordinate axis around the Z-axis.

In this embodiment, a flange coordinate system 72 having an origin located on the surface of the flange 16 of the wrist 15 is set. The flange coordinate system 72 is also referred to as the mechanical interface coordinate system. Flange coordinate system 72 rotates and moves with flange 16 . The origin of the flange coordinate system 72 is set on the drive axis J6 of the robot 1 . The flange coordinate system 72 has X-, Y-, and Z-axes that are orthogonal to each other as coordinate axes. In the example shown in FIG. 1, the flange coordinate system 72 is set such that the direction in which the Z axis extends is parallel to the direction in which the drive axis J6 extends. The flange coordinate system 72 also has a W axis about the X axis, a P axis about the Y axis, and an R axis about the Z axis. The position of the robot 1 corresponds to the position of the origin of the flange coordinate system 72 in the reference coordinate system 71 . Also, the posture of the robot 1 corresponds to the orientation of the flange coordinate system 72 with respect to the reference coordinate system 71 .

FIG. 2 shows a block diagram of the robot apparatus according to this embodiment. Referring to FIGS. 1 and 2, robot 1 includes a robot driving device that changes the position and posture of robot 1 . The robot drive includes robot drive motors 22 that drive components such as upper arm 11 , lower arm 12 and wrist 15 . In this embodiment, a plurality of robot drive motors 22 are arranged corresponding to the respective drive axes J1 to J6. By driving the robot drive motor 22, the orientation of each component changes.

The hand 2 has a hand driving device that drives the hand 2 . The hand drive device includes a hand drive motor 21 that drives the claw portion of the hand 2 . As the hand driving motor 21 is driven, the claw portion of the hand 2 is opened and closed. Note that the hand may be formed to be driven by air pressure or the like.

The robot device 5 includes a control device 4 that controls the robot 1 and the hand 2, and a teaching operation panel 37 for operating the control device 4 by an operator. The control device 4 includes an arithmetic processing device (computer) having a CPU (Central Processing Unit) as a processor. The control device 4 has a RAM (Random Access Memory), a ROM (Read Only Memory), etc. connected to the CPU via a bus.

The teaching operation panel 37 includes an input section 38 for inputting information regarding the robot 1 and hand 2 . The input unit 38 is composed of a keyboard, a dial, and the like. The operator can input an operation program, set values of variables, judgment values of variables, and the like to the control device 4 from the input unit 38 . The teaching operation panel 37 includes a display section 39 that displays information regarding the robot 1 and hand 2 .

A pre-created operation program 46 is input to the control device 4 in order to control the robot 1 and the hand 2 . Alternatively, the operator can set the teaching point of the robot 1 by operating the teaching operation panel 37 to drive the robot 1 . The control device 4 can generate an operation program 46 for driving the robot 1 and the hand 2 based on the teaching points. The control device 4 includes a storage section 42 that stores information regarding control of the robot 1 and the hand 2 . The operating program 46 is stored in the storage unit 42 . The robot device 5 automatically performs work based on the operation program 46 .

The control device 4 includes a motion control section 43 that sends motion commands to the robot 1 and the hand 2 . The motion control unit 43 sends motion commands for driving the robot 1 to the robot driving unit 45 based on the motion program 46 . Robot drive section 45 includes an electrical circuit that drives robot drive motor 22 . The robot driving section 45 supplies electricity to the robot driving motor 22 based on the operation command. The motion control unit 43 also sends an operation command for driving the hand 2 to the hand driving unit 44 based on the operation program 46 . The hand drive section 44 includes an electric circuit that drives the hand drive motor 21 . The hand drive unit 44 supplies electricity to the hand drive motor 21 based on the operation command.

Robot 1 includes a state detector for detecting the state of robot 1 including the position and orientation of robot 1 . The state detector in this embodiment includes a rotational position detector 19 attached to a robot drive motor 22 corresponding to a drive shaft such as an arm. The rotational position detector 19 is composed of an encoder or the like that detects the rotational angle of the robot drive motor 22 . In the present embodiment, the position and posture of robot 1 are detected based on the outputs of multiple rotational position detectors 19 .

The motion control unit 43 controls the robot 1 so that the position and posture of the robot are specified in the motion program 46 . The motion control unit 43 controls the rotation angle of the robot drive motor 22 based on inverse kinematics, for example. A tool coordinate system can be set at the tip of the work tool so as to correspond to the flange coordinate system 72 . The position and orientation of the flange coordinate system 72 correspond to the position and orientation of the tool coordinate system. By controlling the robot 1 so that the flange coordinate system 72 assumes the desired position and attitude, the work tool can be controlled to the desired position and attitude.

By the way, the actual position and orientation of the robot may deviate from the position and orientation specified by the operation program 46 due to manufacturing errors in the components of the robot, assembly errors when assembling the robot, the effects of gravity, and the like. . In this embodiment, a plurality of mechanism error parameters 49 for adjusting control of the robot 1 are set separately from the operation program 46 . A plurality of mechanical error parameters 49 are stored in the storage unit 42 .

The mechanical error parameters 49 include arbitrary parameters that cause positional and attitude errors that occur when the robot 1 is driven. For example, the mechanism error parameters 49 include the length of the link between each drive shaft, the position of each drive shaft, the gear ratio error caused by the backlash in the reducer of each drive shaft, and the gravitational force. It contains parameters such as variables related to the elastic deformation of links that deform under the influence of Table 1 shows examples of mechanical error parameters.

The mechanism error parameters of this embodiment include DH parameters denoted by symbols P1 to P4. In the DH (Denavit Hartenberg) method, a coordinate system is set for each drive axis, and the position and orientation of the robot can be expressed based on the relationship between the coordinate systems of the drive axes. DH parameters are parameters in the DH method, and include parameters DH-θ, DH-D, DH-A, and DH-α, for example.

Further, the mechanism error parameter of the present embodiment includes a spring constant related to the torque around the drive shaft obtained by the Newton-Euler method. These spring constants are parameters relating to the amount of deflection with respect to torque, and are indicated by symbols P5 to P7. The mechanism error parameters include a first direction spring constant θ, a second direction spring constant α, and a third direction spring constant β for each drive shaft.

In addition, an error may occur between the output of the rotational position detector 19 attached to the robot drive motor 22 arranged on each drive shaft and the rotation angle actually transmitted to the arm or the like. This angle error is caused by, for example, a gear ratio error in the speed reducer. The mechanism error parameter of the present embodiment includes the gear ratio error of the speed reducer indicated by symbol P8.

The mechanism error parameter is not limited to these parameters, and any parameter for adjusting the control of the robot can be set. The mechanism error parameter is set when the robot 1 is shipped according to the location where the robot 1 is installed. Mechanism error parameters can be set for each of the drive axes J1-J6. The values of the mechanism error parameters 49 are stored in the storage unit 42 in the form of files.

Referring to FIG. 2, motion control unit 43 calculates the rotation angle of robot drive motor 22 so that the position and posture of robot 1 set in motion program 46 are obtained based on inverse kinematics. At this time, the motion control unit 43 acquires the mechanism error parameter 49 stored in the storage unit 42 . The motion control unit 43 corrects the motion command for the robot drive motor 22 based on each mechanism error parameter. By executing this control, the position and orientation of the robot can be brought closer to the position and orientation designated by the motion program 46 .

The calibration device in this embodiment calibrates the mechanism error parameters that adjust the control of the robot 1 . In this embodiment, the control device 4 functions as a calibration device. The robot device 5 has a three-dimensional measuring device 8 for accurately measuring the position and orientation of the robot 1 . The three-dimensional measuring device 8 of this embodiment is arranged at a position away from the robot 1 .

FIG. 3 shows an enlarged view of the three-dimensional measuring device according to this embodiment. 1 to 3, three-dimensional measuring device 8 in the present embodiment oscillates laser light and receives the laser light reflected by reflector 67 or reflector 68 attached to robot 1 . The three-dimensional measuring device 8 includes a laser head 63 that oscillates laser light as indicated by arrow 91 . The laser head 63 is supported by the support member 62 . The laser head 63 includes an oscillator 81 that oscillates laser light. The laser head 63 has a light receiving section 82 that receives the laser light reflected by the reflector 67 or 68 . The light receiving section 82 is arranged inside the laser head 63 .

The three-dimensional measuring instrument 8 in this embodiment includes a rotating device 64 that changes the orientation of the laser head 63 . The rotating device 64 includes a measuring device drive motor 84 that changes the orientation of the laser head 63 . A rotational position detector 85 such as an encoder is attached to the measuring device driving motor 84 in order to detect the rotation angle of the measuring device driving motor 84 . The rotating device 64 rotates the laser head 63 around a horizontally extending rotating shaft, as indicated by an arrow 92 . Also, the rotating device 64 rotates the supporting member 62 around a rotating shaft extending in the vertical direction, as indicated by an arrow 93 . The rotating device 64 is supported by a tripod 65 . In this way, the three-dimensional measuring device 8 can oscillate laser light in any direction by being driven by the rotating device 64 .

The three-dimensional measuring device 8 includes an arithmetic processing device including a CPU, a RAM, and the like. The arithmetic processing unit of the three-dimensional measuring device 8 includes a position calculator 83 that calculates the positions of the reflectors 67 and 68 . The position calculator 83 calculates the distance from the three-dimensional measuring device 8 to the reflectors 67 and 68 from the phase difference between the oscillated laser light and the received laser light. The position calculator 83 can calculate the positions of the reflectors 67 and 68 based on the distance from the three-dimensional measuring device 8 to the reflectors 67 and 68 and the orientation of the laser head 63 .

A measuring device coordinate system 73 is set in the three-dimensional measuring device 8 of the present embodiment. The measuring instrument coordinate system 73 is set in the control device 4 as a user coordinate system that can be set at any position by the operator. The origin of the measuring device coordinate system 73 can be set at any position inside the three-dimensional measuring device 8 . For example, the origin of the measuring instrument coordinate system 73 can be located at the tip of the laser light source located inside the laser head 63 .

The measuring instrument coordinate system 73 has X, Y, and Z axes orthogonal to each other as coordinate axes. The direction of the measuring device coordinate system 73 can be set to any direction. W-axis, P-axis, and R-axis are set as coordinate axes around the respective X-axis, Y-axis, and Z-axis. In this embodiment, the Z axis is set to be parallel to the vertical direction. The measuring instrument coordinate system 73 is a coordinate system in which the position of the origin is fixed and the directions of the coordinate axes are fixed. Even if the orientation of the laser head 63 changes, the position and orientation of the measuring instrument coordinate system 73 do not change.

In the first control for updating the mechanism error parameter in the present embodiment, the relative position and orientation of three-dimensional measuring device 8 with respect to robot 1 are determined in advance. That is, the relative position and attitude of measuring device coordinate system 73 with respect to reference coordinate system 71 are determined in advance. Here, a method of detecting the relative position and orientation of the measuring device coordinate system 73 with respect to the reference coordinate system 71 will be described.

Referring to FIG. 1, robot 1 of the present embodiment is provided with reflector 68 for detecting the relative position and orientation of measuring instrument coordinate system 73 with respect to reference coordinate system 71 . The reflector 68 of this embodiment is fixed to the surface of the base portion 14 .

The reflector 68 is spherically formed. The reflector 68 is formed so as to reflect the laser light in the same direction as the incident laser light. The reflector 68 has a predetermined position relative to the reference coordinate system 71 . That is, the coordinate values of the reflector 68 in the reference coordinate system 71 are predetermined.

The rotating device 64 of the three-dimensional measuring device 8 adjusts the orientation of the laser head 63 so that the laser light returns to the laser head 63 after being reflected by the reflector 68 . The operator can manually drive the rotating device 64 to adjust the orientation of the laser head 63 . Alternatively, the three-dimensional measuring device 8 may have an automatic search function that scans so that the emitting direction of the laser light draws a circle. In this case, the operator approximately adjusts the orientation of the laser head 63 so that the laser light emitted from the three-dimensional measuring device 8 is directed toward the reflector 68 . After that, the three-dimensional measuring device 8 can adjust the direction of the laser head 63 by the automatic search function so that the laser light reflected by the reflector 68 returns to the laser head 63 .

The rotation device 64 can detect the orientation of the laser head 63 in the measuring device coordinate system 73 based on the output of the rotation position detector 85 . The position calculator 83 calculates the distance from the three-dimensional measuring device 8 to the reflector 68 by receiving light reflected by the reflector 68 . Then, the position calculator 83 can calculate the position of the reflector 68 in the measuring device coordinate system 73 based on the calculated distance and the orientation of the laser head 63 . Since the position of the reflector 68 in the reference coordinate system 71 is predetermined, the position calculator 83 can calculate the relative position and orientation of the measuring device coordinate system 73 with respect to the reference coordinate system 71 . In this way, the position and orientation of the measuring device coordinate system 73 can be set in advance. In the present embodiment, the position and orientation of measuring device coordinate system 73 are calculated based on reflected light from one reflector 68, but the present invention is not limited to this. A plurality of reflectors may be arranged on the base of the robot or the like, and the position and orientation of the measuring device coordinate system may be calculated based on the reflected light from the plurality of reflectors.

FIG. 4 shows a perspective view of the reflector attached to the flange on the tip of the robot. FIG. 4 shows a state in which the hand 2 is removed. A reflector 67 is fixed to the flange 16 of the robot 1 for measuring the position of the measuring instrument coordinate system 73 relative to the flange coordinate system 72 . Reflector 67 has a configuration similar to that of reflector 68 . The reflector 67 is spherically formed. The reflector 67 is formed to reflect the laser light in the incident direction. Reflector 67 is fixed to flange 16 via support member 66 .

In the first control for updating the mechanism error parameter, the support member 66 is formed so that the position of the reflector 67 in the flange coordinate system 72 is determined. That is, the position of reflector 67 with respect to the origin of flange coordinate system 72 is predetermined.

Referring to FIG. 2, the control device 4 has a calibrating section 53 that calibrates the mechanism error parameters. The calibrating unit 53 invalidates some of the mechanical error parameters as the first mechanical error parameters. The calibrator 53 drives the robot 1 to a plurality of positions and postures using second mechanism error parameters other than the first mechanism error parameters. The calibrator 53 measures the measured position of the robot 1 with the three-dimensional measuring device 8 . Also, at this time, the calibration unit 53 acquires information about the state of the robot 1 including the rotation angle of the robot drive motor 22 .

Next, the calibration unit 53 stores information obtained by combining the measured position of the robot 1 and information regarding the state of the robot 1 . The calibration unit 53 calculates the invalidated first mechanical error parameter based on the combined information. Then, without changing the second mechanism error parameter, the invalidated first mechanism error parameter is changed to the calculated first mechanism error parameter, and a new mechanism error parameter file is created.

FIG. 5 shows a flow chart of control of the calibration device in this embodiment. The calibration control of this embodiment can be implemented when the components of the robot 1 are replaced. For example, calibration control can be implemented when robot drive motor 22, lower arm 12, or upper arm 11 are replaced. Calibration control can also be implemented when the speed reducer that reduces the rotational speed of the robot drive motor 22 is replaced. Alternatively, the calibration controls of the present embodiment can be implemented in the event that a component such as upper arm 11 is hit by another device or object.

With reference to Table 1, in the present embodiment, an example of replacing components related to the drive shaft J2, such as a speed reducer, will be described. 2 and 5, at step 101, a first mechanism error parameter to be disabled is set among a plurality of mechanism error parameters. The calibrating unit 53 includes a parameter setting unit 54 that sets some of the plurality of mechanical error parameters as first mechanical error parameters and disables the first mechanical error parameters.

A first mechanism error parameter that overrides the adjustment of the control can be predetermined by the operator. The first mechanism error parameter can be defined in a reference file and stored in the storage unit 42 . The parameter setting unit 54 acquires the reference file from the storage unit 42 and sets the first mechanical error parameter. In the example shown in Table 1, for the drive axis J2, all mechanical error parameters that were set when the robot 1 was shipped are selected as the first mechanical error parameters.

The parameter setting unit 54 sets a mechanical error parameter other than the first mechanical error parameter as a second mechanical error parameter. In the example shown in Table 1, the mechanical error parameters set for the drive axes J1, J3, J4, J5, and J6 are set as the second mechanical error parameters.

The parameter setting unit 54 is not limited to this form, and can set the first mechanism error parameter by arbitrary control. For example, the teaching operation panel 37 displays a list of mechanical error parameters on the display section 39 . Then, the operator operates the input unit 38 to select the first mechanism error parameter to be invalidated. The parameter setting unit 54 can acquire the operator's input and set the first mechanism error parameter.

Next, at step 102, the parameter setting unit 54 disables the first mechanical error parameter. Also, the parameter setting unit 54 effectively sets the second mechanical error parameter.

Next, at step 103, the robot 1 is driven to a plurality of positions using the second mechanism error parameters. The calibration unit 53 has a measurement control unit 57 that drives the robot 1 to multiple positions and orientations using the second mechanism error parameter. The measurement control unit 57 sends operation commands for the robot 1 and the three-dimensional measuring device 8 to the operation control unit 43 . A measurement program 48 for measuring the actual position of the robot 1 is generated in advance by the operator. A measurement program 48 is stored in the storage unit 42 .

The measurement control section 57 changes the position and orientation of the robot 1 based on the measurement program 48 . At this time, the measurement control unit 57 drives the robot 1 without using the first mechanism error parameter. The measurement control unit 57 measures the actually measured position of the robot 1 with the three-dimensional measuring device 8 at each position and orientation of the robot 1 . The measurement control unit 57 also acquires information about the state of the robot 1 when the actual position was measured. The robot 1 state includes the rotational position of the robot drive motor 22 .

The number of measurement points for measuring the actual position of the robot 1 is preferably within the range of several tens to several hundred. A measurement point (position and posture of the robot 1) for measuring the actual position of the robot 1 can be determined by any method. For example, the measurement points can be set so as to be evenly distributed within the operable range of the robot 1 . Alternatively, measurement points can be set on the path set by the operation program 46 . That is, the measurement points can be set so as to match the position and orientation of the robot 1 driven by the motion program 46 . By setting the measurement points on the path set in the motion program 46, it is possible to reduce the amount of deviation in the position and orientation of the robot 1 when the motion program 46 is executed.

Referring to FIG. 1, the position of robot 1 corresponds to the position of flange coordinate system 72 (the position of the origin). The position of reflector 67 is defined with respect to the position of flange coordinate system 72 . The three-dimensional measuring device 8 measures the position of the reflector 67 by a method similar to the method for measuring the position of the reflector 68 .

For example, since the position and orientation of the three-dimensional measuring device 8 with respect to the reference coordinate system 71 are predetermined, the measurement control unit 57 determines the approximate position of the reflector 67 based on the rotation angle information of the robot drive motor 22 . Calculate its position. The measurement control section 57 calculates coordinate values of the reflector 67 in the reference coordinate system 71 . Next, the rotating device 64 of the three-dimensional measuring device 8 adjusts the orientation of the laser head 63 so as to oscillate laser light toward the reflector 67 based on the coordinate values of the reflector 67 in the reference coordinate system 71. do. Then, the three-dimensional measuring device 8 adjusts the orientation of the laser head 63 so as to receive the laser light reflected by the surface of the reflector 67 by the automatic search function. The position calculator 83 can calculate the position of the reflector 67 in the measuring device coordinate system 73 based on the distance from the three-dimensional measuring device 8 to the reflector 67 and the orientation of the laser head 63 .

The relative position and orientation of measuring instrument coordinate system 73 with respect to reference coordinate system 71 are determined in advance. Therefore, the position calculator 83 can calculate the position of the reflector 67 in the reference coordinate system 71 based on the position of the reflector 67 in the measuring device coordinate system 73 . Furthermore, the position calculator 83 can calculate the position of the origin of the flange coordinate system 72 based on the position of the reflector 67 . A certain measured position can be calculated. In this embodiment, the measured position of the robot 1 is calculated based on the reflected light from one reflector 67, but the present invention is not limited to this. A plurality of reflectors may be arranged on a flange or the like, and the measured position of the robot may be calculated based on reflected light from the plurality of reflectors.

The measurement control unit 57 acquires the measured position of the robot 1 from the three-dimensional measuring device 8 . The storage unit 42 stores information obtained by combining the actually measured position of the robot 1 and information regarding the state of the robot 1 for one measurement point. The measurement control unit 57 measures the measured positions of the robot 1 at a plurality of measurement points, combines the measured positions of the robot 1 and information about the state of the robot 1 , and stores them in the storage unit 42 .

Referring to FIGS. 2 and 5, next, at step 104, the first mechanism parameter invalidated at step 102 is calculated. The calibrating unit 53 includes a parameter calculating unit 55 that calculates the first mechanical error parameter based on the actually measured position of the robot and the information regarding the state of the robot. The parameter calculator 55 can calculate the first mechanism error parameter by any method based on information about many measurement points.

Referring to Table 1, in this example, seven mechanism error parameters for drive axis J2 are calculated. The parameter calculator 55 can calculate the position of the robot 1 based on the output of the rotational position detector 19 and all mechanism error parameters at each measurement point. In this embodiment, such a position of the robot 1 is called a calculated position. Then, the parameter calculator 55 can calculate the first mechanical error parameter using the least squares method so that the error of the calculated position with respect to the measured position is small for the plurality of measurement points.

Next, in step 105, the mechanism error parameters are corrected. The calibration section 53 has a correction section 56 that corrects a plurality of mechanism error parameters. The modifying unit 56 changes the first mechanical error parameter disabled by the parameter setting unit 54 to the first mechanical error parameter calculated by the parameter calculating unit 55 without changing the second mechanical error parameter. do. With reference to Table 1, for example, the correction unit 56 changes the mechanism error parameter related to the drive axis J2 that has been disabled for calibration to the mechanism error parameter calculated by the parameter calculation unit 55 . For the mechanism error parameters for the drive axes J1, J3, J4, J5, and J6 other than the drive axis J2, the same values as those used before correction are adopted.

As described above, the calibration apparatus of the present embodiment drives the robot 1 with some of the mechanism error parameters disabled, and calculates the disabled mechanism error parameters based on the measured position of the robot 1. Calibrate the mechanism error parameters. In the calibration apparatus of the present embodiment, in order to update some of the plurality of mechanism error parameters, the measurement for measuring the actually measured position is more difficult than updating all of the mechanism error parameters. The number of points can be reduced. For example, in a robot apparatus installed in a factory or the like, the movement range of the robot may be limited by devices or fences arranged around the robot apparatus. For this reason, the number of measurement points may be limited. Also in this case, the calibration device in this embodiment can calibrate the mechanism error parameters.

Alternatively, since the number of measurement points can be reduced in the calibration apparatus of the present embodiment, the time required to drive the robot 1 and measure the actual position with the three-dimensional measuring device 8 is shortened. Therefore, the work time for calibrating the mechanism error parameters can be shortened. The time during which the robot device 5 is stopped can be shortened. As a result, it is possible to suppress the deterioration of the productivity of the factory.

Of the plurality of mechanism error parameters, some first mechanism error parameters that disable adjustment of control can be set by various methods. For example, the storage unit 42 can store, as parameter information, a first mechanical error parameter that is disabled according to the reason for performing calibration. Parameter information can be stored in a reference file. The parameter setting unit 54 can set the mechanical error parameter defined in the parameter information as the first mechanical error parameter. For example, parameter information when a robot drive motor for a predetermined drive axis is replaced, parameter information when a predetermined arm is replaced, and parameter information when a predetermined component collides with another object are prepared in advance. can be stored in the storage unit 42. The parameter setting unit 54 can set the first mechanical error parameter based on the reason for performing the calibration. For example, the parameter setting unit 54 can automatically set the first mechanism error parameter by inputting the reason for calibration by the operator into the teaching operation panel 37 .

In particular, the parameter information can include a first mechanism error parameter that is disabled in response to replacement of a component of the robot 1 when the component of the robot 1 is replaced. Then, the parameter setting unit 54 acquires information on the replaced components of the robot 1 . The parameter setting unit 54 can set the first mechanical error parameter based on the replaced component of the robot 1 . With this configuration, the operator can automatically select the first mechanism error parameter by inputting information on the replaced component of the robot 1 .

In the example of Table 1 above, all mechanism error parameters associated with drive axis J2 are invalidated because the part on drive axis J2 was replaced. That is, the parameter setting unit 54 sets the mechanism error parameter to be disabled and the mechanism error parameter to be enabled for each drive axis, but the configuration is not limited to this. The parameter setting unit 54 can invalidate any combination of mechanical error parameters among the plurality of mechanical error parameters.

For example, some of the mechanical error parameters associated with one drive axis may be invalidated. In the mechanism error parameters corresponding to one drive axis, it is possible to predetermine the order of priority for setting invalidity. For example, there are cases where the number of measurement points for measuring the actual position cannot be sufficiently increased due to the small operating range of the robot 1 . In this case, the mechanism error parameter with higher priority may be invalidated. For example, referring to Table 1, when the transmission of the drive shaft J2 is replaced, the parameter DH-A of the drive shaft J2 has a lower priority, so the parameter DH-A is set to the second mechanism error parameter. I don't mind.

Also, in Table 1, the mechanism error parameter related to one drive axis is invalidated, but it is not limited to this form. Mechanism error parameters associated with multiple drive axes may be disabled. For example, when the lower arm 12 is replaced, the mechanical error parameter related to the drive axis J2 and the mechanical error parameter related to the drive axis J3 can be set as the first mechanical error parameter. Furthermore, in Table 1, a mechanism error parameter is set to be invalid for each drive axis, but the configuration is not limited to this. may be selected.

Also, the operator may increase or decrease the first mechanism error parameter based on the result of calibrating the mechanism error parameter. For example, the parameter calculator 55 can calculate the calculated position based on the calculated first mechanical error parameter and information about the state of the robot. The parameter calculator 55 can calculate the error of the calculated position with respect to the measured position for all measurement points. The operator may reduce the number of first mechanism error parameters when the average value of this error is large.

Furthermore, the parameter setting unit 54 may automatically select the first mechanical error parameter. For example, a number of mechanism error parameters can be initially set as the first mechanism error parameter. The parameter calculator 55 calculates a first mechanical error parameter. Next, the parameter setting unit 54 deletes the mechanical error parameters one by one based on the priority of the mechanical error parameters. The parameter calculator 55 calculates a first mechanical error parameter. By repeating this control, a plurality of types of first mechanical error parameters can be calculated. The parameter calculator 55 can calculate the average value of the error of the calculated position with respect to the measured position for each of the first mechanism error parameters for all the measurement points. The correction unit 56 can adopt the first mechanical error parameter with the smallest average value of the error of the calculated position with respect to the measured position. Thus, the first mechanism error parameter can be manually selected by the operator or automatically selected.

Further, when the robot 1 is driven using the second mechanism error parameter to measure the measured position of the robot 1, the drive axis for driving the robot 1 can be selected by any method. For example, in the measurement program 48, measurement points can be set such that the robot 1 drives on all drive axes. By adopting this configuration, the first mechanism error parameter can be calibrated with high accuracy. The robot 1 can be driven with high precision for various positions and postures of the robot 1 .

Alternatively, information on the drive axis of the robot 1 associated with each mechanism error parameter can be determined in advance. The storage unit 42 can store this information as drive axis information. The measurement control unit 57 drives the drive axis related to the first mechanism error parameter among the plurality of drive axes of the robot 1, and stops the drive axes other than the drive axis related to the first mechanism error parameter. The robot 1 can be driven to For example, when changing the value of the mechanism error parameter associated with the drive axis J2, it is possible to drive only the robot drive motor 22 of the drive axis J2 and measure the measured position. By implementing this control, the number of measurement points for measuring the actual position can be reduced. As a result, the calibration work time can be shortened.

Next, the second control for updating the mechanism error parameter will be described. In the above embodiment, the position and attitude of measuring device coordinate system 73 with respect to reference coordinate system 71 are measured in advance. That is, the position of the three-dimensional measuring device 8 relative to the position where the robot 1 is installed is predetermined. However, in the calibrating device of this embodiment, many actual positions are measured. Therefore, the relative position and orientation of the measuring instrument coordinate system 73 with respect to the reference coordinate system 71 can be used as variables. For example, the position and orientation of the measuring device coordinate system 73 can be represented by coordinate values in the reference coordinate system 71 . These coordinate values can be set to variables.

The parameter calculator 55 can simultaneously calculate the coordinate values of the measuring instrument coordinate system 73 in the reference coordinate system 71 when calculating the first mechanical error parameter by the least squares method. That is, the parameter calculator 55 can calculate the relative position and orientation of the measuring device coordinate system 73 with respect to the reference coordinate system 71 based on the information about the measured position of the robot 1 and the state of the robot 1 . Thus, the parameter calculator 55 can calculate the position of the three-dimensional measuring device 8 relative to the position where the robot 1 is installed. With this control, the mechanism error parameters can be calibrated without predetermining the position of the three-dimensional measuring device 8 relative to the position where the robot 1 is installed.

Next, the third control for updating the mechanism error parameter will be described. In the third control, the parameter calculator 55 calculates the relative position of the reflector 67 with respect to the position of the flange 16 based on the measured position of the robot and information on the state of the robot. In the third control, the position of the reflector 67 relative to the position of the flange 16 is calculated by the same method as the calculation of the position of the three-dimensional measuring device 8 in the second control. For example, the position of flange 16 corresponds to the position of the origin of flange coordinate system 72 . The position of reflector 67 can be represented by coordinate values of flange coordinate system 72 . The parameter calculator 55 can set the coordinate values in the flange coordinate system 72 as variables.

The parameter calculator 55 can calculate the coordinate values of the reflector 67 in the flange coordinate system 72 together with the first mechanical error parameter by the method of least squares. This control allows calibration of the mechanism error parameters without predetermining the position of reflector 67 relative to the position of flange 16 . For example, the reflector 67 may be attached without using a dedicated jig for determining the position of the reflector 67 with respect to the flange 16 . Even if the reflector 67 is not attached using a special jig, it is possible to calibrate the mechanism error parameters.

The three-dimensional measuring device 8 of the present embodiment is formed so as to be able to measure the positions of the reflectors 67 and 68 by oscillating and receiving laser light, but is not limited to this form. The three-dimensional measuring device can employ any device capable of accurately measuring the actual position and orientation of the robot. Further, in the present embodiment, the position of the robot 1 is measured by the three-dimensional measuring device 8 with the hand 2 attached, but the present invention is not limited to this form. The position of the robot 1 may be measured with the hand 2 removed.

In each of the controls described above, the order of steps can be changed as appropriate within a range in which the functions and actions are not changed.

The above embodiments can be combined as appropriate. In each of the above figures, the same reference numerals are given to the same or equivalent parts. It should be noted that the above embodiment is an example and does not limit the invention. Further, the embodiments include modifications of the embodiments indicated in the claims.

1 robot 4 control device 5 robot device 8 three-dimensional measuring device 16 flange 19 rotational position detector 42 storage unit 43 motion control unit 46 motion program 49 mechanism error parameter 54 parameter setting unit 55 parameter calculation unit 56 correction unit 57 measurement control unit 67 , 68 reflector 71 reference coordinate system 72 flange coordinate system 73 measuring instrument coordinate system 81 oscillator 82 light receiver

Claims (8)

In a robot controller including multiple drive axes,
at least one memory storing a plurality of mechanical error parameters including a first mechanical error parameter and a second mechanical error parameter , wherein the first mechanical error parameter is set for one drive axis of the robot; and the second mechanical error parameter is set for a remaining drive axis of the robot;
moreover,
at least one processor ;
The at least one processor
driving the robot to a plurality of positions and orientations based on the second mechanism error parameter to acquire information about the measured position of the robot and the state of the robot;
calculating a third mechanism error parameter obtained by correcting the value of the first mechanism error parameter based on the measured position of the robot and information about the state of the robot;
A robot controller that controls the robot based on a plurality of mechanism error parameters including the second mechanism error parameter and the third mechanism error parameter. The first and second mechanical error parameters are the length of the links between the drive shafts of the robot, the positions of the respective drive shafts, and the gears caused by the backlash produced in the reducers of the respective drive shafts. 2. The robot controller according to claim 1, including at least one of a ratio error and a variable relating to elastic deformation of a link that deforms under the influence of gravity. The at least one memory stores the drive axis of the robot associated with each mechanism error parameter as drive axis information,
The at least one processor drives a drive axis related to the first mechanism error parameter among a plurality of drive axes of the robot, and stops drive axes other than the drive axis related to the first mechanism error parameter. 2. The robot control device according to claim 1, which drives the robot so as to A plurality of measurement points are predetermined for measuring the actual position of the robot,
4. The robot control device according to any one of claims 1 to 3, wherein the plurality of measurement points are set so as to be evenly distributed within an operable range of the robot. The at least one processor automatically changes a mechanism error parameter designated as the first mechanism error parameter among a plurality of mechanism error parameters to calculate a plurality of the third mechanism error parameters. 5. The robot controller according to any one of 1 to 4. A teaching operation panel connectable to a robot control device that controls the robot based on a plurality of mechanism error parameters,
a display unit capable of displaying information about the robot;
an input unit that accepts input of at least one of information on the replaced component parts of the robot and information on the reason for calibrating the robot based on the information on the robot displayed on the display unit;
A teaching operation panel for causing a controller of the robot to change a first mechanism error parameter selected from a plurality of mechanism error parameters set for the robot based on the information received by the input unit. 7. The teaching console panel according to claim 6, wherein said display unit displays a list of a plurality of mechanism error parameters. 8. The teaching operation panel according to claim 6, wherein the information about the component parts of the robot includes at least one of information about replaced component parts of the robot and information about a hand attached to the robot.

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