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A calibration method for a coordinate system of a workpiece held by a robot manipulator, which includes the following steps: setting a predicted coordinate system on the workpiece; controlling the drive mechanism to drive the workpiece to move a specific distance along a coordinate axis in the predi

A calibration method for a coordinate system of a workpiece held by a robot manipulator, which includes the following steps: setting a predicted coordinate system on the workpiece; controlling the drive mechanism to drive the workpiece to move a specific distance along a coordinate axis in the predicted coordinate system and measuring the distance change of the workpiece in a direction perpendicular to the move; using the measured distance change to determine an orientation error between the predicted coordinate system and the actual coordinate system; correcting the orientation parameters of the predicted coordinate system; controlling the drive mechanism to drive the workpiece to rotate by a specific angle around a coordinate axis of the predicted coordinate system and measuring the distance change after being rotated; using the measured distance change to determine a position error; correcting the position parameters of the predicted coordinate system.

대표청구항 ▼

1. A calibration method for a coordinate system of a robot manipulator, the robot manipulator comprises a drive mechanism, a controller configured to control the drive mechanism, a tool assembled to a distal end of the drive mechanism, the distal end of the drive mechanism having a basic coordinate

1. A calibration method for a coordinate system of a robot manipulator, the robot manipulator comprises a drive mechanism, a controller configured to control the drive mechanism, a tool assembled to a distal end of the drive mechanism, the distal end of the drive mechanism having a basic coordinate system; an assistant measurement tool comprises a measurement device; a workpiece comprises an attachment plane coupled with the tool, a processing plane at the opposite side of the attachment plane, a first side plane and a second side plane connected to the attachment plane and the processing plane, the calibration method comprising: A. making the processing plane of the workpiece face toward the measurement device;B. setting a predicted coordinate system (Xm, Ym, Zm, Rx, Ry, Rz) on the workpiece with assumed position errors (Δx,Δy,Δz) and assumed orientation errors (ΔRx,ΔRy,ΔRz) between the predicted coordinate system and an actual coordinate system;C. controlling the drive mechanism to drive the workpiece a distance L in the direction of an Xm axis in the predicted coordinate system and measuring a distance change from a movement of the processing plane of the workpiece to obtain ΔRy via the measurement device;D. modifying the value of (Rx,Ry,Rz) in the predicted coordinate system according to A Ry, and redefining the predicted coordinate system as a first new predicted coordinate system (Xm1, Ym1, Zm1, Rx1, Ry1, Rz1) with a position error (Δx1, Δy1, Δz1) and an orientation error (ΔRx1, ΔRy1, ΔRz1) between the predicted coordinate system and the actual coordinate system;E. controlling the drive mechanism to drive the workpiece a distance L′ in the direction of an Ym1 axis in the first new predicted coordinate system and measuring the distance change from the movement of the processing plane of the workpiece to obtain ΔRx1 via the measurement device;F. modifying the value of (Rx1, Ry1, Rz1) in the predicted coordinate system according to Δ Rx1, and redefining the predicted coordinate system as a second new predicted coordinate system (Xm2, Ym2, Zm2, Rx2, Ry2, Rz2) with a position error (Δx2, Δy2, Δz2) and an orientation error (ΔRx2, ΔRy2, A Rz2) between the predicted coordinate system and the actual coordinate system;G. controlling the drive mechanism to drive the work piece a distance L″ in the direction of an Xm2 axis or an Ym2 axis in the second new predicted coordinate system and measuring the distance change from the movement of the first side plane of the workpiece or the movement of the second side plane of the workpiece to obtain ΔRz2 via the measurement device;H. modifying the value of (Rx2, Ry2, Rz2) in the predicted coordinate system according to A Rzz, and redefining the predicted coordinate system as a third new predicted coordinate system (Xm3, Ym3, Zm3, Rx3, Ry3, Rz3) with a position error (Δx3, Δy3, Δz3) and an orientation error (ΔRx3, ΔRy3, ΔRz3) between the predicted coordinate system and the actual coordinate system;I. controlling the drive mechanism by the controller to drive the workpiece to rotate by 180 degrees around an axis Zm3 in the third new predicted coordinate system and measuring the distance change between one point of the first side plane before being rotated and another point of the first side plane after being rotated to obtain Δy3;J. modifying the value of (Xm3, Ym3, Zm3) in the predicted coordinate system according to Δy3 and redefining the predicted coordinate system as a fourth new predicted coordinate system (Xm4, Ym4, Zm4, Rx4, Ry4, Rz4) with a position error (Δx4, Δy4, Δz4) and an orientation error (ΔRx4, ΔRy4, ΔRz4) between the predicted coordinate system and the actual coordinate system;K. controlling the drive mechanism by the controller to drive the workpiece to rotate by 180 degrees around an axis Zm4 in the fourth new predicted coordinate system, and measuring the distance change between one point of the second side plane before being rotated and another point of the second side plane after being rotated to obtain Δx4;L. modifying the parameter of (Xm4, Ym4, Zm4) in the predicted coordinate system according to Δx4 and redefining the predicted coordinate system as a fifth new predicted coordinate system (Xm5, Ym5, Zm5, Rx5, Ry5, Rz5) with a position error (A x5, A y5, A z5) and an orientation error (ΔRx5, ΔRy5, ΔRz5) between the predicted coordinate system and the actual coordinate system;M. controlling the drive mechanism by the controller to drive the workpiece to rotate by −90 degrees around an axis Ym5 in the fifth new predicted coordinate system and measuring the distance change between one point of the second side plane before being rotated and another point of the processing plane after being rotated to obtain Δz5;N. modifying the value of (Xm5, Ym5, Zm5) in the fifth predicted coordinate system according to Δz5 and redefining the predicted coordinate system as a calibrated coordinate system (Xm6, Ym6, Zm6, Rx6, Ry6, Rz6). 2. The calibration method of claim 1, wherein the assistant measurement tool further comprises a data transmitting module, wherein the data transmitting module is electrically coupled to the controller and configured to transmit measured data to the controller. 3. The calibration method of claim 1, wherein the controller is configured to control the drive mechanism to drive the second side plane of the workpiece to contact the measurement device to obtain the first measurement value d1″, the drive mechanism drives the work piece to rise by a height H″, the drive mechanism then rotates the workpiece by −90 degrees around an axis Ym5 of the predicted coordinate system Tm5, the controller is configured to control the drive mechanism to descend by a height (H″+h/2) and drive the processing plane of the workpiece to contact the measurement device to obtain the second measurement value d2″, the distance change after the movement of the work piece is Δ d″=d2″-d1″ , and Δz5=d2″-d1″. 4. The calibration method of claim 1, wherein measuring the distance change as Δc occurs via the measurement device after steps C and D, and determining if Δc is larger than a maximum allowable position deviation or not, if Δc is larger than the maximum allowable position deviation, then repeating steps C and D for the calibration, if Δc is less than or equal to the maximum allowable position deviation, then finishing the calibration of ΔRy and going to step E. 5. The calibration method of claim 1, wherein measuring the distance change as Δc′ occurs via the measurement device after steps E and F, and determining if Δc′ is larger than a maximum allowable position deviation or not, if Δc′ is larger than the maximum allowable position deviation, then repeating the steps E and F for the calibration, if Δc′ is less than or equal to the maximum allowable position deviation, then finishing the calibration of ΔRx1 and going to step G. 6. The calibration method of claim 1, wherein measuring the distance change as Δc″ occurs via the measurement device after the steps G and H, and determining if Δc″ is larger than a maximum allowable position deviation or not, if Δc″ is larger than the maximum allowable position deviation, then repeating steps G and H for the calibration. if Δc″ is less than or equal to the maximum allowable position deviation, then finishing the calibration of ΔRz2 and going to step I. 7. The calibration method of claim 1, wherein the controller is configured to control the drive mechanism to move the workpiece back to an original starting location after ending each step steps C, E, G, I, K and M. 8. The calibration method of claim 1, wherein the drive mechanism is a multi-axis drive mechanism. 9. The calibration method of claim 1, wherein the measurement device is a digital indicator. 10. The calibration method of claim 1, wherein the measurement device is a mechanical indicator. 11. The calibration method of claim 1, wherein the measurement device is a laser displacement sensor. 12. The calibration method of claim 1, wherein the object held by a robot is a rectangular calibration block for a non-rectangular workpiece, with the calibration block has dimensions that replicate the rectangular external bounds of the actual workpiece.