Payload control and robot stabilization
- Csaba Mucsi
Collaborative robots are generally very sensitive to the weight and center of gravity of the attached payload. The robot settings must always correspond to the actual payload in order to work properly. Changing the payload settings too early or too late will result in instant protective stops due to false collision alarms. Especially in palletizer applications where heavy boxes are picked and released, it is essential to manage payload settings as accurately as possible.
Pally has built-in routines for monitoring errors in the robot position, which may occur due to sudden changes in the payload. During picking and releasing boxes with a vacuum gripper, the program can automatically adjust the delays between switching the vacuum valve(s) and updating the payload weight and center of gravity on time. This can significantly reduce the occurrence of unexpected protective stops at the pick and drop positions without affecting robot safety requirements.
Note: This function may introduce small delays when picking and releasing boxes.
The following Pally variables are provided for fine tuning the robot stabilization engine.
rf_joint_deviation_err | Maximum allowed difference (in radians) between actual joint positions and target joint positions before operating the gripper. Before picking and releasing, the robot has to stop completely, and the joint deviation error has to go below the threshold value given here. Setting to 0 will disable joint deviation monitoring at this point. | Default: 0.0001 (in radians) |
rf_joint_deviation_max | Maximum allowed difference (in radians) between actual joint positions and target joint positions while the gripper is being operated during pickup and release. The program will override the default delays and proceed immediately if the joint deviation error exceeds the threshold given here. Setting to 0 will disable joint deviation monitoring at this point. | Default: 0.0043 (in radians) |
To turn off the feature completely, set both rf_joint_deviation_max=0 and rf_joint_deviation_err=0.