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Smooth real-time target-update movement on UR
/ Most recent by Br0t
For remote control or visual servo application, I’d like to stream the target position every 10-50 milliseconds from my Linux PC, and each update would only change the destination around 1-100 millimeter. By doing this, I’d like to create a smooth motion. I want to realize both in Cartesian space control and in Joint space control, but let’s discuss Cartesian space first.
My problem is that the robot movement is very jittery. I’m using RTDE (real-time data exchange) and running the same urp file which you can find here: https://www.universal-robots.com/how-tos-and-faqs/how-to/ur-how-tos/real-time-data-exchange-rtde-guide-22229/
The motion I tried to create was simple: just moving up 200 millimeters toward +Z direction, then moving down 200 millimeters toward -Z direction. I was sending the target update (absolute target position in robot’s Base Frame) every 50 msec, and I was changing 10 millimeters for every update. However, the movement was very jittery or the repetition of small “start and stop” movement. The original urp file uses “MoveL” command, so I tried to tune the parameters (by changing from “Stop at this point” to “Blend with radius”), but it didn’t work.
When I implemented the similar functionality on ABB, I could use EGM (Externally Guided Motion), which you can stream the point, and the robot follows the point it gets every update. Alternatively, when I implemented for DensoWave or Mitsubishi, I could use “Cancel” or “Skip” command for each “Move” command to override the old target. I’m wondering if there are any commands/options that I can use for Universal Robots.
Are there any ways/commands to realize above smooth real-time target-update movement?