[Question] When play the task Isaac-Reach-UR10-v0, the robotic arm always shakes near the target point

[YanmingChang666]

Problem Summary
I trained for 1000 epochs and 20000 epochs respectively, and during play the modle, the robotic arm always shakes near the target point.

Here are the results of my two training sessions and a demonstration video. Is it because the total reward is not high?

Environment Details
Isaac Lab version: [2.0.0]
Task:Isaac-Reach-UR10-v0
Device: CUDA

Could you please investigate this issue? Thank you for your time and consideration!

[YanmingChang666]

e2eed77011a459a9833fcf279e186dac.mp4

[YuHoChau]

Try disable the noise.

[RandomOakForest]

Thank you for posting this. I'll move the post to our Discussions section for follow up. Here are a few notes you may consider trying.

Joint Drive Tuning Procedure

Follow this iterative process for each joint to stabilize movement:

1. Set damping to zero and tune stiffness first¹.
2. Increase stiffness incrementally until the joint converges near the target position without overshoot¹.
3. Reduce stiffness by one order of magnitude from the initial stable value¹.
4. Add damping at one order of magnitude lower than the final stiffness value¹.
5. Fine-tune both gains to balance response speed and stability, avoiding excessive values that cause oscillations¹².

Configuration Adjustments

• Disable gravity for all robot rigid bodies in the properties panel to prevent gravity-induced drift¹³.
• Set joint friction to zero to avoid unintended resistance that amplifies oscillations⁴.
• Avoid zero stiffness: This prevents movement entirely; use minimal non-zero values instead²³.

Training Considerations

• Policy refinement: If oscillations persist after tuning, adjust the RL policy’s action constraints to reduce aggressive velocity commands near targets⁵.
• Actuator model: Use implicit actuators for better compliance control, as they handle joint dynamics more effectively than direct effort commands⁴.

Troubleshooting Notes

• Persistent oscillations often indicate insufficient damping relative to stiffness or excessive policy aggressiveness⁵.
• Kinematic simulation (without physics) isn’t natively supported; tuning gains remains essential even with gravity disabled²³.

Also, consider to explicitly override damping/friction parameters in asset configuration files to ensure values align with the tuning process above⁴.

Footnotes

1. https://docs.omniverse.nvidia.com/isaacsim/latest/advanced_tutorials/tutorial_advanced_joint_tuning.html ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

2. https://forums.developer.nvidia.com/t/how-can-i-control-or-eliminate-oscillation-when-the-robot-arm-moves-to-the-target-position/329175 ↩ ↩² ↩³

3. https://forums.developer.nvidia.com/t/how-to-simulate-a-robot-arm-in-isaac-sim-without-physics-no-gravity-or-inertia/328982 ↩ ↩² ↩³

4. https://github.com/isaac-sim/IsaacLab/discussions/2470 ↩ ↩² ↩³

5. https://forums.developer.nvidia.com/t/no-movement-has-been-assigned-to-the-head-of-the-robot-but-it-is-still-moving-in-simulation-after-training/321266 ↩ ↩²

[YanmingChang666]

Thank you for your reply! I am trying to modify these parameters and train again.