Important: Isaac Sim support
Note: For Isaac Sim support, the community is gradually transitioning from this forum to the Isaac Sim GitHub repository so that questions and issues can be tracked, searched, and resolved more efficiently in one place. Whenever possible, please create a GitHub Discussion or Issue there instead of starting a new forum topic.
Note: For any Isaac Lab topics, please submit your topic to its GitHub repo ( GitHub - isaac-sim/IsaacLab: Unified framework for robot learning built on NVIDIA Isaac Sim ) following the instructions provided on Isaac Lab’s Contributing Guidelines ( Contribution Guidelines — Isaac Lab Documentation ).
Please provide all relevant details below before submitting your post. This will help the community provide more accurate and timely assistance. After submitting, you can check the appropriate boxes. Remember, you can always edit your post later to include additional information if needed.
4.5.0
Operating System
Ubuntu 22.04
GPU Information
- Model: RTX4070super
- Driver Version: 560.35.03
Topic Description
Caster wheel jitter causes unintended rotation and unstable motion in a two-wheel robot
I am experiencing severe jitter and instability caused by the caster wheel when controlling a two-wheel differential robot in Isaac Sim.
I imported a two-wheel robot URDF into Isaac Sim and configured it to be controlled via ROS 2 (similar to a Carter robot setup). The robot has two driven wheels and one caster wheel for support. My goal is for the robot to move straight forward in the direction it is facing by applying the same translational velocity (tv = 0.5) to both drive wheels.
However, due to continuous jittering of the caster wheel, the robot does not move straight as expected. Instead, an unexpected force appears to be applied to the robot, causing its heading to drift or rotate unintentionally. In more severe cases, the robot suddenly bounces or is pushed away as if an external impulse were applied.
Previously, I removed the caster wheel joint entirely and was able to drive the robot stably. However, in the current setup, the caster wheel is required and cannot be removed. I have confirmed that the caster wheel successfully rotates to align with the direction of motion, but despite this, the robot is still disturbed by an unknown force originating from the caster wheel interaction with the ground.
As a result, the caster wheel jitter significantly interferes with normal locomotion and makes stable forward driving impossible.
Steps to Reproduce
-
Import a two-wheel robot URDF with a caster wheel into Isaac Sim.
-
Configure the robot to be controlled via ROS 2 (similar to a Carter robot or differential drive setup).
-
Apply the same translational velocity (tv = 0.5) to both drive wheels.
(Add more steps as needed)
Error Messages
nothing
Screenshots or Videos
Additional Information
What I’ve Tried
I have already tried several approaches to mitigate the caster wheel jitter issue, but none of them resolved the problem.
Specifically, I attempted to adjust the joint damping values of the caster wheel to reduce oscillations. I also experimented with changing the collision mesh types (e.g., switching between visual mesh and simplified collision geometry). In addition, I disabled self-collision for the robot links to rule out internal collision effects.
Despite these changes, the caster wheel jitter and the resulting unstable robot motion persist.
Related Issues
(If you’re aware of any related issues or forum posts, please link them here)
Additional Context
There is mesh and urdf of my robot.
if u need something for solving problem, tell me. plz
I hope to go to sleep…
mesh_and_urdf.zip (22.7 KB)
I have an additional question regarding wheel behavior.
It seems that the driven wheels may not have sufficient friction with the ground. When the robot starts moving, the wheels often spin for about one full rotation before the robot actually begins to move forward, as if the wheels are slipping on the ground.
Could this behavior be caused by missing or incorrectly configured wheel friction? If so, I would like to know the correct way to configure friction for driven wheels in Isaac Sim.