Robot's movement is not correct in "Velocity-G1-Flat v0" training

[cyborgsince90s]

When running the training of "Velocity-G1-Flat-v0" for 10K and 50K iterations, The Produced movement is very weird like one leg is getting folded very high as if its skipping.

How do I get a smooth walking movement with the default training scripts?

Steps to reproduce

Simply run the "Velocity-G1-Flat-v0" RSL_RL training for about 10K Iterations to visualize the bug.

System Info

• Commit: [e.g. a697c75]
• Isaac Sim Version: 5.1.0
• OS: Ubuntu 22.04
• GPU: L40
• CUDA: 12.4

Notice one leg is getting raised very high - This is at 50K iterations on 4096 environment

[RandomOakForest]

Thank you for posting this. To get smooth walking movement using the default scripts, you should:

1. Adjust the joint stiffness and damping parameters in the configuration files, increasing stiffness and damping slightly to stabilize the leg movements.
2. Tune the reward weights in the reward function to penalize fast joint torque changes and rapid changes in action rate. This helps increase trajectory smoothness.
3. Use proper curriculum settings to gradually increase velocity commands, starting with slow speeds on flat terrain to help the robot learn stable walking before increasing difficulty.
4. Ensure observations include noise for robustness, and include penalties for vertical linear velocity and angular velocities that contribute to unstable motions.
5. Monitor foot air time rewards, encouraging the feet to stay in the air sufficiently for balanced steps rather than hopping or skipping.
6. Validate that the initial joint angles and center of gravity settings used in the robot's URDF and configuration files are appropriate for stability.

Generally, smooth locomotion emerges after many iterations (e.g., beyond 40K) with proper tuning of the action stiffness, damping, and reward parameters in the default training scripts provided by Isaac Lab.

If you want precise step-by-step changes, it is recommended to start from the default config files for Velocity-G1-Flat-v0 and:

• Increase joint stiffness to around 60,
• Increase damping to about 1.5,
• Penalize fast action changes,
• Use a curriculum that starts with low velocity commands,
• Track and tune joint velocities and angular velocities carefully.