Is Linear Feedback on Smoothed Dynamics Sufficient for Stabilizing Contact-Rich Plans?

Designing planners and controllers for contact-rich manipulation is extremely challenging as contact violates the smoothness conditions that many gradient-based controller synthesis tools assume. Contact smoothing approximates a non-smooth system with a smooth one, allowing one to use these synthesis tools more effectively. However, applying classical control synthesis methods to smoothed contact dynamics remains relatively under-explored. This paper analyzes the efficacy of linear controller synthesis using differential simulators based on contact smoothing. We introduce natural baselines for leveraging contact smoothing to compute (a) open-loop plans robust to uncertain conditions and/or dynamics, and (b) feedback gains to stabilize around open-loop plans. Using robotic bimanual whole-body manipulation as a testbed, we perform extensive empirical experiments on over 300 trajectories and analyze why LQR seems insufficient for stabilizing contact-rich plans. The video summarizing this paper and hardware experiments is found here:this https URL.

@article{shirai2025_2411.06542,
  title={ Is Linear Feedback on Smoothed Dynamics Sufficient for Stabilizing Contact-Rich Plans? },
  author={ Yuki Shirai and Tong Zhao and H.J. Terry Suh and Huaijiang Zhu and Xinpei Ni and Jiuguang Wang and Max Simchowitz and Tao Pang },
  journal={arXiv preprint arXiv:2411.06542},
  year={ 2025 }
}