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arXiv · 2005.11431

LQR-Assisted Whole-Body Control of a Wheeled Bipedal Robot with Kinematic Loops

Victor Klemm·Alessandro Morra·Lionel Gulich·Dominik Mannhart·David Rohr·Mina Kamel·Yvain de Viragh·Roland Siegwart
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Abstract

We present a hierarchical whole-body controller leveraging the full rigid body dynamics of the wheeled bipedal robot Ascento. We derive closed-form expressions for the dynamics of its kinematic loops in a way that readily generalizes to more complex systems. The rolling constraint is incorporated using a compact analytic solution based on rotation matrices. The non-minimum phase balancing dynamics are accounted for by including a linear-quadratic regulator as a motion task. Robustness when driving curves is increased by regulating the lean angle as a function of the zero-moment point. The proposed controller is computationally lightweight and significantly extends the rough-terrain capabilities and robustness of the system, as we demonstrate in several experiments.

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Victor Klemm, Alessandro Morra, Lionel Gulich, Dominik Mannhart, David Rohr, Mina Kamel, Yvain de Viragh, Roland Siegwart. 2020-05-23. LQR-Assisted Whole-Body Control of a Wheeled Bipedal Robot with Kinematic Loops. https://doi.org/10.1109/lra.2020.2979625

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