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First steps toward formal controller synthesis for bipedal robots

Ames, Aaron D. and Tabuada, Paulo and Schürmann, Bastian and Ma, Wen-Loong and Kolathaya, Shishir and Rungger, Matthias and Grizzle, Jessy W. (2015) First steps toward formal controller synthesis for bipedal robots. In: Proceedings of the 18th International Conference on Hybrid Systems: Computation and Control. Association for Computing Machinery (ACM) , New York, NY, pp. 209-218. ISBN 978-1-4503-3433-4.

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Bipedal robots are prime examples of complex cyber-physical systems (CPS). They exhibit many of the features that make the design and verification of CPS so difficult: hybrid dynamics, large continuous dynamics in each mode (e.g., 10 or more state variables), and nontrivial specifications involving nonlinear constraints on the state variables. In this paper, we propose a two-step approach to formally synthesize control software for bipedal robots so as to enforce specifications by design and thereby generate physically realizable stable walking. In the first step, we design outputs and classical controllers driving these outputs to zero. The resulting controlled system evolves on a lower dimensional manifold and is described by the hybrid zero dynamics governing the remaining degrees of freedom. In the second step, we construct an abstraction of the hybrid zero dynamics that is used to synthesize a controller enforcing the desired specifications to be satisfied on the full order model. Our two step approach is a systematic way to mitigate the curse of dimensionality that hampers the applicability of formal synthesis techniques to complex CPS. Our results are illustrated with simulations showing how the synthesized controller enforces all the desired specifications and offers improved performance with respect to a controller that was utilized to obtain walking experimentally on the bipedal robot AMBER 2.

Item Type:Book Section
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URLURL TypeDescription ItemJournal Article
Ames, Aaron D.0000-0003-0848-3177
Tabuada, Paulo0000-0002-3417-0951
Ma, Wen-Loong0000-0002-0115-5632
Kolathaya, Shishir0000-0001-8689-2318
Grizzle, Jessy W.0000-0001-7586-0142
Additional Information:© 2015 ACM. This research is supported by NSF CPS Awards 1239055, 1239037 and 1239085.
Funding AgencyGrant Number
Record Number:CaltechAUTHORS:20191118-150734255
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99908
Deposited By: Tony Diaz
Deposited On:19 Nov 2019 00:01
Last Modified:16 Nov 2021 17:50

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