Analysis results and tools for the control of planar bipedal gaits using hybrid zero dynamics

• Published in: Autonomous robots Vol. 23; no. 2; pp. 131 - 145
• Main Authors: Westervelt, E R, Morris, B, Farrell, K D
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01-08-2007
• Subjects: Actuation; Controllers; Decoupling; Gait; Singularities; Steady state
• ISSN: 0929-5593; 1573-7527
• DOI: 10.1007/s10514-007-9036-9

New analysis and tools are presented that extend the hybrid zero dynamics (HZD) framework for the control of planar bipedal walkers. Results include (i) analysis of walking on a slope, (ii) analysis of dynamic (decoupling matrix) singularities, and (iii) an alternative method for choosing virtual constraints. A key application of the new tools is the design of controllers that render a passive bipedal gait robust to disturbances without the use of full actuation—while still requiring zero control effort at steady-state. The new tools can also be used to design controllers for gaits having an arbitrary steady-state torque profile. Five examples are given that illustrate these and other results.