Hybrid Zero Dynamics of Planar Bipedal Walking

Summary. Models of bipedal robots in motion are fundamentally hybrid due to the presence of continuous phases, discrete transitions, and unilateral constraints arising from the contact forces between the robot and the ground. A major challenge in the control of bipedal robots has been to create a feedback theory that provides systematic synthesis methods, provable correctness and computational tools for designing asymptotically stable, periodic walking motions, especially walking motions that are dynamic unlike the quasi-static, flat-footed gaits that are prevalent in today’s machines. This chapter highlights the fundamental role of zero dynamics in obtaining truly dynamic walking gaits that include underactuated phases. The theoretical analysis is verified with experimental work.

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