Making a double pendulum walk: from compass- to whip-like gait

FELIPE CINTO; MATÍAS A. NACUSSE; HERNAN HAIMOVICH

San Juan

Congreso; 2022 IEEE Biennial Congress of Argentina (ARGENCON); 2022

The double pendulum is the main mechanical struc-ture on which simple biped robots with compass-like gait arebased. Although being very energy efficient, the compass-likegait bears the inherent problems of forcing the swing-leg tip tobelow-ground position while walking and allowing for almostno terrain irregularities. In this paper, an underactuated bipedbased on the double pendulum is made to walk via swingingthe leg in the direction opposite to that of the compass-likegait. Actuation torque on the stance foot is required to changesigns during leg swing in order for the pre- and post-impactstates to allow for stable limit-cycle walking. This sign-changingtorque is implemented by means of a simple control strategythat generates a whip-like gait and allows the biped to walk overirregular terrain and to admit a broad range of initial conditions.Simulations are given including control tuning guidelines forstable walking.