High-Speed Stealth Walking of Underactuated Biped Utilizing Effects of Upper-Body Control and Semicircular Feet

Stealth walking is a way of walking carefully and noiselessly, and is an approach to stable legged locomotion of underactuated robotic walkers on irregular terrains. This paper proposes a method for generating a high-speed stealth walking gait without including double-limb support phase, and discusses the effect of upper-body control and semicircular feet on the gait properties. First, we introduce a model of a 3-link planar underactuated biped with an upper body and semicircular feet, and derive the approximate target initial state of the upper body by using the linearized equation of motion. Second, we conduct numerical simulations of the nonlinear model to observe the typical stealth walking gaits, and analyze the changing tendency of the upper body motion with respect to the foot radius. Furthermore, we discuss the advantage of semicircular feet through parametric studies of the gait efficiencies.