Generation of Stealth Walking Gait on Low-friction Road Surface

Abstract

The author has investigated the method of stealth walking for generating adaptive walking gaits of underactuated walkers without having the control torques at the feet. This approach is also effective for achieving careful walking on the frictionless road surface by applying angular momentum constraint control (AMCC); the generated gait completes in one step while maintaining the horizontal ground reaction force to zero. The result is mathematically thorough, but is not realistic because any uncertainties in the system cannot be permitted. This paper then discusses more realistic slidingresistant situation: stealth walking on the low-friction road surface. First, we introduce a model of a planar underactuated rimless wheel, and describe the equation of motion and the control input for AMCC. Second, we specify the linearized equation of motion with AMCC, and derive the analytical solution of the stance-leg motion which is used as a desired trajectory for the nonlinear model. Furthermore, we discuss the optimality of the upper-body control during the double-limb support phase from the sliding-resistant characteristics point of view through mathematical and numerical investigations.