Stability improvement of a dynamic walking system via reversible switching surfaces
Safa, A.T - Mohammadi, S - Naraghi, M - Alasty, A
Inspired by the effects of a switching surface on the stability of passive dynamic walking (Safa and Naraghi in Robotica 33(01):195–207, 2015; Safa et al. in Nonlinear Dyn. 81(4):2127–2140, 2015), this paper suggests a new control strategy for stabilization of dynamic bipedal locomotion. It verifies that the stability improvement of a dynamic walking system is feasible while preserving the speed, step-length, period, natural dynamics, and the energy effectiveness of the gait. The proposed control policy goes behind the three primary principles: (i) The system’s switching surface has to be replaced by a new one if an external disturbance is induced. (ii) The new switching surface has to be reshaped back into its old style, together with the disturbance rejection. (iii) The stabilization procedure has to be performed with as small energy consumption as possible. Because of the reversibility effects of the switching surfaces in the above rules, the terminology of “Reversible Switching Surfaces” (RSS) is employed to address the control scheme; so the control objective would be the implementation of RSS for a bipedal robotic system. In this paper, this aim is achieved by a kinematically controlled foot scheme that is implemented on a simple structured biped. The presented idea is validated by a commercial version of MSC Adams software. © 2017, Springer Science+Business Media B.V., part of Springer Nature.