Soft landing control strategy for biped robot

Abstract

Purpose The purpose of this paper was to present a soft landing control strategy for a biped robot to avoid and absorb the impulsive reaction forces (which weakens walking stability) caused by the landing impact between the swing foot and the ground. Design/methodology/approach First, a suitable trajectory of the swing foot is preplanned to avoid the impulsive reaction forces in the walking direction. Second, the impulsive reaction forces of the landing impact are suppressed by the on-line trajectory modification based on the extended time-domain passivity control with admittance causality that has the reaction forces as inputs and the decomposed swing foot’s positions to trim off the forces as the outputs. Findings The experiment data and results are described and analyzed, showing that the proposed soft landing control strategy can suppress the impulsive forces and improve walking stability. Originality/value The main contribution is that a soft landing control strategy for a biped robot was proposed to deal with the impulsive reaction forces generated by the landing impact, which enhances walking stability.