Gait Generation of Hexapod Robot for the CPG Controller by Using the Delayed Van der Pol Oscillators

摘要

Abstract In this study, we construct a type of CPG (central pattern generator) controller by using the delay-coupling Van der Pol (VDP) oscillators and propose an analysis method of parameter modulation to illustrate the locomotion gait of a hexapod robot. The structure topology of the CPG controller is scheduled as a unidirectional ring network consisting of six identical units. Each unit has independentparameters to modulate amplitude and frequency of the period activity. Employing the Hopf bifurcation, we first propose parameter conditions to guarantee the existence of the period activity for the delayed CPG controller, where coupling delay can induce generation and extinction of the period activity. Due to the symmetry structure of the proposed CPG controller, the period activity induced by coupling delay presents multiple spatiotemporal patterns with a constant phase difference. Based on theoretical analysis of the equivariant Hopf bifurcation, we further pinpoint parameter regions for the corresponding spatiotemporal patterns. Then using the invariable phase difference between signal outputs of the VDP oscillators, we assign connection order of the CPG units to link the hexapod’s legs and produce the hexapodal locomotion gaits. The results show that the coupling delay in the delayed VDP-CPG controller is an effective method to obtain many types of the hexapodal locomotion gaits.