Smooth gait transition in hardware-efficient CPG model based on asynchronous coupling of cellular automaton phase oscillators

Abstract

In this paper, a central pattern generator (CPG) model based on asynchronous coupling of cellular automaton (CA) phase oscillators for a hexapod robot is presented. The presented CPG model is composed of the CA phase oscillators whose discrete state transitions are triggered by multiple asynchronous clocks. Then, evaluation functions to quantify synchronization states for target gait patterns in the presented CPG model are introduced. Analyzing the synchronizations using the evaluation functions, this paper clarifies that the presented CPG model is suitable to perform smooth gait transitions for the hexapod robot than a CPG model whose discrete state transitions are triggered by a single clock (i.e., synchronous coupling). The presented CPG model is implemented in a field programmable gate array (FPGA); experiments verify that the hexapod robot mounted with the FPGA, in which the presented CPG model is implemented, can perform smooth gait transitions.