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.

Analysis of pattern generation in non-periodic clock-driven unidirectionally coupled phase oscillators in a ring

“…CPGs have been mostly modeled by coupled nonlinear oscillators utilizing their synchronization and stability properties, for example, spiking neurons [3][4][5], Van der Pol oscillators [6][7][8], Hopf oscillators [9][10][11], and Kuramoto oscillators [12][13][14]. These models have been applied to gait generation for various types of bio-inspired robots and clinical prosthetic devices [15][16][17][18][19][20][21]. In such models, since one synchronization pattern corresponds to one gait pattern of legged animals, it is required to synchronize from any transient state to a desired pattern (Fig.…”