Adaptive running of a quadruped robot on irregular terrain based on biological concepts

This paper presents a new neural system and mechanical system for quadruped robots with compliant legs, a spring mechanism located at the ankle joint. PD-controller at hip and knee joints constructs the virtual spring-damper system as the visco-elasticity model of a muscle. The neural system model consists of a CPG (Central Pattern Generator) and reflexes. A CPG changes the own active phase based on sensory information. The desired angle and P-gain of each joint in the virtual spring-damper system is switched based on the phase signal of the CPG. The pitching motion of the body is entrained into the CPG as a sensory feedback. Therefore, adaptive running can be generated. Some experimental results of running on terrain of low degrees of irregularity are used to verify the effectiveness of the designed neuro-mechanical system.