Dynamic control of walking leg joints: a building block model perspective

Animals like stick insects can adaptively walk on the complex terrain with different gait patterns. The change of gait patterns involves the adaptation of moving frequency and duty cycle of swing-stance period of individual legs. Inspired by the coupled Matsuoka and resonate-and-fire neuron models, we present a nonlinear oscillation model as the central pattern generator (CPG) for rhythmic gait pattern generation. This dynamic model can be used, as a building block, to actuate the motoneurons on a leg joint with adjustable driving frequencies and duty cycles by changing a few of model parameters. Three identical CPG models being used to drive three joints can make an arthropod leg of three degrees-of-freedom (DOFs). With appropriate model parameter settings, and thus suitable phase lags among joints, the leg is expected to walk on a complex terrain with adaptive steps.