Reactive Force Analysis and Modulation of the Individual Legs in a Running Hexapod Robot

Abstract

This paper describes an analysis of the ground reaction forces (GRF) of the individual legs of a running hexapod robot. A control strategy that remedied the force difference between the fore and hind legs of the robot was developed based on a reduced-order rolling spring-loaded inverted pendulum (R-SLIP) model. The experimental results showed that the fore and middle legs in the stance phase exhibited more braking, while the hind legs exhibited more thrust, matching the force pattern observed in insects. A position-force hybrid control strategy was utilized to modulate the offset touchdown and liftoff timings of the legs. The experimental results showed that the stance times increased, and the profiles of body pitch became more stable in comparison to the position-only control.