Dynamic Period-two Gait Generation in a Hexapod Robot based on the Fixed-point Motion of a Reduced-order Model

This research explored the generation of period-two dynamic running motion in a robot, based on the passive dynamic period-two motion of the reduced order, rolling spring-loaded inverted pendulum (R-SLIP) model. Each cycle of period-two motion consists of two stance phases separated by two flight phases. The distribution of the period-two fixed points of the model was analyzed using a return map. Models with the same or different landing angles per motion cycle were studied, and two sets of period-two motion trajectories were implemented in a robot for experimental evaluation. Without sensory feedback or control, this evaluation relied on the open loop trajectory of the model. Based on the experiments, the robot was capable of performing dynamic period-two motion.