Walking dynamics for an ascending stair biped robot with telescopic legs and impulse thrust

In this study, an ascending stair biped robot model with impulse thrust is presented. The biped robot contains a hip joint and two legs with massless telescoping actuator. Impulse thrust is applied at the ankle joint of robot's stance leg to simulate the forward push-off of the ankle during human walking. The nonlinear ascending stair biped model is linearized and a discrete map is obtained. The conditions for the existence and stability of period-1 gait are obtained by means of this discrete map. The expressions of torques to ensure robot walking are derived and Flip bifurcation is investigated. Numerical simulations, such as phase diagram of period-1, 2, 4 gaits and bifurcation diagram, are given in an example. Theoretical analysis and numerical results obtained in this study provide a theoretical basis for stable walking of ascending stair biped robot with periodic gaits.