Kinetic Energy Attenuation Method for Posture Balance Control of Humanoid Biped Robot under Impact Disturbance

For the situation of the robot's foot soles rotating around their edges, the current posture balance control methods only used linear controllers and ignored the system's nonlinearity. For this problem, we propose a posture balance control method, which actively attenuate kinetic energy of the robot. Based on simplified dynamics model established for the foot rotating situation, our control law is deduced to adjust the amplitude of the ground contact force (GCF) and the angular acceleration of the robot foot rotation simultaneously. Then the posture balance controller against the impact force disturbance is designed. Stability of the foot rotation phase space is analyzed for our controller and other two existing controllers. Also, the situation of no balance controller is analyzed as a presentation of the system's passive characteristic. Then area of the stable region is compared between these three controllers. Simulations under frontal impact disturbances are also conducted. The results demonstrate that, our controller is able to resist stronger impact disturbance and make the robot recover its balance in a shorter time. This indicates that, compared with other posture control methods, the proposed control method makes better use of the robot joint motion to attenuate the robot's kinetic energy.