A control study of a kneeless biped locomotion system

In this paper, a control study on a three-degree-of-freedom kneeless biped locomotion system is performed. Based on the biped dynamics and joint trajectories of the walking gait, a robust adaptive control scheme consisting of a control law and an adaptation law was used. The control law has the structure of the inverse dynamics servo but uses estimates of the dynamics parameters in the computation of torques which propel the biped. The adaptation law uses the tracking error to compute the parameter estimates for the control law. To improve the convergence of the estimated parameters, we modify the timing of applying the adaptation by incorporating a dead-zone operation. Our simulation results show that the adaptive control technique can be effectively used for the biped locomotion control. The joint tracking errors can be made acceptably small and the performance is also robust despite relatively large deviations in the initial estimates of the system parameters.