Biped Robots' Push Recovery based on Viscoelastic Model^∗

Biped robots have great practical value. High stability and anti-disturbance ability are the prerequisites for the practical applications of biped robots. For standing stability research, the current methods could be roughly divided into three groups: ankle strategy, hip strategy, step strategy. For the first two strategies, the virtual model control method is always used. However, many above methods adopt virtual spring damping model as the basic control model, which is too stiff and lacks flexibility. Therefore, the robots controlled by the virtual spring damping model may be easy to fall down when the disturbance is large. To solve the problem of spring damping model's poor performance while dealing with large disturbance, the viscoelastic model is introduced in this paper, and this paper proposes a control algorithm for the underactuated biped robot to stand stably and resist disturbance in the two-dimensional environment. The new algorithm makes the robot perform a higher flexibility. The method includes the construction of linear quadratic regulator(LQR) with using viscoelastic model, the use of LQR controller to control the stable standing of biped robot and the realization of anti-disturbance function, etc. The comparsion simulations prove the better performance of the virtual viscoelastic model than the virtual spring damping model. The validity and effectiveness of the algorithm are verified through experiments.