Approaches for stabilizing of biped robots in a standing position on movable support
Subject of research. The problem of stabilization for biped walking robots on the surface is considered. The angle and angular velocity of the movable surface varies randomly in a limited range. Methods. Two approaches of stabilization of biped robots are proposed. The first approach requires the construction of kinematic and dynamic models of the robot. Dynamic equations were obtained using the Euler-Lagrange method. The control algorithm is based on the method of inverse dynamics, in which the original nonlinear dynamic model is linearized by a feedback. The second stabilization algorithm uses only the kinematic model of the robot. A hybrid controller is developed for this approach. In the case of low angular velocities of the movable support the robot stabilization is performed by PD controller on the basis of the angle error of deflection of the servo shaft. In the case of relatively high angular velocities of the support the controller also uses the gyroscope readings mounted in the robot torso. Maintenance of the robot’s gravity center over the center of bearing area for providing a stable position was chosen as a goal of control in both approaches. Main results. Efficiency and effectiveness of the proposed approaches for stabilization of biped robots on the moving surface are demonstrated by the numerical simulation. Both methods provide stability of the balancing robots on changing the angle of inclination and angular velocity of the moving surface in the ranges fÎ(-50°; 50°) and wÎ(-40° / sec; 40° / sec), respectively. Comparative analysis of these approaches under identical requirements for quality indicators of transients is also provided: transient time tп < 0.2 sec and overshoot s = 0%. The conditions under which each of the control methods will be more effective in practice are identified. Practical significance. The developed control approaches are usable to stabilize similar robots, as well as to serve as a basis for the construction of regulators for more complex models of walking mechanisms that have a greater number of degrees of freedom and walk on a movable support.