Research Of Walking Attitude Tracking Control Method Of Biped Robots

Walking attitude tracking control of biped robots is technology fundamental for the walking stability of biped robots. Biped robots system require its system status will have better convergence ability in athletic process, so the designed attitude tracking control laws should have more rapid convergence. The complexity and strong coupling of biped robots structure cause that we cannot create an accurate mathematical model, so we need to simplify the biped robot and study the simplified model. There are many uncertain factors in biped robots system and environment, so the designed attitude tracking control laws for biped robots should have strong robustness. In this paper, for the dynamic model of the simplified biped robots with uncertain disturbances, the attitude tracking control problem of biped robots is studied based on terminal sliding mode control method.Firstly, according to the characteristics of biped robots structure, a simplified model is established to reflect the dynamic characteristics. We define a kinematic model for the simplified model using Denavit-Hartenberg matrix method and generalized coordinates method, and using Lagrange dynamic equation based on generalized coordinates role in the simplified link model, we obtain a dynamic model convenience in researching attitude tracking control, which provides a theoretical foundation for attitude tracking control research. Secondly, based on the ZMP stability theory, the ZMP calculation formulas is derived for the link model and the basic conditions are given for biped robots stable walking, that provides a reasonable theory basis for researching gait planning and attitude tracking control method. Thirdly, through the geometric constraint and acceleration constraint, we design cycle gait of biped robots forward movement. According to constraint conditions, we deduce trajectory functions of the hip and ankle joint, as well as joint Angles. Through the ZMP track, the walking stability of biped robots is judged, and matlab simulation results illustrate the rationality of the programming method. Finally, for the dynamic model of the simplified biped robots system with uncertain disturbances, we design a global finite-time nonsingular terminal sliding tracking controller and realize complete tracking of the desired trajectory in a limited time. Through the further improvement of controller, the system chattering can be basically eliminated. Additionally, matlab simulation results verify the effectiveness of the control method.