Planning Studies, Zmp-based Biped Robot Gait

Biped robot has much better adaptation to environment in human living-space than wheel type, crawl type and pedrail type mobile robots. This advantage is much more obvious under unconstructed environment. In this dissertation, a biped robot platform, named Walker-I, is proposed. The structure of the biped is designed and the degrees of freedom are configured properly. Through a 3D-modeling software, the model of the biped is well constructed. Compared with other drivers, the servo motor(S5301, FUTABA) is chosen for its high accuracy, easy servicing, better programme control and centralized control.The theory of homogeneous coordinate conversion needed in mathematical modeling is outlined. In the D-H coordinate, direct kinematic model and inverse kinematic model are built based on the previously presented theory, and this provides the foundation for gait plan. By lagrange dynamic equations, the dynamic model of the simplified biped is given respectively in the period of single-foot support and double- foot support, and this model is easy to control.ZMP stability condition under which the biped can walk successfully in the sagittal plane is deduced based on the theory of linear inverted pendulum model(LIPM), and the stability in the lateral plane is discussed as well as. Based on ZMP stability condition, the tracks of the foot and hip joint are planned related to parameters through 3rd order spline interpolation, and this plan confirms that stability margin is big enough. After that, the other joint angles are also gained through inverse kinematic formulas. The method proves to be reasonable and effective based on the simulation results under Matlab. We know that start and stop are very important in the whole walking process. Unfortunately, few researchers concern this problem. Therefore, the author discusses the start gait and stop gait in-depth. It should be indicated that some gaits respectively under environment with obstacles, rough terrain and up-down stairs can also be gained through setting proper parameters. The method, with better adaptation to environment, provides theory proofs for biped-developing.