Dynamics and motion regulation of a five-linked biped robot walking in the sagittal plane

Five-link biped has been developed for decades with advantages of its simplicity in modeling and adequacy in representing typical bipedal locomotion. However, establishment of modeling and control for the five-link biped has not been achieved satisfactorily. This thesis presents a systematic study of the dynamics and control of five-link biped walking on level ground.; Firstly, the dynamic model of a complete gait cycle in the sagittal plane is developed, which includes the single support phase, double support phase and impact. A novel kinematic model has been constructed for the five-link biped by modifying the conventional definition of certain physical parameters of the system and it has greatly simplified the derivation procedure and the final form of the dynamic equations. A general model to describe the impact dynamics of planar multi-link robotic collisions is also formulated and solved for cases when the Jacobian matrices are either full-ranked or rank-deficient.; Next, a systematic method is proposed for synthesizing a cyclic biped gait allowing for adjustments to various ground conditions. A method of formulating the compatible trajectories with time polynomial functions for the hip and the swing leg end tip motion is first provided and the joint angle profiles are determined accordingly. Based on the dynamic formulation and motion planning, the sliding mode control law is developed, for the first time, to regulate the motion during the double support phase where the biped is treated as a redundant manipulator. The stability and the robustness of the controller are also investigated, and its effectiveness is demonstrated by computer simulations.; Finally, the impact dynamics and its effects on the contact events of a five-link biped walking are studied. A parametric analysis is performed to correlate the type of impact with certain gait parameters and the results are presented in graphical form in the parameter space. Through the parametric analysis, the regions are identified, for the first time in literature, where none of the single or double impact can occur or both types of impact may occur. These results reveal important physical insights into the mechanisms of biped impact and facilitate motion planning and motion regulation such that desired gait with prescribed contact events can be produced.; The work enables us to gain an in-depth understanding of dynamics and control of bipedal locomotion. It also serves as a stepping stone to the study of the mechanics of human walking and to the development of biped robots. The formulation and methodology developed here can not only benefit the research on biped systems, but also make contributions to the analysis of many multi-link serial chain robotic systems.