On The Gait Control Strategy And Structural Optimization For Dynamic Walking Bipedal Robot

The research on the passive dynamic walking bipedal robot has attracted increasing attention in the recent years, which will become a breakthrough in the field of humanoid robot research. Many research labs in the world have developed various prototypes of bipedal robots, such as Mike, Flame, Babbite and so on. In this thesis, the main research work is the gait control and structural optimization of passive dynamic bipedal walker, which is based on the passive dynamic characteristics of the robot. This work is supported by the National High Technology Research and Development Program of China (863Program) (Grant No. 2006AA04Z251), and National Nature Science Fund Project (No. 60974067).The main work in this paper is as follows:1) Present the characteristics of robot's kinematic and dynamics. A method to build the mathematical model of a class of planar walking robots with n DOFs is presented. Then, we give two kinds of planar biped robot models. They are the simplest two-link robot and the three-link robot model respectively. The two models are the basic models for our following research.2) The gait stability of passive biped robot is sensitive to the initial walking state, which must be adjusted precisely for continuous gaits. In this thesis, a torque shaping control method is proposed to obtain the initial stable gait for stable limit cycle walking in a single gait period. This control method enlarges the scope of the initial value. Besides, it has good robustness and fast convergence.3) In order to make the gait of robots varied in the walking process, we control the walking speed and gait for crossing obstacle respectively. On the basis of speed control, the co-control of speed changing and slope changing is researched. From the viewpoint of bionics, base on the special function of bi-articular muscles for limb movement, the mathematical model is given. Then the bi-articular muscle model is applied to step over the obstacle for the biped robot during walking.4) The mechanical design of the biped robot is another key point. We improve the robot foot structure on the prototype PADW-JLUⅡ. After building the dynamic model of biped robot with foot and then analyzing the effectiveness of different foot shape, the optimized foot shape is achieved for our prototype.The proposed torque shaping control algorithm can adjust the initial value easily, which can provide the possibility for generating and control of complex gait; The combination of speed control and slope control can make walking to achieve an ideal gait; The analysis of bi-articular muscles model is an exploration of actuation for the various gaits; The optimization foot shape can improve the walking performance and guide the prototype design.In conclusion, a series of research about the theory analysis and structural optimization for dynamic walking biped robot in this thesis has positive meaning.