Motion Control And Gait Planning Of Biped Robot Driven By Hydraulic Cylinder

Biped robot can work in various kinds of complex terrain environment, and is a current research focus.The key point of biped robot research is to realize stable rapid walking, the first problem to solve is gait planning and stability control during walking. Besides, compared with servo motor drive, hydraulic actuators have very high power-to-weight ratios, high bandwidth and fast response capability. Hydraulic actuators can be very effective for high power applications, such as rapid walking. Based on these problems, this paper is mainly focus on the problem of gait planning and motion control for a hydraulic actuated biped robot. The mainly work we do are included in the following:(1) The freedom number of the biped robot is determined and the mechanical structure is designed based on the structure of human beings and actual requirement for walking. The biped robot prototype is constructed which is actuated by hydraulic cylinder. Then we finished the control system design, including hardware system construct, software programming, and digital servo of the cylinder and so on. All of these works help us to realize the motion control of the biped robot.(2) The mathematical model for the prototype is gotten. The kinematic model is set up by D-H method based on the pose matrix and inverse kinematic model is gotten using inverse solution and geometric logic of spherical triangle. Both of the two models help us get a theoretical basis of gait plan using position control with geometric constraint. Besides, two simplified dynamic models are also described: invert pendulum model and table-car model.(3) Gait planning problem for biped robot is studied. First, we finished static gait plan, and made an improvement according the problems during walking. Then we accomplished some movement plan by cubic spline interpolation method, like step, walking forward and backward, and lateral shift. After that, the research is focused on gait planning algorithm based on ZMP. For this kind of method, we chose preview control method to realize our goals. Last, we talked about some ways to make sure the stability during walking.(4) The simulation and experiment are done to verify the algorithm we finished before. In the simulation, we made a comparison between static walk and the improvement method. During robot test, we realized movements of step, forward, backward, left and right. The tests are done both on soft and hard floor. The result proved that the robot we developed can realize static walk with our gait planning algorithm and met project requirement.Through all above works, we initially realized stability walking of the biped robot we developed, and met the requirement of project. All these achievements make the future research about biped robot proceed easily.