Research On Stability And Trajectory Planning Of A Wheel-legged Quadruped Robot

In this paper,a wheel-legged quadruped robot is proposed,and its kinematics and dynamics are analyzed.Based on the stability analysis of the robot,a trajectory planning method under the maximum stability strategy is proposed,and the error calibration experiment is carried out.Firstly,a serial--parallel hybrid wheel-legged quadruped robot based on(2UPS-U)+R is proposed.The whole mechanism of the robot is introduced.The degree of freedom and workspace of the single leg are solved.The forward and inverse solutions of the position of the single leg mechanism are calculated,and the formulas are verified.Secondly,based on the method of static stability margin,the stability margin of the robot in static gait is solved,and the calculation method of the stability margin is analyzed by solving the coordinates of the landing point and the projection coordinates of the center of gravity.The dynamic model of the robot's single leg mechanism is established and solved by Lagrange method.Thirdly,before the trajectory planning of the robot,the joint angle and moment constraints of the robot are analyzed.The workspace of the robot body is solved,the trajectory planning equation of the robot's center of gravity is analyzed and solved,and the trajectory of the center of gravity is optimized under the strategy of maximum stability of the robot body.Aiming at the trajectory planning of the robot's foot endpoint,the trajectory planning equations of conventional trajectory planning and step climbing are analyzed and solved,and the tracking accuracy of the joint is simulated and corrected by using the fuzzy PID controller.Finally,a single-leg of wheel-legged quadruped robot is developed and debugged.A single leg trajectory tracking system is built.In the process of robot walking,the foot endpoint trajectory is tracked,and the foot endpoint trajectory curve is generated.Compared with the theoretical trajectory curve,the causes of error are analyzed.