Research On The Jump Control Of Hydraulic Wheel-leg Biped Robot

The hydraulically driven bipedal wheel-leg robot has the advantages of fast speed of movement,strong environmental adaptation,large driving power density ratio,flexible movement ability,etc.Therefore,it has great application potential in future production,living,disaster rescue and field exploration and other fields.In order to improve the environmental adaptability and obstacle crossing ability of wheel-legged robot,this paper will focus on the balance control and jump trajectory optimization of biped wheel-legged robot,including the following five aspects.Dynamics Modeling of Wheel-legged Robot.In this paper,the biped wheel-legged robot is simplified to a plane model,set up the dynamic equation of the plane model of the floating bas wheel-legged robot by using the Lagrange method,and the ground constraint is applied in the touch phase and transformed into the dynamic equation with ground constraint.In order to ensure that the robot can land safely after taking off,the influence of the angular momentum of the robot on the jump is analyzed,and the calculation method of the angular momentum of the wheel-legged robot around the center of mass is given.In order to design the balance controller of wheel-legged robot,the wheel-legged robot was simplified as a wheel inverted pendulum(WIP)model based on the ideas of decoupling and equivalence,and the dynamics equation of the wheel-legged inverted pendulum model was set up.Which lays the model foundation for the optimization generation of jump trajectory and the design of balance controller.Design the balance controller of wheeled legged robot based on uncertainty and disturbance estimator(UDE).Which can increase the robustness of the balance controller and offset the disturbance caused by the parameter changes caused by the rapid movement of robot body during takeoff.Combine the uncertainty and disturbance estimator with the wheeled inverted pendulum model,design the reference model,lowpass filter and error transfer matrix respectively,so that the influence of unmodeled and external disturbances on the robot could be estimated and compensated into the balance controller,and the balance controller with strong robustness was obtained.Centroid trajectory generation based on double mass spring inverted pendulum(DM-SLIP)simplified model.The wheel-legged robot was simplified to a DM-SLIP model,and the model parameters of the robot in each motion phase were obtained through optimization method,including the original spring length and spring stiffness of the DM-SLIP model.Finally,the trajectory of the center of mass during the wheellegged robot jumping process was optimizedHierarchical real-time operation space control method based on quadratic programming(QP).The takeoff of the robot is divided into two priorities: balance control with higher priority and jump control with lower priority.The centroid trajectories generated by the simplified model were mapped to the joint space by quadratic programming method.By applying the kinematic and dynamic constraints,the joint trajectories were generated online throughout the jump stage,which could track the expected centroid trajectories.Jumping experiment of wheeled legged robot.The experimental platform of the WLR-4P wheel-leg robot was built.In order to get a more accurate dynamic model,the dynamic parameters of the waist joint and trunk of the robot was identified.The position tracking controller based on the flow equation of servo valve is designed and the position tracking experiment is carried out.Finally,a wheel-legged robot jumping experiment was carried out to make the WLR-4P robot jump on a platform with a height of 0.4m,which verified the rationality of the control scheme and algorithm in this paper.