Dynamic Analysis And Motion Control Of Hydraulic Leg In High Speed Quadruped Robot

Compared with the traditional wheeled and tracked mobile robots,the step foot mobile robots have a stronger ability to adapt to the unstructured environment.But the system of the step foot mobile robots is complex,which have not reached the moving speed of traditional wheeled and tracked mobile robots.Based on the need for the speed of the walking mobile robots which comes from the real background,how to improve the moving speed of a walking robot based on its adaptability to unstructured environment becomes one of the research hotspots.In this paper,the four-legged mobile robot,a representative of the walking robot family,is taken as the research object.Combined with the principle of bionics,starting from the analysis of four-legged robots how to achieve high speed running,the key to realize high speed running performance of the four-legged robots is its single leg performance.The performance of the single leg is closely related to its structural parameters and control strategy.Starting from the analysis of the movement characteristics of the four-legged robots,the running process of the four-legged robot can be decomposed into the single-leg fixedbase movement phase and the single-leg floating base movement phase.According to whether considering the mass of hydraulic cylinder and piston rod,the simplified dynamic model of fixed base and the dynamic model of fixed base are established respectively,and the influence of the mass of hydraulic cylinder and piston rod on the output force of hydraulic cylinder under the phase of single-leg fixed base movement is analyzed,and the quantitative influence factors of fixed base hydraulic cylinder and piston rod are put forward.On the basis of the simplified dynamic model of fixed base and the kinematics of single leg,an algorithm for generating the trajectory of the foot based on the optimization of the dynamic model is proposed.The results show that the trajectory generated by this algorithm can effectively reduce the output force of the hydraulic cylinder under the phase of fixed base and provide a foundation for the control of fixed base movement of single leg.According to whether considering the hydraulic cylinder and piston rod mass,the simplified dynamic model of the floating base and dynamic model of the floating base are established,the influence of the mass of hydraulic cylinder and the piston rod are analyzed under the single leg floating base movement phase on the output capacity of hydraulic cylinder,and the quantitative influence factors of fixed base hydraulic cylinder and piston rod are put forward,which provides a relatively accurate results to the hydraulic cylinder design.The results show that single leg in small load the hydraulic cylinder and piston rod mass influence should not be neglected under the phase of singleleg floating base,and provide a basis for the single leg floating base motion control.Model based on kinetics of fixed base model and the floating base single leg motion control algorithm are given,in order to verify the validity of the algorithm,using the ADAMS software to build a single leg virtual prototype,using SIMULINK to build the motion control algorithm,using the ADAMS and SIMULINK simulation tool to achieve the goal one leg speed control,the results preliminary verified the effectiveness of bill of lading leg motion control algorithm.