Research On Active Compliance Compound Control Of Leg Drive System Of Robot

There are several DOFs on every robot leg.Every DOF is driven by a highly integrated hydraulic driving unit(HDU).Combing with active compliance cont rol,HDU can relieve the external impact and protect the mechanical structure and electric appliance.But the application of HDU also brings some problems such as strong non-linearity,coupling problems,parameter time-variation and various load force.Those problems make it difficult to control.So,an active compliance control method with high performance has great significance in the industrialization of hydraulic legged robots.To reach a high performance active compliance control method,the following things are researched in this paper:(1)Implementation of position-based and force-based impedance control for robot leg.Including mechanical dynamics and position/force control system,a general mathematical model of the leg driving system is built;The position-based and force-based impedance control method is researched,the nonlinear simulation model of the control system is built,the performance of position-based and force-based impedance control in different conditions is analyzed;The performance test platform of leg hydraulic system,load simulation platform and performance test platform of HDU are built,the performance of control methods is verified by experiments.The experiments show that,the position/force-based impedance control method equip the leg drive system with desired compliance.(2)Parameter sensitivity analysis of position-based and force-based impedance control system.An accurate second-order sensitivity method is presented,the dynamic sensitivity of 12 parameters is analyzed;two sensitivity indexes is designed to quantization the results from sensitivity analysis and study the difference of methods of different orders;Orthogonal test design is applied to analyze the variation laws of different methods;Performance test platform and load simulation platform are used to verify the sensitivity analyze method.(3)Dynamic compliance analysis of leg hydraulic driving system.Analyze the dynamic compliance of HDU in position-based and force-based control system and the serial-parallel composition of dynamic compliance;In combination with mechanical kinematics,HDU dynamic compliance theory is applied to the whole leg hydraulic driving system;The leg dynamic compliance of two kinds of impedance control methods are verified by performance test platform and load simulation platform.(4)Compensation methods for position-based and force-based impedance control methods.A general control strategy of HDU is presented.A inner loop dynamic compliance compensation method for the whole control system is studied.Combined with compensation methods of control inner loop,a feedforward compensation method of position/force control systems is studied to compensate control outer loop of overall control system.The compliance of the improved control system is verified by performance test platform of leg hydraulic system and load simulation platform.(5)Match every joint with suitable impedance control method to reach the best whole body performance;Study the new compound impedance control method by experiments in different working conditions;A new compound impedance control method with high performance is finally presented.