Research On Impedance Control Of Heavy-load Foot Robot Joint Drive System

With the development of science and technology,since the new century,the international development of robot technology has been paid more and more attention.This paper aims to use the direct drive volume control electrohydraulic servo system to meet the heavy load foot robot bearing capacity,flexibility and good requirements,compared to the traditional valve control more energy efficient,with the impedance control to make the robot can walk smoothly,Adaptive to optimize the impedance control,and the current impedance control used in direct drive volume control electro-hydraulic servo system is not much,in this regard also need further study and exploration.Firstly,a three-dimensional model of the robot is established.A geometrically decoupled four-link mechanical leg model is selected.The displacement of the joint is solved by simple geometric relation.The positive and negative kinematics of the robot is established.The kinematics model of SimMechanics was established,and the kinematics analysis of the single leg of the robot was carried out.The calculation of the foot displacement and the displacement of the simulation model were carried out to verify the validity of the kinematic equation and the application of the joint impedance control lay the foundation.Then,the dynamic mechanism of the new direct drive type volumetric control system is modeled.Some aspects are simplified and the feedforward correction is carried out for the whole model system.The simulation of the Bode diagram is adjusted to the 2Hz double ten index.Then,a position-based impedance control system model is established.Based on the position loop,the force closed loop is introduced,and the influence of the impedance control parameters on the system performance is analyzed.On the basis of the joint drive system model,The force tracking effect of the impedance control based on position is simulated and the tracking response curve of the force signal is verified.The correctness of the theoretical analysis is obtained.The impedance control can meet the requirement of reducing the contact force Peak requirements.In the optimal design of the impedance,the design scheme of the indirect adaptive controller which is relatively stable and suitable for reducing the peak value of the contact force is selected according to the related literature.The indirect adaptive derivation process is given,and then the indirect adaptive The controller has carried on the situation of the environment position and the environmental stiffness change and the dynamic expectation response,and through the simulation comparison,it is found that the designed adaptive controller has good performance.Although the experiment did not achieve the optimal state,but can achieve the purpose of reducing the peak of contact force,the experimental comparison of the situation is ideal.In view of the shortcomings in the experiment process,some suggestions are put forward.