Research On Compliance Control Of Single Leg Joint Of Hydraulic Driven Robot

Legged robot is one of the most adaptable robots in the field of mobile robot research.It can walk on various complex roads and has high application value.In order to enhance the walking ability and the adaptability of the foot robot on the complex ground,this paper mainly studies the force control and compliance control strategy of the hydraulic driven unit on the single-leg joint of the foot robot,including the following five parts.Modeling and analysis of hydraulic drive unit.The servo control object of hydraulic drive unit is a hydraulic drive unit,which is mainly composed of a small servo hydraulic cylinder,a flow servo valve,a displacement sensor and a force sensor.By calculating and analyzing the transfer function of the position control and force control of the hydraulic system,a simulation model is constructed to lay the foundation for the later research on hydraulic drive servo control.Hydraulic drive unit position control algorithm and force control algorithm analysis.In order to improve the servo control performance of hydraulic drive unit,different control strategies are added into the hydraulic drive unit model.In this paper,three kinds of position control algorithms,PID position control,fuzzy control and robust control,are designed for the foot robot hydraulic driving unit.Then PID force control and velocity compensation control are designed.Through theoretical calculation and simulation experiment to determine the specific parameters,and then through the system response speed and tracking performance to evaluate the advantages and disadvantages of the control algorithm,finally get the characteristics of different algorithms.Establish a kinematic model and dynamic model of a hydraulic one-legged robot.The kinematics model and dynamics model of the single-leg robot are calculated by the size and mass distribution of the single-leg robot.The relationship between joint angle and hydraulic cylinder stroke,joint torque and hydraulic cylinder output force is established by the four-link transmission mechanism of the single-legged robot and the linear guide transmission mechanism.Based on this,the motion and force of single-leg robot are studied,and the effect of servo control performance of hydraulic driving unit on joint motion control is analyzed.Analysis of joint impedance control.Impedance control is a common strategy to achieve compliance control.Impedance control is a common strategy to achieve compliant control.The real-time feedback signal and impedance control algorithm of force sensor and displacement sensor simulate the desired impedance characteristics of the robot joint to achieve the goal of single-leg robot compliance control.This section mainly analyzes the two methods of position-based impedance control and force-based impedance control.Compare the characteristics of the two and select the appropriate control strategy according to the actual application scenario of the robot.Hydraulic drive unit servo control and single leg robot compliance control experiments.The experimental platform of hydraulic drive unit and single-leg robot were built respectively.The position control algorithm and force control algorithm of hydraulic drive unit are verified and compared.Impedance control strategy is applied to one-legged robot to reduce external impact.Experimental results show that the servo control algorithm of hydraulic drive unit studied in this paper can effectively reduce the impact force of the foot and meet the requirements of compliant control.