| Pneumatic artificial muscles(PAMs),as a new type of actuator,have many advantages,such as safety and flexibility,high power/weight ratio,their similar properties compared with biological muscles and so on,which has been given attention by scholars recently.However,the position,force and stiffness control accuracy of PAM are severely influenced by its defect such as nonlinearity.Four problems are investigated in this paper:one is to establish the model of the PAM,the second is to design sliding mode controller,the third is to design impedance controller of the elbow joint,finally,the application of bionic arm is studied.In order to obtain the joint force and stifness model,the test platform was established to test the single pneumatic muscles.First,establish the static model between displacement,output force and air pressure of the pneumatic artificial muscles.A static mathematical model of single pneumatic artificial muscle was established,and the parameters of the model were identified by the experimental data.According to the identification results,the force and stiffness model of antagonistic bionic elbow joint with double root pneumatic artificial muscle was established.Based on the mathematical model,the position of single pneumatic artificial muscle is tracked by PID control and Sliding Mode Control(SMC)respectively.The experimental results show that SMC has a better trajectory tracking effect.Based on the mathematical model of bionic elbow joint,this paper designs a dual-input and dual-output sliding mode controller to track and control the force and stiffness of the antagonistic joint.The saturation function is designed and improved.The experimental results show that the optimized sliding mode control rate can reduce the chattering of the traditional sliding mode control,and prove the effectiveness of the SMC control method.Double-input and double-output control algorithm experiments show that force and stiffness control with good tracking effect.Based on the PID position control,the impedance controller is designed to correct the given position to achieve the compliance movement of the bionic elbow joint.The influence of the three impedance parameters on the impedance control is analyzed.Based on the impedance control experiment platform,the impedance control experiment was done under different conditions.The experimental results show that the elbow joint has a good active and passive compliance.Finally,based on the previous theoretical research to complete flexible biomimetic manipulator system design and integration.Kinematics analysis is carried out for it.Design test experiment of joint compliant under different force,force safety threshold and so on.Then flexible biomimetic manipulator is controlled integrally to achieve the object grasp and handing. |
