Research On Disturbance Observer Of Robot Joint Motor

With the development of population aging and industrial upgrading,robots have been more and more widely used in daily life,logistics,transportation and industrial production.Permanent magnet synchronous motors have gradually replaced the application of DC motor in robot joints for its advantages of high power density,good controllability and high efficiency.The robot joint motors suffer from complex motion conditions and variable load.This paper mainly studies the load torque observation methods for robot joint motor,which estimates and compensates the load disturbance and parameter perturbation.The main work is as follows:Firstly,this paper proposes a load torque observation algorithm based on disturbance observer.Through the analysis of the minimum order observer,a disturbance observer(DOB)is designed to estimate and compensate the load torque and parameter perturbation,and the tracking characteristics,stability and robustness against parameters variations of the DOB system are analyzed and tested.Secondly,this paper proposes a DOB-based inertia identification algorithm.This algorithm takes advantage of the characteristic of the orthogonal relationship between the variables in the DOB.By applying the periodic square wave speed signal,the inertia variation term in the disturbance observation value can be extracted,and then the real inertia value can be obtained by calculation.Thirdly,this paper proposes a motion control strategy based on DOB,including current loop and position loop.The dead-beat predictive current control(DPCC)strategy with a proportional-integral(PI)controller is adopted in the current loop.The current loop can achieve fast dynamic response and good robustness against parameters variations.The DOB-based proportional-differential(PD)controller is adopted in the position loop,which uses a DOB to estimate and compensate the load torque,and uses proportional-derivative(PD)control to regulate dynamic response performance.The position loop can achieve flexible dynamic performance and good anti-disturbance ability,which ensures the normal operation of the joint motor.Finally,the dragging experiment platform and the two-link manipulator experiment platform are built.The performance of the proposed load observe algorithm,inertia identification algorithm and motion control method are tested,and the feasibility and effectiveness of the proposed algorithm are verified.