Research On Motor Control Strategy Of Main Manipulator Hand Joint Of Multi-dof Medical Robot

Compared with traditional surgery,medical surgery robot can not only perform operation on patient remotely,but also improve the safety and stability of operation.However,doctor move master manipulator on the basis of overcoming the external force of master manipulator during operation,which will not only increase the risk of misoperation by doctor,but also bring challenge to the physical strength of doctors.Therefore,it is necessary to install hollow cup motor motors with fast dynamic response at the joint of master manipulator,and make use of the output electromagnetic torque of motors to complete external force compensation in the movement of master manipulator in real time.This paper studies the control strategy of the joint motor of the master manipulator of medical robot and the main works are as follows:Firstlly,the D-H mathematical model of the master manipulator of medical robot is studied.The forward kinematics process of master manipulator is analyzed,and the correctness of the forward kinematics of master manipulator is verified by simulation.The dynamic equation of master manipulator is established based on Lagrange function method.According to the gravitational potential energy and kinetic energy of master manipulator,the gravity compensation model and kinetic energy compensation model of master manipulator are studied respectively,and the torque that each joint motor needs to compensate for the self-balancing of the mechansim of master manipulator is obtained.Secondly,to solve the problem of large current pulsation caused by small electrical time constant of motor,a current sampling method combining Σ-Δmodulator and Sinc3 digital filter is used.In order to control the average torque of motor,single-point sampling method and multi-point sampling method are adopted to obtain the average value of the current of motors in the control period.Bipolar and unipolar pulse width modulation are adopted to inverter respectively to achieve accurate torque control of DC motor.The above mentioned contents are verified by experiments,and the performance of motor current closed-loop under different modulation modes is compared.Thirdly,based on the PI controller,the accurate current control of the hollow cup BLDC is completed by using vector control,three-phase six-state control with constant current and three-phase six-state control with constant torque.Simulation and experiment are carried out to verify the above mentioned contents.Finally,a torque predictive control algorithm based on unipolar pulse width modulation is proposed,and the dynamic response of the average electromagnetic torque of the output of BLDC is increased.The mathematical model of the motor and the inverter of motor is established.The electromagnetic torque is controlled during the conduction and commutation respectively by using the torque predictive control strategy.The above mentioned contents are verified by simulation.Finally,the torque predictive control algorithm during conduction of the motor is verified by experiment.