Design And Implementation Of Soft Contract Manipulator Joint Control System

Space docking technology is mainly used for space missions such as on-orbit maintenance and on-orbit defense,it can greatly reduce the loss caused by the failure of the spacecraft under the premise of ensuring the normal operation of the spacecraft,so it has a promising application prospect and research value.Soft contact manipulator is the key component of the space docking mission,in the process of operation,the manipulator needs to complete joint positioning and vibration suppression after the collision.According to the technical requirement of the soft contact manipulator in the space docking task,this paper deeply studies the control system design method of the soft contact manipulator joint.This paper focuses on the control method and simulation analysis of the brushless DC motor(BLDCM)and magneto rheological damper(MRD).The software implementation and the hardware implementation of the control system are completed based on FPGA.This paper is supported by from the National Natural Science Foundation of China(51305039)and Fundamental Research Funds for the Central Universities(2014PTB-00-01).The main contents of this paper are as follows:First of all,aiming at the structure and the main functions of the soft contact manipulator joint,the overall scheme design of the joint control system is carried out.The joint control system is divided into two parts,the motor control subsystem and the MRD control subsystem.Secondly,this paper presents a design scheme of the compound motor position controller based on the fuzzy-PID theory according to the joint position function of the soft contact manipulator.In the position control subsystem,the position loop uses the compound fuzzy-PID controller,the speed loop and the current loop use the PI controller.And the effectiveness of the compound motor position controller is verified by MATLAB simulation.According to the vibration suppression function of the soft contact manipulator joint,the MRD control scheme is designed.The expected damping force of the damper is calculated by particle swarm optimization,the expected current is obtained by using the inverse model of the MRD,and in the end,the expected current is output by programmable power to control the damping force.Thirdly,this paper designs and implements the hardware structure of the soft contact manipulator joint control system,specifically includes a number of modules such as the core control module,the communication module,the motor driver,the joint angle measurement module,the force sensor module,the voltage conversion module and the damper current module.Furthermore,the software structure of the control system is designed and implemented,mainly includes the CAN bus communication module,the motor control module,the damper control module and the signal processing module.These modules are respectively programmed by Verilog HDL and C language.Finally,the experimental platform of the soft contact manipulator joint control system is established,and the experiment verification is carried out.The experiment results show that,the joint control system can make the soft contact manipulator joint completes effectively track of the predetermined trajectory.When the soft contact manipulator suffered collision,the control system can quickly attenuate the joint vibration by controlling the MRD input current,and finally realizes the vibration suppression of the soft contact manipulator.