Research On Permanent Magnet Synchronous Motor Direct Torque Control Of Exoskeleton Joint

The exoskeleton robot is a machine that supply extra power to people,it has become a hot topic in the field of robotics over the past decade.The driving device is the power source of the exoskeleton movement,the choice and control of the drive device has a very important effect on whether the entire exoskeleton can successfully complete the instruction.Permanent Magnet Synchronous Motor(PMSM)is a kind of high performance drive motor,which is more and more used in exoskeleton robot.As a high dynamic performance of the motor control method,Direct Torque Control(DTC)continue to be concerned about and researched in recent years.However,the performance with traditional direct torque control is still limited and difficult to meet the high demand,the emergence of intelligent control bring new ideas to the motor control.Based on these,the main content of this article is as follows:Firstly,the research status of exoskeleton driving system and permanent magnet synchronous motor control method is summarized,and the structure of exoskeleton control system and motor control module is analyzed.Then walk condition is simulated in ADAMS environment,and put forward the requirements for motor control module.The characteristics of different types of motors are analyzed,and the square wave driven permanent magnet synchronous motor is selected.,which also named as Brushless Direct Current Motor(BLDCM).This article completed the motor parameter calculation and type selection.The structure of the permanent magnet synchronous motor and the commonly used coordinate system and the coordinate transformation principle are introduced.On this basis,the model of the BLDCM in different coordinate systems is established.Finally,the control method of the BLDCM is analyzed,and it is shown that the direct torque control can satisfy the following control and is more suitable for the motor control of the exoskeleton robot.This paper analyzes and compares the characteristics of traditional DTC and non-flux observation DTC of BLDCM.After analyzing the mechanism of zero vector,the zero vector is applied into the torque loop,and the simulation is carried out to analyze the influence of the zero vector on the torque ripple and the starting time.This paper designs the three-loop control of BLDCM without flux observation DTC,introduced in the speed loop fuzzy control,design weight self-adjusting fuzzycontroller,Fuzzy control is applied to design the weight self-adjusting fuzzy controller in the speed loop.On this basis,the single neuron PID is applied in the position loop to improve the high performance position control of the square wave driven permanent magnet synchronous motor.Finally,the simulation results are completed in MATLAB environment.Compared with the simulation results,the control strategy has some advantages of strong Anti-jamming capability,small error and good control effect.