Research On The Control System Of Time Grating Direct-drive Turnable Based On DSP Technology

The direct-drive motor has the characteristics of high dynamic response,large output torque,strong load capacity and high processing efficiency due to its direct drive load.Usually direct-drive motor and high-precision angle sensors are packaged for direct-drive turntables,and high-precision grating is used as the turntable angle measuring element to achieve high-precision control of the turntable.The high-precision grating relies on imports.At present,domestic time grating angle sensors are gradually being used on direct-drive turntables.As a new technology,the application of time grating in the field of direct-drive motors still needs to be studied.Although the direct-drive motor has many advantages,after the intermediate transmission mechanism is eliminated,it is more susceptible to the influence of external and internal interference,which causes the performance of the control system to decrease.To solve these problems,a design scheme of time grating direct-drive turntable control system with high positioning accuracy and good speed stability is proposed.After analyzing the motor controller and control strategy,the time grating direct-drive turntable control system based on DSP technology is designed.Firstly,the hardware circuit of the control system is designed in detail.The circuit is mainly divided into 4 parts: acquisition circuit,communication circuit,power drive circuit and minimum system circuit.Secondly,the software part is designed based on the hardware circuit and control strategy.The functions of vector control and current,speed and position three closed-loop control are realized through the software.The vector control can decouple some variables of the motor,reduce the difficulty of control,and improve the control accuracy of the turntable,and the three closed-loop control can accurately control the position and speed of the turntable.Thirdly,using Matlab/Simulink software to simulate and analyze the control system.Compare the traditional PID control and fuzzy PID control of the speed loop,and choose the better fuzzy PID control as the control method of the speed loop.The simulation results of the whole control system shows that the control system has better response speed and anti-interference ability.Finally,the experimental platform for the time grating direct-drive turntable was built,a specific experimental method was designed,and the positioning accuracy and speed stability experiments of the turntable were completed.The experimental results show that the positioning accuracy of the turntable is ±4.5″,and the speed stability can reach ±3rpm at 200 rpm.Finally,the error analysis of the positioning accuracy and speed stability of the turntable is carried out.