| AC servo system has an important position in the field of modern industrial automation.Industrial applications include robotics,high-precision CNC machine tools and other high-precision motion control machinery.AC servo system has been widely used in the field of industrial robots.The industrial robot is a collection of industrial mechanical arm with multiple degrees of freedom.At least one AC servo system is required for each joint of the industrial robot.Due to the real-time and synchronization of the servo system communication,the reliability and precision of the servo system are put forward,and the practical AC servo technology of industrial robots in China is started late,the application experience is less and so on.So most of the industrial robotic arm servo system is occupied by foreign brands.In this context,the key technology of AC servo system for industrial mechanical arm is studied in this paper.AC servo system torque observer,online parameter variables,communication bus and servo system all digital design,etc.In these areas done a lot of theoretical analysis and experimental research.Developed a set of high-performance,all-digital,dual-axis AC servo control system,which is based on EtherCAT bus communication.The content of this research falls into the following:1.The implementation of space vector pulse width modulation vector control algorithm in field programmable gate array is proposed.Based on the analysis of the mathematical model of AC permanent magnet synchronous motor(PMSM),the principle of coordinate transformation of AC servo motor is described in detail.The principle of voltage space vector pulse width modulation(SVPWM),which is the most widely used in AC servo system,is discussed in this paper.The research and implementation of SVPWM vector control algorithm based on FPGA is completed.2.The three closed loop mathematical model of AC servo control system is designed.According to the modern control theory,the transfer function of AC servo system is analyzed.The transfer function provides the theoretical basis for the implementation of the load torque observer and the realization of parameter self-tuning based on the identification result.And the mathematical model of the current loop,velocity loop and position loop of the AC servo system is established by the transfer function.Discussion and analysis of the current controller,speed controller and position controller design methods.And the correctness of the controller design is verified by simulation test,which provides a basis for further research on system performance.3.The design of load torque observer based on Lyapunov principle is proposed.Based on the load torque identification results,the parameters of the speed loop are optimized online.As the industrial robotic arm has different load torque in different applications,will affect the control performance of AC servo system.In order to make AC servo can have good control performance,and also to improve the reliability of the system.Using the permanent magnet synchronous motor stator shaft current and speed equation to build the equation for the motor dynamics.Then the load torque observer based on Lyapunov theory is constructed.According to the estimation results of the observer,the speed loop controller is redesigned,and the parameter optimization of the speed loop is realized.The simulation and bench test show that the design method is feasible.Tracking performance of system speed and torque response capability have been improved.After optimization of control parameters,the control system can effectively improve the dynamic performance of the servo system,and the robustness of AC servo system is enhanced.4.The rapid design of EtherCAT slave station is presented,which has the characteristics of low cost,miniaturization and modularization.The demand for real-time and reliability of communications is analyzed,which is used in industrial robotic arm AC servo control system.The design of EtherCAT bus communication technology based on FPGA IP core is designed.Its data link layer and application layer are implemented in the FPGA.The functionality of the EtherCAT slave control chip(ESC)and slave microprocessor chips is implemented in a single FPGA chip.This design has the advantages of modularity,easy portability,and miniaturization.The transmission delay in the communication process is analyzed and calculated theoretically.Combined with the test,the synchronization and real-time verification.The results show that the design scheme is effective,and the requirement of the industrial robotic arm AC servo system to the bus communication is realized.5.A dual axis AC servo control system for industrial manipulator is developed.Based on the analysis of the theory of AC servo system,the digital design of AC servo control system of industrial robotic arm is completed.The hardware platform of digital AC servo system is designed,and the vector control algorithm of AC servo motor based on DSP + FPGA architecture is developed.The three closed loop design of AC servo system is completed.And on the basis of the hardware and software of the system,the design of the main circuit,the detection circuit and the protection circuit of the AC servo system is completed.The software architecture and function design of the AC servo system are realized.6.Test and simulation.In this paper,the design of AC servo system for industrial robot is verified by simulation and test.This system supports three phase 380V + 15%,current loop,speed loop,position loop control cycle is 62.5us.When the end speed of the industrial mechanical arm is 0.2m/s,the position stability time is 0.026ms,and the position overshoot is 0.111mm.And,when the end speed of the industrial mechanical arm is 1.0m/s,the position stability time is 0.9ms,and the position overshoot is 0.123mm.It meets the requirements of the industrial mechanical arm to the servo control system.The results show that the AC servo system designed by this method has good robustness.And this system control is simple and easy to implement,has a certain practicality. |
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