Study On Permanent Magnet Synchronous Motor Servo Control System For Harvesting Robot Joints

After entering a new era,the problem of aging is becoming more and more serious.The contradiction between the shortage of social labor resources and the increasing demand for fruits and vegetables is highlighted.The promotion of agricultural mechanization,automation and intelligence is an important way to solve this contradiction.Agricultural harvesting robot,belonging to the advanced agricultural automation equipment,is a hot issue in the field of agricultural science and technology in twenty-first Century.In this paper,a permanent magnet synchronous motor servo control system with high precision,high response speed,high robustness and openness is designed to control the joint shafting of a motor driven agricultural harvesting robot.The main contents are as follows.1.Analyzing the control requirements of the harvesting robot and making the design plan.It shows that the PMSM servo control system for harvesting robot has high requirements for system accuracy,response speed and robustness.Then,the advantages and disadvantages of various driving systems are analyzed and compared,and the most suitable driving mode for picking robots is motor drive.Finally,the mathematical model of PMSM is established on the d-p axis,which provides a theoretical basis for the controller design.2.The three closed-loop control structure is adopted for the PMSM control system.The design of current loop used PI algorithm.In the design of speed loop,an adaptive variable speed exponential approach law is adopted.The reaching law introduces the first order norm of state variables,and adaptively adjusts exponential approaching speed and constant speed approaching speed according to the distance between the state variables and equilibrium points.And the system can shorten the approaching time while weakening the chattering.Meanwhile,the disturbance observer is designed to observe the value of load torque and external disturbance,and feedback it to the sliding model controller.The fast terminal sliding mode control law is used to design the high accuracy fast terminal sliding mode position controller in the design of position loop.It improves the response speed while ensuring the accuracy of position system.The feasibility of the controller is verified by Simulink simulation,and the effect is good.3.Software and hardware design of permanent magnet synchronous motor servo control system for robot joints.The hardware design is mainly divided into two parts: control plate and driving plate.The control plate includes power supply module,DSP minimum system module,A/D acquisition module,encoder signal conversion module and RS485 communication module.And the driving plate mainly includes power module,IPM intelligent power module and its peripheral drive circuit,hall current sensor module.In the software design,CCS the DSP development environment and its function is introduced firstly.Then the overall structure of the software is displayed and the important interrupts and subroutines is designed in the end.4.verifying the system performance by experiment.First,the open loop output waveform of hardware is collected by oscilloscope,which indicates that the hardware system designed in this paper is stable and reliable.Then,through the experimental analysis and comparison,it shows that the permanent magnet synchronous motor servo control system designed in this paper has high precision,fast response speed,good robustness and strong anti-interference ability,and can basically meet the control requirements of the joint of the harvesting robot.