Design On The Control System For Eggs Graspping

Based on Mechatronic Technology and realization of automation, the purpose of thispaper was to research design and realization of control system for Eggs graspping byrefered abundant information about robot field in agriculture, especially structure andcontrol system of the robot for the fruits and vegetables pick.The system is composed by the hardware and software. The hardware is composedby Master control computer which is put forward, the RS232 communication circuit,Slave control computer, the motor-driven circuit, stepping motor, Rotary encoder, thedoubling circuit, approach-switching circuit and the solenoid valve control circuit,possessing the function of structuring the data communication channel, driving steppingmotor, motor rotation speed & the localization feedback and grasping eggs. This paperadopted PC as Master control computer, which commands and supervises the Slavecontrol computer's work. Communication circuit, whose core chip is MAX232, providedata communication channel for Master and Slave control computer. AT89S52 wasadopted as the Slave control computer. The AT89S52 is a low-power, high-performanceCMOS 8-bit microcomputer with 8K bytes of Flash programmable and erasable read onlymemory. The device is manufactured using Atmel's high-density nonvolatile memorytechnology and is compatible with the industry-standard MCS-51 instruction set andpinout. The paper used L298N chip to compose the Motor-driven circuit. L298N is aspecial driver for bipolar or quadrupole stepping motor, including four logic-drivencuircuit channels. L298N can supply voltage up to 46V and total DC current up to 2A.Stepping motor adopt quadrupole stepping motor, angle of step pitch is 0.9°/1.8°, themaintenance torque is 0.54 N·m, the localization torque is 0.025 N·m, and the weight is0.36 Kg. Control system chosed rotary encoder as feed back device for the motor's closedloop control. Rotary encoder produce 100 pulses per revolution, but stepping motorproduce 400 pulses per revolution. In order to improve precision of stepping motor conrol,a doubling ciucuit was connected between rotary encoder and control computer. When thecupule approaches the eggs, the switching circuit send out the low level signal. AfterMCU received the signal, the magnetic valve become power failure by control circuit thatmake Air pressure debased, then the cupule can absorb the eggs.Software includes master and slave procedures, possessing the function of exch-anging data, localization control & rotation speed adjustment for stepping motor.First, using VC++6.0 to design master computer communication procedure to senddata to slave computer, including a simple interface. Second, using Keil softwar- e to designed slavecomputer procedure, including communication procedure, stepp-ing motor frequency elevation and depression procedure, PID rotate speed controlprocedure. After the slavecomputer received address from master computer, com-munication procedure will receive the data from master computer if address wasaccordant for local machine's, otherwise the data will be abandoned. For the step-ping mot-or with arriving the highest rotate speed rapidly, it has studied that exp-onent Rise and Drop Frequency method which accord with Torque and Frequencycharacteristic. PID rotate speed control procedure is in charge of rotate speed reg-ulation. Application of PID rotatespeed control procedure distinctly improved thedynamic performance of rotate spe-ed regulation. To obtained the most excellentPID control parameter(proportion modulus K_P =1.1, integral time T_i=0.081, differen-tial time T_D=0.068), it has studied that mathematics model of stepping motor andapplication of Simulink emulator.Finally the experiment is made. The experiment results indicate that the system canReal-time measure and control the rotate speed of stepping motor, orientation precisionless than 100 steps for stepping motor which satisfied the system's design request.