1.Key Laboratory of Advanced Process Control for Light Industry,
Jiangnan University, Wuxi, Jiangsu 214122, China; 2.State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, Heilongjiang 150080, China
Abstract：A dynamic and high precision weighing scale is designed for powder/granular agricultural products. The mechanical structure and the control system of the scale is desigened. The main components of the control system include S7-200 PLC, Siwarex_MS weighing model and servo motor. The servo motor, the PLC system (integrated weighing module) and the implementation mechanical structure constitutes a closed loop control system. Comparing to the open-loop control structure which mainly contain cylinder and single casting gate, it can significantly improve the accuracy of the scale. In order to overcome the nonlinear disturbance factors and the varing air materials(materials in the air with casting gate closed) which effecting on the weighing accuracy, the RBF neural network PID controller is used to the process of fine materials casting, and the adaptive correction method for the air materials was adopted. In the experiment, 25 kg rice is weighed, with an average accuracy of ±0.114% and the maxmum speed of 1100 times/h.
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2013, Vol. 34 
