Design of Double Closed Loop for Granular Material Automatic Weighing System

摘要

The weighing of granular materials is generally implemented through the detection and control of weighing instruments, which control the vibration intensity according to the weight of incoming material measured by the sensor, and finally assure the material weighing accuracy under certain speed. Vibration feeding equipment is classified into crude feeding and fine feeding. The former is at high rate but with less accuracy while the later is with high accuracy but at lower rate. The final weighing accuracy depends on the aerial weight of material during fine feeding process. The aerial weight can be set, but is still influenced by many factors. Here, in this paper, these factors will be discussed and analyzed. Furthermore, an instrument of dual close-loop of accuracy and feeding rate was designed. This instrument adopts STM32 microcontroller as the processor and applies high-speed 24-bit AD conversion chips in the analogue sampling part and performs well in practical application, solving the longstanding practical difficulties that easier to control static accuracy while hard to control dynamic accuracy.