Research On Precise Control Of Dynamic Weighing System For Asphalt Concrete Mixing Plant

With the development of China’s economy,the demand for infrastructure construction has increased,and the quality of asphalt concrete is crucial for road engineering.Asphalt concrete is composed of a variety of raw materials,requiring preset proportions and manufacturing using precise weighing systems.A good weighing system has an important impact on improving the quality of asphalt concrete and reducing the production cost of asphalt concrete.This article conducts in-depth research on the dynamic weighing system of asphalt concrete mixing plants based on the characteristics of domestic and foreign asphalt concrete mixing plants,using advanced weighing control strategies and computer simulation technology.The paper mainly completed the following tasks:(1)Starting from the overall requirements of the dynamic weighing system of the asphalt concrete mixing plant,a synchronous+asynchronous step-by-step feeding control strategy is proposed for asphalt according to the actual weight of aggregates weighed and the proportion,in order to achieve precise control of asphalt feeding.In the aggregate weighing system,the impact of aggregate falling and the impact of flying materials on the closing time of the aggregate bin door were considered.In the asphalt weighing system,the overall structure of the feeding equipment spiral scale has been designed;a mathematical model of the asphalt weighing servo system was established,and precise weighing of asphalt was achieved by adjusting PID parameters.In addition,in order to improve the accuracy of the ratio of aggregate and asphalt,the method of impulse correction was adopted for control.(2)The software design of the dynamic weighing system for aggregates in asphalt concrete was carried out using a programmable logic controller(PLC).The control system adopts Siemens S7-1200 as the control core,and achieves system detection and control functions through sensors and other devices.This article introduces the control process of the feeding and weighing parts of the dynamic weighing system of the aggregate belt scale,and compiles the PLC program diagram of the dynamic weighing system.(3)Considering that the weighing control system of the belt scale belonged to a nonlinear control system,the system was designed as a closed loop,and PID control method was used for system adjustment in order to improve control accuracy.To improve the system’s reliability,an aggregate dynamic weighing control algorithm that combined particle swarm optimization and fuzzy PID control was proposed,and a simulation model was built in MATLAB/Simulink.The simulation results show that the system response speed of this method is faster,the overshoot is smaller,and the time to reach steady state is shorter.Moreover,the system exhibits excellent adaptive ability and robustness,and can still maintain strong anti-interference ability in the face of interference,thereby improving the weighing accuracy of the aggregate belt scale.