在线射流混药浓度控制系统

为了解决在线射流混药存在的混药比可调范围窄、控制精度低的问题,实现射流混药的精确、智能控制,以LabVIEW为开发环境,设计上位机人机交互界面,以TI公司控制芯片TMS320F2812为核心设计下位机系统,上位机与下位机之间通过串口通信实现数据的共享.上位机可实现数据的输入与数据的显示及存储,下位机负责射流混药器水流量与药流量的独立控制,通过电动机转速与水流量的标定试验拟合得两者函数关系,通过电控阀控制电压与药流量的标定试验拟合得两者函数关系.基于此控制系统,研究了在不同混药比状况下射流混药器进水量及进药量的控制精度.通过水流量控制跟踪性能、药液吸入量随水流量变化、药原液控制跟踪性能等试验表明,水流量控制相对误差在2%以内,药流量控制相对误差在3%以内;设置混药控制系统,可获得适合实用的混药比值,显著（数十倍）增加混药比调节宽度.

Online jet mixing control system of pesticide concentration

The problems such as narrowed adjustable concentration and poor control accuracy are pre- valent in common online pesticide concentration control systems in jet mixing process. In order to solve these problems so as to realize an accuracy and intelligent control on pesticide concentration in the process, an advanced control system was developed here. In the system, the control chip--TMS- 320F2812 produced by TI was used as the hypogynous computer and a human-computer interaction in- terface was composed on the host computer in LabVIEW environment. The host and hypogynous com- puters sharing data was realized by means of the communications between serial ports. The host com- puter was responsible for data input, display and storage. The hypogynous computer regulated the flow rates of water and pesticide into the mixer, respectively. The analytical relation between the motor rota- tional speed and the flow rate of water was obtained by fitting their experiment data; similarly, the mathematical relation between the control voltage of the electric-magnetic valve and the flow rate of drug could be gained as well. The control accuracies on the flow rates of both water and pesticide that were pumped into the jet mixing tank were studied at different mixing ratios based on the system. In the experiments, the flow rates of water and drug, the relation between two flow rates were tracked. It was demonstrated that the errors of control on flow rates of water and pesticide were less than 2% and 3%, respectively. Since the mixing ratio of water and drug is adjustable in the concentration control system, a practical ratio can be achieved. As a result, the mixing ratio varying range can be expanded significantly （more than 10 times）.