Abstract： The problems such as narrowed adjustable concentration and poor control accuracy are prevalent 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—TMS320F2812 produced by TI was used as the hypogynous computer and a humancomputer interaction interface was composed on the host computer in LabVIEW environment. The host and hypogynous computers sharing data was realized by means of the communications between serial ports. The host computer 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 rotational speed and the flow rate of water was obtained by fitting their experiment data; similarly, the mathematical relation between the control voltage of the electricmagnetic 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).
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