An Intelligent and Customized Electrical Conductivity Sensor to Evaluate the Response Time of a Direct Injection System

摘要

In pesticide application based on direct injection systems, the sprayer response time plays an important role for the spraying quality, mainly when operating in real time. The response time is defined as the time elapsed from the time of injection until the concentration of the mixture (water mixed with herbicide) reaches 95% of its regime value in the spray nozzles. Therefore, in the response time the transport delay and the rise time for achieving the desired concentration are considered. This paper describes an intelligent sensor mounted near the spray nozzles to measure the concentration response time in a herbicide direct injection system, which uses a highly stable sinusoidal excitation signal. The sensor calibration was performed with NaCl solutions at concentrations similar to those found in actual application conditions. Using an integrated system based on the Arduino platform, an algorithm was developed to relate the measurements to the response time. The integrated system comprises the sensor with its own sensing hardware, A/D converter, processing and storage capabilities, software drivers, self-assessment algorithms and communication protocols. The immediate application of the integrated system is in the monitoring of the response time of a precision pesticide application. The results point to the next generation of smart devices that have embedded intelligence to support decision making in precision agriculture.