2.2. Experiment Setup
The proposed DNIS was 21 m of length, and was equipped with 42 direct injection units which
were divided into seven boom sections. Within one section, six direct injection units were controlled
by a same PWM signal as shown in Figure 2a. Figure 2b shows the structure of one direct injection
unit, which includes a carrier valve, a RRV, a mixing chamber, an EC sensor, and a spray nozzle.