Experimental analysis of ground speed measuring systems for the intelligent agricultural machinery

Measuring machine´s speed precisely is quite critical for intelligent agricultural machinery. With Advanced RISC Machines (ARM) as the speed measurement terminal, speed measurement precision was tested and studied when the sensor was served by the encoder, inductance near-switch, doppler-radar and Global Positioning System (GPS) in the Autumn-ploughed farmland. In a 40m-long testing distance, the measurement precision of the above sensors was tested when the tractor driving at 4.0km/h, 5.0km/h and 6.0km/h. After the measured speed data were contrasted to the theoretical data, the result proves that the coefficient of variation (CV) of GPS is the highest; the data from the radar is most close to the theoretical data with the error of 2.03%; the biggest error of the inductance near-switch is 2.82%; the biggest error of the encoder is 2.85%. The performance price ratio of the inductance near-switch is the highest among the four, and it can meet the requirement of intelligent agricultural machinery.