A LiDAR Sensor-Based Spray Boom Height Detection Method and the Corresponding Experimental Validation

Sprayer boom height (H(b)) variations affect the deposition and distribution of droplets. An H(b) control system is used to adjust H(b) to maintain an optimum distance between the boom and the crop canopy, and an H(b) detection sensor is a key component of the H(b) control system. This study presents a new, low-cost light detection and ranging (LiDAR) sensor for H(b) detection developed based on the principle of single-point ranging. To examine the detection performance of the LiDAR sensor, a step height detection experiment, a field ground detection experiment, and a wheat stubble (WS) height detection experiment as well as a comparison with an ultrasonic sensor were performed. The results showed that the LiDAR sensor could be used to detect H(b). When used to detect the WS height (H(WS)), the LiDAR sensor primarily detected the WS roots and the inside of the WS canopy. H(WS) and movement speed of the LiDAR sensor (V(LiDAR)) has a greater impact on the detection performance of the LiDAR sensor for the WS canopy than that for the WS roots. The detection error of the LiDAR sensor for the WS roots is less than 5.00%, and the detection error of the LiDAR sensor for the WS canopy is greater than 8.00%. The detection value from the LiDAR sensor to the WS root multiplied by 1.05 can be used as a reference basis for adjusting H(b), and after the WS canopy height is added to the basis, the value can be used as an index for adjusting H(b) in WS field spraying. The results of this study will promote research on the boom height detection method and autonomous H(b) control system.