Evaluation of a laser scanning sensor for variable-rate tree sprayer development

摘要

Accurate canopy measurement capabilities are prerequisites to automate variable-rate sprayers. A 270° radial range laser scanning sensor was tested for its scanning accuracy to detect tree canopy profiles. Signals from the laser sensor and a ground speed sensor were processed with an embedded computer along with a touch screen mounted on a tractor. An algorithm for data acquisition and 3-dimentioal (3-D) canopy image reconstruction were designed with C++ language and MATLAB software. The system accuracy was tested under indoor laboratory conditions with four regular-shape objects and two artificial trees and outdoor conditions with three field trees. Statistical analyses demonstrated the sensor measurements of the objects were not significantly different from those of the actual measurements. The mean RMS errors were not significant for scanning distance of 2 to 5 m and sensor travel speeds of 3.2 to 8.0 km h' Both indoor and outdoor tests verified that the wide-range laser sensor had the capability to accurately measure different sizes and shapes of objects. This confirmation offers the potential for the sensor to be integrated into spraying systems and provide variable-rate functions for tree crop applications.