Real-time Tree Foliage Density Estimation with Laser Scanning Sensor for Variable-Rate Tree Sprayer Development

摘要

Trees even in the same orchard or nursery can have considerably different structures and foliage densities. Conventional chemical applications often spray the entire field at a constant rate without considering field variations, resulting in excessivechemical waste and spray drift. To address this problem, a foliage density estimation method was developed specifically for the development of an experimental variable-rate sprayer. A ground laser-scanning sensor was utilized to achieve the 3D range measurements of the target tree canopy structure. An algorithm was designed to calculate the foliage density in real time. Laboratory evaluations on artificial trees showed that the calculated and measured foliage densities of trees correlated very well with R2 ranging from 0.94 to 1. The algorithm could also identify the ground, sky, sensor height, tree row center, and background tree row automatically. Test results demonstrated that this density algorithm along with the instant calculation speed enabledthe sensor detection system to provide density measurement in real time for variable rate sprayer development.