Intelligent Crop Spraying: A prototype development.

Site-specific application of pesticides reduces both the costs of plant protection and environmental pollution. An active laser imaging system with adjustable accuracy and capable of working day or night, for automatic detection and spraying of plant material has been developed. The system uses two laser diodes with wavelengths either side of the so-called ‘red-edge’, where there is a large step in reflectance of plant material from the red through to the infrared. The laser beams are combined into one and scanned in front of a spraying boom. The diodes are modulated at two different frequencies so that the scattered light can be detected with a single detector and extracted from the ambient light. A retro-collective light gathering scheme is used to avoid saturation of the avalanche photodiode due to sunlight. The image generated by the reflectance difference is used to control spray nozzles