Design of a remotely-operated field robot to detect olive trees infected with Xylella fastidiosa using proximal sensing

A small electric field robot has been designed and built to transport proximal sensing equipment to allow the monitoring of olive trees in search of an early infection by Xylella fastidiosa. The robot is operated remotely. Two batteries allow continuous use for six hours, which allows the inspection of a field of approximately 4 ha. Due to the height of the trees, a system of elevation of the cameras has been designed so that they can be raised up to 200 cm. An encoder connected to the axis of one of the motors measures the distance travelled by the vehicle allowing the computer to trigger the cameras at programmable intervals. A series of tests have been carried out in an olive testing orchard in the region of Apulia, (southern Italy), which showed mild symptoms of Xf infection. The sensing equipment consisted of a digital SLR camera, another digital SLR camera modified to capture NDVI images and a multispectral camera capable of acquiring eight wavelengths in the region of 550 to 850 nm. The system was programmed to capture an image for each meter of the robot’s advance. In addition, a 2D LIDAR scanner was used to obtain three-dimensional (3D) structural characteristics of the trees. Preliminary tests were carried out in which the robot captured images and data with all the sensors in different atmospheric conditions (from intense sun to intense rain). The vehicle advanced in each row acquiring the images of the trees on one side and returning in the same row acquiring the images of the trees on the other side, thus obtaining information of the whole tree. These tests served to adjust all the developed software, electronics, and sensors, as well as to improve some key aspects of the robot in terms of battery life and ease of operation. In addition, the sensors worked correctly and the collected data is now serving to create different spectral and vegetative maps, which will then be compared with in situ observations and molecular analyzes of collected leaves.