An Autonomous Electrical Vehicle Based on Low-cost Ultrasound Sensors for Safer Operations Inside Greenhouses

Abstract

The main target of this research activity is to develop and test different low cost sensors that can enable a multifunctional tracked electrical vehicle to move autonomously inside a greenhouse with tomatoes cultivation. Big effort has been put on finding solutions that require minimum or no apparatus installation in the greenhouses while performing centimetre-level accuracy at a fraction of the cost of a DGPS commercial system. The used low cost sensors are described, while description of the electrical vehicle and its capabilities can be found in previous works. Two main kinds of sensors systems have been developed using low cost ultrasound sensors. The first system uses a set of eight ultrasound transmitter/receiver couple. These sensors can compute time by time the distance and the rotation angle of the robot with respect to the plants rows. This information could be used to correct the robot trajectory, allowing the system to move along the centre line between rows. The second system that has been tested is a Local Positioning System (LPS). It uses a set of low cost ultrasound receiver sensors mounted on the greenhouse structure in a regular grid while an ultrasound transmitter is mounted onboard the robot that is moving between rows. The system allows to know the relative coordinate of the robot with respect to a reference inside the greenhouse. At this stage, different trials on the sensors have been performed inside a greenhouse in different condition; these trials allowed to evaluate systems accuracy and performance.