Precise Positioning and Heading for Autonomous Scouting Robots in a Harsh Environment

This document describes the design and verification of the GreenPatrol localization subsystem. Greenpatrol is an autonomous robot system intended to operate in light indoor environments, such as greenhouses, detecting and treating pests in high-value crops such as tomato and pepper. High accuracy positioning is required for performing this in a trustable and safety manner. The proposed localization solution is described hereafter. Test have been carried out in the real greenhouse environment. The proposed localization subsystem consists of two differentiate parts: (1) an absolute localization module which uses precise positioning GNSS techniques in combination with the robot proprioceptive sensors (i.e. inertial sensors and odometry) with an estimated position error lower than 30 cm, and (2) a relative localization module that takes the absolute solution as input and combines it with the robot range readings to generate a model of the environment and to estimate the robot position and heading inside it. From the analysis of the tests results it follows that the absolute localization is able to provide a heading solution with accuracy 5\(^\circ \) more than a 85% of the time. The relative localization algorithm, on the other hand, gives an estimation of the robot position inside the map which does not improve significantly the absolute solution, but it is able to refine the heading estimation and to absorb transitory error peaks.