This paper describes a human-inspired method (HIM) and a fully integrated navigation strategy for a wheeled mobile robot in an outdoor farm setting. The proposed strategy is composed of four main actions: sensor data analysis, obstacle detection, obstacle avoidance, and goal seeking. Using these actions, the navigation approach is capable of autonomous row-detection, row-following, and path planning motion in outdoor settings. In order to drive the robot in off-road terrain, it must detect holes or ground depressions (negative obstacles) that are inherent parts of these environments, in real-time at a safe distance from the robot. Key originalities of the proposed approach are its capability to accurately detect both positive (over ground) and negative obstacles, and accurately identify the end of the rows of bushes (e.g., in a farm) and enter the next row. Experimental evaluations were carried out using a differential wheeled mobile robot in different settings. The robot, used for experiments, utilizes a tilting unit, which carries a laser range finder (LRF) to detect objects, and a real-time kinematics differential global positioning system (RTK-DGPS) unit for localization. Experiments demonstrate that the proposed technique is capable of successfully detecting and following rows (path following) as well as robust navigation of the robot for point-to-point motion control.
MIMO ANTENNAS FOR A TERRESTRIAL POINT-TO-POINT WIRELESS LINK: FROM THE OPTIMUM ANTENNA SPACING TO A COMPACT ARRAY
