Automation and navigation of a terrestrial vehicle

[摘要] ENGLISH ABSTRACT:This thesis presents the design and implementation of an autonomous navigational systemand the automation of a practical demonstrator vehicle. It validates the proposednavigation architecture using simple functional navigational modules on the said vehicle.The proposed navigation architecture is a hierarchical structure, with a mission plannerat the top, followed by the route planner, the path planner and a vehicle controller withthe vehicle hardware at the base. A vehicle state estimator and mapping module runs inparallel to provide feedback data.The controls of an all terrain vehicle are electrically actuated and equipped with feedbacksensors to form a complete drive-by-wire solution. A steering controller and velocitycontrol state machine are designed and implemented on an existing on-board controllerthat includes a six degrees-of-freedom kinematic state estimator.A lidar scanner detects obstacles. The lidar data is mapped in real time to a localthree-dimensional occupancy grid using a Bayesian update process. Each lidar beam isprojected within the occupancy grid and the occupancy state of a ected cells is updated.A lidar simulation environment is created to test the mapping module before practical implementation.For planning purposes, the three-dimensional occupancy grid is convertedto a two-dimensional drivability map.The path planner is an adapted rapidly exploring random tree (RRT) planner, that assumesDubins car kinematics for the vehicle. The path planner optimises a cost functionbased on path length and a risk factor that is derived from the drivability map.A simple mission planner that accepts user-de ned waypoints as objectives is implemented.Practical tests veri ed the potential of the navigational structure implementedin this thesis.

[发布机构] Stellenbosch University