Continuous local motion planning & control for unmanned vehicle operation within complex obstacle-rich environments

This thesis considers the guidance and control of unmanned vehicles within complexenvironments. A systems engineering approach was adopted where significant effortwas directed towards defining a high level capability requirement and subsequentproblem exploration, decomposition and definition, prior to addressing the technicalfocus. The goal of this approach was to ensure that technical work was directedtowards realistic end user requirements and operational scenarios.As the complexity of an operational environment increases, so does the requirement toconsider the local obstacle space continually, and this is aided by splitting the motionplanning functionality into distinct global and local layers. The technical focus of thisthesis is on the development and simulation-based testing of a new local motionplanning and control framework, where knowledge of i) feasible vehicle manoeuvreconstraints ii) local obstacle map iii) current environment conditions are all combinedinto a continuous receding horizon approach. This framework separates the output andcontrol space elements of the problem, reducing the complexity of the local motiontrajectory optimisation and therefore enabling faster design and increased horizonlength. Bezier polynomial functions are used to describe local motion trajectories whichare constrained to vehicle performance limits and optimised to achieve a specifiedgoal. The primary problem addressed is ‘situation-aware’ trajectory tracking, but otherlocal motion planning modes are also considered.Development and testing of the new framework is undertaken within simulation(Matlab), based on a nonlinear 6 degree of freedom model of a quadrotor unmannedair vehicle. Situation-aware trajectory tracking is demonstrated in the presence of staticand dynamic obstacles, as well as the presence of realistic turbulence and gusts. Theimmediate-term deconfliction of multiple unmanned vehicles, and multiple formations ofunmanned vehicles, is also demonstrated, including the provision of rules-of-the-airtype behaviour