Automated landing of a quadrotor Unmanned Aerial Vehicle on a translating platform

[摘要] ENGLISH ABSTRACT: In this thesis the design, implementation and practical testing of an autolanding systemresponsible for landing a quadrotor Unmanned Aerial Vehicle (UAV) on a moving platformare presented.The goal of the system was to land the quadrotor used in the Surface Launched Aerial Decoyelectric (SLADe) project autonomously on the deck of a moving ship. The quadrotor, whichis designed completely in-house in the Electronic Systems Laboratory at the University ofStellenbosch, has full autonomous flight capabilities and has a payload carrying capacityof 6 kg. This thesis specifically concentrates on the translational movement of the shipdeck, and not rolling, pitching and heaving motion. The goal of the project was successfullyobtained through modification of the quadrotor's flight control system as well as the DifferentialGlobal Position System (DGPS) sensing method of the platform and the UAV, andthrough implementation of a state machine that guided the aircraft through the autolandingprocedure.The flight control system of the UAV was thoroughly analysed, and shortcomings in thecontrol system for this project were identified. The flight control system was not capable oftracking a moving platform with zero steady-state error and lacked disturbance rejection.The shortcomings were amended by modifying the architecture and increasing the bandwidthof the control loops responsible for horizontal velocity and horizontal position control of theUAV. A fundamental change was made to the aircraft's positional sensing method, expandingthe DGPS capabilities of the vehicle. The DGPS, which is manufactured by Novatel, wasmodified to provide centimetre-level accurate relative position measurements between theplatform and the UAV. The modifications allowed for accurate control of the position of theUAV relative to the moving platform. A state machine was implemented to safely guide thequadrotor through the landing procedure. The state machine consists of four consecutivestates, and incorporates several safety checks to ensure that the quadrotor touches downsafely within the required bounds.The quadrotor successfully performed autonomous landings on a translating platform atspeeds of 10, 20 and 30 km/h, and touched down within 36 cm of the designated landing mark.

[发布机构] Stellenbosch University