The design and implementation of vision-based autonomous rotorcraft landing

[摘要] ENGLISH ABSTRACT: This thesis presents the design and implementation of all the subsystems required toperform precision autonomous helicopter landings within a low-cost framework.To obtain high-accuracy state estimates during the landing phase a vision-based approach,with a downwards facing camera on the helicopter and a known landing target, was used.An e cient monocular-view pose estimation algorithm was developed to determine thehelicopter's relative position and attitude during the landing phase. This algorithm wasanalysed and compared to existing algorithms in terms of sensitivity, robustness andruntime.An augmented kinematic state estimator was developed to combine measurements fromlow-cost GPS and inertial measurement units with the high accuracy measurements fromthe camera system. High-level guidance algorithms, capable of performing waypoint navigationand autonomous landings, were developed.A visual position and attitude measurement (VPAM) node was designed and built to performthe pose estimation and execute the associated algorithms. To increase the node'sthroughput, a compression scheme is used between the image sensor and the processorto reduce the amount of data that needs to be processed. This reduces processing requirementsand allows the entire system to remain on-board with no reliance on radiolinks. The functionality of the VPAM node was con rmed through a number of practicaltests. The node is able to provide measurements of su cient accuracy for the subsequentsystems in the autonomous landing system.The functionality of the full system was con rmed in a software environment, as well asthrough testing using a visually augmented hardware-in-the-loop environment.

[发布机构] Stellenbosch University