Research On UAV Shipborne Precise Landing System Based On Visual Guidance

Shipboard unmanned aerial vehicle(UAV) has become the ideal weapon in modern navy with the pursuit of "contactless" and "zero casualty" because of its operational flexibility, strong autonomy advantages. However, the precise, safety landing of shipboard UAV has been the focus of research in many countries. This paper researches on the visual-based landing system for shipboard UAV with the requirement of precise landing.Firstly, a visual landing navigation system is designed on both sides of the aircraft carrier runway according to the characteristics of shipboard UAV landing and requirements of the navigation system, and the principle of the system, working flow, tracking control and position calculation are analyzed. Then, the position calibration of navigation system is designed based on infrared vision and tested.Secondly, in order to obtain the position of the UAV, the Adaboost algorithm is chosen to detect the UAV target, the rectangle feature of the UAV is selected and the calculation of the characteristic value is simplified by using the integral figure according to the actual situation, and the adaboost algorithm is improved by weight updating scheme and asymmetric learning. By using the positive and negative samples training cascade classifier, the accurate detection of UAV target is realized.Thirdly, in order to ensure the shipboard UAV fly along the desired glide path, total energy control and L1 nonlinear control methods are used separately to design the longitudinal and lateral guidance control law. Semi-physical simulation is applied to verify the guidance control law of the landing ship.Finally, the designed visual navigation system and the guidance control law are verified by the field flight tests. The experimental results show that the visual navigation system has a high precision of position calculation, and longitudinal and lateral guidance control law based on the total energy control method and the nonlinear L1 method could precisely ensure the UAV to fly along predetermined path and landing point of the mobile platform. The research results have important reference value for the engineering realization of the vision guided landing technology of shipboard UAV.