With the increasingly wide application range of rotorcraft and the rapid development of computer vision technology and artificial intelligence technology,more and more experts and scholars combine research on rotorcraft as a carrier with artificial intelligence technology.As a key technology of aircraft intelligence,the visual landing technology of aircraft has received extensive attention.How to make the aircraft land at the designated position more accurately needs to be further studied.In this paper,the four-rotor aircraft is selected as the research object,and the whole process of visual landing of aircraft is deeply studied,including the design of landmark and corresponding recognition algorithm,the research of aircraft pose estimation method,and the control of landing process,etc.,in order to improve the accuracy of fixed-point landing of aircraft,the specific work is as follows:Firstly,a cooperative landmark with two features is proposed,and the corresponding recognition algorithms are designed based on the two features respectively.Then,the detection results are fitted to obtain the coordinates of feature points,which provides data guarantee for the relative position of the center of mass of aircraft and the landmark center.Secondly,according to the characteristics of landmarks,a two-stage pose estimation method was designed to solve the problem that traditional landmarks could not provide yaw attitude reference for aircraft.The estimation result is taken as the input of the control system in the landing process,and the landing process is controlled by the position controller based on the semi-autonomous pilot,so as to ensure the stability of the aircraft in the landing process.Finally,experimental verification is carried out,including simulation verification and real machine verification.Firstly,the simulation experiment is carried out,and the numerical simulation of the feature extraction algorithm and the control system is carried out.The experimental results show that the system scheme has certain feasibility and stability.Secondly,the real machine verification was carried out.The landing test was completed by setting up the development environment,and the system scheme was verified by calculating the deviation between the landing site and the landmark center.The results show that the maximum error in the direction of X axis is 9.2cm,and the maximum error in the direction of Y axis is 7.5cm,which meets the requirement of the aircraft visual landing position error within 10cm in this paper,and realizes the four-rotor accurate landing function based on visual information. |