Research On Flight Control Technology For Unmanned Helicopter Based On Vision

With a wide application foreground in both military and civil field, more and more attention focuses on the development of the Unmanned Helicopter (UH). At the same time, with the technology development of computer vision technology, many institutions at home and abroad carry out the research on combining visual servoing control with UH flight control. In this dissertation, based on present research results, UH flight control technology based on vision is studied.First of all, to achieve the UH flight control based on visual servoing, control system structure is designed. By selecting the number and installation methods of Charge Coupled Device (CCD), image acquisition and processing is carried out. Based on the feature of visual servoing control, the overall control scheme of UH control is given, and then control technology is analyzed.Then, MIT's X-cell 60 Miniature Unmanned Helicopter (MUH) is chosen as research platform. With analysis of the rotor dynamics, aerodynamic forces and moments, and based on the characteristic of hovering and low translational speed flight dynamic, MUH dynamic model is regarded as body dynamic model combined with rotor dynamic model. Also, a six-degree-of-freedom nonlinear predigestion model is developed and the open-loop simulation is given based on VC++6.0.Following, to get the path information, image processing methods are given. Path is separated from background by threshold segmentation method, in which noise is elimated by smoothing, and images of path boundary are achieved by edge detection. Based on Hough transform method, the equations of boundary, centerline of path and yaw angle are obtained.Finally, flight controller for UH tracking trajectory is investigated. Based on linear model, by station feedback method, the attitude controller is designed. Using the nonlinear model, backstepping method is proposed to design the altittude controller and the simulation is given. On this basis, cascade controller is proposed to control the attitude and locations of UH, and simulation is given by combining the image information with control system.