Research On Quad Rotor Helicopter Control System For Bridge Inspection

With continuously development and maturity of aerospace technology, theUnmanned Aerial Vehicle (UAV) has become one of the most important directions ofspace field in the world. Among them, quadrotor helicopter not only owns advantagesof low manufacturing cost with unmanned aircraft systems, less harm for operator whileperforming the task but also excellent maneuverability and flexibility. It needs lessspace for launching and landing and has a strong controllability while encounteringintensive obstacles. Moreover, with high advantage of keeping attitude, quadrotorhelicopter has gradually become a hotspot in miniature unmanned aerial vehicle (UAV)researching.In this paper, based on application of four rotor aircraft in bridge detection, somekey technologies of four rotor aircraft are proposed, which involves mathematical model,hardware design, PN code location algorithm and altitude evaluation algorithm,etc. Themain contents are as follows:(1) Quadrotor helicopter dynamic model is built according to flying structureanalysis and working principle.(2) In view of quadrotor helicopter used in the brige inspection, the paperintroduces the components of the helicopter and their main functions.(3) Since it is decided by rapid evaluation to achieve flying stability, a attitudeestimation system based on catadioptric system, Extended Kalman Filter and InertialMeasurement Unit are introduced. The three controllers are combined together to formmulti-threaded concurrent processing and collaboration, and can obtain quadrotorhelicopter attitude information, and which makes the helicopter flight fast and stably.(4) In this paper, accuracy quadrotor helicopter location algorithm-PN(Pseudo-random Noise) algorithm is proposed. PN code electromagnetic waves are sentsimultaneously using three anchor nodes. Receiver in quadrotor helicopter then receivesthe electromagnetic waves. The phase error of the three electromagnetic waves isobtained by enlargement and demodulation. Therefore the distance between thequadrotor helicopter and anchor nodes, also the accuracy location of the quarotor can becalculated by geometric calculation. (5) Both inside and outside circuit of quadrotor helicopter, including attitudecontrol loop and the position control loop, are built by using PID controller. The circuitsare simulated in MATLAB environment.(6) The system is built by adopting embedded control technology. High quality andlow cost ARM processors of STM32family, which is dedicated designed to performdigital signal process, is selected as main controller.By building hardware platform ofquadrotor helicopter，flying tests are performed. The tests verify Extended KalmanFilter, accuracy location algorithm and PID controlling algorithm.