Research On Reliability Enhancement For Navigation And Control System Of Rotorcraft

With the development of robotics technology,the application of aerial robots is becoming widespread.Rotorcraft is a highly flexible platform of aerial robots,which attracts more and more attention.Therefore,the flight performance of rotorcraft is demanding.The key criteria to evaluate the flight performance of the rotorcraft is the accuracy and stability of the flight controller,the flight reliability and anti-jamming capability of the Unmanned Aerial Vehicle(UAV).For the rotorcraft in complex environment,its flight reliability is mainly associated with the ability of rotorcraft to adapt to the environment.When the rotorcraft is in dynamic condition and the UAV is disturbed by uncertain wind,if the response ability of the controller is insufficient,it will inevitably cause the divergence of the controller.Therefore,this thesis mainly studies how to enhance the reliability of UAV when it is in dynamic condition,focusing on the methods to improve the fast response performance of the controller.The main contributions of this thesis are:1)Performance analysis of rotorcraft navigation sensor.The characteristics of different navigation sensors are analyzed,based on the comparison on sensor's merits and demerits,and comparison on their measurement noise,and a rational fusion filter is modeled.2)Research on fast response method of rotorcraft flight control system.A time synchronization errors compensation method for a 6DOF motion estimation method with integration of multi-sensors is proposed.The effect of time synchronization errors,on attitude and position estimation,is analyzed by theoretical derivation and simulation.Based on this analysis,a fusion algorithm which can estimate the 6DOF motion and time synchronization errors simultaneously is presented.This algorithm includes a time-alignment-lock feedback in the closed loop to improve the estimation precision.Furthermore,to improve the convergence of this algorithm,a calibration method for a rough time alignment is discussed.The estimation algorithm is implemented in an embedded microprocessor,and therefore high-performance computational units are not necessary.These estimates serve as the navigation solution for a small rotorcraft.The accuracy and reliability of the designed system are tested under flight experiments with different intentional delays added to the initial GPS receiver output.3)Optimal design of controller based on neural network.For the controller reliability,a method for tuning controller parameters for cascade controller with application to rotorcraft is proposed.With specifically designed system identification procedures,a neural network mapping is obtained automatically when the UAV is flying around the target height.With this network system model,a gradual regression and optimization algorithm is proposed to tune the controller.The regression model primly illustrated the relation between controller parameters with controller performance,and the construction for optimization cost function takes the physical significance of step response performance of flying machine into account.4)Flight test verification of rotorcraft.A practical UAV navigation control system hardware is developed.Experimental data collected from fight experiment when auto-tuner is implemented on a self-developed quad-rotorcraft demonstrates the efficiency of the proposed methods.