Attitude Measurement For Quadrotor Based On ASCKF

Due to the rapid development of electronic technology and the progress of production technology,the micro-attitude sensor technology required by the quadrotor UAV has been mature.It makes the rotorcraft UAV with simple structure,vertical takeoff and landing,easy operation and low cost widely used in civil and military fields.Attitude system is an indispensable part of UAV system.In order to bring the UAV to the market,the first thing is to ensure its safe,stable and reliable flight,and the attitude information can be obtained through the attitude sensor,thus making the UAV easier to control and complete the assigned tasks.Accelerometers,magnetometers,and gyroscopes measure the three-axis acceleration,geomagnetism,and angular velocity components of the current UAV's body coordinate system.Through the information of the accelerometer,we can calculate the pitch angle and the roll angle,and then the output information of the magnetometer can obtain the yaw angle of the drone.Three attitude angles are also available through the gyroscope information.However,the attitude angle error obtained by a single sensor is often too large.It is now common practice to fuse data from multiple sensors,and this approach often results in a more accurate attitude angle.In this paper,the adaptive square root cubature Kalman filter method is applied to the attitude calculation of quadrotor UAV.The main work of this paper is as follows:Firstly,the development process and research status of the rotorcraft UAV are introduced,and the research status of the attitude calculation method is explained.The structure,flight principle and common coordinate system of the quadrotor UAV are introduced in detail.The two methods of the UAV attitude description are described in detail by the Euler angle representation and the quaternion representation.The work of this piece is mainly to explain the basic knowledge of the quadrotor UAV.Secondly,this paper introduces the attitude sensor required for the attitude calculation of the quadrotor UAV.The basic working principle,the error model and the derivation of the single sensor attitude angle solving process are described in detail.The cubature Kalman filter algorithm is introduced emphatically.The third-order spherical-radial cubature criterion is expounded in principle,and the formula of the cubature Kalman filter algorithm is deduced in detail.Finally,aiming at the problems existing in the traditional kalman filtering algorithm,this paper adds the square root technique and the adaptive algorithm on the basis of the cubature kalman filtering to form the adaptive square root cubature kalman filtering algorithm.The large error caused by linearization of extended kalman filter and positive qualitative loss of unscented Kalman filter,cubature Kalman filter covariance matrix are solved.A nonlinear mathematical model is established for the attitude calculation of the UAV,and the adaptive square root cubature Kalman filter algorithm is described in detail.The turntable experiment and actual flight experiment based on pixhawk flight control board are designed.The experimental data show that the proposed algorithm has the highest filtering accuracy compared with traditional EKF,UKF,CKF and SCKF.In the filtering time,the algorithm is close to SCKF,and has a greater advantage than CKF and UKF.