Research On Spatial Drift Suppression Of Quadrotor

Because the quadrotor equipped with gyroscopes,accelerometers,magnetometer,pressure gauge and GPS can't obtain enough accurate position information,so the quadrotor's spatial drift in the horizontal and vertical direction of the geodetic coordinate system is too large,so the aircrafts can not be applied to areas such as low altitude(6m below)trajectory planning and indoor flight and other high requirements area.In order to make the four rotor aircraft suitable for the fields above,it has great significance to study how to control its spatial drift.In order to effectively control the spatial drift of quadrotor,this article first optimized PID control of altitude,then combined the measurement of the pressure gauge and the ultrasonic sensor with the improved Kalman filter algorithm for obtaining more accurate height data and introduced the data into the feedback loop of altitude PID control,then obtained the algorithm of control vertical drift;after that we optimized double loop PID control of attitude,obtain accurate horizontal velocity of aircraft with the optical module which loaded PryLK optical flow algorithm,the module will be introduced to the inner loop of the PID attitude control to speed up the inner regulation time and obtained the horizontal drift algorithm.Finally,integrated the optimized PID altitude control algorithm and the optimized double loop PID attitude control algorithm through the FreeRTOS algorithm,with jobs done above,we got an algorithm for suppression of aircraft's spatial drift.Through the results of simulation and test that using the algorithm of control horizontal and vertical drift shows us:1)The original height PID control has a 0.89 m drift in vertical direction,the quadrotor controlled by original double loop PID algorithm has a vary range of horizontal velocity in ?0.28m/s to 0.20m/s and a large horizontal drift;2)The height PID control,optimized by the improved Kalman filter algorithm,compared with the PID control optimized by original Kalman filtering algorithm,can further reduce the vertical drift of the quadrotor and improves the convergence rate of the algorithm.3)The double loop PID attitude control based on the improved PryLK optical flow algorithm compared with the PID control based on the original PryLK optical flow algorithm,the double loop PID attitude control can further reduces the horizontal drift of the quadrotor and reduces the calculating time of the algorithm.4)Although the control for spatial drift of the quadrotor doesn't have the performance as good as the algorithm that only control the vertical drift or horizontal drift,but the algorithm reduced the vertical drift of quadrotor to 0.5m,and the horizontal velocity variation range is reduced to 0.12m/s-0.11m/s,in other words,the algorithm reduces the spatial drift of quadrotor.