Research On Intelligent Control Theory Of Quadcopter

Quadcopter,a kind of VTOL vehicle,has a simple structure and is easy to be driven.So it is widely used in aerial photography,surveying,agriculture,etc.The research contents based on quadcopter are as follows.The mathematical model of quadcopter was built by mechanism modeling method,including motor model,body model and driven distribution model.By simplifing the mathematical model reasonably and linearizing it at hovering point,the attitude and attitude angle transfer function as well as two key parameters that influence vehicle's performance were achieved.To get the attitude of quadcopter,we adopted complementary filtering algorithm to combine accelerometers and gyroscopes,including gravity component extraction,complementary filtering,solving quaternion differential equation and the transformation between quaternion and euler angles.The experiments confirmed the effects of vibration on inertial sensors.The quadcopter's attitude was controlled by double-loop PID,and the angular rate control model was transferred into second order optimal control system by the method of pole assignment.We put forward the concept of attitude sensitivity and basic sensitivity by calculating the control law.So the controller can be adapted to different size of quadcopter and users can adjust the parameters very easily without worrying about crash.The coordinated turn and gravity compensation model was built to improve the mobility of the quadcopter.According to the operator's habit,the hovering algorithm,including head mode and headless mode,was presented,which can make the quadcopter's moving speed be proportional to the rudder during movement and the quadcopter hover when the rudder is zero.On the basis of hovering algorithm,linear tracking algorithm and curve tracking algorithm were proposed and simulated in matlab.Finally,we designed the circuit of flight controller based on STM32 MCU,including power management,IMU sensor,external flash,status indicators and communications ports.We tested the attitude control mode,hovering mode and route mode.The test results showed that the quadcopter's attitude has fast response and high hover precision,and can fly straight route very well.