Research On The Quad-Rotor UAV Flight Attitude Measurement Algorithms

The quad-rotor is a kind of vertical take-off and landing aircraft. The quad-rotor is equipped with four rotors to have a capability of omni-direction movements as well as a stable hovering posture in the air. The capability of stable hovering posture allows many possible applications in practice including typical surveillance and monitoring tasks. The quad-rotor is a under actuated system with six degrees of freedom and four drivers and strong coupling system with four rotors distributing in cruciform structure symmetrically and uniformly. The flight attitude can be controlled by the variant rotor of changing the lift force.In this article, on the basis of the unique mechanical structure and flight principle of the micro quad-rotor UAV, New-Euler equation is used to establish the nonlinear dynamic equation in order to improve its flight performance and control stability.On the basis of the theory, in our design, the STM32F103RBT6, a kind of MCU from the STMicroelectronics NV, is used to be the main control chip. In order to get the flight attitude, we get dates from the gyroscope, compass, accelerometer and then sent them to the Quaternion Converter. To get the flight geographical coordinates, we should get dates from the GPS and the barometer.By means of control the attitude of the quad-rotor by the PID controller, the aircraft can fly in the air stable.Axis UAV software algorithms mainly by the accelerometer calibration, posture and attitude control calculated three components. This article take the least squares method calibration accelerometer. Sampling and analysis of its correction effect, got the error ratio. Through theoretical analysis and experimental data analysis, comparison of the attitude interpolation method, gradient descent method, advantages and disadvantages of complementary filtering method, and choose complementary filtering method solver axis UAV attitude. UAV performed axis attitude control method using the Euler angles and quaternion.Finally,RVMDK compiler of C language programming algorithm.