Nonlinear Control Research Of Quad-Rotor UAV

Quad-rotor UAV is a kind of rotary wing UAV with excellent performance. Compared with conventional fixed-wing UAV, quad-rotor UAV possesses many advantages, such as simple mechanical structure capability of vertical take-off and landing(VTOL), good security, capability of inverted fly, side fly, etc. It has wide application prospects in military, civil and so on. This paper uses a quad-rotor UAV as research object, while study the whole scheme design of UAV, nonlinear modeling, nonlinear control algorithm design, attitude measurement and other issues.Firstly, according to the specific design requirements of our research group, after considering the whole design schemes of its airframe, hardware selection and software design, we design a quad-rotor UAV flight test platform. Here, the whole airframe design is analyzed from the points of mechanical requirements, control performance and mission requirements. And the selection of each module is based on the principles of light and flexible. As for the software design, an overall software process on quad-rotor UAV is designed, and initialization, sensor data acquisition, safety test is designed further.Secondly, the mathematical model for micro quad-rotor UAV is established, and its control system is designed. The nonlinear dynamic model of quad-rotor UAV is built based on UAV’s flight theory and spatial rigid motion equation, combined with specific object of UAV. For the quad-rotor UAV, it is very difficult to establish a precise model, so active disturbances rejection control (ADRC) method is used, at the same time, taking into account the specific form of the model in the attitude links, the ADRC interference decoupling controller on roll, pitch and yaw channel are designed. And then use simulations to verify the performance of the controllers.Finally, taking into account the existence of a large measurement error induced by sensor module, an attitude measurement system is designed to improve the overall performance of the UAV sensor module. Based on the analysis of the causes of errors in measuring sensor, combines with the gyro, accelerometer and magnetic sensor measurement characteristics to fuse multi-sensor measurement information,and use Iterated Extended Kalman Filter (IEKF) algorithm to design quad-rotor UAV attitude measurement system. The effectiveness of the design is verified through experiments.