Nonlinear output feedback flight control method for quad-rotor unmanned aerial vehicle

Abstract

The invention discloses a nonlinear output feedback flight control method for a quad-rotor unmanned aerial vehicle. The nonlinear output feedback flight control method for the quad-rotor unmanned aerial vehicle comprises the following steps of: (1) determining a kinematic model of the quad-rotor unmanned aerial vehicle under an inertial coordinate system and a kinematic model of the quad-rotor unmanned aerial vehicle under a body coordinate system; (2) designing an attitude control system of the quad-rotor unmanned aerial vehicle; defining tracking errors of the attitude angle and the angular speed of the quad-rotor unmanned aerial vehicle; designing a filter to perform online estimation on an angular speed signal and obtain an open loop dynamic equation of the tracking errors; and estimating unknown functions in the open loop dynamic equation by adopting neural network feedforward, and designing attitude system control output of the quad-rotor unmanned aerial vehicle; and (3) designing a height control subsystem of the quad-rotor unmanned aerial vehicle; defining height tracking errors and defining auxiliary filtering tracking errors; and designing a height subsystem controller. According to the nonlinear output feedback flight control method for the quad-rotor unmanned aerial vehicle disclosed by the invention, the polarity problem is effectively avoided, a wide-range stable control effect is achieved, the robust performance of the system is greatly improved, and the dependence of a flight controller on an airborne sensor is greatly reduced.

Description

technical field [0001] The invention relates to attitude control of a quadrotor unmanned aerial vehicle. In particular, it relates to a non-linear output feedback flight control method for a quadrotor unmanned aerial vehicle. Background technique [0002] In recent years, with the development of material technology, microprocessor technology and sensor technology, quadrotor unmanned aerial vehicles have attracted extensive attention from military and civilian circles. Due to its small size, light weight, vertical take-off and landing, and precise hovering, quadrotor UAVs are widely used in fire monitoring, emergency response, and indoor investigation. The four-rotor unmanned aerial vehicle adopts a symmetrical structure and is equipped with four propellers with fixed angles of attack. By adjusting the speed of the propellers, the displacement and attitude angle in three directions can be changed. Reliable attitude and altitude control can ensure the safe flight of the quad...

AI Technical Summary

Problems solved by technology

Since the power of the quadrotor unmanned aerial vehicle is a nonlinear system, which is not applicable to the principle of separation, the design and stability of the observer are very difficult to prove, and it is difficult to achieve the control effect of asymptotic tracking

[0004] Based on the above analysis, it can be found that the main problems faced by the design of the attitude controller of the quadrotor UAV include: the polarity problem of the traditional Euler angle attitude description method, and the difficulty of accurately measuring the state of the entire system of the aircraft

First, the nonlinear resistance and resistance moment experienced by the aircraft during flight, these nonlinear functions are related to the linear velocity and angular velocity of the aircraft during flight, but it is difficult to accurately model them

Second, there are parameter uncertainties in the dynamic model of the quadrotor unmanned aerial vehicle. Since the load of the quadrotor unmanned aerial vehicle is different in each flight, this change will lead to changes in the mass and moment of inertia of the aircraft. Moreover, it is difficult to accurately identify the aerodynamic damping parameters in the aircraft dynamics model

Third, the aircraft is susceptible to external disturbances such as wind, system noise, and ground effects during flight, and these disturbance terms further increase the uncertainty of the system

Obviously, this method can only realize the control of attitude, and cannot track and control the height at the same time

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