模型不确定和未知扰动下四旋翼无人机位置与姿态控制

Position and Attitude Control of Quadrotor UAV with Model Uncertainties and Unknown Disturbances

在模型不确定和未知扰动下,针对由六个自由度组成的四旋翼无人机控制问题,提出一种自适应滑模控制方法,该方法能实现位置与姿态跟踪控制。首先,根据四旋翼无人机动力学系统,将其分为全驱动、欠驱动子系统,充分考虑无上下限约束的模型不确定和未知扰动,提炼出各子系统的集合干扰项;然后,借助于径向基函数神经网络对包含集合干扰项的等效控制器进行实时逼近和估计,同时运用自适应控制方法估计逼近误差项,设计带有等效控制器和逼近误差项估计值的滑模控制器和对应的自适应更新律,并根据Lyapunov理论,对各子系统状态轨迹所在滑模面的可达性及其收敛性进行了分析说明;最后,所提方法的有效性通过对比仿真得到了验证。

An adaptive sliding mode control method is proposed for the control problem of a quadrotor UAV composed of six degrees of freedom under model uncertainties and unknown disturbances.This method can be used to realize position and attitude tracking control of quadrotor UAV.Firstly,based on the dynamics quadrotor system,the fully actuated and under-actuated subsystems are divided.The model uncertainties and unknown disturbances without upper and lower limit constraints are fully considered,and the lumped disturbance terms of each subsystem are extracted;Then,with the help of radial basis function neural network,the real-time approximation and estimation of the equivalent controller containing the extracted lumped disturbance terms are inplemented in progress.At the same time,adaptive control method is used to estimate the approximation error term.The sliding mode controller with the estimated values of the equivalent controller and approximation error terms and the corresponding adaptive update laws are designed.Based on Lyapunov theory,the reachability and convergence of the sliding mode surface where the state trajectories of each subsystem lies are analyzed and introduced.Finally,the comparative simulations are used to verify the effectiveness of the proposed method fairly well.