An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle (VSNSV) in the presence of uncertainties and disturbances. The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online. To improve the flight robust performance, robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation. Moreover, a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control (DSC) approach. According to the common Lyapunov function theory, it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller. The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.
针对变后掠翼近空间飞行器(near space vehicle,NSV)在大包络、多任务模式飞行运动过程中具有非线性、快时变、强耦合和不确定的特性,提出了基于径向基神经网络(radialbasis function neural network,RBFNN)的鲁棒自适应跟踪控制策略。首先,利用RBFNN在线逼近NSV飞行过程中外部干扰。其次,应用backstepping设计光滑的反馈控制器。其中,采用微分器避免backstepping设计中出现微分膨胀问题,利用鲁棒项减少RBFNN估计误差对系统的影响。然后,通过公共Lyapunov函数证明所提出的控制器可以保证在任意飞行模态中NSV的输出跟踪误差均可以收敛到任意小的有界集内。最后,仿真结果表明该飞控系统具有良好的控制性能。
In order to improve weapon assignment(WA)accuracy in real scenario,an artificial neural network(ANN)model is built to calculate real-time weapon kill probabilities.Considering the WA characteristic,each input representing one assessment index should be normalized properly.Therefore,the modified WA model is oriented from constant value to dynamic computation.Then an improved invasive weed optimization algorithm is applied to solve the WA problem.During search process,local search is used to improve the initial population,and seed reproduction is redefined to guarantee the mutation from multipoint to single point.In addition,the idea of vaccination and immune selection in biology is added into optimization process.Finally,simulation results verify the model′s rationality and effectiveness of the proposed algorithm.
