基于串级模型预测控制的倾转旋翼机过渡段控制

Transitional State Control of Tilt Rotor Aircraft Based on Cascade Model Predictive Control

针对倾转旋翼机过渡阶段存在的纵垂向控制通道切换问题,基于串级控制框架提出了一种具有自适应权重矩阵的模型预测控制(model predictive control,MPC)策略。首先,通过分析直升机模态和定翼机模态的控制结构差别,构造了兼容全部飞行模态的增广串级控制结构。然后,在确立了倾转旋翼机的模糊建模策略后,设计了MPC目标函数中权重矩阵的参数自适应变化律,从而使内环和外环中高度、前飞速度的跟踪误差惩罚项根据所处模态的不同有着不同的惩罚占比。这样可以使在过渡阶段设计的增广串级控制结构能始终满足时标分离原则。该控制方案将2个飞行模态和过渡阶段的控制纳入一个统一的控制结构中,实现了各飞行模态间的自由切换。仿真结果表明,所提控制方案有良好的控制效果,控制量较为平滑。

Based on the cascade control framework,a model predictive control(MPC)strategy with adaptive weight matrix is proposed to solve the problem of longitudinal and vertical control channel switching in the transition phase of tilt rotor aircraft.Firstly,an augmented cascade control structure compatible with all flight modes is constructed by analyzing the control structure differences between the helicopter mode and the wing mode.Then,after the fuzzy modeling strategy of the tilt rotor aircraft is established,adaptive change law of the parameters of weight matrix for the MPC objective function is designed.Therefore,the tracking error penalty terms of height and forward speed in internal and external loops have different penalty proportions according to the different modes,so the designed augmented cascade control structure can always satisfy the time-scale separation principle in the transition phase.This control scheme incorporates the control of the two flight modes and the transition phase into a unified control structure,and free switching between the flight modes is achieved.The simulation results show that the proposed control scheme has a good control effect and the control variables are smooth.