Mixed H∞/H2 decoupling control of the aircraft lateral-directional axis during powered approach

There is an inherent coupling between roll rate and sideslip during powered approach phase. The notion of sideslip is opposite to the sign of roll rate in low angle of attack scenarios. The proverse will degenerate the handling quality and decentralize the energy of pilot for line up during powered approach. In the current work, the mixed H_∞/H₂ LPV approach is presented to solve aircraft lateral-directional axis decoupling control during powered approach. H₂ can guarantee the performance of the closed-loop system with respect to the disturbance and reduce the coupling between different channels, and make the aircraft handling quality achieve the desired handling quality and reduce the workload of the pilots. The aircraft model is linearized at different operating points to obtain an LPV open model, whose state-space entries depend on angle of attack which is a time-varying parameter and is able to be measured in real time. Besides, the closed-loop system performance can be further improved by employing the switching control theory of piecewise multi-Lyapunov functions.