Case study comparison of robust linear quadratic design and mixed-sensitivity H∞ control

The aim of the paper is to compare the respective advantages of time-domain robust linear quadratic and frequency-domain H, control laws in the presencc of real parametric and frequency-dependent uncertainties. Designapplication considerations for each method are also offered. For the time-domain design, the LQL method is used, which is a minimax robust state estimation maximin state feedback closedloop control scheme for linear systems with L2 bounded uncertainties. For comparison, the freq uency-domain mixed-sensitivity H, approach is also examined. To improve its poor parametric robustness owing to the LHP pole-zero cancellation property of H, controllers, increasing system bandwidth and inner-loop feedback enhancing the damping are applied simultaneously. The context of this design comparison is the HIT-3T2 flight simulator. The simulation results, once again, reveal the close relationship of LQL and H, control synthesis on the basis of game theory.