IEE Proceedings-Control Theory & Applications, Vol.144, No.5, 476-480, 1997
Case study comparison of robust linear quadratic design and mixed-sensitivity H infinity control
The aim of the paper is to compare the respective advantages of time-domain robust linear quadratic and frequency-domain H-infinity control laws in the presence of real parametric and frequency-dependent uncertainties. Design-application 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 closed-loop control scheme for linear systems with L-2 bounded uncertainties. For comparison, the frequency-domain mixed-sensitivity H-infinity approach is also examined. To improve its poor parametric robustness owing to the LHP pole-zero cancellation property of H-infinity 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-infinity control synthesis on the basis of game theory.
Keywords:ALGEBRAIC RICCATI EQUATION;OPTIMIZATION