Fixed order robust H2 stability augmentation for Micro air Vehicle — Design and validation

This paper presents a generic design methodology of fixed order robust H₂ controller and onboard computer for Micro air Vehicles. The efficacy of the proposed method is demonstrated by designing a fixed order robust H₂ stability augmentation system for longitudinal dynamics of a Micro air Vehicle, named Sarika-1. Strengthened discrete optimal projection equations, which approximate the first order necessary optimality condition, are used for the controller design. Effect of low frequency gust disturbance and high frequency sensor noise is alleviated through the output sensitivity and control sensitivity minimization. Digital Signal Processor (DSP) based onboard computer named Flight Instrumentation Controller (FIC) is designed to operate under automatic or manual mode. At first, the controller is validated in offline both using linear and nonlinear simulations models. In addition, the robustness of the designed controller is demonstrated using different LMI based robust performance analysis methods. Parametric uncertainties due to modeling errors or due to operating point changes have been considered. Finally, the controller is ported on to the FIC, and subsequently, it is validated through the real-time hardware-in-loop-simulation, (HILS). The responses obtained from the hardware-in-loop-simulation matches well with those obtained from the off-line simulations.