The performance and robustness of a classical multivariable controller and one H∞
compensator are assessed on a model rotor rig. Both control schemes are subjected to sinusoidal and step input tests in the pitch and roll axes under a range of operating conditions and configurations. A brief description of the characteristics of the rotor mathematical model is provided, followed by a summary of the design assessment criteria. Following a description of the two control law design techniques, the performance of each controller is verified on the mathematical model prior to evaluation on the rotor rig. In absolute terms, there is a poor correlation between the simulated and experimental values of the design assessment criteria for both controllers. However, in relative terms, the H∞
control law achieves higher levels of damping and lower cross-couplings than the classical scheme although the measured improvements are not as substantial as predicted. In experimental frequency response tests at increasing advance ratios and various rotorspeeds, the H∞
scheme again consistently achieves the lowest levels of cross-coupling. In summary, the results show that although there are practical performance and robustness benefits to be gained by employing more complex control algorithms, model uncertainty will substantially reduce the predicted benefits.