Robust H∞H∞ attitude control of a laboratory helicopter

• Tracking control performances of the 3-DOF laboratory helicopter is improved.
• The model is considered as a linear system with equivalent disturbances.
• Equivalent disturbances contain various uncertainties.
• A robust compensator is introduced to restrain effects of equivalent disturbances.
• Experiments demonstrate the improved performances of the proposed control strategy.

This paper deals with the attitude tracking control problem for a three degree-of-freedom laboratory helicopter, which aims to improve tracking control performances of elevation and pitch channels. The model of each channel is considered as a linear system with equivalent disturbances which contain nonlinear uncertainties, coupling effects, parameter perturbations, and external disturbances. A state-feedback H∞H∞ controller is applied to the linear model and a robust compensator is introduced to restrain the effects of equivalent disturbances. The robust properties of the closed-loop control system with the proposed controller are shown better than the standard H∞H∞ controller. Experimental results demonstrate the improved performances of the proposed control strategy.