Modelling and fixed order robust H_∞ control of aerial vehicle: Simulation and experimental results

Purpose - The purpose of this paper is to model a 3DOF helicopter system and to design an adequate robust controller algorithm. This study presents an improved real time H_∞ controller. Design/methodology/approach - The challenge is to control the helicopter dynamics. Given that, disturbance and parametric uncertainties make classical control structure, as PID controller, usually not effective to stabilize this system. On the other hand, robust control is often known by its higher order. Consequently, a fixed-order control design is proposed to reduce the complexity of the standard H_∞ structure. A real time controller is implemented and performed. Findings - A comparative study between a classical PID and fixed-order H_∞ controllers are performed. Simulation and experiment results confirm the capability of this proposed control strategy not only to maintain the system stability in nominal condition but also to counteract the disturbance effect. Research limitations/implications - In prospect, it will be interesting to develop an active fault tolerant control to enhance stability and ensure high performance. Originality/value - This study dealt with modeling and control of a 3DOF Helicopter. The purpose was to find a robust controller able to maintain a robustness against of various uncertainties (measurement errors, external disturbance). To this end, an improved robust H_∞ controller is developed. The new version so-called fixed-order H_∞ controller is able to solve standard H_∞ complexity.