Multi-Variable Integral Sliding Mode Control of a Two Degrees of Freedom Helicopter

In this paper, a multi-variable nonlinear control-oriented model of a twin rotor aerodynamic system (TRAS) is presented. The mathematical description of the multibody system is derived using Lagrange's equations. Based on the resulting state-space representation, a multi-variable integral sliding mode control is designed to accurately track desired trajectories for both the azimuth angle and the pitch angle. Due to unmeasurable states and uncertainties stemming from simplifications at modelling as well as disturbance torques, a discrete-time extended Kalman filter (EKF) is employed and combined with a discrete-time implementation of the nonlinear control law. The proposed control strategy allows for an excellent tracking behaviour as highlighted by experimental results. (C) 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.