Horizontal Path-following Control Based on ESO for Parafoil Systems with Error Constraint

This paper investigates the problem of horizontal path-following control for parafoil systems with error constraint. Frist, by introducing the guidance theory, the horizontal position control is converted to the control of the azimuth angle of the parafoil system. The error signal of the angle is transformed to a new error variable, such that the error is constrained into the prescribed boundaries. Next, the methods of backstepping and output feedback are employed in the controller design. The uncertainties in parafoil system modeling and external disturbances are estimated using the lineaer extended state observer (LESO). The stability analysis based on Lyapunov method shows that all the error signals are uniformly ultimately bounded. Simulation results of a 6 degree-of-freedom parafoil system illustrate the effectiveness of the proposed method.