Boundary Control for a Suspension Cable System of a Helicopter With Saturation Nonlinearity Using Backstepping Approach

In this paper, the problems of vibration reduction and trajectory tracking are investigated for a suspension cable system of a helicopter in the presence of input saturation and external disturbances. First, an auxiliary system is proposed to compensate for the error between control input and actuator output which is caused by input saturation. Then, based on the introduced auxiliary system, an adaptive boundary control scheme is proposed to track a desired trajectory and restrain the vibration by using backstepping method. Under the designed control scheme, the uniform ultimate boundedness of closed-loop system is guaranteed. Moreover, the vibration amplitude and the trajectory tracking error will be guaranteed to converge ultimately to a small neighborhood of zero by selecting suitable parameters. The rationality and validity of designed control law is verified by a numerical simulation.