No abstract

No abstract

A tilt-rotor has a rotor on each side of its airframe and each rotor can be tilted to provide lift or thrust. With the tilt on rotors, the model of tilt-rotor has a significant change. Conventional control methods based on linearized model need extensive gain scheduling with the nacelle angle and flight condition. In order to alleviate this requirement, a design of attitude control based on ESO(Extended State Observer) is developed. The kernel of this method is the estimation and compensation of the disturbance on model. The disturbance includes the model error and coupling between different channels. By the compensation of the disturbance, the controller achieves the decoupling of the system and the compensation of model error and other disturbance at the same time. This control architecture is based on the nonlinear model of the aircraft and the parameters of the controller are available in wide ranges. Nonlinear feedback law is designed for outer loop controller to guarantee the dynamic performances. Simulation results in different flight conditions show that the design of attitude control is feasible. Key Words: tilt-rotor aircraft, aircraft model, extended state observer, attitude control 852 978-1-4799-7016-2/15/$31.00 c 2015 IEEE

To efficaciously eliminate the effect of chattering caused by parametric uncertainties and external disturbances on attitude tracking control of missile systems, a chattering-free backstepping sliding mode controller based on parameters online adjusting and square of disturbance upper bound estimating is proposed in this paper for the quaternion-described missile model, which is nonlinear in aerodynamics. The controller comprises the back stepping sliding mode strategy and several adaptive laws. First, one adaptive law is applied to adjust the uncertain parameters, involving inertias, atmospheric moment coefficients, and steering efficiencies online, which reduces the upper bound of the equivalent disturbances. Then, another adaptive law, estimating square of the disturbance upper bound, is introduced. Combining with the backstepping sliding mode controller, the expected missile attitude can be tracked asymptotically. Compared with other missile attitude controllers, key innovation of the proposed control laws are that the controller is based on the novel online adjusting model rather than the conventional fixed-parameter reference model and square of disturbance upper bound is estimated rather than the upper bound itself, which thoroughly abstains the chattering problem. Simulation results of a specific missile model demonstrate that the proposed controller is independent of the parametric uncertainties and can achieve a fast convergence rate without any chattering.