Memory Augmented Neural Network-Based Intelligent Adaptive Fault Tolerant Control for a Class of Launch Vehicles Using Second-Order Disturbance Observer

This paper focuses on the MANN-based intelligent adaptive fault tolerant control for a class of launch vehicles. Firstly, the attitude dynamic model of the launch vehicles suffering from the actuator faults and disturbances has been formulated. Secondly, the second-order disturbance observer has been designed for the launch vehicle to achieve the exact estimation and compensation of the time-varying disturbances. Meanwhile, the MANN has been introduced as online approximator, suppressing the adverse influence of the unknown nonlinearities. Moreover, several adaptive laws have been proposed to achieve the quick response to the actuator faults and the update of the MANN weights. As a result, the MANN-based intelligent adaptive fault tolerant control structure has been constructed for the launch vehicles. It has been proven that all the signals in the closed-loop system are bounded. Simulation results demonstrate the desired performance and the advantages of the proposed control algorithm.

Robust Dual-Channel Disturbance Rejection Attitude Control for a Quadrotor UAV: Theory and Experiment

In this paper, a robust dual-channel disturbance rejection control based on an inner-outer loop control framework is proposed for the attitude control of the quadrotor under modeling uncertainties and unknown disturbances. In the outer loop, a tracking differentiator is introduced to obtain smooth tracking signals and their derivatives. In addition, an outer loop controller is developed with the tracking signals set as the desired signals. In the inner loop, a robust dual-channel disturbance rejection controller based on a sliding mode observer is constructed, which contains an inner disturbance rejection channel (IDRC) and an outer disturbance rejection channel (ODRC). In the IDRC, a disturbance rejection compensator is designed to obtain the disturbance compensation values and to compensate a part of the lumped disturbances in the attitude dynamic model. In the ODRC, an inner loop controller with variable-gain switching terms and constant-gain switching terms is designed, whose switching terms are used to compensate the remaining part of the lumped disturbances in the attitude dynamic model. By using the proposed control scheme, the robustness is guaranteed, and the chattering phenomenon caused by the variable-gain switching terms is greatly reduced. The stability of the proposed scheme is analyzed by using the Lyapunov theory. Finally, the effectiveness is tested by the platform experiments.

Trajectory tracking control for quad-rotor system in the presence of velocity constraint

This article mainly considers the problem of trajectory tracking control problem of quad-rotor system with velocity constrain under the consideration of safety. A model-based nonlinear controller is proposed which can guarantee not only the asymptotical stability for control system but also the velocity under a safe range. Firstly, based on backstepping design, a position tracking controller with velocity constraint is proposed to ensure that the desired position can be tracked with velocity constrains. At the second step, considering attitude subsystem, an attitude controller is proposed to improve the attitude dynamic response performance. Finally, the validity and superiority of the design has been verified in simulation results.