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This paper proposes two different adaptive robust sliding mode controllers for attitude, altitude and position control of a quadrotor. Firstly, it proposes a backstepping non-singular terminal sliding mode control with an adaptive algorithm that is applied to the quadrotor for free chattering, finite time convergence and robust aims. In this control scheme instead of regular control input, the derivative of the control input is achieved from a non-singular terminal second-layer sliding surface. An adaptive tuning method is utilized to deal with the external disturbances whose upper bounds are not required to be known in advance in the inner loop. Secondly, a nonlinear disturbance observer based on the integral sliding mode with adaptive gains is proposed for position control, which is known as the outer loop. Stability and robustness of the proposed controller are proved by using the classical Lyapunov criterion. The simulation results demonstrate the validation of the proposed control scheme.

In this paper, a solution for the problem of uncertainty presence in the estimated position of a target is indicated. The dynamic error of ground moving target tracking with special unknown bounded uncertainty has been described. To solve this problem, a class of the second-order sliding mode has been proposed. In order to increase the robustness of the proposed controller against unknown uncertainty, a set of adaptive rules has been added to the guidance law. New adaptive terms have been used to estimate the higher unknown bound of the uncertainty. The offered method, based on the sliding mode strategy, has reduced the chattering phenomena, which is harmful for the production of the command states. Finally, a fast adaptive guidance law has been added and its stability has been proved by the Lyapunov criterion. The designed adaptive fast guidance law improves the classical sliding mode control guidance law. Various simulations and comparison studies have been applied to verify the efficiency of the modified guidance law despite the disturbance and uncertainty. The results show that the uncertain terms have been compensated and the tracking position has been satisfied accurately.

This paper proposes two different adaptive robust sliding mode controllers for attitude, altitude and position control of a quadrotor. First it proposes a backstepping non-singular terminal sliding mode control with adaptive algorithm which applied to the quadrotor for free chattering, finite time convergences and robust aims. In this control scheme instead of regular control input, the derivative of the control input is achieved from non-singular terminal second-layer sliding surface. And an adaptive tuning method is utilized to deal with the external disturbances whose upper bounds are not required to be known in advance in the inner loop. Second nonlinear disturbance observer based on integral sliding mode with adaptive gains is proposed for position control which is known as outer loop. Stability and robustness of the proposed controller are proved by using the classical Lyapunov criterion. The simulation results demonstrate the validation of the proposed control scheme.

This paper considers the output tracking problem for micro-electro-mechanical systems (MEMS) under uncertainties and external disturbances. The robust non-linear controllers are designed by two methods. The first method consists of a backstepping strategy combined with a first-order sliding mode controller. Also, in order to reduce the chattering effect and to improve the robustness of the proposed scheme, a new variable universe fuzzy control action with an adaptive coefficient is used instead of the signum function in the switching control law. In the proposed fuzzy scheme, the centres of the output membership functions are optimized via three heuristic optimization algorithms including the artificial bee colony (ABC) algorithm, ant colony optimization (ACO) and particle swarm optimization (PSO). In the second method, a class of second-order sliding mode controller is combined with the backstepping strategy. The second controller includes the proposed optimal fuzzy controllers of the first method. The stability of the closed-loop systems in both approaches are proved via the Lyapunov stability criterion and the conditions of stabilization are provided by linear matrix inequalities (LMIs). Numerical simulations are carried out to verify the theoretical results and to demonstrate the robust performance of the proposed controller in output tracking of the time-varying reference signal.