Abstract
This paper introduces a robust dynamic sliding mode control algorithm using a nonlinear disturbance observer for system dynamics. The proposed method is applied to provide a rapid adaptation and strictly robust performance for the attitude and altitude control of unmanned aerial vehicles (UAVs). The procedure of the proposed method consists of two stages. First, a nonlinear disturbance observer is applied to estimate the exogenous perturbation. Second, a robust dynamic sliding mode controller integrated with the estimated values of disturbances is presented by a combination of a proportional–integral–derivative (PID) sliding surface and super twisting technique to compensate for the effect of these perturbations on the system. In addition, the stability of a control system is established by Lyapunov theory. A numerical simulation was performed and compared to recently alternative methods. An excellent tracking performance and superior stability of the attitude and altitude control of UAVs, exhibiting a fast response, good adaptation, and no chattering effect in the simulation results proved the robustness and effectiveness of the proposed method.
Highlights
The effects of undesirable disturbances widely occur in various practical engineering systems and provide an adverse performance to the precise control, and stability of a control system
In [24,25,26,27,28], advanced robust adaptive controllers are introduced to guarantee the stability of attitude and position of unmanned aerial vehicles (UAVs) in the presence of external disturbances and parametric uncertainties based on combining the radial basic function neural network method (RBFNN), integral Sliding Mode Control (SMC), and robust backstepping SMC
The numerical simulation was carried out through several assumptions: (i) the parameters of a quadcopter UAV, initial conditions, controller gains, and desired states are given in Tables 2 and 3; and (ii) the dynamics of attitude and altitude were simultaneously affected by the different exogenous disturbances as follows:
Summary
The effects of undesirable disturbances widely occur in various practical engineering systems and provide an adverse performance to the precise control, and stability of a control system. Disturbance rejection is one of the crucial criteria and important objectives in designing a controller. Many advanced control algorithms to deal with this problem have been proposed in recent years. The existent research can be classified into two groups. Various controllers for a nonlinear system in the presence of disturbances have been introduced by using an adaptive or robust control technique to overcome the effects of these perturbations on the engineering systems. A disturbance observer method is presented to estimate the unknown external disturbances and afterward a robust controller is achieved to compensate for the effect of perturbations on the system
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