scholarly journals A tracking controller design with preview action for a class of nonlinear Lur'e systems with time-varying delays and external disturbances

Kybernetika ◽  
2021 ◽  
pp. 78-101
Author(s):  
Xiao Yu ◽  
Fucheng Liao
Keyword(s):  
Controller Design ◽  
Time Varying ◽  
External Disturbances ◽  
Lur’E Systems ◽  
Tracking Controller

Inertia-free nonlinear attitude tracking with disturbance compensation using adaptive-sliding control based on quaternion algebra

SIMULATION ◽  
2019 ◽  
Vol 96 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Mohammadreza Alipour ◽  
Farhad Fani Saberi ◽  
Mansour Kabganian
Keyword(s):  
Quaternion Algebra ◽  
Controller Design ◽  
Sliding Mode ◽  
Control Variable ◽  
Three Dimensions ◽  
Time Varying ◽  
Mathematical Operation ◽  
External Disturbances ◽  
Actuator Dynamics ◽  
Attitude Tracking

The main objective of this paper is to develop and simulate a nonlinear attitude tracking control algorithm. In this research, the designed controller is supposed to track the desired time varying attitude of a satellite in the presence of inertia uncertainties and external disturbances. Another restriction for this novel controller is that it should be implementable and more applicable for implementation in a real-time situation. In order to have an accurate and thorough model, the actuators are reaction wheels and the actuator dynamics are modeled in addition to spacecraft dynamics. By modeling actuator dynamics, the control signal is direct current motor voltage, which is the most fundamental control variable, and can be generated easily by a motor driver in practical cases. To achieve a robust tracking of the desired time varying attitude, a sliding mode controller is designed and adaptive techniques are developed based on sliding mode control to overcome the inertia uncertainties and to estimate and compensate for external disturbances. Since the quaternion illustration of equations makes it more straightforward to deal with the mathematical operation in three dimensions, and there are advantages such as singularity rejection, the kinematic equations of the satellite are parameterized using quaternion parameters and a novel control law will be derived by using a new facilitating approach to controller design, which is based on quaternion algebra. Using this approach, it will be easier to deal with tedious mathematical operations and, in contrast with most of the previous studies, the terms corresponding to derivatives of the desired attitude are not neglected and the tracking capability is retained. The global stability of both methods is investigated and proved using the Lyapunov stability theorem.

scholarly journals New Time-Varying Sliding Surface for Switching Type Quasi-Sliding Mode Control

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3811
Author(s):  
Katarzyna Adamiak ◽  
Andrzej Bartoszewicz
Keyword(s):  
Sliding Mode Control ◽  
Continuous Time ◽  
Sliding Mode ◽  
Representative Point ◽  
Time Varying ◽  
Sliding Surface ◽  
External Disturbances ◽  
Mode Control ◽  
Switching Type ◽  
Time Systems

This study considers the problem of energetical efficiency in switching type sliding mode control of discrete-time systems. The aim of this work is to reduce the quasi-sliding mode band-width and, as follows, the necessary control input, through an application of a new type of time-varying sliding hyperplane in quasi-sliding mode control of sampled time systems. Although time-varying sliding hyperplanes are well known to provide insensitivity to matched external disturbances and uncertainties of the model in the whole range of motion for continuous-time systems, their application in the discrete-time case has never been studied in detail. Therefore, this paper proposes a sliding surface, which crosses the system’s representative point at the initial step and then shifts in the state space according to the pre-generated demand profile of the sliding variable. Next, a controller for a real perturbed plant is designed so that it drives the system’s representative point to its reference position on the sliding plane in each step. Therefore, the impact of external disturbances on the system’s trajectory is minimized, which leads to a reduction of the necessary control effort. Moreover, thanks to a new reaching law applied in the reference profile generator, the sliding surface shift in each step is strictly limited and a switching type of motion occurs. Finally, under the assumption of boundedness and smoothness of continuous-time disturbance, a compensation scheme is added. It is proved that this control strategy reduces the quasi-sliding mode band-width from O(T) to O(T3) order from the very beginning of the regulation process. Moreover, it is shown that the maximum state variable errors become of O(T3) order as well. These achievements directly reduce the energy consumption in the closed-loop system, which is nowadays one of the crucial factors in control engineering.

Robust finite-time trajectory tracking control for a space manipulator with parametric uncertainties and external disturbances

2021 ◽  
pp. 095441002110147
Author(s):  
Qijia Yao
Keyword(s):  
Trajectory Tracking ◽  
Finite Time ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Parametric Uncertainties ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Space Manipulator ◽  
Tracking Controller

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this study, a robust finite-time tracking control method is proposed for the rapid and accurate trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of parametric uncertainties and external disturbances. First, a baseline finite-time tracking controller is designed to track the desired position of the space manipulator based on the homogeneous method. Then, a finite-time disturbance observer is designed to accurately estimate the lumped uncertainties. Finally, a robust finite-time tracking controller is developed by integrating the baseline finite-time tracking controller with the finite-time disturbance observer. Rigorous theoretical analysis for the global finite-time stability of the whole closed-loop system is provided. The proposed robust finite-time tracking controller has a relatively simple structure and can guarantee the position and velocity tracking errors converge to zero in finite time even subject to lumped uncertainties. To the best of the authors’ knowledge, there are really limited existing controllers can achieve such excellent performance under the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control method.

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