scholarly journals Methods of Ensuring Invariance with Respect to External Disturbances: Overview and New Advances

Mathematics ◽  
2021 ◽  
Vol 9 (23) ◽  
pp. 3140
Author(s):  
Aleksey Antipov ◽  
Svetlana Krasnova ◽  
Victor Utkin
Keyword(s):  
Control Plant ◽  
Dynamic Feedback ◽  
State Variables ◽  
External Disturbances ◽  
Control Laws ◽  
Single Output ◽  
Static Feedback ◽  
Feedback Synthesis ◽  
Control Principle ◽  
And Control

In this paper, we carry out a demonstration and comparative analysis of known methods of the synthesis of various control laws ensuring the invariance of the output (controlled) variable with respect to external disturbances under various assumptions about their type and channels of acting on the control plant. Methods of the synthesis are presented on the example of a third-order nonlinear system with single input and single output (SISO-systems), dynamic feedback synthesis is presented at a descriptive level and the focus is on procedures of static feedback synthesis. For the systems in which the matching conditions are not satisfied, it is concluded that it is expedient to introduce smooth and bounded nonlinear local feedbacks. Within the framework of the block control principle, we developed an iterative procedure of synthesis of S-shaped sigmoid feedbacks for such systems. Nonlinear local feedbacks ensure stabilization of the output variable with the given accuracy and settling time as in a system with traditionally used linear local feedbacks with high gains. However, in contrast to it, sigmoid functions do not lead to a large overshoot of state variables and control actions.

Attitude stabilization of a rigid spacecraft with actuator delay and fault

2017 ◽  
Vol 40 (7) ◽  
pp. 2340-2351 ◽  
Author(s):  
Alireza Safa ◽  
Mahdi Baradarannia ◽  
Hamed Kharrati ◽  
Sohrab Khanmohammadi
Keyword(s):  
Feedforward Control ◽  
State Observer ◽  
Extended State Observer ◽  
Actuator Faults ◽  
State Variables ◽  
Extended State ◽  
External Disturbances ◽  
Modelling Uncertainties ◽  
Rigid Spacecraft ◽  
And Control

Time delays and actuator faults are phenomena which are frequently encountered in practical control systems and are found to have significant effects on the performance of operation and control. It is shown that even a very small delay may destabilize the spacecraft system. Therefore, besides considering the effects of modelling uncertainties and external disturbances, time delay and actuator fault effects should be properly handled in the spacecraft to achieve reliable and accurate control. This paper describes a simple and effective method to attitude stabilize a spacecraft. The proposed method works by augmenting a backstepping controller with a modified extended state observer-based feedforward control law. The backstepping control is used to compensate for an unknown delay in the inputs, while the feedforward term attenuates the effects of modelling uncertainties, external disturbances and actuator faults. In particular, actuator faults, modelling uncertainties and external disturbances are viewed as unknown nonlinear functions of the measurable state variables, estimated using a modified extended state observer, and then compensated for. The effectiveness of the proposed control algorithm is analytically authenticated and verified via simulation studies.

Automatically Controlled Anti-Collision Manoeuvre and its Numerical Simulation with Disturbances

2013 ◽  
Vol 210 ◽  
pp. 156-165
Author(s):  
Jerzy Graffstein
Keyword(s):  
Numerical Simulation ◽  
Control System ◽  
Automatic Control ◽  
Numerical Simulations ◽  
Abrupt Change ◽  
State Variables ◽  
Control Laws ◽  
Analysis Of Results ◽  
System Robustness ◽  
And Control

The article presents the discussion focused on specific features of the problem of flying objects motion when performing an example of anti collision manoeuvre. To realise this task, the structure of automatic control system with appropriate control laws are proposed. The nature of discussed manoeuvre needs the appropriate numerical method for computing desired values of state variables for subsequent phases of objects motion. These values are obtained adequately for their roles in several phases of motion. Numerical simulations are completed for the aircraft performing the anti collision manoeuvre consisted in abrupt change of yaw. Objects behaviour was tested in case of motion affected by disturbances. The analysis of results obtained by numerical simulations makes possible conclusions on stability of objects motion and control system robustness to assumed kind and level of disturbances.

scholarly journals Design of the impact controlling structure applying conventional digital control laws

2005 ◽  
Vol 18 (3) ◽  
pp. 361-377
Author(s):  
Milic Stojic ◽  
Milan Matijevic
Keyword(s):  
Digital Control ◽  
Disturbance Rejection ◽  
Internal Model ◽  
Design Procedure ◽  
Experimental Setup ◽  
External Disturbances ◽  
Control Laws ◽  
Internal Model Principle ◽  
And Control ◽  
The Impact

The design of a simplified IMPACT (Internal Model Principle and Control Together) structure comprising conventional digital control laws is presented. The design procedure is accomplished to enable the extraction of a known class of immeasurable external disturbances and easy setting of the controller parameters. In the proposed controlling structure, the set point transient response and speed of disturbance rejection can be adjusted independently. The efficiency and robustness of the proposed controlling structure are verified and tested by the simulation and experimental setup.

scholarly journals Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Chang-Jian Ru ◽  
Rui-Xuan Wei
Keyword(s):  
Control Method ◽  
Safety Issue ◽  
State Variables ◽  
Control Laws ◽  
Control Approach ◽  
Guidance And Control ◽  
Aerial Vehicle ◽  
Safe Control ◽  
Autonomous Recovery ◽  
And Control

With unmanned aerial vehicles (UAVs) widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

Nanotechnology as a Smart Way to Promote the Growth of Plants and Control Plant Diseases

2021 ◽  
pp. 1-16
Author(s):  
Heba Mahmoud Mohammad Abdel‐Aziz ◽  
Mohammed Nagib Abdel‐ghany Hasaneen
Keyword(s):  
Control Plant ◽  
Plant Diseases ◽  
And Control

scholarly journals Modeling and Control of a Thermoelectric Structure with a Peltier Element Subject to External Disturbances

2020 ◽  
Vol 53 (2) ◽  
pp. 7771-7776
Author(s):  
Alexander Gavrikov ◽  
Georgy Kostin ◽  
Harald Aschemann ◽  
Andreas Rauh
Keyword(s):  
External Disturbances ◽  
Peltier Element ◽  
Modeling And Control ◽  
And Control

A novel robust finite-time tracking control of uncertain robotic manipulators with disturbances

2020 ◽  
pp. 107754632098244
Author(s):  
Hamid Razmjooei ◽  
Mohammad Hossein Shafiei ◽  
Elahe Abdi ◽  
Chenguang Yang
Keyword(s):  
Finite Time ◽  
Control Method ◽  
Sliding Mode ◽  
Robotic Manipulators ◽  
Sliding Mode Controller ◽  
Time Varying ◽  
State Variables ◽  
Terminal Sliding Mode ◽  
Control Laws ◽  
Finite Time Boundedness

In this article, an innovative technique to design a robust finite-time state feedback controller for a class of uncertain robotic manipulators is proposed. This controller aims to converge the state variables of the system to a small bound around the origin in a finite time. The main innovation of this article is transforming the model of an uncertain robotic manipulator into a new time-varying form to achieve the finite-time boundedness criteria using asymptotic stability methods. First, based on prior knowledge about the upper bound of uncertainties and disturbances, an innovative finite-time sliding mode controller is designed. Then, the innovative finite-time sliding mode controller is developed for finite-time tracking of time-varying reference signals by the outputs of the system. Finally, the efficiency of the proposed control laws is illustrated for serial robotic manipulators with any number of links through numerical simulations, and it is compared with the nonsingular terminal sliding mode control method as one of the most powerful finite-time techniques.

Observer-based synchronization of uncertain chaotic systems subject to input saturation

2017 ◽  
Vol 40 (8) ◽  
pp. 2526-2535 ◽  
Author(s):  
S Mohammadpour ◽  
T Binazadeh
Keyword(s):  
Chaotic Systems ◽  
Actuator Saturation ◽  
Input Saturation ◽  
State Variables ◽  
Adaptive Stabilization ◽  
External Disturbances ◽  
Van Der Pol ◽  
Robust Synchronization ◽  
Effective Performance ◽  
Uncertain Chaotic Systems

This paper considers the synchronization between two chaotic systems (i.e. master and slave systems) in the presence of practical constraints. The considered constraints are: the unavailability of state variables of both master and slave system, the presence of non-symmetric input saturation, model uncertainties and/or external disturbances (matched and/or unmatched). Considering these constraints, an adaptive robust observer-based controller is designed, which guarantees synchronization between the chaotic systems. For this purpose, a theorem is given and, according to a Lyapunov adaptive stabilization approach, it is proved that the robust synchronization via the proposed observer-based controller is guaranteed in the presence of actuator saturation and it is shown that even if the control signal is saturated, the proposed controller leads to a robust synchronization objective. Finally, in order to show the applicability of the proposed controller, it is applied on the Van der Pol chaotic systems. Computer simulations verify the theoretical results and show the effective performance of the proposed controller.

Modelling and control of manipulators with flexible links working on land and underwater environments

Robotica ◽  
2010 ◽  
Vol 29 (3) ◽  
pp. 461-470 ◽  
Author(s):  
Levent Gümüşel ◽  
Nurhan Gürsel Özmen
Keyword(s):  
Fuzzy Control ◽  
Control Method ◽  
Robot Manipulator ◽  
Control Methods ◽  
Control Laws ◽  
Linear Ordinary Differential Equations ◽  
Intelligent Technique ◽  
Wide Range ◽  
Classical Control ◽  
And Control

SUMMARYIn this study, modelling and control of a two-link robot manipulator whose first link is rigid and the second one is flexible is considered for both land and underwater conditions. Governing equations of the systems are derived from Hamilton's Principle and differential eigenvalue problem. A computer program is developed to solve non-linear ordinary differential equations defining the system dynamics by using Runge–Kutta algorithm. The response of the system is evaluated and compared by applying classical control methods; proportional control and proportional + derivative (PD) control and an intelligent technique; integral augmented fuzzy control method. Modelling of drag torques applied to the manipulators moving horizontally under the water is presented. The study confirmed the success of the proposed integral augmented fuzzy control laws as well as classical control methods to drive flexible robots in a wide range of working envelope without overshoot compared to the classical controls.

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