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.

Disturbance Rejection for Discrete-Time Linear Systems with Time-Delays via Internal Model Principle

2014 ◽  
Vol 590 ◽  
pp. 478-481
Author(s):  
Shao Ting Ge ◽  
Zhi Min Liu ◽  
Xue Xia Gao ◽  
Mei Xing Wang ◽  
Yu Qing Feng
Keyword(s):  
Linear Systems ◽  
Discrete Time ◽  
Disturbance Rejection ◽  
Delay System ◽  
Time Delay System ◽  
State Delay ◽  
Internal Model Principle ◽  
Disturbance Rejection Control ◽  
And Control ◽  
Time Linear

The disturbance rejection problem for discrete-time linear systems with both state delay and control delay is considered. Using a model transformation, the time-delay system is transformed into a nondelayed system. The disturbance rejection control law is obtained by solving its optimal regulation problem.

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.

Sliding Mode Control Laws Design by the ADAR Method with Subsequent Invariant Manifolds Aggregation

2019 ◽  
Vol 20 (8) ◽  
pp. 451-460 ◽  
Author(s):  
A. A. Kolesnikov ◽  
A. A. Kuz’menko
Keyword(s):  
Robust Control ◽  
Invariant Manifolds ◽  
Closed Loop ◽  
Sliding Mode ◽  
Design Procedure ◽  
Sliding Surface ◽  
Closed Loop System ◽  
External Disturbances ◽  
Control Laws ◽  
The Stability

Sliding mode control (SMC) laws are commonly used in engineering to make a system robust to parameters change, external disturbances and control object unmodeled dynamics. State-of-the-art capabilities of the theory of adaptive and robust control, the theory of fuzzy systems, artificial neural networks, etc., which are combined with SMC, couldn’t resolve current issues of SMC design: vector design and stability analysis of a closed-loop system with SMC are involved with considerable complexity. Generally the classical problem of SMC design consists in solving subtasks for transit an object from an arbitrary initial position onto the sliding surface while providing conditions for existence of a sliding mode at any point of the sliding surface as well as ensuring stable movement to the desired state. As a general rule these subtasks are solved separately. This article presents a methodology for SMC design based on successive aggregation of invariant manifolds by the procedure of method of Analytical Design of Aggregated Regulators (ADAR) from the synergetic control theory. The methodology allows design of robust control laws and simultaneous solution of classical subtasks of SMC design for nonlinear objects. It also simplifies the procedure for closed-loop system stability analyze: the stability conditions are made up of stability criterions for ADAR method functional equations and the stability criterions for the final decomposed system which dimension is substantially less than dimension of the initial system. Despite our paper presents only the scalar SMC design procedure in details, the ideas are also valid for vector design procedure: the main difference is in the number of invariant manifolds introduced at the first and following stages of the design procedure. The methodology is illustrated with design procedure examples for nonlinear engineering systems demonstrating the achievement of control goals: hitting to target invariants, insensitivity to emerging parametric and external disturbances.

K-Fold Exosystem and the Robust Nonlinear Servomechanism Problem

1998 ◽  
Vol 120 (1) ◽  
pp. 149-153 ◽  
Author(s):  
Jie Huang
Keyword(s):  
Feedback Control ◽  
Nonlinear Systems ◽  
Output Feedback ◽  
Disturbance Rejection ◽  
Internal Model ◽  
Output Feedback Control ◽  
Uncertain Nonlinear Systems ◽  
Internal Model Principle ◽  
Asymptotic Tracking

Asymptotic tracking and disturbance rejection in uncertain nonlinear systems is studied in the context of output feedback control. This study is facilitated by formalizing the notion of k-fold exosystem and generalizing the internal model principle to the nonlinear setting.

Combined Feedback and Feedforward Control for an Inertial Stabilization System

2013 ◽  
Vol 415 ◽  
pp. 101-108
Author(s):  
Kritsanun Malithong ◽  
Viboon Sangveraphunsiri
Keyword(s):  
Disturbance Rejection ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Design Procedure ◽  
Stabilization System ◽  
Model Uncertainties ◽  
Configuration Change ◽  
Aerial Vehicle ◽  
The Impact ◽  
Disturbance Torque

This paper presents environmental disturbance rejection in a 2-DOF inertial stabilization system by a combination of feedback and feedforward control. For feedback control, sliding mode control and the line of sight (LOS) stabilization are used for compensation of the nonlinearities, model uncertainties, friction and disturbances from outside environment. Although our mechanisms are carefully designed with statically balance, the center of the gravity will changed due to the configuration change during moving of the gimbal relative to an aerial vehicle. The disturbance torque from unbalance mass and gimbal geometry is unavoidable under the effect of the vibration of the aerial vehicle, which will lead to degrade the systems accuracy. Since the acceleration of the aerial carrier, due to the disturbance torque, can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results confirm the validity of the control design procedure for the two-axis gimbaled stabilization system. The proposed controller is capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance.

scholarly journals Suppression of torsional oscillations based on IMPACT controlling structure

2006 ◽  
Vol 33 (3) ◽  
pp. 181-198
Author(s):  
Milan Matijevic ◽  
Milic Stojic ◽  
Slobodan Vukosavic ◽  
Miladin Stefanovic
Keyword(s):  
Dynamic Properties ◽  
Impact Structure ◽  
Servo Drive ◽  
Servo Systems ◽  
Torsional Oscillations ◽  
Internal Model Principle ◽  
Electrical Drives ◽  
Digitally Controlled ◽  
And Control ◽  
The Impact

In this paper, an algorithm for suppression of the torsional oscillations, in the computer controlled servo systems, is purposed. A few modification of the IMPACT structure (Internal Model Principle and Control Together) in the digitally controlled electrical drives are proposed. The IMPACT structure suitable for suppression of the torsional oscillations in a servo system with the flexible coupling has been presented. The approach, proposed in this paper, gives better solutions for the problem of the mechanical resonance in the modern servo drive than the previous ones. The presented structure is simple with a small number of adjustable parameters that could be easily set to achieve the desired robust, filtering, and dynamic properties of the system.

scholarly journals Practical Limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

2021 ◽  
Vol 8 ◽  
Author(s):  
Ewan S. Douglas ◽  
Kevin Tracy ◽  
Zachary Manchester
Keyword(s):  
Control Systems ◽  
Attitude Control ◽  
Test Case ◽  
External Disturbances ◽  
Control Scheme ◽  
Pointing Accuracy ◽  
General Limit ◽  
Environmental Limits ◽  
And Control ◽  
The Impact

Accurate and stable spacecraft pointing is a requirement of many astronomical observations. Pointing particularly challenges nanosatellites because of an unfavorable surface area–to-mass ratio and a proportionally large volume required for even the smallest attitude control systems. This work explores the limitations on astrophysical attitude knowledge and control in a regime unrestricted by actuator precision or actuator-induced disturbances such as jitter. The external disturbances on an archetypal 6U CubeSat are modeled, and the limiting sensing knowledge is calculated from the available stellar flux and grasp of a telescope within the available volume. These inputs are integrated using a model-predictive control scheme. For a simple test case at 1 Hz, with an 85-mm telescope and a single 11th magnitude star, the achievable body pointing is predicted to be 0.39 arcseconds. For a more general limit, integrating available star light, the achievable attitude sensing is approximately 1 milliarcsecond, which leads to a predicted body pointing accuracy of 20 milliarcseconds after application of the control model. These results show significant room for attitude sensing and control systems to improve before astrophysical and environmental limits are reached.

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