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Fuzzy compensator in control of multivariable systems with input constraints
, Article IEEE International Conference on Industrial Technology, IEEE ICIT 2002, 11 December 2002 through 14 December 2002 ; Volume 1 , 2002 , Pages 208-213 ; 0780376579 (ISBN) ; Aalam, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2002
Abstract
Input nonlinearities of many physical systems due to their actuator constraints are important points which have to be considered by designers. One of the recent method for dealing with this problem is to use compensation after controller. In this paper, a new approach based on fuzzy sets theory, as a solution, has been proposed. The main objective of the proposed method is to provide a feasible controller output if it is not in the legal ranges to keep the system output performance as high as possible. © 2002 IEEE
Nested saturation control based on the extended state observer: twin rotor MIMO system
, Article 5th International Conference on Control, Instrumentation, and Automation, ICCIA 2017, 21 November 2017 through 23 November 2017 ; Volume 2018-January , 2018 , Pages 55-59 ; 9781538621349 (ISBN) ; Ahi, B ; Haeri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper is concerned with the control of a laboratory setup called the twin rotor MIMO system. A novel nested saturation controller based on well-known extended state observer is proposed. Extended state observer has been utilized to tackle control difficulties due to existence of a high coupling between system channels. Nested saturation control is also utilized to improve closed-loop performance of system considering inevitable input saturation constraint. Besides the complexity of system, the proposed method can be simply designed and implemented. Numerical simulations are utilized to demonstrate the effectiveness of proposed method in comparison with the existing ones. © 2017 IEEE
Control of a Bioreactor Using Artificial Intelligent Methods
,
M.Sc. Thesis
Sharif University of Technology
;
Shahrokhi, Mohammad
(Supervisor)
Abstract
The goal of this project is finding an appropriate method for controlling four different bioreactors with unknown dynamics. At first, an introduction to bioreactor dynamic hase been presented, then their nonlinear behavior has been discussed. In the following, four output control systems using adaptive neural network have been designed separately for four different dynamics. The applied control method has been adapted from a method of references with some changes. Performances of designed controllers in set point tracking, load rejection and model mismatch have been evaluated using simulation. In these studies, input saturation has been considered in simulations but it is not existed in...
Modeling, control and simulation of a new large scale cable-driven robot
, Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009 ; Volume 7, Issue PARTS A AND B , 2009 , p. 11-16 ; ISBN: 9780791849040 ; Behzadipour, S ; Ghahremani, F ; Alasty, A ; Vanini, S. A. S ; Sharif University of Technology
Abstract
In this paper, modeling and control of a new cable-driven robot is presented. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motion. The mechanism has potentials for large scale manipulation and robotics in harsh environments. In this article kinematics and dynamics models for the proposed cable-driven architecture are derived. Additionally, Feedback linearization under input constraints is used for the control of the robot. The control algorithm ensures the cable tensions are positive while minimizing the sum of all the torques exerted by the actuators. Finally, the implementation of the proposed method is...
Modeling, control and simulation of a new large scale cable-driven robot
, Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009, 30 August 2009 through 2 September 2009 ; Volume 7, Issue PART A , August , 2010 , Pages 11-16 ; 9780791849040 (ISBN) ; Behzadipour, S ; Ghahremani, F ; Alasty, A ; Sadough Vanini, S. A ; The Design Engineering Division, ASME; The Computers and Information in Engineering Division, ASME ; Sharif University of Technology
2010
Abstract
In this paper, modeling and control of a new cable-driven robot is presented. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motion. The mechanism has potentials for large scale manipulation and robotics in harsh environments. In this article kinematics and dynamics models for the proposed cable-driven architecture are derived. Additionally, Feedback linearization under input constraints is used for the control of the robot. The control algorithm ensures the cable tensions are positive while minimizing the sum of all the torques exerted by the actuators. Finally, the implementation of the proposed method is...
Application of Adaptive Neural Network Systems in Controller Design of Nonlinear Processes
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
In this project design of adaptive neural network controller for uncertain nonlinear systems in the presence of different restrictions has been investigated. After providing introduction and motivation, two general forms of nonlinear systems including strict- feedback and pure- feedback have been introduced. In order to solve the problem caused by each restriction, a solution has been proposed. For the strict- feedback nonlinear systems several restrictions are considered such as, unknown dynamic model, unmeasured state, input saturation, unknown control directions, time delays in states and input. Stability analysis based on the Lyapunov theorem has been established. In addition, two kinds...
Control Design for Nonlinear Stochastic Processes in the Presence of Input Constraint
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
Due to the presence of a random variable in the process dynamics or due to the presence of measurement noise, many processes have stochastic in nature. Behaviors of these processes are different from the deterministic processes and therefore their controllers are also different. The aim of this research is to design adaptive controller for stochastic processes with a non-strict feedback structure and in the presence of input constraints. Also, the considered system has other limitations such as the unmeasured states, actuator failure, unknown dynamics and fixed time stability is desired. The input limitation can be caused by the limitation of the final control element, because the input...
Economic Model Predictive Control with Time Varying Constraints
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
In today's world we are dealing with many devices and processes with the goal of efficiency and performance improvement. In many processes particularly chemical ones, the goal is to control the output according to its constraints in the way that the performance is economically efficient, such as reducing energy consumption and energy loss and increasing efficiency. In order to control a process with economical goals, an economical cost function is used and after determination of optimal values a controller is used to guide the process so can achieve them. Model predictive control (MPC) is very common in this economic control Due to advantages such as considering the problem constraints. In...
Modeling, control and simulation of a new large scale cable-driven robot
, Article Proceedings of the ASME Design Engineering Technical Conference, 30 August 2009 through 2 September 2009 ; Volume 7, Issue PARTS A AND B , 2009 , Pages 11-16 ; 9780791849040 (ISBN) ; Behzadipour, S ; Ghahremani, F ; Alasty, A ; Sadough Vanini, S.A ; Sharif University of Technology
Abstract
In this paper, modeling and control of a new cable-driven robot is presented. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motion. The mechanism has potentials for large scale manipulation and robotics in harsh environments. In this article kinematics and dynamics models for the proposed cable-driven architecture are derived. Additionally, Feedback linearization under input constraints is used for the control of the robot. The control algorithm ensures the cable tensions are positive while minimizing the sum of all the torques exerted by the actuators. Finally, the implementation of the proposed method is...
Predictive directional compensator for systems with input constraints
, Article ISA Transactions ; Volume 45, Issue 3 , 2006 , Pages 393-405 ; 00190578 (ISSN) ; Aalam, N ; Sharif University of Technology
ISA - Instrumentation, Systems, and Automation Society
2006
Abstract
Nonlinearity caused by actuator constraint plays a destructive role in the overall performance of a control system. A model predictive controller can handle the problem by implementing a constrained optimization algorithm. Due to the iterative nature of the solution, however, this requires high computation power. In the present work we propose a new method to approach the problem by separating the constraint handling from the predictive control job. The input constraint effects are dealt with in a newly defined component called a predictive directional compensator, which works based on the directionality and predictive concepts. Through implementation of the proposed method, the...
Efficient algorithms for online tracking of set points in robust model predictive control
, Article International Journal of Systems Science ; Volume 48, Issue 8 , 2017 , Pages 1635-1645 ; 00207721 (ISSN) ; Haeri, M ; Sharif University of Technology
Abstract
This paper presents some computationally efficient algorithms for online tracking of set points in robust model predictive control context subject to state and input constraints. The nonlinear systems are represented by a linear model along with an additive nonlinear term which is locally Lipschitz. As an unstructured uncertainty, this term is replaced in the robust stability constraint by its Lipschitz coefficient. A scheduled control technique is employed to transfer the system to desired set points, given online, by designing local robust model predictive controllers. This scheme includes estimating the regions of feasibility and stability of the related equilibriums and online switching...
A nonlinear model predictive controller based on the gravitational search algorithm
, Article Optimal Control Applications and Methods ; Volume 42, Issue 6 , 2021 , Pages 1734-1761 ; 01432087 (ISSN) ; Alizad, M ; Nasrollahi, S ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
A heuristic nonlinear model predictive controller is proposed, based on the gravitational search algorithm. The proposed method models a constrained nonlinear model predictive control problem in the form of a dynamic optimization and uses a set of virtual particles, moving within the search space, to find the best control sequence in an online manner. Particles affect the movement of each other through the gravitational forces. The optimality of the points, experienced by the particles, is evaluated by a cost function. This function reduces the tracking error, control effort, and control chattering. The better control sequence a particle finds, the more mass is assigned to that particle....
A framework for prescribed-time control design via time-scale transformation
, Article IEEE Control Systems Letters ; 2021 ; 24751456 (ISSN) ; Assadian, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
This letter presents a unified framework for the design of prescribed-time controllers under time-varying input and state constraints for normal-form unknown nonlinear systems with uncertain input gain. The proposed approach is based on a time-domain mapping method by which any infinite-time system can be corresponded to a prescribed-time system and vice versa. It is shown that the design of a constrained nonasymptotic prescribed-time controller can be reduced to the asymptotic control design for an associated constrained infinite-time system. Faà di Bruno’s formula and Bell polynomials are used for a constructive representation of the associated infinite-time system. The presented results...
A framework for prescribed-time control design via time-scale transformation
, Article IEEE Control Systems Letters ; Volume 6 , 2022 , Pages 1976-1981 ; 24751456 (ISSN) ; Assadian, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This letter presents a unified framework for the design of prescribed-time controllers under time-varying input and state constraints for normal-form unknown nonlinear systems with uncertain input gain. The proposed approach is based on a time-domain mapping method by which any infinite-time system can be corresponded to a prescribed-time system and vice versa. It is shown that the design of a constrained nonasymptotic prescribed-time controller can be reduced to the asymptotic control design for an associated constrained infinite-time system. Faà di Bruno's formula and Bell polynomials are used for a constructive representation of the associated infinite-time system. The presented results...