scholarly journals Optimal Performance of Variable Stiffness Devices for Structural Control

2006 ◽  
Vol 129 (2) ◽  
pp. 171-177 ◽  
Author(s):  
John Leavitt ◽  
Faryar Jabbari ◽  
James E. Bobrow
Keyword(s):  
Optimal Control ◽  
Feedback Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Structural Control ◽  
Vibration Suppression ◽  
Variable Stiffness ◽  
Experimental Results ◽  
Control Law ◽  
Structural Vibrations

This paper addresses control of structural vibrations using semi-active actuators that are capable of manipulating stiffness and∕or producing variable stiffness. Usually vibration suppression is achieved using damping devices rather than stiffness ones. However, stiffness devices can produce large forces and have significant advantages for shock isolation purposes. In this work we use a passivity approach to establish the requirements for the control law for a structure equipped with semi-active stiffness devices. We also solve an optimal control problem that demonstrates that our passive, resetting feedback control law approximates the optimal control. Simulation and experimental results are presented in support of the proposed approach.

scholarly journals Optimal Control Based on the Polynomial Least Squares Method

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Constantin Bota ◽  
Bogdan Cǎruntu ◽  
Mǎdǎlina Sofia Pașca ◽  
Marioara Lǎpǎdat
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Variational Problem ◽  
Least Squares ◽  
Least Squares Method ◽  
Lagrange Equation ◽  
Control Law

In this paper an approach for computing an optimal control law based on the Polynomial Least Squares Method (PLSM) is presented. The initial optimal control problem is reformulated as a variational problem whose corresponding Euler-Lagrange equation is solved by using PLSM. A couple of examples emphasize the accuracy of the method.

An improved footprint generation method for entry vehicles

2016 ◽  
Vol 231 (10) ◽  
pp. 1951-1956 ◽  
Author(s):  
Tao Wang ◽  
Hongbo Zhang ◽  
Yongyuan Li ◽  
Guojian Tang
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Coordinate Transformation ◽  
Performance Index ◽  
Engineering Application ◽  
Control Law ◽  
Bank Angle ◽  
Root Finding ◽  
Important Index

Entry landing footprint is an important index of the flight capability of an entry vehicle. Footprint generation methods can be classified into three categories, namely, methods based on the interpolation of the drag profile, methods based on the maximum cross-range, and methods based on virtual targets. This paper proposes a procedure for improving the methods based on virtual targets method by avoiding the problem of setting virtual targets. Taking the cross-range of the vehicle as the performance index, the optimal control law is used to develop the bank angle control law. Through coordinate transformation, the optimal control problem is transformed into a univariate root-finding problem that is similar to the result of the methods based on virtual targets method. But the method in the paper is more convenient for engineering application. At last, the footprint of the EG13 mission of X-33 is generated.

CONSTRUCTION OF SUBOPTIMAL FEEDBACK CONTROL FOR CHAOTIC SYSTEMS USING B-SPLINES WITH OPTIMALLY CHOSEN KNOT POINTS

2001 ◽  
Vol 11 (09) ◽  
pp. 2375-2387 ◽  
Author(s):  
H. W. J. LEE ◽  
K. L. TEO ◽  
W. R. LEE ◽  
S. WANG
Keyword(s):  
Optimal Control ◽  
Feedback Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Numerical Approach ◽  
Optimal Feedback Control ◽  
B Splines ◽  
Decision Variables ◽  
Spline Basis ◽  
The Lorenz System

In this paper we consider a class of optimal control problem involving a chaotic system, where all admissible controls are required to satisfy small boundedness constraints. A numerical approach is developed to seek for an optimal feedback control for the optimal control problem. In this approach, the state space is partitioned into subregions, and the controller is approximated by a linear combination of a modified third order B-spline basis functions. The partition points are also taken as decision variables in this formulation. An algorithm based on this approach is proposed. To show the effectiveness of the proposed method, a control problem involving the Lorenz system is solved by the proposed approach. The numerical results demonstrate that the method is efficient in the construction of a robust, near-optimal control.

REDUCED MODEL OF PLASMA DISCHARGE CONTROL IN TOKAMAK WITH IRON CORE

2020 ◽  
Vol 7 (3) ◽  
pp. 11-22
Author(s):  
VALERY ANDREEV ◽  
◽  
ALEXANDER POPOV
Keyword(s):  
Optimal Control ◽  
Inverse Problem ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Nonlinear Behavior ◽  
Plasma Discharge ◽  
Reduced Model ◽  
Iron Core ◽  
Power Sources ◽  
Real Power

A reduced model has been developed to describe the time evolution of a discharge in an iron core tokamak, taking into account the nonlinear behavior of the ferromagnetic during the discharge. The calculation of the discharge scenario and program regime in the tokamak is formulated as an inverse problem - the optimal control problem. The methods for solving the problem are compared and the analysis of the correctness and stability of the control problem is carried out. A model of “quasi-optimal” control is proposed, which allows one to take into account real power sources. The discharge scenarios are calculated for the T-15 tokamak with an iron core.

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