• Journal of applied mathematics & informatics
• /
• v.13 no.1_2
• /
• pp.85-97
• /
• 2003

An indefinite stochastic linear-quadratic(LQ) optimal control problem with cross term over an infinite time horizon is studied, allowing the weighting matrices to be indefinite. A systematic approach to the problem based on semidefinite programming (SDP) and .elated duality analysis is developed. Several implication relations among the SDP complementary duality, the existence of the solution to the generalized Riccati equation and the optimality of LQ problem are discussed. Based on these relations, a numerical procedure that provides a thorough treatment of the LQ problem via primal-dual SDP is given: it identifies a stabilizing optimal feedback control or determines the problem has no optimal solution. An example is provided to illustrate the results obtained.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.331-334
• /
• 1993

It is a standard problem that designs a controller to minimize the $H_{\infty}$-norm of a given plant. By reducing a standard problem to a model-matching problem, we can obtain all the parameters which consist of a controller. After presenting a practical model and applying it to a tracking model, we design an $H_{\infty}$ controller and an LQ controller to concrete that $H_{\infty}$ control theory is far more robust than LQ control theory. And we show the advantage of an $H_{\infty}$ controller by obtaining a desired Bode diagram and comparing it with that of an LQ controller.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.25-29
• /
• 2003

LQ actuator selection problem for multi-input system discussed in this paper is to determine optimal actuator out of many actuators and input sequences so as to minimize the quadratic control performance. The solution of this problem depends on initial values and has a combinatorial property, so it is extremely difficult to get an optimal solution. For this difficulty, we proposed the concept of comparability of actuators and showed the uniqueness of the solution[1] . Further, to get general optimal solution for LQ problem with actuator selection strategies, we derived the equivalent condition for the comparability of actuator in single-input system . In this paper we extend this result to the case of multi-input system. The derived sufficient condition is applicable in the case of positive semi-definite comparability matrices.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.5
• /
• pp.412-418
• /
• 2007

An inverse optimal problem for homing guidance with angular constraint is addressed. The gains of BPN(Biased PN) are investigated by duality analysis related to the weighting matrices of the performance index in the LQ control problem. Moreover, the criteria for the existence of optimal gains are derived from the generalized Riccati equation. Based on the conditions we achieve the gain set of BPN to be optimal solution to the LQ problem with terminal constraints. To validate and demonstrate the proposed approach 3-DOF simulations are carried out.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.11
• /
• pp.35-41
• /
• 2006

This paper proposes an algorithm for switching LQ(Linear Quadratic) controllers designed at each flight envelope without a bump phenomenon. This algorithm is derived to apply to LQ controller more easily than existing implementation algorithm and is proposed to consider trim points of nonlinear models, which is adequate to real applications. This paper exemplifies the control performance improvement via simulations applied to LQ control of a supersonic test aircraft as a benchmark problem to test the proposed algorithm performance.

• Elastomers and Composites
• /
• v.57 no.4
• /
• pp.129-137
• /
• 2022

Low molecular weight liquid butadiene rubber (LqBR) is a processing aid that can resolve the migration problem of tire tread compounds. Various studies are being conducted to replace the petroleum-based processing oil with LqBR. However, the effect of the loading time of LqBR in the compounding process on silica dispersion and vulcanizate properties is not well known. In this study, we analyzed silica dispersion, vulcanizate properties, and viscoelastic properties of silica-filled tire tread compound according to the processing aid type (TDAE oil, non-functional LqBR) and, silane terminated LqBR) and input timing. In the non-functional LqBR compounds, the 'with TESPT' mixing procedure showed excellent dynamic viscoelastic properties while silane-terminated LqBR compounds showed that the 'after TESPT' mixing procedure was good for 300% modulus and abrasion resistance.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.3
• /
• pp.249-254
• /
• 2009

This paper studies the problem of pole placement by an LQ controller for system having two distinct real poles. Using the so-called Pole's Moving Range (PMR) drawn in the s-plane and relational equations between closed-loop system poles and weighting matrices, we calculate the state weighting matrix to move two distinct real poles to a pair of complex poles. By numerical examples, we show that the proposed method is applied to improve system performance.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10b
• /
• pp.864-867
• /
• 1990

In this paper, a state space solution to the discete time H$_{\infty}$ control problem is presented. It is shown that there exist LQ game problem corresponding to H$_{\infty}$ control problems and the H$_{\infty}$ controller can be obtained by solving the LQ game problem. Explicit state space formulae are given for the state feedback H$_{\infty}$ controller and output feedback H$_{\infty}$ controllers.lers. state feedback $H_{\infty}$ controller and output feedback $H_{\infty}$ controllers.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.41 no.3
• /
• pp.1-8
• /
• 2004

This paper proposes an LQ-PID controller to reduce errors occurring between input and output speeds in braking or emergency braking and to solve delay of speed or the excessive overshoot problems occurring at the speed control of induction motor. The conventional LQ controller is a method that move the poles in locations that satisfy design specifications such as overshoot and settling time etc. by state-feedback. So it may not be able to satisfy the overshoot requirement in case of the existence of zero in the closed loop transfer function. To attack this zero-problem it is presented a new design methodology of LQ-PID controller by introducing an analytic technique to eliminate the effect of zeros on the closed loop transfer function.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.11
• /
• pp.1048-1052
• /
• 2007

This paper presents a rank-constrained linear matrix inequality(LMI) approach to simultaneous linear-quadratic(LQ) optimal control by static output feedback. Simultaneous LQ optimal control is formulated as an LMI optimization problem with a nonconvex rank condition. An iterative penalty method recently developed is applied to solve this rank-constrained LMI optimization problem. Numerical experiments are performed to illustrate the proposed method, and the results are compared with those of previous work.