scispace - formally typeset
Search or ask a question
Topic

Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.


Papers
More filters
Patent
Scott Richard Wilson1
07 Feb 2003
TL;DR: In this article, an n-channel MOSFET switch topology for bi-directional field excitation to null the effects of a rotor's permanent magnets is presented.
Abstract: An H-bridge switching topology for bi-directional field excitation to null the effects of a rotor's permanent magnets uses both a low-side and a high-side field excitation driver to control the rotor's average field current. A standard proportional control signal for generators using uni-directional field excitation is used to control an H-bridge for bi-directional field excitation. The H-bridge consists of two pair of power switches. In a preferred embodiment, the switches are n-channel MOSFETs. A drive circuit interfaces a logic block with the H-bridge in order to properly bias the power switches.

58 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a system dynamics model of a typical service-sector business process, such as is used in processing administrative paperwork in insurance, banking, and so on, and find that a control process based on system backlog is generally more robust than the alternatives in the sense that adequate performance is achieved over a broader range of control parameters.
Abstract: It is widely accepted that any well-designed organizational process includes a control mechanism through which management decides which aspects of the performance of the process are to be measured and how these measurements are to be used to change the level of resources utilized in the process. Little is known, however, about the best ways to design such a control mechanism for typical business processes. Our goal in this research is to identify control mechanisms for business processes that are effective in different types of environments. In this article we present a system dynamics model of a typical service-sector business process, such as is used in processing administrative paperwork in insurance, banking, and so on. These processes are subject to random, time-varying, and non-postponable demands for service. They are also subject to randomness in processing times, as well as delays in the observation of system performance and in the execution of control actions. We assume management has the dual objectives of maximizing profits (revenues on completed work less the costs of labor employed) and keeping cycle times below a predetermined ceiling. In order to achieve these objectives it observes the state of the process and adjusts its labor force accordingly. Management must chose which of several aspects of process performance to measure (cycle time, backlog, or demand) and the parameters governing the control process. Our analysis highlights the interactions among the demand environment faced by the process (e.g., random or seasonal), the control signal chosen (e.g., cycle time or backlog), and the type of control used (e.g., proportional or differential). Our results suggest that, regardless of the demand environment, a control process based on system backlog is generally more robust than the alternatives in the sense that adequate performance is achieved over a broader range of control parameters. We also find that, in most cases, proportional control by itself is inadequate to provide effective performance and that differential control is a necessary adjunct. We conclude the article with a discussion of the managerial implications of this research.

58 citations

Journal ArticleDOI
Moon-Ghu Park1, Nam Zin Cho1
TL;DR: In this paper, a time-optimal control method consisting of coarse and fine control stages is described, where the maximum control effort is used to direct the system toward the switching boundary, which is set near the desired power level.
Abstract: A time-optimal control method which consists of coarse and fine control stages is described. During the coarse control stage, the maximum control effort (time-optimal) is used to direct the system toward the switching boundary, which is set near the desired power level. At this boundary, the controller is switched to the fine control stage in which an adaptive proportional-integral-feedforward controller is used to compensate for any unmodeled reactivity feedback effects. This fine control is also introduced to obtain a constructive method for determining the (adaptive) feedback gains against the sampling effect. The feedforward control term is included to suppress the over- or undershoot. The estimation and feedback of the temperature-induced reactivity are also discussed. >

58 citations

Proceedings ArticleDOI
01 Aug 1999
TL;DR: In this article, a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems is investigated.
Abstract: Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the right body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases.

57 citations

Journal ArticleDOI
TL;DR: In this paper, the authors explored a new methodology for active control of structures through the use of time delayed, positive feedback proportional control, which may not necessarily be small when compared with the natural periods of vibration of a structure.
Abstract: This paper explores a new methodology for the active control of structures through the use of time delayed, positive feedback proportional control. The idea is to utilize intentional time delays, which may not necessarily be small when compared with the natural periods of vibration of a structure. Such time delayed systems are infinite dimensional. Analytical and computational results related to both system and non-system poles are herein provided for the first time. Results related to the stability of the presented control methodology are given. The efficacy of the control design is illustrated by applying it to a structure modelled as a single-degree-of-freedom system subjected to strong earthquake ground shaking. It is shown that while displaying good stability characteristics, the performance of such time delayed positive feedback proportional control can be even superior—in terms of both, reduced structural response, and reduced control effort—to standard proportional negative feedback control designs with no time delay. Copyright © 2005 John Wiley & Sons, Ltd.

57 citations


Network Information
Related Topics (5)
Control theory
299.6K papers, 3.1M citations
93% related
Control system
129K papers, 1.5M citations
92% related
Robustness (computer science)
94.7K papers, 1.6M citations
85% related
Optimization problem
96.4K papers, 2.1M citations
80% related
Electric power system
133K papers, 1.7M citations
80% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202217
202162
2020110
2019150
2018150