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Accommodation of springback error in channel forming using active binder force control: Numerical simulations and experiments

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JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME 1996年第3期118卷 426-435页

作者： Sunseri, M Cao, J Karafillis, AP Boyce, MC Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139-4307

Springback in a forming process is due to the elastic deformation of the part during unloading. This manufacturing defect can be accounted for through proper tooling design or through proper design and control of the magnitude and history of restraining force. Using finite element analysis of the process: (1) the effects of restraining force on the springback phenomena when stamping channels from aluminum sheet are investigated;(2) a strategy to control the binder force during the forming operation in order to reduce springback and simultaneously avoid tearing failure is described;and (3) a binder force control strategy which provides robustness in the presence of process parameter uncertainty is implemented. The process history and controller design using finite element analyses is then experimentally verified : excellent agreement between simulation and experiments is obtained. A binder force history, which leads to a significant reduction in the amount of springback incurred by the formed part without reaching critical stretching conditions, was proposed. Although an optimal forming history was found, in order to ensure that part shape error remained minimized even in the event of variations in processing parameters such as friction, a closed-loop control algorithm was developed whereby the binder force is altered during the process in order to provide a robust, repeatable stretching history. Experiments were performed using a double-action servo-controlled process and were found to produce the desired results demonstrating both the accuracy of the numerical simulation and the success of the proposed active-binding force control method to obtain net shape.

关键词： Errors Metal stamping Simulation control algorithms Uncertainty Force control Shapes Binders (Materials) Deformation Servomechanisms Tooling Robustness Computer simulation Friction Design Failure control equipment Aluminum Manufacturing Finite element analysis

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Robust point-to-point iterative learning control with trial-varying initial conditions

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IET control THEORY AND APPLICATIONS 2020年第19期14卷 3344-3350页

作者： Tao, Hongfeng Li, Jian Chen, Yiyang Stojanovic, Vladimir Yang, Huizhong Jiangnan Univ Inst Syst Engn Wuxi 214122 Jiangsu Peoples R China Soochow Univ Sch Mech & Elect Engn Suzhou 215137 Peoples R China Univ Kragujevac Fac Mech & Civil Engn Dept Automat Control Robot & Fluid Tech Kraljevo 36000 Serbia

Iterative learning control (ILC) is a high-performance technique for repeated control tasks with design postulates on a fixed reference profile and identical initial conditions. However, the tracking performance is only critical at few points in point-to-point tasks, and their initial conditions are usually trial-varying within a certain range in practice, which essentially degrades the performance of conventional ILC algorithms. Therefore, this study reformulates the ILC problem setup for point-to-point tasks and considers the effort of trial-varying initial conditions in algorithm design. To reduce the tracking error, it proposes a worst-case norm-optimal problem and reformulates it into a convex optimisation problem using the Lagrange dual approach. In this sense, a robust ILC algorithm is derived based on iteratively solving this problem. The study also shows that the proposed robust ILC is equivalent to conventional norm-optimal ILC with trial-varying parameters. A numerical simulation case study is conducted to compare the performance of this algorithm with that of other control algorithms while performing a given point-to-point tracking task. The results reveal its efficiency for the specific task and robustness against trial-varying initial conditions.

关键词： learning systems robust control convex programming iterative methods trial-varying initial conditions iterative learning control high-performance technique tracking performance point-to-point tasks worst-case norm-optimal problem robust ILC algorithm norm-optimal ILC trial-varying parameters control algorithms point-to-point tracking task

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Level control of cascade coupled flotation tanks

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control ENGINEERING PRACTICE 2002年第4期10卷 443-448页

作者： Stenlund, B Medvedev, A Lulea Univ Technol Control Engn Grp SE-97187 Lulea Sweden

At the Boliden's concentrator in Aitik, bulk flotation constitutes an important part of the process for extracting valuable minerals from the ore. A series of flotation cells consists of five tanks connected in cascade with control valves between the tanks and a slowly varying flow of mineral slurry into the first tank. This paper deals with a comparative study of control strategies for level control in a flotation series in Aitik. The aim is to show the potential performance improvements taking into account couplings between the process state variables. Two control strategies are considered;a decoupling controller and a Linear quadratic (LQ) optimal multivariable, controller. Experiments with both structures show a significant enhancement of the level control performance as compared to the original SISO design. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： control engineering industrial control control applications computer controlled systems control systems control algorithms

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control of Supercritical Organic Rankine Cycle based Waste Heat Recovery System Using Conventional and Fuzzy Self-tuned PID controllers

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INTERNATIONAL JOURNAL OF control AUTOMATION AND SYSTEMS 2019年第11期17卷 2969-2981页

作者： Chowdhury, Jahedul Islam Thornhill, David Soulatiantork, Payam Hu, Yukun Balta-Ozkan, Nazmiye Varga, Liz Bao Kha Nguyen Cranfield Univ Sch Water Energy & Environm Cranfield MK43 0AL Beds England UCL Dept Civil Environm & Geomat Engn London WC1E 6BT England Queens Univ Belfast Sch Mech & Aerosp Engn Belfast BT9 5AH Antrim North Ireland Univ Sheffield Dept Automat Control & Syst Engn Sheffield S1 3JD S Yorkshire England Univ Sussex Sch Engn & Informat Brighton BN1 9QT E Sussex England

This research develops a supercritical organic Rankine cycle (ORC) based waste heat recovery (WHR) system for control system simulation. In supercritical ORC-WHR systems, the evaporator is a main contributor to the thermal inertia of the system, which is greatly affected by transient heat sources during operation. In order to capture the thermal inertia of the system and reduce the computation time in the simulation process, a fuzzy-based dynamic evaporator model was developed and integrated with other component models to provide a complete dynamic ORC-WHR model. This paper presents two control strategies for the ORC-WHR system: evaporator temperature control and expander output control, and two control algorithms: a conventional PID controller and a fuzzy-based self-tuning PID controller. The performances of the proposed controllers are tested for set point tracking and disturbance rejection ability in the presence of steady and transient thermal input conditions. The robustness of the proposed controllers is investigated with respect to various operating conditions. The results show that the fuzzy self-tuning PID controller outperformed the conventional PID controller in terms of set point tracking and disturbance rejection ability at all conditions encountered in the paper.

关键词： control algorithms fuzzy logic organic Rankine cycle PID controller supercritical condition waste heat recovery

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Near-optimal online control of dynamic discrete-event systems

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DISCRETE EVENT DYNAMIC SYSTEMS-THEORY AND APPLICATIONS 2006年第4期16卷 419-449页

作者： Grigorov, Lenko Rudie, Karen Queens Univ Sch Comp Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada

A class of time-varying discrete-event systems, named dynamic discrete-event systems, is defined. The goal of this paper is to provide a method which is modular and can be applied in real solutions for the optimization of the online control of such systems. First, a simple control algorithm is presented, followed by illustrative examples of different issues that can arise if it is used. Afterward, a more complicated near-optimal online control algorithm with normalization of string values is proposed. The time variability of the systems is accounted for and the average computational time is drastically reduced. This is demonstrated with a set of simulations of the performance of the new algorithm.

关键词： discrete-event systems time-varying systems dynamic behaviour on-line control optimal control control algorithms uncertain systems

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SOFTWARE FOR 8-BIT MICROPROCESSORS IN MULTIVARIABLE DIGITAL-control SYSTEMS

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JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND control-TRANSACTIONS OF THE ASME 1982年第4期104卷 305-310页

作者： SWEET, LM GERBER, JC MEHTA, RS WONG, EY Department of Mechanical and Aerospace Engineering Princeton University Princeton N.J. 08544

This paper compares computer programs implementing linear multivariable digital control algorithms written in high level and assembly languages for eight-bit microprocessors. The execution speeds of the programs are compared for fixed-point and floating-point formats for controllers of increasing order, with faster speeds allowing greater achievable controller sampling rates. Methods are presented for optimizing the high level language programs using in-line assembly code in critical program modules and performing floating-point computations on a dedicated arithmetic function processor. Quantitative results are presented for achievable sampling rates as functions of the order of the controller, the number of inputs and outputs, language level used for the control program, and optimization method. Design guidelines are given for development of controller software for different applications.

关键词： Computation Optimization control algorithms Design control systems Computer software control equipment Manufacturing

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Active and semi-active control of structures - theory and applications: A review of recent advances

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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES 2012年第11期23卷 1181-1195页

作者： Casciati, Fabio Rodellar, Jose Yildirim, Umut Univ Pavia Dept Struct Mech I-27100 Pavia Italy Univ Politecn Cataluna Dept Appl Math 3 Barcelona Spain

It is internationally recognized that structural control was introduced in civil engineering through a pioneering article by Yao and through the implementations promoted by Kobori. The concepts of active and semi-active structural control in civil and infrastructure engineering date back 40 years and much progress has been recorded during these four decades. Periodically, state-of-the-art manuscripts have been published and technical books were also printed to testify the maturation of the topic. This article only covers the period from the second semester of 2009 to the first semester of 2011, emphasizing the developments in terms of theoretical, numerical and experimental studies, as well as the use of control algorithms and devices in actual implementations. It is observed that there are still several operational limitations to prevent from the expected growth of the applications in standard design. Nevertheless, some innovative concepts help to foresee future developments within special sectors of applications.

关键词： active control control algorithms intelligent systems laboratory testing semi-active control structural control

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Time-averaged ventilation for optimized control of variable-air-volume systems

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ENERGY AND BUILDINGS 2017年第Mar.期139卷 465-475页

作者： Kaam, Soazig Raftery, Paul Cheng, Hwakong Paliaga, Gwelen Univ Calif Berkeley Ctr Built Environm Berkeley CA 94720 USA Taylor Engn 1080 Marina Village PkwySuite 501 Alameda CA 94501 USA TRC 436 14th StSuite 1020 Oakland CA 94612 USA

Typical variable air volume (VAV) terminals spend the majority of time at their minimum airflow set points. These are often higher than the minimum ventilation requirements defined by code, resulting in excess energy use and a risk of over-cooling the spaces. We developed and tested a time-averaged ventilation (TAV) control strategy in an institutional building on the UC Berkeley campus to address this issue. Whenever a zone does not require cooling, TAV alternates the VAV damper between partially open and fully closed so that the average airflow matches a predefined ventilation setpoint. Compared to the existing, base case scenario using single-max VAV logic, this strategy reduced the mean zone airflow fraction from 0.44 to 0.27 during the intervention period. The corresponding reductions in average heating, cooling, and fan power were 41%, 23%, and 15% respectively. In addition to being programmed directly in a native control system, TAV may be applied via sMAP as a low-cost retrofit strategy in any building that has a BACnet network and direct digital control (DDC) to each VAV terminal. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Air conditioning Air distribution VAV system control algorithms Minimum airflow setpoints Ventilation

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Adaptive control of coupled-drives apparatus based on polynomial theory

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART I-JOURNAL OF SYSTEMS AND control ENGINEERING 2006年第I7期220卷 641-654页

作者： Kubalcik, M. Bobal, V. Tomas Bata Univ Fac Appl Informat Dept Proc Control Zlin 762072 Czech Republic

control of a coupled-drives apparatus laboratory model as a two-input-two-output system is presented. control algorithms based on polynomial theory and pole assignment methods are proposed. Three control algorithms are implemented and compared. Both one-degree-of-freedom and two-degree-of-freedom control system configurations were used. Problems of decoupling, where compensators suppress the interactions between control loops, were also solved. Adaptive algorithms were used to control the model. The recursive least-squares method with directional forgetting was used for the identification process. The results of real-time experiments are also included.

关键词： multivariable control control algorithms adaptive control polynomial methods pole assignment

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On the limitations of force tracking control for hydraulic servosystems

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JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND control-TRANSACTIONS OF THE ASME 1999年第2期121卷 184-190页

作者： Alleyne, A Liu, R Univ Illinois Dept Mech & Ind Engn Urbana IL 61801 USA

This paper presents analysis of a particular force tracking control problem for rectilinear hydraulic actuators governed by a servovalve. It presents no new theory, bur rather uses a revealing model reduction insight coupled with Classical analysis to explain a physical phenomenon. As such, this work is an attempt to explain why a seemingly innocuous problem is more subtle than initially believed. A motivation for this problem is given along with prior attempts at a simple solution. It is shown that simple controller solutions are quite adequate for other types of control objectives such as force regulation or position tracking. However, most simple solution methods are shown to be inadequate for force tracking due to fundamental limitations of the problem formulation. Due to an inherent feedback mechanism, the poles of the plant being forced by the hydraulic actuator become zeros of the open loop force transfer function. Therefore, more advanced control algorithms are shown to be a necessity rather than a luxury.

关键词： Actuators Tracking control Poles (Building) control algorithms Hydraulic actuators Transfer functions Feedback control equipment Servomechanisms

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