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IEEE International symposium on Industrial Electronics (ISIE)

作者： Eunjeong Lee Texas Center for Superconductivity University of Houston Houston TX USA Space Science Branch NASA-Johnson Space Center USA

A new approach to the interaction control of systems with unknown dynamics has been developed by combining natural admittance control (NAC) with time delay control (TDC). The proposed nonlinear controller does not require specific knowledge of the system's dynamics or the environment nor does it necessitate the estimation of system parameters, except inertia, rendering it easy to implement. It rejects unmodeled dynamics, nonlinearities and disturbances without difficult characterization process while preserving the desired dynamics. The simulation results demonstrate not only good external disturbance rejection, robustness to parameter changes and insensitivity to noise, but also demonstrate good trajectory following providing good rejection of internal Coulomb friction. This novel control technique is also used to develop a nonlinear bang-bang impact controller (NBBIC) for stabilization of a robot manipulator upon collision with a stiff environment. It uses the above-mentioned NAC/TDC control algorithm with negative force feedback to absorb impact forces and stabilize the system. This control input alternates with zero when no environment force is sensed due to loss of contact. This alternation of control action repeats until the impact transient subsides and steady state is established. After impact transient, proportional-derivative force control is used. It is shown via simulations that NBBIC provides stable interaction between the robot with severe nonlinear joint friction and a stiff environment and achieves rapid response while minimizing force overshoots.

关键词： Force control Robot control Delay effects control systems Nonlinear dynamical systems Friction Robot sensing systems Manipulator dynamics Admittance Nonlinear control systems

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Accurate modelling and simulation of a DC brushless motor drive system for high performance industrial applications

Accurate modelling and simulation of a DC brushless motor dr...

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IEEE International symposium on Circuits and systems (ISCAS)

作者： R.A. Guinee C. Lyden Cork Institute of Technology Cork Ireland National Microelectronics Research Centre University College Cork Cork Ireland

An accurate mathematical model of a three phase brushless motor drive (BLMD) system, based on physical principles, is presented for simulation in performance prediction studies of proposed embedded drive systems. This model can also be deployed for parameter identification of the adjustable speed drive (ASD) dynamics in optimal PID controller design and in adaptive system control. Model validation is provided, as an essential feature of the identification process, by step response transient simulation of motor current feedback and shaft velocity and comparison with actual drive test data. Penalty cost function simulation, based on the observed motor variables, is used to provide insight into the error surface topography and global minimizer location with the type of parameter search strategy that may be employed in the minimization process.

关键词： Brushless motors Variable speed drives Optimal control Mathematical model Predictive models Parameter estimation Three-term control Adaptive systems Programmable control Adaptive control

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Monitoring the control loop on the basis of reduced process model-application to the DC motor-generator

Monitoring the control loop on the basis of reduced process ...

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IEEE International symposium on Industrial Electronics (ISIE)

作者： M. Zele D. Juricic Jožef Stefan Institute Ljubljana Slovenia

A statistical test for detecting changes in the control loop based on the reduced order model is presented. The residuals are obtained by comparing the behaviour of the reduced order nominal model with the process behaviour. Any discrepancy might indicate a change in the process. However, there are two possible reasons for the discrepancy: process anomalies; and model error. The model error might cause false alarms, if it is not properly considered in the test statistics. Namely, in classical test statistics the residuals variance is invariant, while the residuals of the reduced order model depends on the process input. This paper describes the way of including unmodelled dynamics into the test statistics when the undermodelling is described by the stochastic embedding method proposed by Goodwin and co-workers (1992). The result of such a procedure is a decrease of false alarms. The performance of the proposed test statistics are tested on a DC motor-generator laboratory set-up.

关键词： Monitoring Testing Statistical analysis Reduced order systems control systems Transfer functions Stochastic processes Laboratories Electrical equipment industry Industrial control

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An environment for model-checking of logic control systems with hybrid dynamics

An environment for model-checking of logic control systems w...

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IEEE International symposium on Computer Aided control System Design (CACSD)

作者： S. Kowalewski N. Bauer J. Preussig O. Stursberg H. Treseler Process Control Laboratory Department of Chemical Engineering CT-AST University of Dortmund Dortmund Germany Technische Universitat Dortmund Dortmund Nordrhein-Westfalen DE

This paper presents the modeling environment VERDICT which intends to make the method of formal verification applicable to logic controlled chemical plants. The tool offers textual and graphical editors to set up models of plant and controller. The plant model can be specified as hybrid dynamical or (timed) discrete systems, which are then translated automatically into models that are verifiable with existing model-checking tools. Furthermore, VERDICT allows one to include the controller model by specifying it in Instruction List (IL) code directly. The paper illustrates the different features of the framework, the underlying modeling paradigm, and some aspects of the analysis using a simple technical example.

关键词： Logic control system synthesis Valves process control Switches Formal verification Automatic control Communication system control Inductors Chemicals

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An investigation into the printing characteristics and mechanical dynamics of advanced squeegee mechanisms

An investigation into the printing characteristics and mecha...

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IEEE/CHMT(CPMT) International Electronics Manufacturing Technology symposium

作者： M. Howarth S.A. Silvester M. Lacey K. Sivaygonathan Department of Mechanical and Manufacturing Engineering Nottingham Trent University Nottingham UK

The new breed of solder paste deposition systems, such as the DEK ProFlow, incorporate a contained solder paste chamber enabling independent control of machine parameters, pressure, down force and print speed. Previous work by Ekere et al. (1994) and Monaghan et al. (1991-2) have modelled conventional squeegee systems, but only part of this work is applicable to the new mechanism. Practical experimentation has been employed, both to gain an appreciation of the printing characteristics in general and to serve as reference for purely analytical models. Flow visualisation experiments have provided useful indications of flow dynamics within the print head, highlighting dominant flow patterns, velocity profiles and other phenomena such as evidence of air entrapment or cavitation. The FIDAP CFD package is used to perform detailed analysis, providing measures of data not practically obtainable through physical measurement. Pressure, shear and temperature profiles are obtained for a range of operating conditions and their influence on ink/solder paste transfer can be evaluated, leading to the identification of operational limits. Results from the FIDAP model compare very well with the experimental work and have identified the critical areas of the squeegee mechanism. This analysis is now being used to refine the process, to extend its application to lower viscosity materials and to incorporate simpler control systems than have been found to be necessary with conventional squeegee mechanisms (Lofti and Howarth, 1998; Zhuang et al., 1997).

关键词： Printing control systems Force control Pressure control Metalworking machines Analytical models Visualization Magnetic heads Computational fluid dynamics Packaging

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Simultaneous steady state and dynamic design of process systems using structural indicators

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COMPUTERS & CHEMICAL ENGINEERING 1999年第Sup期23卷 S55-S58页

作者： Walsh, AM Cameron, IT Univ Queensland Dept Chem Engn Comp Aided Proc Engn Ctr Brisbane Qld 4072 Australia

The simultaneous design of the steady-state and dynamic performance of a process has the ability to satisfy much more demanding dynamic performance criteria than the design of dynamics only by the connection of a control system. A method for designing process dynamics based on the use of a linearised systems' eigenvalues has been developed. The eigenvalues are associated with system states using the unit perturbation spectral resolution (UPSR), characterising the dynamics of each state. The design method uses a homotopy approach to determine a final design which satisfies both steady-state and dynamic performance criteria. A highly interacting single stage forced circulation evaporator system, including control loops, was designed by this method with the goal of reducing the time taken for the liquid composition to reach steady-state. Initially the system was successfully redesigned to speed up the eigenvalue associated with the liquid composition state, but this did not result in an improved startup performance. Further analysis showed that the integral action of the composition controller was the source of the limiting eigenvalue. Design changes made to speed up this eigenvalue did result in an improved startup performance. The proposed approach provides a structured way to address the design-control interface, giving significant insight into the dynamic behaviour of the system such that a systematic design or redesign of an existing system can be undertaken with confidence.

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Estimation of constant parameters in a class of time varying plants by means of smoothing

Estimation of constant parameters in a class of time varying...

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IEEE International symposium on Industrial Electronics (ISIE)

作者： D. Juricic Department of Computer Automation and Control Jožef Stefan Institute Ljubljana Slovenia

The problem addressed in this paper is as follows. Consider a nonlinear discrete time system with parameters, which can be a priori classified into two groups: constant parameters and time varying ones. It is also assumed that loose attributes like "slow" or "fast" express the only prior information concerning the dynamics of varying parameters. The question of interest is how to estimate the constant parameters of the process (on the basis of a recorded batch of input and output data) so that possible alterations of the parameters that are expected to vary with time are taken into account. To deal with this kind of nonlinear fixed-interval smoothing problem a two-level procedure based on rectangular window technique and Gauss-Newton method is presented. All the computations are performed offline. The procedure is applicable in a pre-processing stage of adaptive parameter estimation where the parameters that are evidently time invariant are identified from past records. Thus the number of parameters that have to be tracked (i.e. estimated) on-line is reduced. The efficiency of the scheme is illustrated on a simulated industrial process.

关键词： Parameter estimation Smoothing methods Bellows Raw materials Noise measurement Time measurement Automation Automatic control Discrete time systems Time varying systems

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Tracking the predefined optimal policies for multiple-fraction batch distillation by using adaptive control

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COMPUTERS & CHEMICAL ENGINEERING 1999年第sup1期23卷 S281-S284页

作者： Li, P Wozny, G Tech Univ Berlin Inst Prozess & Anlagentech D-10623 Berlin Germany

Predefined optimal policies will be tracked with control systems to realize the optimum of multiple-fraction batch distillation. Adaptive control is proposed to carry out this task. Characteristics of batch distillation control are analyzed and a proper system is designed for controlling such processes. Besides tracking the optimal reflux ratio profile, the maximum vapor load will be maintained during the batch. In addition, a changing temperature profile of the condenser should be followed to reduce the operating energy with a possibly minimum subcooling. Recursive least square estimation (RLSE) with a variable forgetting factor is applied to the on-line identification of the plant to follow the changing dynamics of the process. Generalized predictive control (GPC) is used to track the predefined policies. The effectiveness of the control strategy is verified with a pilot batch column and the tracking performance is compared with that of PID controllers.

关键词： multiple-fraction batch distillation tracking optimal policies adaptive control

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A general approach for simulating robots for flexible material handling

A general approach for simulating robots for flexible materi...

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IEEE International symposium on Assembly and Manufacturing (ISAM)

作者： O. Rogalla R. Dillmann G. Frugoli M. Bordegoni Institute for Process Control & Robotics University of Karlsruhe Karlsruhe Germany Industrial Engineering Department University of Parma Parma Italy

Kinematic modelling of robots and flexible material simulation have been an important aspect in robotic research issues over the last years. In this article a new approach for the design of arbitrary gripper and robot architectures are presented. It is shown how these robot systems can be simulated based on the presented design structure. Further, the integration of flexible material simulation is displayed. A particle based object models are shown and the mathematical basics described. Finally, the integration of the flexible material simulation into the robot simulation software is given and evaluated.

关键词： Robots Materials handling Kinematics Solid modeling Object oriented modeling Manipulator dynamics Grippers Libraries Packaging Deformable models

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Computer-aided experiments for a course in dynamic systems and control technology

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COMPUTERS & CHEMICAL ENGINEERING 1999年第Sup期23卷 S633-S636页

作者： Lammerts, IMM Preisig, HA Eindhoven Univ Technol Dept Appl Phys & Chem Technol NL-5600 MB Eindhoven Netherlands

A new laboratory course has been developed with a set of computer-controlled experiments. The objective is to offer the students 5 to 10 different experiments that build on a generic infrastructure, namely a standard personal computer, an intelligent process interface and an experiment. The processor board communicates through a back plane bus with the instrumentation cards and on the other side provides standard communication interfaces such as RS232 for the communication with the personal computer. This allows the students to use their own notebook computer, which is made available to every student in the university since last year. The user interface is presently built in LabView and the combination of Matlab and Simulink is used for simulations and other analytical off-line tasks. The experimental setups are designed such that they are mobile, flexible and easy to maintain. Furthermore,they can be used for both educational and research activities in our group.

关键词： laboratory course computer-controlled experiments measurement and data-acquisition modelling dynamics testing controllers

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