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Adaptive Control of Temperature in Arc Welding

IEEE Control Systems 1994年第4期14卷 4-12页

作者： Nishar, D.v. Schiano, J.L. Perkins, W.R. Weber, R.A. Cummins Engine Company Columbus IN United States Department of Electrical Engineering Pennsylvania State University University Park PA United States Harvard University Cambridge MA United States Welding Technology Center U.S. Army Construction Engineering Research Laboratories Champaign IL United States

We have outlined our approach for developing an integrated system for controlling centerline bead temperature in arc welding. An optical thermography system, based on an inexpensive and readily available video camera, was presented. Temperature measurements obtained with this system are within 10% of those measured by a calibrated two-color optical pyrometer. A low-order model describing the centerline temperature dynamics was developed. Two strategies for tuning a simple PI temperature controller were given. We first used off-line sensitivity-based tuning to optimize the controller gains. This method is adequate for systems whose dynamics are time invariant. For GMAW, however, the plant parameters can vary widely due to changes in plate thickness as well as other operating parameters. For this reason we applied a sensitivity-based pseudogradient adaptive algorithm for self-tuning the PI controller. The self-tuning controller is robust to changes in the operating conditions and is therefore more useful than a PI controller with fixed gains. It is also insensitive to the noise present in the GMAW system. The control design presented in this paper makes no attempt to counter the delay between the arc current command and centerline temperature output. Instead, the sample time was deliberately increased so that this delay could be ignored. To increase the bandwidth of the closed-loop system it is necessary to incorporate a Smith predictor or similar mechanism to increase the response time of the closed-loop system. We are currently investigating the design of a predictive controller.< >

关键词： Adaptive control Welding Delay Temperature control optical sensors Temperature sensors optical tuning Control systems Cameras Temperature measurement

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Use of chemical sensors and process control methods to improve HF chemical etching of dielectric films in a manufacturing environment

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Proceedings of SPIE - The International Society for optical engineering 1994年 2336卷 133-140页

作者： Dolcin, John L. Anyanwu, v.E. Chung, B.C. Draper, Clif W. Ellis, R.Jr. Karp, A. AT&T Microelectronics Allentown PA USA

ISBN: (纸本)081941669X;9780819416698

We report on the use of HF chemical sensors to improve the control of both 100:1 and 15:1 HF etch baths used in a bipolar technology manufacturing line. The commercial HF sensor selected for this application is based on the induction of a current from a primary coil to a secondary coil when the coils are immersed in hydrofluoric acid-water solutions. The design of the sensor is such that only polymer surfaces are exposed to the acid. The output of the sensors are used in a Wet Chemical Advisor we have developed to improve the operator control of the etch baths. We present data demonstrating how the Advisor was used to understand the sources of both episodic and drift variations to the specified bath chemistries. The use of the Wet Chemical Advisor platform has eliminated the need for process monitor wafers, and has greatly reduced the time required by operators for making up or maintaining the facilities within specifications. Historical information is stored in the PC for back reference and for quality control documentation.

关键词： Sensors

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Lithography error budget

Lithography error budget

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64-to 256-Megabit Reticle Generation: Technology Requirements and Approaches: A Critical Review 1993

作者： Canning, John Shelden, Gilbert v. SEMATECH Lithography Division AustinTX78741 United States

As design rules shrink to meet the needs of advanced chips, the allocation of allowable errors between sources gets ever more critical. This paper will examine the error sources and budgets for current technologies and project the requirements for future 64 and 256 megabit generations. The emphasis will be on overlay and critical dimension as a function of design rule generation for the photomask, the photolithographic process and the etching process. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Budget control

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Grumman autonomous Long Life vehicle (LLv)

Grumman autonomous Long Life Vehicle (LLV)

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Mobile Robots vIII Mobile Robots vIII Mobile Robots vIII

作者： Lim, William Y. Peck, Alex N. Sullivan, Edward v.

ISBN: (纸本)0819413232

This paper introduces the Grumman Autonomous Long Life vehicle (LLv) research platform currently under development within Grumman's Corporate Research Center. Topics to be discussed include the system architecture, mechanical design, the actuators, the sensor subsystems, the computing and control hardware, the software system, and safety issues. current progress and plans for the project also are described.

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AN ADAPTIvE NEUROCONTROL design APPLIED TO THE ATTITUDE-CONTROL PROBLEM 5

AN ADAPTIVE NEUROCONTROL DESIGN APPLIED TO THE ATTITUDE-CONT...

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5th International Conference on Applications of Artificial Neural Networks

作者： DRACOPOULOS, DC JONES, AJ UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED DEPT COMPLONDON SW7 2BZENGLAND

ISBN: (纸本)0819415472

A general architecture for neuro-genetw adaptive control is described and contrasted with purely neural approaches to adaptive control. The system is demonstrated on the attitude controiproblem for a rigid body (satellite) equipped with thrusters about each principal axis. By simulating the dynamic system and applying standard neural network techniques a locally predictive network is first trained to the prevailing dynamics. The inputs for the network are a small history of system states up to the present and a set of current control inputs, the outputs are the next system state. It is assumed that a hardware implementation of this network is used to evaluate hypothetical control inputs very rapidly. A genetic algorithm with a simple goal function then searches the space of hypothetical control inputs, whose fitness is evaluated by the neural network, so as to find a satisfactory set of control inputs before the end of the predicted time interval-the whole process is then repeated. The results indicate that such an architecture is able to master the attitude control problem for arbitrary slew angles, with arbitrary unknown dynamics, large unknown deterministic perturbing forces (which left to themselves induce chaotic motion), and noise in the sensor system. © 1994 SPIE. All rights reserved.

关键词： Attitude control

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ADAPTIvE TIME-DELAY NEURAL CONTROL IN LARGE SPACE STRUCTURES 5

ADAPTIVE TIME-DELAY NEURAL CONTROL IN LARGE SPACE STRUCTURES

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5th International Conference on Applications of Artificial Neural Networks

作者： YEN, GG BEAZEL, vM USAF PHILLIPS LABDIV STRUCT & CONTROLSKIRTLAND AFBNM 87117

ISBN: (纸本)0819415472

The design of control algorithms for large space structures, possessing nonlinear dynamics which are often time-varying and likely ill-modeled, presents great challenges for all current methodologies. These limitations have led to the pursuit of a robust and fault tolerant structural controller. In the present paper, we propose the use of adaptive time-delay radial basis function (ATDRBF) networks as a learning controller in system identification and dynamic control of flexible structures. The ability of such neural networks to approximate arbitrary continuous functions offers an efficient means of vibration suppression and trajectory maneuvering for precision pointing capability. The ATDRBF network, which incorporates adaptive time-delays and interconnection weights, provides a feasible and flexible modeling technique to effectively capture all of the spatiotemporal interactions among the structure members. In the spirit of model reference adaptive control, we utilize the ATDRBF network as a building block to allow the neural network to function as a closed-loop controller. The controller regulate the dynamics of the nonlinear plant to follow a prespecified reference model asymptotically. This paper addresses the theoretical foundation of the architecture and demonstrates its applicability via specific examples.

关键词： Neurons Neural networks Control systems Actuators Sensors Adaptive control System identification Aerospace engineering Algorithm development Finite element methods

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A 23,000-FRAME-PER-SECOND 256X128 CAMERA WITH DIGITAL-CONTROL

A 23,000-FRAME-PER-SECOND 256X128 CAMERA WITH DIGITAL-CONTRO...

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Conference on Image Acquisition and Scientific Imaging Systems

作者： LULA, JJ MIETHIG, M LITWILLER, DJ DOODY, BC WASHKURAK, WD CHAMBERLAIN, SG DALSA INC WATERLOO N2V 2E9ONTARIOCANADA

ISBN: (纸本)0819414689

This paper describes the design of a 10 bit, 23,000 frame per second camera with digital control. The camera is based around a 64-tap 256×128 element interline transfer CCD with a current mode output. Readout is at 12MHz per tap for an aggregate data rate of 768 megapixels per second. 16MHz operation (30000 frames per second) is possible with reduced performance. Digitization is to 10 bits with 8.5 bits r.m.s. effective. The signal processing chain allows for digital control of the analog gain and features a feedback loop to maintain offset stability. Linearity of the processing chain is 0.2%. Additional features included digital control of the integration time and readout rate, and digital compensation of light level. Digitized data is transmitted over high speed serial links to a remote rack that emulates the target processing system. An automated analysis system is able to exercise the system and measure performance characteristics. © 1994 SPIE. All rights reserved.

关键词： Cameras

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"Conventional" underwater camera systems-an update

"Conventional" underwater camera systems-an update

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OCEANS

作者： D.J. Stewart Simrad Osprey Limited Aberdeen UK

Despite the emerging developments of exotic laser-based visual imaging systems for underwater use, there is still a significant place for "conventional" camera and lighting systems. This paper seeks to review this fairly mature conventional technology, by examining the trends in the underlying technologies which determine its continuing place in oceanic science and engineering. Specific existing sensors are reviewed, together with sensor developments, in order to establish a useful end-user perspective on current sensor choices. Some prospects for future developments are also presented for consideration by those involved in more advanced programmes.< >

关键词： Cameras Charge coupled devices Sensor phenomena and characterization Marine technology Monitoring Inspection Signal resolution Lighting Laser theory optical design

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Adaptive neurocontrol design applied to the attitude control problem

Adaptive neurocontrol design applied to the attitude control...

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Applications of Artificial Neural Networks v

作者： Dracopoulos, Dimitris C. Jones, Antonia J. Imperial College (United Kingdom)

ISBN: (纸本)0819415472

A general architecture for neuro-genetic adaptive control is described and contrasted with purely neural approaches to adaptive control. The system is demonstrated on the attitude control problem for a rigid body (satellite) equipped with thrusters about each principal axis. By simulating the dynamic system and applying standard neural network techniques a locally predictive network is first trained to the prevailing dynamics. The inputs for the network are a small history of system states up to the present and a set of current control inputs, the outputs are the next system state. It is assumed that a hardware implementation of this network is used to evaluate hypothetical control inputs very rapidly. A genetic algorithm with a simple goal function then searches the space of hypothetical control inputs, whose fitness is evaluated by the neural network, so as to find a satisfactory set of control inputs before the end of the predicted time interval - the whole process is then repeated. The results indicate that such an architecture is able to master the attitude control problem for arbitrary slew angles, with arbitrary unknown dynamics, large unknown deterministic perturbing forces (which left to themselves induced chaotic motion), and noise in the sensor system.

关键词： Genetics Control systems Satellites Genetic algorithms Sensors Adaptive control Neural networks Device simulation Kinematics Dynamical systems

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Analysis, synthesis, and fabrication of vLSI Si detector arrays for optoelectronic interconnections

Analysis, synthesis, and fabrication of VLSI Si detector arr...

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作者： Ouellette, Edward Joseph Massachusetts Institute of Technology

学位级别：硕士

Optics possesses many benefits over electronics for high-speed interconnections. Fur- thermore, the reliability and affordability of current Si CMOS vLSI technologies over other heterogeneous technologies, such as GaAs, suggests that Si optoelectronic mi- crosystems can be a viable, low-cost solution to high-speed interconnect problems. This thesis focuses on the receiver end of optoelectronic interconnects, and more specifically addresses the issues of optimal Si photodetector design within the con- straints of an unmodified CMOS vLSI technology. various photosensors are compatible with a standard Si CMOS vLSI process. The simple graded-junction N+N/P diode was shown to have the best optical and electrical performance of all the types investigated, hence, it was used as a template for a photodetector analysis, synthesis and parasitic extraction CAD tool. A fabricated Si photodetector array in a standard AT&T CMOS process had 0.56 A/W responsivity at 850 nm wavelengths with only 2.5v of reverse bias; the device capacitance was 70 pF/mm 2, and the dark current was 61 nA/mm 2, in agreement with simulations. A new CAD tool was written to address the need for computer automation in the area of photodetector design and analysis. The tool provides analysis and opti- mization of photodiode parameters, synthesis of photodetector array mask geometries (including array wiring) for several photodiode styles, and parasitic model extraction for SPICE simulations. It is both process-technology and hardware-platform inde- pendent allowing portability. Moreover, the output format is compatible with the MOSIS shuttle service, aiding in quick, inexpensive turn-arounds of optoelectronic designs.

关键词： Electrical engineering and Computer Science

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