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Control Systems, IEEE

Issue 2 • Date April 1997

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Displaying Results 1 - 7 of 7
  • Experimental evolutionary programming-based high-precision control

    Publication Year: 1997 , Page(s): 66 - 74
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1161 KB)  

    Conventional linear control schemes often fail to provide precise positioning of a control object under the influence of friction, deadzone, saturation, etc. This article proposes a high-precision control scheme for a precise point-to-point positioning system, called an X-Y table, even under the above-noted influences. The proposed scheme is composed of a fuzzy precompensator and a PD controller. The fuzzy precompensator is employed to improve the performance of the PD controller. Its fuzzy rules are obtained from experimental evolutionary programming (EEP), not from an expert. The effectiveness of the scheme is demonstrated by experiments on the X-Y table, with a positioning error of less than 1 μm and settling time of less than 0.15 s, where the maximum velocity and acceleration are 0.25 m/s and 1.7 m/s2, respectively. View full abstract»

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  • Execution of saccades for active vision using a neurocontroller

    Publication Year: 1997 , Page(s): 18 - 29
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1880 KB)  

    An important mechanism in active vision is that of fixating to different targets of interest in a scene. We present a two-stage design of a neurocontroller for the execution of saccades. The first stage is an “open loop” mode based on a learned spatial representation while the second stage is a closed-loop “visual servoing” mode. Explicit calibration of the kinematic and imaging parameters of the system is replaced with a self-organized learning scheme, thereby providing a flexible and efficient saccade control strategy. Experiments on the University of Illinois Active Vision System (UIAVS) are used to establish the feasibility of this approach View full abstract»

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  • Developing commercial applications of intelligent control

    Publication Year: 1997 , Page(s): 94 - 100
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (824 KB)  

    Intelligent control techniques that emulate characteristics of biological systems offer opportunities for creating control products with new capabilities. In today's competitive economic environment, these control techniques can provide products with the all-important competitive edge that companies seek. However, while numerous applications of intelligent control have been described in literature, few get past the simulation stage to become laboratory prototypes, and only a handful make their way into products. The ability of research work to impact products hinges not so much on finding the best solution to a problem but on finding the right problem and then solving it in a marketable way. The author offers some comments on how to find the “right” problem for intelligent control and what constitutes a marketable solution. Examples from fuzzy logic and neural network based control are used to illustrate the principles View full abstract»

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  • Cell mapping for controller design and evaluation

    Publication Year: 1997 , Page(s): 52 - 65
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1584 KB)  

    Cell mapping is a powerful computational technique for analyzing the global behaviour of nonlinear dynamical systems. It simplifies the task of analyzing a continuous phase space by partitioning it into a finite number of disjoint cells and approximating system trajectories as cell transitions. The resulting cell map provides global measures of stability and other performance characteristics that are valuable in system analysis and controller design. This article shows how cell mapping can be used to design high-performance, conventional and fuzzy, controllers. It also shows how cell maps can provide global performance measures of the designed controllers, including time optimality, controllability, and empirical assessments of robustness. Evaluating controller performance based on these global measures is superior to simply examining time domain responses for various initial conditions View full abstract»

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  • Fuzzy guidance controller for an autonomous boat

    Publication Year: 1997 , Page(s): 43 - 51
    Cited by:  Papers (30)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    A fuzzy guidance controller is developed for waypoint following guidance on a small autonomous boat. The boat is a prototype vehicle developed at the MIT Sea Grant College Program and is designed to perform autonomous oceanographic research. The fuzzy controller is programmed in C and down-loaded to a small onboard computer for execution. Navigation data is found in real-time using a digital compass and a differentially corrected GPS receiver. The fuzzy controller was found to be relatively easy to develop, simple to tune, and robust to external disturbances. Field test results are presented and show that the guidance controller performed well on complex paths View full abstract»

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  • A systematic classification of neural-network-based control

    Publication Year: 1997 , Page(s): 75 - 93
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1944 KB)  

    Successful industrial applications and favorable comparisons with conventional alternatives have motivated the development of a large number of schemes for neural-network-based control. Each scheme is usually composed of several independent functional features, which makes it difficult to identify precisely what is new in the scheme. Help from available overviews is therefore often inadequate, since they usually discuss only the most important overall schemes. This work breaks the available schemes down to their essential functional features and organizes the latter into a multi-level classification. The classification reveals that similar schemes often get placed in different categories, fundamentally different features often get lumped into a single category, and proposed new schemes are often merely permutations and combinations of the well-established fundamental features. The classification has two main sections: neural network only as an aid; and neural network as controller View full abstract»

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  • Neurofuzzy model-based weld fusion state estimation

    Publication Year: 1997 , Page(s): 30 - 42
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1320 KB)  

    Proper fusion is crucial in generating a sound weld. Successful control of the fusion state requires accurate measurements of both the topside and back-side bead widths. A top-side sensor-based system is preferred so that the sensor can be attached to and moved with the torch. Thus, the system must be capable of estimating the back-side bead width with high accuracy. Because skilled human operators can estimate the fusion state from the observed weld pool, a neurofuzzy system is developed to infer the backside bead width from the pool geometry in this work. It is found that the back-side bead width can be estimated with satisfactory accuracy by the identified neurofuzzy model. Thus, accurate feedback of the fusion state can be provided for its control View full abstract»

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Jonathan P. How
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