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Control Systems Technology, IEEE Transactions on

Issue 4 • Date Jul 1998

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Displaying Results 1 - 13 of 13
  • Design and analysis of synchronization for real-time closed-loop control in robotics

    Page(s): 445 - 461
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    In the framework of the ORCCAD system, periodic and multirate control laws are implemented in terms of a set of computing tasks to be executed under a real-time operating system. Simulations and experiments demonstrate that partially synchronizing such tasks can improve the practical performance of the implementation. However, using synchronizations may lead to dead-locks or temporal inconsistencies. In this paper, we examine the consequences of introducing such synchronization in terms of structural and temporal problems which may occur and how they may be detected using Petri net modeling and analysis. We conclude with some guidelines about how to add such synchronization to design deadlock-free and efficient implementations of real-time periodic control laws View full abstract»

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  • Controller development for a prototype high-speed low-tension tape transport

    Page(s): 534 - 542
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    This paper describes the entire MIMO process control system design for a prototype tape spooler that is used for conducting research into the dynamics of high-speed and low-tension tape transport. The tape speed and tension are regulated by controlling the torque applied to the supply and the take-up reels. Each reel is directly driven by a motor, and no capstan is used. The system has slowly time-varying dynamics due to changing reel packs, but more challenging are dynamics associated with low-tension operation. The spooler operates near a hard nonlinearity, because the tape only supports positive tension. At low tension, air entrainment in between layers of tape in the take-up reel causes the effective spring constant of the tape to rapidly decrease during start-up. This paper describes: physical modeling of the transport, iterative MIMO system identification and controller optimization. Adaptive tension ripple cancellation and fault detection and compensation are demonstrated View full abstract»

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  • High-order iterative learning identification of projectile's aerodynamic drag coefficient curve from radar measured velocity data

    Page(s): 563 - 570
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    Extracting projectile optimal fitting drag coefficient curve Cdf from radar measured velocity data is considered as an optimal tracking control problem (OTCP) where Cdf is regarded as a virtual control function while the radar measured velocity data are taken as the desired output trajectory to be optimally tracked. With a three-degree of freedom point mass trajectory prediction model, a high-order iterative learning identification scheme with time varying learning gains is proposed to solve this OTCP with a minimax performance index and an arbitrarily chosen initial control function. The convergence of the high-order iterative learning identification is analyzed and a guideline to choose the time varying learning gains is given. The curve identification results from a set of actual flight testing data are compared and discussed for different learning gains. These results demonstrate that the high-order iterative learning identification is effective and applicable to practical curve identification problems View full abstract»

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  • Coordinated control of blending systems

    Page(s): 495 - 506
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    Blending is an important unit operation in chemical process industries. Based on Luyben's work (1990), a coordinated control is proposed to overcome the system interaction and process nonlinearity in blending processes. Blending systems with ideal and nonideal mixing are explored. Furthermore, unusual dynamic behavior is observed for blending systems coupled with complex dynamics arisen from the process side. Controlling the blending of streams from different sidestream locations of a distillation column is studied and, based on physical insight, a simple procedure is proposed for the selection of sidedraw locations. The disturbance rejection aspects of blending control are discussed and practically important issues such as model uncertainties and measurement noise are also treated. Simulation results show that the control of blending systems is not as trivial as it was thought and, more importantly, improvement in the performance can be achieved using the proposed coordinated control View full abstract»

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  • Model reference adaptive control of heart rate during wheelchair ergometry

    Page(s): 507 - 514
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    This study used parametric methods to identify a model of the wheelchair user's heart rate response to changes in physical workload while on a wheelchair dynamometer. A model reference adaptive control (MRAC) algorithm was developed based upon the results of the system identification process. Based upon subject's maximum speed, ten random levels from zero to maximal speed were selected to form a tracking input vector. Two autoregressive models with exogenous inputs were developed using a stepwise regression-based algorithm. Analysis of variance results imply that the model development and model validation groups were different. Linear regression was used to compare the model predicted heart rates with recorded heart rates for the validation group. The application of indirect MRAC appears to be feasible for controlling heart rate kinetics of people with paraplegia or lower limb impairments during wheelchair propulsion on a computer-controlled wheelchair dynamometer View full abstract»

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  • Modeling and L2-stability of a shape memory alloy position control system

    Page(s): 473 - 481
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    Shape memory alloys (SMAs) are inherently nonlinear devices exhibiting significant hysteresis in their stress-strain-temperature characteristic. As a consequence most SMA actuator systems presented in the literature employ some form of proportional-integral-derivative (PID) or pulse-width modulated (PWM) control. However, due to the hysteresis of the SMA, the theoretical stability of these systems has been largely ignored. This paper extends the work of Ikuta et al. (1991) to arrive at a new model of an SMA actuator. The key feature of the model is its ability to model minor hysteresis loops. The model is suitable for computer simulation, even of closed-loop control systems, as well as control system analysis. Indeed, the model is used to prove the L2-stability of a position control system View full abstract»

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  • Genetic-based fuzzy clustering for DC-motor friction identification and compensation

    Page(s): 462 - 472
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    A fuzzy-logic-based model describing the friction present in a DC-motor system is derived. Based on fuzzy clustering techniques, the structure, as well as the premise and consequence parameters are inferred in an off-line manner. The fine-tuning of these parameters is accomplished through a genetic algorithm which minimizes a system modeling relevant functional. The genetic algorithm encodes these parameters as chromosomes, and creates the next generation of fuzzy models through natural selection and survival of the fittest chromosome. This model is used as a feedforward term for tracking purposes of the DC-motor's angular velocity. The proposed feedforward compensation scheme, coupled to a classical feedback controller improves the system's response in typical DC-motor micromaneuvers. Experimental results are offered to validate the performance of the proposed friction fuzzy model and the control technique View full abstract»

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  • A dissipativity approach to stability of a shape memory alloy position control system

    Page(s): 554 - 562
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    This paper deals with the L2 stability of a shape memory alloy (SMA) actuated position control system, based on a single SMA wire under constant axial load. It is shown that the system stability can be guaranteed for a large class of controllers having certain dissipativity characteristics. In particular, the results can be used to show stability under approximated proportional integral derivative (PID), PI, and PD control. Experimental step responses are given for two different PI controllers. The first controller guarantees a stable response, based on the work presented. While the second system displays superior performance and seems stable, but it does not satisfy the stability criterion of the paper. This comparison underscores the conservative nature of the stability result View full abstract»

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  • Development and autocalibration of an input-output model of chlorine transport in drinking water distribution systems

    Page(s): 543 - 553
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    Chlorine concentrations within drinking water distribution systems (DWDS) must be maintained between an Environmental Protection Agency enforced minimum and maximum values driven by formation of harmful disinfectant byproducts. The DWDS input-output (I-O) model developed expresses the chlorine concentration at a given pipe junction and time as a weighted average of exponentially decayed values of the concentrations at all adjacent upstream junctions. The upstream junction concentrations are known if they are a chlorine treatment point, or can be calculated in the same manner as the original unknown junction concentration. This is the basis for a recursive procedure with which the I-O model backtracks through the DWDS until all paths from consumption to treatment are found. Since the I-O model finds all paths from treatment to a given measurement, the reaction rate associated with chlorine decay at the pipe wall can be adjusted to improve predicted chlorine concentrations View full abstract»

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  • A comparative study of conventional nonsmooth time-invariant and smooth time-varying robust compensators

    Page(s): 571 - 576
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    Variable structure-based robust compensators are general approaches to deal with uncertain nonlinear dynamic systems. The bang-bang (discontinuous-type) compensator and the saturation (continuous-type) compensator are the two common robust compensators used in variable structure controllers. This paper presents a comparative study of these two nonsmooth time-invariant robust compensators with a smooth time-varying compensator and reveals the superiority of the smooth time-varying compensator over the nonsmooth robust compensators View full abstract»

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  • Path-tracking for articulated vehicles with off-axle hitching

    Page(s): 515 - 523
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    A technique that complements path-tracking controller design procedures based on exact linearization is proposed. The objective is to make these procedures applicable to vehicles whose kinematic model is not necessarily exactly linearizable (as a tractor-trailer with off-axle hitching or a load-haul-dump mining vehicle). A key element of our approach is to control a inexactly linearizable vehicle by associating to it an auxiliary (ghost) vehicle whose model can be exactly linearized and whose behavior satisfies certain compatibility conditions. Main features of this approach are illustrated by considering articulated vehicles with off-axle hitching (which are not exactly-linearizable), and by focusing attention to a geometric path-tracking design procedure recently developed by Sampei et al. (1993, 1995) View full abstract»

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  • Robust control of a flexible robot arm using the quadratic d-stability approach

    Page(s): 524 - 533
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    This paper shows how the quadratic d-stability design method provides a solution to a flexible robot arm control problem. The experimental process exhibits time delay, nonminimum phase behavior and lightly damped modes. The method is based on pole placement considerations and involves the resolution of two parameter dependent Riccati equations with an extra condition. Performances achieved numerically by the designed controller are tested on the physical system View full abstract»

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  • Algorithms for sensitivity analysis of Markov systems through potentials and perturbation realization

    Page(s): 482 - 494
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    We provide algorithms to compute the performance derivatives of Markov chains with respect to changes in their transition matrices and of Markov processes with respect to changes in their infinitesimal generators. Our algorithms are readily applicable to the control and optimization of these Markov systems, since they are based on analyzing a single sample path and do not need explicit specification of transition matrices, nor infinitesimal generators. Compared to the infinitesimal perturbation analysis, the algorithms have a wider scope of application and require nearly the same computational effort. Numerical examples are provided to illustrate the applications of the algorithms. In particular, we apply one of our algorithms to a closed queueing network and the results are promising View full abstract»

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