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Control Systems Technology, IEEE Transactions on

Issue 1 • Date Jan 2000

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Displaying Results 1 - 18 of 18
  • Reinforcement adaptive learning neural-net-based friction compensation control for high speed and precision

    Page(s): 118 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    There is an increasing number of applications in high-precision motion control systems in manufacturing, i.e., ultra-precision machining, assembly of small components and micro devices. It is very difficult to assure such accuracy due to many factors affecting the precision of motion, such as frictions and disturbances in the drive system. The standard proportional-integral-derivative (PID) type servo control algorithms are not capable of delivering the desired precision under the influence of frictions and disturbances. In this paper, the frictions are identified by a neural net, which has a critic element to measure the system performance. Then, the weight adaptation rule, defined as reinforcement adaptive learning, is derived from the Lyapunov stability theory. Therefore the proposed scheme can be applicable to a wide class of mechanical systems. The simulation results on a 1-degree-of-freedom mechanical system verify the effectiveness of the proposed algorithm View full abstract»

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  • Poles identification of an analog filter for nuclear spectroscopy via subspace-based techniques

    Page(s): 127 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    In this paper, a method for the identification of the poles-zeros position of an analog amplifier for nuclear spectroscopy is presented. The proposed technique is based upon a subspace-based system state-space identification (4SID) method, which is well suited to a data set constituted by a noisy measurement of the impulse response of the circuit. The 4SID method is complemented with a preprocessing technique of the data, which improves the accuracy of the estimation. The identification method is tested both on simulated and real data sets View full abstract»

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  • Multipredictive adaptive control of arc welding trailing centerline temperature

    Page(s): 159 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    This application paper addresses the use of adaptive predictive control on arc welding trailing centerline temperature control. For tackling the high level of uncertainty in the process the multivariable multipredictive adaptive regulator (MUSMAR) adaptive algorithm, relying on separate estimation of predictive models is used. Experimental results presented include characterization of plant uncertainty and of the effect in control performance of various available knobs, in particular in the presence of plates with variable geometry View full abstract»

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  • Constrained output feedback control of a multivariable polymerization reactor

    Page(s): 87 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A multivariable nonlinear control strategy which accounts for unmeasured state variables and input constraints is developed for the free-radical polymerization of methyl methacrylate in a continuous stirred tank reactor. Monomer concentration and reactor temperature are controlled using a technique which combines nonlinear input-output decoupling and linear model predictive control. Input constraints are handled explicitly by applying linear model predictive control to the constrained linear system obtained after feedback linearization and constraint transformation. Unmeasured initiator and solvent concentrations are accounted for by treating the live polymer concentration as an unknown parameter which is estimated online. The performance of the control strategy is compared to other nonlinear control techniques through closed-loop simulations View full abstract»

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  • Numerical solution of nonlinear ℋ2 and ℋ control problems with application to jet engine compressors

    Page(s): 98 - 111
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    We describe an effective numerical approach to solving nonlinear ℋ2 or ℋ optimal control problems. Our principal goal is to use this approach to solve the important problem of jet engine compressor control. The technique is demonstrated first with the tutorial example of the control of a pendulum. We then apply the numerical approach to the problem of controlling jet engine compressor stall and surge instabilities (three-dimensional Moore-Greitzer model) while imposing saturation constraints. Standard in this model is a curve of equilibria along which one may operate the engine. Here, the instabilities are hardest to control near the highest performance equilibria. Our numerical results tell us rather dramatically which equilibrium one can optimally control to and which are unmanageable. The magnitude of the rate saturation constraint on the controller turns out to dominate this phenomenon. We choose a high-performance manageable equilibrium E and compute the ℋ2 optimal law which will control the system to E. We then describe plots which allow one to find a neighborhood of the equilibrium within which the closed-loop system is guaranteed to remain. The technique should work with little modification in dimensions 4 and 5, at which point the “curse of dimensionality” forces restrictions View full abstract»

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  • A discrete Fourier transform approach to a constrained mixed H2 sensitivity optimization with applications

    Page(s): 138 - 150
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    This paper addresses a robust controller design for multiinput-multioutput (MIMO) discrete-time systems by approximately solving a constrained mixed H2 sensitivity minimization problem. Using some of the digital image restoration techniques and by working in the discrete Fourier transform (DFT) domain, we convert the H 2 control problem into a constrained vector minimization problem in the l2-space. A two-stage solution approach is detailed and the robust controller is constructed. The advantage of using the proposed method is that the l2-space solution can be analytically expressed and efficiently calculated via existing multichannel algorithms due to the partially block circular structure of the matrices involved in the DFT domain. The approximation can be made arbitrarily close to the original H2 control problem if the number of the DFT points is large. Several examples are given to demonstrate the feasibility of the proposed method View full abstract»

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  • Level control in the steam generator of a nuclear power plant

    Page(s): 55 - 69
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    Poor control of the steam generator water level in the secondary circuit of a nuclear power plant can lead to frequent reactor shutdowns. Such shutdowns are caused by violation of safety limits on the water level and are common at low operating power where the plant exhibits strong nonminimum phase characteristics and flow measurements are unreliable. There is, therefore, a need to systematically investigate the problem of controlling the water level in the steam generator in order to prevent such costly reactor shutdowns. The paper presents a framework for addressing this problem based on an extension of the standard linear model predictive control algorithm to linear parameter varying systems View full abstract»

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  • High-precision positioning of a mechanism with nonlinear friction using a fuzzy logic pulse controller

    Page(s): 151 - 158
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A new approach to very accurate positioning of mechanical devices with nonlinear (stick-slip) friction is presented in this paper. The proposed controller applies narrow torque pulses to move a mechanism to a desired position despite nonlinear friction. The pulse shapes generated by the controller are computed using a fuzzy logic approximation of the dependence between the desired displacement and the torque pulse shape. The closed-loop stability conditions for the proposed controller are derived taking into consideration a random variation of friction. A detailed experimental study of the system response to different torque pulse shapes and a detailed controller design are presented for a direct-drive mechanism. In the experiments it was demonstrated that the proposed controller achieves positioning accuracy which is within the limits of the position encoder resolution View full abstract»

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  • Experimental evaluation of predictive temperature control for a batch reactor system

    Page(s): 2 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    A nonlinear generalized predictive control (NLGPC) algorithm developed by Katende and Jutan (1996) is tested on a nonlinear batch reactor system by carrying out a number of experiments and comparing its performance with other control strategies. This experimental setting allows a more practical comparison of the relative merits of these controllers. The NLGPC is shown to outperform the constrained self-tuning PID (STPID) controller by Katende and Jutan (1993), and the generalized minimum variance (GMV) controller by Clarke and Gawthrope (1975). It is also shown to have better performance than the well-known generalized predictive control (GPC) algorithm by Clarke et al. (1987). The advantage of the NLGPC over the other controllers is attributed to its adaptive nature and use of nonlinear process models in its design View full abstract»

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  • An intelligent contraflow control method for real-time optimal traffic scheduling using artificial neural network, fuzzy pattern recognition, and optimization

    Page(s): 183 - 191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    Contraflow operation is frequently used for reducing traffic congestion near tunnels and bridges where traffic demands from the opposite directions vary periodically. In this work, a generic real-time optimal contraflow control method has been introduced. The introduced method integrates two important functional components: 1) an intelligent system with artificial neural network and fuzzy pattern recognition to accurately estimate the current traffic demands and predict the coming traffic demands, and 2) a mixed-variable, multilevel, constrained optimization to identify the optimal control parameters. Application of the developed method to a case study-dynamic contraflow traffic operation at the George Massey Tunnel in Vancouver, BC, Canada-has significantly reduced traffic delay and congestion View full abstract»

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  • Engine idle speed control using actuator saturation

    Page(s): 192 - 199
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    Presented in this paper is the design and experimental validation of a saturating engine idle speed controller for a Ford V-8 fuel injected engine. The nonmeasurable external torque disturbance perturbing engine speed is delivered from the power steering pump. The performance specification is an allowable engine speed tolerance of 140 r/min about a desired set speed of 600 r/min. The controlled input is a voltage to the bypass air valve (BPAV) which regulates the air ingested into the engine. The BPAV voltage available for engine speed regulation is bounded by 0.8 V. A frequency domain controller design methodology is used to design the controller The performance objective is satisfied using saturation control during large engine speed transients. During steady-state operation, the controlled input is not saturated View full abstract»

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  • Variable camshaft timing engine control

    Page(s): 23 - 34
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    Retarding camshaft timing in an engine equipped with a dual equal camshaft timing phaser reduces the unburned hydrocarbons (HC) and oxides of nitrogen (NOx) emitted to the exhaust system. Apart from this positive effect to feedgas emissions, camshaft timing can cause large air-to-fuel ratio excursions if not coordinated with the fuel command. Large air-to-fuel ratio excursions can reduce the catalytic converter efficiency and effectively cancel the benefits of camshaft timing. The interaction between the camshaft timing and the air-to-fuel ratio results in an inherent tradeoff between reducing feedgas emissions and maintaining high catalytic converter efficiency. By designing and analyzing a decentralized and a multivariable controller, we describe the design limitation associated with the decentralized controller architecture and we demonstrate the mechanism by which the multivariable controller alleviates the limitation View full abstract»

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  • Robust control of flexible structures against structural damage

    Page(s): 170 - 182
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    This paper deals with the vibration suppression control problem of flexible structures against potential damage. The controller is required not only to robustly stabilize the structure but to satisfactorily suppress the vibration under all the predicted damages that might occur in the 20-bay truss structure under study. The damage to the flexible structure we consider here is represented by the various stiffness losses of predetermined elements. The structure with the predicted damages is modeled as an interval transfer function. The controller design is based on the μ-synthesis in conjunction with the extremal properties of interval systems. Unlike conventional μ-synthesis, the technique enables us to use a fixed-size uncertainty block [four real blocks for the single input-single output (SISO) case] regardless of the number of parameters, resulting in a fast, reliable, and simple synthesis procedure View full abstract»

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  • Force sensing control for electric powered wheelchairs

    Page(s): 112 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    People with many types of disabilities use electric powered wheelchairs (EPWs) for mobility. Excessive intention tremor, limited range of motion, athetoid motions, and spastic rigidity can reduce or prohibit the control over an EPW. This study focused on the design and testing of a newly developed isometric joystick (IJ) for EPW control. The IJ was tested against existing performance standards and compared to a commercial position sensing joystick (PSJ). When averaged across all subjects (both controls and impaired subjects) the root-mean-square tracking error and time to complete the driving course were not significantly different when using the rule (p<0.05). Results within a subject, however, did show significance. Across all subjects, nevertheless, the IJ was superior to the PSJ for two tasks: driving straight and driving in a circle. Further development of control algorithms, especially the implementation of digital control, could lead to greater improvement in performance with the IJ View full abstract»

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  • Robust nonlinear speed control of PM synchronous motor using boundary layer integral sliding mode control technique

    Page(s): 47 - 54
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    A digital signal processor (DSP)-based robust nonlinear speed control of a permanent magnet synchronous motor (PMSM) is presented. A quasi-linearized and decoupled model including the influence of parameter variations and speed measurement error on the input-output feedback linearization of a PMSM is derived. Based on this model, a boundary layer integral sliding mode controller is designed and compared to a feedback linearization-based controller that uses proportional plus derivative (PD) controller in the outer loop. To show the validity of the proposed control scheme, DSP-based experimental works are carried out and compared with the conventional control scheme View full abstract»

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  • Shape control systems for Sendzimir steel mills

    Page(s): 70 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Deals with the problem of shape (or flatness) control for Sendzimir 20-roll cold-rolling steel mills. Such mills, with a variety of shape actuators, offer the control engineer considerable choice in the configuration and design of a shape control system. In addition, the Sendzimir mill is a reversing mill, with shape measurement devices at either end of the mill, providing a facility for feedforward of incoming shape disturbances. The multivariable problem presented by the mill has a significant singularity problem, which is tackled in the paper using a variety of approaches, motivated by both practical (operational) considerations and formal theoretical procedures. A final challenge lies in the desire to economize on the number of controllers required to cover the mill over its wide range of operating conditions. The paper compares and contrasts various controller possibilities and is intended to provide a “cookbook” of shape control tools and strategies for Sendzimir mills View full abstract»

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  • Applications of radial basis network technology to process control

    Page(s): 14 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Modern industrial process automation systems are organized as hierarchical systems, with at least three levels: field, direct control, and supervisory level. The paper presents applications of radial basis function (RBF) networks in each one of these levels. The first example illustrates the application of these networks to improve the performance of a control valve. The second example demonstrates the potential of an RBF network to deal with nonlinear processes as direct controller. The third example, illustrates the use of a supervisory system to tune proportional integral controllers, implemented in a distributed environment. These examples do not only present some applications of RBF technologies to process control, but also demonstrate, through practical examples, that this technology can be implemented in existing control systems View full abstract»

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  • Estimation and control for a modular wheeled mobile robot

    Page(s): 35 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    In this paper the problem of fully decentralized data fusion and control for a modular wheeled mobile robot (WMR) is addressed. This is a vehicle system with nonlinear kinematics, distributed multiple sensors, and nonlinear sensor models. The problem is solved by applying fully decentralized estimation and control algorithms based on the extended information filter. This is achieved by deriving a modular, decentralized kinematic model by using plane motion kinematics to obtain the forward and inverse kinematics for a generalized simple wheeled vehicle. This model is then used in the decentralized estimation and control algorithms. WMR estimation and control is thus obtained locally using reduced order models with reduced communication requirements, in a scalable network of control nodes, If communication of information between nodes is carried out after every measurement (full rate communication), the estimates and control signals obtained at each node are equivalent to those obtained by a corresponding centralized system. Transputer architecture is used as the basis for hardware and software design as it supports the extensive communication and concurrence requirements which characterize modular and decentralized systems. The advantages of a modular WMR vehicle include scalability, application flexibility, low prototyping costs and high reliability View full abstract»

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