Showing papers on "Smith predictor published in 2002"

Internet-based teleoperation using wave variables with prediction

Abstract: Wave-based teleoperation has been previously attempted over the Internet, however, performance rapidly deteriorates with increasing delay. This paper focuses on the use of a modified Smith predictor, a Kalman filter and an energy regulator to improve the performance of a wave-based teleoperator. This technique is further extended for use over the Internet, where the time delay is varying and unpredictable. It is shown that the resulting system is stable even if there are large uncertainties in the model of the remote system (used in prediction). Successful experimental results using this technique for teleoperation in a master-slave arrangement over the Internet, where the control signal is streamed between Atlanta (Georgia) and Tokyo (Japan), are also given.

Neural methods for dynamic branch prediction

Abstract: This article presents a new and highly accurate method for branch prediction. The key idea is to use one of the simplest possible neural methods, the perceptron, as an alternative to the commonly used two-bit counters. The source of our predictor's accuracy is its ability to use long history lengths, because the hardware resources for our method scale linearly, rather than exponentially, with the history length. We describe two versions of perceptron predictors, and we evaluate these predictors with respect to five well-known predictors. We show that for a 4 KB hardware budget, a simple version of our method that uses a global history achieves a misprediction rate of 4.6p on the SPEC 2000 integer benchmarks, an improvement of 26p over gshare. We also introduce a global/local version of our predictor that is 14p more accurate than the McFarling-style hybrid predictor of the Alpha 21264. We show that for hardware budgets of up to 256 KB, this global/local perceptron predictor is more accurate than Evers' multicomponent predictor, so we conclude that ours is the most accurate dynamic predictor currently available. To explore the feasibility of our ideas, we provide a circuit-level design of the perceptron predictor and describe techniques that allow our complex predictor to operate quickly. Finally, we show how the relatively complex perceptron predictor can be used in modern CPUs by having it override a simpler, quicker Smith predictor, providing IPC improvements of 15.8p over gshare and 5.7p over the McFarling hybrid predictor.

Control of integral processes with dead-time. Part 1: Disturbance observer-based 2DOF control scheme

Abstract: This paper reveals that a disturbance observer-based control scheme is very effective in controlling integral processes with dead time. The controller can be designed to reject ramp disturbances as well as step disturbances, even arbitrary disturbances. Only two parameters are left to tune when the plant model is available . One is the time constant of the setpoint response and the other is the time constant of the disturbance response. The latter is tuned according to the compromise between disturbance response and robustness. This control scheme has a simple, clear, easy-to-design, easy-to-implement structure and good performances. It is compared to the best results (so far) using some simulation examples. Index Terms: Dead-time compensator, robustness, integral processes, disturbance observer, Smith predictor, 2DOF IMC

An extension of predictive control, PID regulators and Smith predictors to some linear delay systems

Abstract: We investigate an extension of predictive control, PID controllers, and Smith predictors to some classes of linear delay systems which are most encountered in practice The predictive part is provided by extending flatness-based predictive control Generalized PI regulators lead to a 'PID and Smith predictor'-like scheme which permits us to easily handle (deadtime-dominant) unstable systems Numerous examples with thorough simulations demonstrate the performance of the proposed control strategy

Teleoperation systems design using augmented wave-variables and Smith predictor method for reducing time-delay effects

Abstract: The performance of a wave-based teleoperator is heavily dependent on the amount of time delay present in the system. Although wave variables provide a very promising method to establish teleoperation in the presence of any time delay, the tracking error in a wave-based teleoperator will be increased by increasing the time delay. In this paper, we introduce a new method for reducing time delay effects in teleoperation systems. By the proposed method, the wave variable method is combined with the Smith predictor. The simulation result is presented and it is shown that the new approach provides good performance compared with the wave variable technique alone.

Control of integral processes with dead-time. 2. Quantitative analysis

Abstract: Several different control schemes for integral processes with dead time resulted in the same disturbance response. Moreover, it has already been shown that such a response is subideal. Hence, it is quite necessary to quantitatively analyze the achievable specifications and the robust stability regions. This paper is devoted to do so. As a result, the control parameter can be quantitatively determined with compromise between the disturbance response and the robustness. Four specifications — (normalized) maximal dynamic error, maximal decay rate, (normalized) control action bound and approximate recovery time — are given to characterize the step-disturbance response. It shows that any attempt to obtain a (normalized) dynamic error less than is impossible and a sufficient condition on the (relative) gain-uncertainty bound is . Index Terms: Dead-time compensator, robustness, integral processes with dead time, disturbance observer, Smith predictor

Multirate predictor control scheme for visual servo control

Abstract: An attractive control scheme for a position-based dynamic "look-and-move" eye-in-hand visual servo system is proposed. The multi-rate predictor control scheme is used to overcome the inherent delay in the vision system and the multi-rate nature of the dynamic look-and-move visual servo control scheme. The control scheme takes the form of a simple predictor placed in the major feedback of the standard Smith predictor control scheme. This in turn eliminates the delay time between the dynamics of the observed target and the control, in a similar fashion to the feedforward Smith predictor. Hence the proposed control scheme is also known as the modified Smith predictor (MSP) control scheme. A detailed analysis of the proposed control scheme is presented for visual servo control. Representative computer simulation studies are presented to verify the effectiveness of the proposed multi-rate predictor control scheme for dynamic visual tracking.

Optimal and robust integral sliding mode filter design for systems with continuous and delayed measurements

Abstract: In this paper, the optimal filtering problem for a linear system over observations with a fixed delay is treated, proceeding from the general expression for the stochastic Ito differential of the optimal estimate and its variance. As a result, the optimal filtering equations similar to the traditional Kalman-Bucy filter are obtained in the form dual to the Smith predictor, commonly used control structure for model-based time delay compensation. The paper then presents a robustification algorithm for the obtained optimal filter based on sliding mode compensation of disturbances. As a result, the sliding mode control of observations leading to suppression of the disturbances in a finite time is designed. This control algorithm also guarantees finite-time convergence of the estimate based on the corrupted observations to the optimal estimate satisfying the obtained optimal filtering equations over delayed observations.

A Smith-prediction based haptic feedback controller for time delayed virtual environments systems

Abstract: A modified Smith predictor for linear delayed haptic interaction is presented. The objective is to design a feedback law which compensates the time delay by its somehow elimination from the characteristic equation of the closed loop system. This method is robust within a certain safe prediction interval. The applicability of Smith predictor in the case of haptic interaction using computer haptic algorithms is shown.

2-Degree-of-Freedom Proportional-Integral-Derivative-Type Controller Incorporating the Smith Principle for Processes with Dead Time

Abstract: The Smith predictor is the most effective control scheme for processes with dead time while the proportional−integral−derivative (PID) controller is the most widely used controller in industry. This paper presents a control scheme which combines their advantages. The proposed controller is inherently a PID-type controller in which the integral action is implemented using a delay unit rather than a pure integrator while retaining the advantage of the Smith predictor (Smith principle). The setpoint response and the disturbance response are decoupled from each other and can be designed separately. Another advantage of this control scheme is that the robustness is easy to analyze and can be guaranteed explicitly, compromising between the robustness and the disturbance response. Examples show that this controller is very effective in the control of processes with dead time.

Automatic Smith-predictor tuning using optimal parameter mismatch

Abstract: The Smith-predictor is famous for its delay-free characteristic and suitable for regulating systems with an excessively long time delay. However, it is sensitive to plant parameter variations based on some frequency domain studies. In this paper, detailed analyzes of the system performance through parametric and temporal mismatch are investigated and accompanied with closed form solutions. Based on the derived solutions, the optimal performance and stability characteristic of a Smith-predictor compensated control system is examined. It is found that the system performance can be improved by introducing an intentional parametric or temporal mismatch and the corresponding optimal tunings are determined based on the value of a normalized plant parameter. The theoretical results are also summarized to form an automatic Smith-predictor tuning procedure and verified experimentally on a fluid temperature control system for a quiet hydraulic precision lathe.

ATM available bit rate congestion control with on-line network model identification

Abstract: In this paper, the design of available bit rate (ABR) congestion control in ATM (asynchronous transfer mode) networks is considered. The goals of congestion control are high link utilization, low cell loss, and low network delay. Various algorithms for congestion control can be found in the literature. Most of them are based on a network model, which is assumed to be known. In this paper a recursive least square (RLS) algorithm for on-line identification of the network model is implemented and combined with a generalized predictive controller (GPC) and with an I-controller based on the Smith predictor. Simulations were carried out to prove the effectiveness of the proposed algorithms.

Design of a vehicle steering assist controller using driver model uncertainty

Abstract: Single vehicle road departure (SVRD) accidents lead to over 1/3 of highway fatalities in the United States. A steering assist controller to reduce SVRD accidents is proposed. Previous studies using driving simulator data illustrate that the parametric uncertainty can represent the change in driver steering behaviour during long driving task. The uncertainty results show that occasionally the driver can perform very poorly. A serial steering control approach is investigated. The controller is used to attempt robust performance under the influence of driver uncertainty. A robust Smith predictor controller is employed to handle the delay in the driver model. The results indicate that the poor stability situations are successfully avoided and robust stability is achieved. However, due to large variations in driver behaviour, robust performance is not achieved. An adaptive version of the robust Smith predictor controller is shown to reduce the uncertainty in the driver model. The designed controllers are evaluated using frequency domain analyses and computer simulations.

Optimal Smith-Predictor Design Based on a GPC Approach

Abstract: In this paper, an optimal Smith-predictor design based on a generalized predictive control (GPC) approach is developed. The basic idea is to back-calculate the Smith control parameters based on the...

Improved self-adaptive Smith predictive control scheme for time-delay system

Abstract: This paper presents an improved self-adaptive Smith predictive control scheme for time-delay systems. An FNNC (Fuzzy Neural Network Controller) is used to control the plant instead of the conventional PID controller, an improved identification algorithm with an adaptive vector forgetting factor is used to identify time-varying parameters, and the Smith predictor is realised. Simulation results show that this method can suppress the effects of parameter variations.

Design of a PID-Deadtime Control for Time-Delay Systems Using the Coefficient Diagram Method

Abstract: The insertion of a time delay into the integral feedback circuit of a PI/PID controller yields a transfer function similar to a Smith predictor or an internal-model controller. Although it enables better regulatory performance than a conventional PID control algorithm for lag-dominant processes, a systematic design method for this PID-deadtime controller is still lacking. In this paper, we design a PID-deadtime controller using the coefficient diagram method (CDM), which is a kind of model matching approach. The design procedure is simple since it only involves solving a simple optimization problem to determine the controller parameters. The simulation results show that the designed PID-deadtime control loop exhibits a good balance of stability, response and robustness for deadtime-dominant processes.

A novel Smith predictor with double-controller structure

Abstract: Aiming at the disadvantage of the conventional Smith predictor with weak robustness, a novel one with double-controller is proposed in this paper. It has a two-degree of freedom structure so that the setpoint response is decoupled from the disturbance response. Thus, the setpoint tracking and disturbance attenuation controllers can be designed separately. At the same time, the two controllers are all designed into PID structures whose parameters can be adjusted by a parameter, respectively, so that the corresponding response tends to be optimal.

Optimal solution, quantitative performance estimation, and robust tuning of the simplifying controller.

Abstract: Recently, a simplifying controller has been proposed based on the principal of simplification of the control system transfer functions, which offers improved control for processes with large time delay. It is the purpose of this complementary paper to give a comprehensive analysis on the scheme. First, the relationship among the simplifying controller, the Smith predictor, and the internal model control are discussed. Second, and analytical design procedure is developed based on the internal model control (IMC) and optimal solution is derived. Third, the problem of estimating the time domain performance of the closed loop system, quantitatively, is discussed. Fourth, a simple robust tuning procedure is presented. Numerical examples are provided to illustrate the proposed method.

Modified Smith Predictor with DeMenthon-Horaud pose estimation algorithm for 3D dynamic visual servoing

Abstract: This paper presents an attractive position-based visual servoing approach for camera-in-hand robotic systerns. The major contribution of this work is in devising an elegant and pragmatic approach for 3D visual tracking, which yielded good target tracking performance. It differs from the other known techniques, in its approach for image interpretation and the introduction of a Smith-like predictor control structure to overcome the inherent multi-rate time delayed nature of the visual servoing system. A complete description is made of the proposed MSP-DH visual servoing system. Experiments on the target tracking performance on XY planar motion using an AdeptOne robotic system are presented to illustrate the controller performance. In addition, experimental results have clearly shown the capability of the MSP-DH visual servoing system in performing 3D-dynamic visual servoing.

A Learning Control Strategy for Non-minimum Phase Nonlinear Processes

Abstract: This paper presents a learning control strategy for nonlinear process systems having inverse response. Implemented in a generalized Smith predictor configuration, the proposed control scheme integrates a learning-type nonlinear controller and a statically equivalent, minimum-phase predictor. The incorporated minimum-phase predictor is used to compensate an undesired inverse response behavior, which therefore enables the nonlinear controller to learn to control the nonlinear, non-minimum phase processes adaptively by simply using an output-error based learning algorithm. The effectiveness and applicability of the proposed scheme are demonstrated through controlling a nonlinear Van de Vusse reactor in the presence of inverse response characteristics. Performance comparison of the proposed scheme with a previously reported nonlinear technique is performed extensively in this work. The simulation results show that the proposed learning control strategy appears to be an effective and promising approach to the direct control of non-minimum phase nonlinear processes.

Novel controller for integrating and stable processes with long time delay

Abstract: In this paper, a novel control scheme is proposed on the basis of the well-known Smith predictor for the control of integrating processes with long time delay. It can provide one and half degree-of-freedom for the closed loop system tuning. System- atic design procedure is developed by employing optimal control theory, and simple and efficient tuning rules are derived analytically. It is shown that the design procedure can be directly extended to the control of stable processes with time delay. Numerical exam- ples are given to illustrate the proposed method. Copyright © 2002 IFAC