Showing papers on "Smith predictor published in 1991"

Analysis of a Smith-predictor-based-control concept eliminating the right-half plane zero of continuous mode boost and buck-boost DC/DC converters

Abstract: It is pointed out that the small-signal transfer function of a boost or a buck-boost converter shows a zero located in the right-half complex plane for continuous operation This zero makes the stabilization of the system considerably difficult The authors use a boost converter as an example to show that application of the principle of linear prediction (as originally proposed for the control of systems with dead times) yields the mirror image of the control circuit zero This shift of the zero into the left-half s-plane is achieved with unchanged location of the poles Thereby the small signal transfer function is split into two parts: a phase-minimum system and a nonphase-minimum system The latter can be interpreted as a linear Pade approximation of a dead-time element For the design of a robust control system it is necessary to investigate the shift of the poles of the closed system depending on the change of the operating point How the predictor influences the small- and large-signal system disturbance responses for changes of the load and for input voltage changes is also analyzed >

A design method of self-tuning Smith predictor for unknown time delay system

Abstract: A design method of the self-tuning Smith predictor for an unknown time delay system is proposed The Smith predictor is used instead of the k-step ahead predictor for overcoming the assumption that the dead-time of the plant is unknown The validity of the proposed method has been investigated by numerical simulation The self-tuning dead-time control (ST-DTC) is shown to be applicable to non-minimum phase systems, and to unknown time delay systems The control rule of ST-DTC is simple, and the calculation time of control variables is short A numerical example indicates that the control ability of ST-DTC is superior to other design techniques, for example, the fixed PID (proportional plus integral plus derivative) controller >

Control of a pH process using variable structure regulator and Smith predictor

Abstract: The authors present a variable structure sliding mode control for the pH regulation problem. A variable structure controller is designed considering the nonlinearities and high uncertainties of the pH process characteristics. A Smith predictor is utilized to account for the pH process time delay. Simulation results show that satisfactory performance is obtained even though the pH process has nonlinear characteristics, time delay, and model uncertainties. >

mu analysis and synthesis of time delay systems using Smith predictor

Abstract: The robust performance of the Smith predictor properties is addressed using the structured singular value ( mu ). By employing the properties of the Smith predictor, this time-delay design problem is converted to a corresponding delay-free problem. This conversion not only makes the analysis and synthesis easier, but also avoids problems due to rational time delay approximations. >

Experimental Evaluation of a Kalman Filter based Multistep Adaptive Predictive Controller

Abstract: A Kalman-Filter based Predictor is used for Long Range Predictive Control (LRPC). Special attention is focussed on the performance of the predictor in the presence of time-delay mismatch. The ratio of the measurement and process noise covariances is found to be a very important tuning parameter for the predictor. By increasing the value of this parameter, the predictor gives good future predictions even in the presence of significant time-delay mismatch. The predictor was coupled with a LRPC scheme and the controller was tested on a pilot-scale stirred tank heater, where time-delay mismatches can be easily contrived. The controller not only gave satisfactory servo and regulatory performances in the presence of relatively large time-delay, but it is also very simple to use.

Suboptimal H ∞ and optimal LQG controllers for continuous-time transport-delay systems

Abstract: A polynomial-based solution is presented to the continuous-time LQG and H ∞ control design problems for systems with transport delays. Polynomial solutions to these problems are not currently available in the literature. The multivariable LQG problem is first considered and solved using a Wiener type of analysis. The polynomial solution to this problem is then presented for the scalar case and this result is then used to derive the H ∞, optimal controller. In this latter case an approximation must be introduced but this does not affect the stability of the solution. The H ∞ and LQG controller structures for stable plants resemble a Smith predictor. However, the solution is also applicable to open–loop unstable systems. The solution of the H ∞ problem in both generic and non-generic cases is obtained. A detailed example is presented of the solution procedure for both of these cases. The system description and cost function are quite general.

Multivariable control of the robot manipulator in the presence of time delay

Abstract: A controller design method based on a control scheme for trajectory tracking of the robot manipulators is presented in the presence of time delay. The Smith predictor is used to eliminate the delay from the characteristic equation in order to allow the application of the controller design method developed with the assumption that a time delay is not present in the robot dynamics. Thus, the control problem for the manipulator in the presence of a delay is converted to one without a time delay. >

Distributed Computing for Basis Weight Control in Paper Production

Abstract: This paper deals with controlling bi-directional basis weight of paper by utilizing the control theory and the methods of distributed computing. The paper variance is partitioned into its machine directional (MD), cross directional (CD), and random (R) components, to provide a regulator that yields a uniformly high quality product while minimizing waste. The nonlinear distributed model with interactions between both directions is developed for tractability. The suggested reduced model has interactions limited in extent and has been linearized. Pole placement and LQR technique is used to provide an accurate setting of manipulated variables to control the final process values (basis weight). Also, the multivariate Smith Predictor is used to compensate for the process delays which made it possible to use optimum control design policy for a process with no delays. The implementation by distributed processors are discussed, including their advantages.