Showing papers on "Smith predictor published in 1992"

A predictive PI controller for processes with long dead times

Abstract: A predictive PI (proportional-integral) controller with dead-time compensation is described. Its advantage compared with previous dead-time compensating controllers is that although it also contains five parameters, only three are adjusted by the operator, namely, the gain, the integral time and the dead time. The controller is also suited for processes with varying dead times. Conceptually, the new controller can be considered as a special case of the Smith predictor or the Morari-Zafiriou IMC. >

A closed loop neural network automatic tuner

Abstract: A closed loop neural network based autotuner develops optimized proportional, integral and/or derivative parameters based on the outputs of other elements in the loop. Adjustments are initiated by making a step change in the setpoint which may be done by a user or automatically. A Smith predictor may also be employed.

Deadtime compensation for nonlinear processes with disturbances

Abstract: The control problem of time delay non-linear systems that are perturbed by disturbances is discussed. By coordinate transformations and feedback and prediction of the transformed states, we first linearize the perturbed non-linear systems into controllable quasi-linear systems with disturbances. Then, we can apply the well-developed linear control theory to stabilize the transformed systems. Thus, stable quasi-linear systems with time delay can be obtained. Furthermore, we may implement powerful deadtime compensation methods to study the performance of the proposed dynamic compensators, a Smith predictor and a new modified Smith predictor, for disturbance rejection. Finally, a typical non-linear chemical process, a continuous stirred tank reactor, is used as an example system to demonstrate the effectiveness of these deadtime compensators

Variable structure predictor controller with quasi-sliding mode for systems with delay

Abstract: The main feature of variable structure control systems is the sliding mode. In the sliding mode, the eigenvalues of the system are specified and the system enjoys invariance to parameter variations and disturbances. Then, how can one apply this control method to the systems with time delay? In this paper, the discrete variable structure controller is first reviewed and discussed. Combined with the predictor control method, the authors propose a variable structure predictor controller with quasi-sliding mode. Simulation results are presented illustrating the effectiveness of the control method. >

A new adaptive Smith predictor controller

Abstract: The principle of normal-mode-inaction (NMI) adaptation is utilized to derive an adaptive Smith predictor controller. This new adaptive system differs from a conventional adaptive Smith predictor in that the adaptation of its control parameters only occurs during the instances of an unambiguous abnormality. This abnormality is defined as a significant change in the magnitude or phase of certain points on the continuously tracked Nyquist plot. The ability of the NMI adaptive Smith predictor controller to overcome the effects of an unmeasurable load disturbance is superior to that of the conventional adaptive Smith predictor. The NMI adaptive Smith predictor controller uses a relay auto-tuner, and the adjustment of the controller parameters is based on the Ziegler-Nichols tuning formula. Simulation examples demonstrate the usefulness and the advantages of the new adaptive control scheme. >

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

Abstract: A method for the design of a self-tuning controller (STC) for a single-input nonminimum-phase system with unknown or varying time-delay is proposed. First, an improved parameter estimation algorithm is given. It uses one of two adaptive control blocks according to the estimated results. When the dead time of the plant is unknown or changing, the STC is structured as a self-tuning Smith predictor. The validity of the proposed method has been investigated by numerical simulation. >

Gaze Behaviors for Robotics

Abstract: Five control systems loosely corresponding to primate saccadic, vergence, pursuit, vestibuloocular, and head control operate on a simulated two-eyed robot head maneuvered by a robot arm. The goal is to get some qualitative understanding of the interaction of such reflexes under various assumptions. The simulation is meant to be relevant to U. Rochester’s robot. Thus it incorporates kinematics of the robot head but assumes a ”tool-coordinate” system available to robot arm commands, so that arm kinematic calculations are unnecessary. Dynamics are not modeled, since they are handled by the commercial controllers currently used in the Rochester robot. Even small delays render the effect of delay-free controllers unstable, but multi-delay version of a Smith predictor can to cope with delays. If each controller acts on the predicted system and ignores other controllers, the situation is improved but still potentially unstable if controllers with different delays act on the same control output. The system’s performance is much improved if controllers consider the effect of other controllers, and the resulting system is stable in the presence of a certain amount of stochastic disturbance of control delays and inputs, and also in the presence of systematic error arising from inaccurate plant and world models.

Design of compensators for the Fly-back type ZVS-QRC

Abstract: Fly-back type SMPS (Switching-Mode-Power-Supply) has been used on many area for its simplicity and reliability The resonant switch is adopted to reduce its size and losses Flyback type ZVS-QRC(Zero-Voltage-Switc­hing-Quasi-Resonant-Converter) has 4 operation modes due to its switching conditions State equation can be deri­ved by the state space averaging method It has zero in RHP(Right-Half-Plane) The zero in RHP makes the system response tardy or unstable when we construct the closed loop system The Smith predictor is used to compen­sate the zero in RHP Therefore the ZVS-QRC fly-back system can be converted to minimum phase system with first order all pass filter by Pade approximation A PI controller is designed for regulating output voltage Simulation has been performed in order to show the effectiveness of the algo­rithm