Mingcong Deng

A parallel feedforward compensator virtually realizing almost strictly positive real plant

Deals with the design problem of a parallel feedforward compensator which virtually realizes an almost strictly positive real (ASPR) plant. It is well-known that several output feedback based control techniques can easily be applied to the plants having ASPR characteristics. Unfortunately, most real plants do not satisfy this condition. To improve such a situation, the implementation of a parallel feedforward compensator (PFC) which causes a non-ASPR plant to become virtually ASPR has been discussed. Here, a simple and systematic method of composing such a PFC, which can be applied to a broader class of SISO plants, is considered. The effectiveness of the result obtained is examined by applying them to an example of simple adaptive control.<<ETX>>

Simple adaptive control of processes with time-delay

Abstract This paper is concerned with the development of tuning guidelines and robustness evaluation tools for a simple adaptive control (SAC) scheme. The adaptive technique requires knowledge of only the relative degree of the plant and an upperbound of the process gain. This is an explicit or direct adaptive scheme. The SAC method is evaluated by simulated applications to two processes. The application of SAC to a process with time-delay is also considered in this paper. This issue has both theoretical, because of the strictly positive real (SPR) requirements, as well as practical appeal. Simulation results show the practicality and usefulness of the proposed algorithm.

Robust parallel compensator design for output feedback stabilization of plants with structured uncertainty

Abstract This paper deals with a design problem of robust parallel compensator which guarantees the existence of a constant gain output feedback controller for plants with structured uncertainty. First, robust design conditions of such a compensator are derived by using Kharitonov’s Theorem. Then, based on conditions provided, the parallel compensator is designed by utilizing the maximal range of interval perturbations of the plant. A numerical example is given to demonstrate the validity of the results.

Design of multivariable PID controllers on frequency domain based on partial model matching

Abstract This paper deals with a design method of multivariate PID controllers based on partial model matching on frequency domain. Stability of the resulting control system is also considered. In this method, the PID controller parameters are determined from the optimal solution of a constrained performance index which satisfies Rosenbrocks stability theorem. The design scheme is also examined from the view point of improving the tracking performance and robustness. The effectiveness of the proposed method is confirmed through a numerical example.

Robust parallel compensator for the existence of static output feedback of plants with structured and unstructured uncertainties

This paper deals with the design problem of a robust parallel compensator (RPC) for plants with structured and unstructured uncertainties. The compensator is designed so that the augmented plant with this compensator satisfies the sufficient condition of static output feedback stabilization. As an extension of the basic results, a design scheme of RPC for the above-mentioned plants with small perturbations (such as control spillover and/or observation spillover) is also discussed.

Robust Parallel Compensator for Output Feedback Stabilization of Processes with Uncertainties

Abstract The main objective of this paper is to solve evaluation and design problems on process control systems with a static output feedback (SOF). Most actual processes with time delays and uncertainties do not satisfy the sufficient condition of SOF stabilization. Modelling method and robust parallel compensator (RPC) design scheme for delay processes with uncertainties are derived so that the resulting augmented process with the RPC, which is virtually regarded as a new controlled process, can be robustly stable by SOF. The effectiveness of the proposed method is confirmed through a numerical simulation.

Simple Adaptive Control with a Parallel Feedforward Compensator for Processes with Time Delay

Abstract This paper deals with a design problem concerning a simple adaptive control (SAC) system for processes with time delays or higher order lag elements. The SAC method, which is a type of direct model reference adaptive control (MRAC) based on the command generator tracker (CGT) theorem, is fundamentally applicable to plants satisfying the so-called almost strictly positive real (ASPR) condition. Most processes with higher order lag elements do not satisfy the ASPR condition. A design method of a parallel feedforward compensator (PFC) for processes with time delays is derived so that the resulting augmented plant with the PFC, which is virtually regarded as a new controlled plant, will be ASPR. As a result, the SAC can be applied to a broader class of controlled plants including processes with higher order lag elements. The effectiveness of the proposed method is confirmed through a numerical simulation.

Model output following control based on CGT approach for mimo processes with unmodelled dynamics

Abstract This paper is concerned with a design problem of a model output following control (MOFC) system based on static output feedback (SOF) characteristics and command generator tracker (CGT) theorem for multi-input/multi-output (MIMO) processes with unmodelled dynamics. The effect of structured uncertainty is investigated by a modelling method. Further, a design scheme of modelling-based robust parallel compensator (RPC) which makes the MIMO process SOF-able is proposed. The results allow us to explore the role of different tuning parameters for perfect output tracking and also evaluate robust stability of the obtained control system.

A Parallel Feedforward Compensator for MIMO Plants Virtually Realizing an Almost Strictly Positive Real Plant

Abstract This paper deals with the design problem of a parallel feedforward compensator for MIMO plants which virtually realizes an almost strictly positive real (ASPR) plant. It is well-known that several output feedback based control techniques, including adaptive controls, can be easily applied to plants having ASPR characteristics. Unfortunately, most real plants do not satisfy this condition. To improve such a situation, the implementation of a parallel feedforward compensator (PFC), which causes a non-ASPR plant to become virtually ASPR, has been discussed. Here, a simple and systematic method of composing such a PFC for MIMO plants is considered for expanding an applicable class of output feedback type control schemes.