Two-degree Of Freedom Control Systems Research Articles

Estimated Response Iterative Tuning with signal projection

This paper discusses about a data-driven control method which is called Estimated Response Iterative Tuning (ERIT). ERIT focuses on a two-degree of freedom control system, and updates the feedforward controller from one-shot experiment. The main contribution of this paper is to propose a pre-processing for ERIT to improve robustness against noise. In particular, this paper proposes to project the measured output onto a subspace, and regard the projected signal as a noise-free output. How to design this subspace is also proposed in this paper. A practical experiment with flexible link system is shown to demonstrate the effectiveness of the proposed method.

How to Teach Control System Optimization (A Practical Decompisition Approach for the Optimization of TDOF Control Systems)

Abstract The optimality in a generic two-degree of freedom control system can be decomposed into three major steps, because the control error has three major parts: design-, realizability- and modeling-loss. The second term can be made zero for inverse stable processes only. This decomposition opens new ways for practical optimization of two-degree-of-freedom (TDOF) systems and helps the construction of new algorithms for robust identification and control. It is more reasonable to teach the optimization of control systems using these components.

ASPR based Output Feedback Control with an Adaptive Predictive Feedfoward Input for MIMO Systems

This paper deals with an output feedback regulation control system design problem. An almost strictly positive real or ASPR based output feedback control system with the adaptive predictive feedforward input will be proposed for MIMO linear systems. The adaptive output predictor proposed for SISO systems will be expanded for MIMO systems and the stability of the resulting control system will be maintained by designing two-degree of freedom control system via ASPR based output feedback. The proposed control strategy has relatively simple structure with a novel simple adaptive output predictive control and ASPR based simple output feedback. The effectiveness of the proposed method will be confirmed through numerical simulations.

Simple two degree of freedom structures and their properties

A two-degree of freedom control system that is most frequently encountered in practice is the so-called Internal Model Control (IMC) structure. However, the design procedure of such a structure does not present an easy task, which implies a limited utility of IMC. In this paper two alternative solutions are proposed that may be lumped together as Model-Following Control (MFC). These are two-loop control systems being easy to implement and offering interesting properties. Theoretical assumptions have been verified experimentally on a two-joint robot manipulator. Both qualitative and quantitative results yielded by experiments are presented and discussed.

Anti-Windup Strategy for Two Degree of Freedom Control System Based on Left Coprime Factorization

In this paper, the anti-windup strategy for two degree of freedom (TDOF) control system is proposed. In TDOF control system, the input saturation can be avoided by designing the suitable command response property for nominal model. In real controlled systems, however, the input saturation may occur because of unknown disturbance or plant variation. The proposed method can suppress the windup phenomena by modelling the limiter into TDOF controller and adjusting the limitation between feedback and feedforward control. The proposed anti-windup controller (AWC) has the form of left coprime factorization of feedback and feedforward controllers. The proposed method is evaluated by simulation and experiment of position control system of DC servo motor.

PID×(<i>n</i>-2)/2 Stage PDA Cascade Robust Controllers

This paper presents a design technique for the two-degree of freedom control system using PID×(n-2)/2 stage PDA as a cascade robust controller for a class of nth order plants. It is intended to satisfy both transient and steady state response specifications based on root locus approach. This controller can be used instead of a conventional PID controller for the higher order plant to obtain better performances. By this design technique, the controlled system is approximated as a second order system, and the desired performances are satisfied. For the plant with stable poles including the case with small dead time, the closed-loop poles are located on the left half of the s-plane and the controlled system become robustly stable. The cascade robust controller gain is adjusted to meet faster responses with a small or no overshoot. Robustness properties given by the controllers proposed in this paper have also been demonstrated by illustrative examples.