Yao-Wen Tsai

A newly robust controller design for the position control of permanent-magnet synchronous motor

A robust controller which is designed by employing variable-structure control and linear-quadratic method is presented for a permanent-magnet synchronous motor (PMSM) position control system. It is to achieve accurate control performance in the presence of plant parameter variation and load disturbance. In addition, it possesses the design flexibility of the conventional state feedback control. It is applied to the position control of a PMSM. Simulation and experimental results show that the proposed approach gives a better position response and is robust to parameter variations and load disturbance.

Technical Communique: A dynamic output feedback controllers for mismatched uncertain variable structure systems

This paper proposes a dynamic output feedback controllers for variable structure systems. It is based on the concept of output feedback controllers, introduced by Zak and Hui (IEEE Trans. Automat. Control AC-38 (1993) 1509) and Kwan (IEEE Trans. Automat. Control AC-41 (1996) 1691) for matched uncertain variable structure systems in which the state is unavailable and no estimated state is required. In this paper, we extend this idea to a class of mismatched uncertain variable structure systems. A modified variable structure controllers is derived to guarantee the existence of the sliding mode by using output feedback only. The stability of the equivalent reduced-order system in the sliding mode is assured under certain conditions.

A modified variable structure controller

It has long been known that one of the difficulties with the conventional variable structure systems (VSS) design is the chattering problem. In this paper, a modified variable structure controller (VSC) is proposed to alleviate this problem, at the same time, retaining the benefits achieved in conventional VSS design, namely, fast response, good robustness and disturbance rejection.

Decentralized variable structure control for mismatched uncertain large-scale systems: a new approach

Abstract In this paper, a decentralized variable structure controller for a class of large-scale systems with mismatched uncertainties is proposed. In every subsystem, two sets of switching surfaces is introduced. New invariance conditions are derived such that the system in the new sliding mode is completely invariant to both matched and mismatched uncertainties. To demonstrate the effectiveness of the proposed scheme, a decentralized variable structure controller is synthesized to perform the new sliding mode. Moreover, the stability analysis of the overall system is also provided.

Dynamic output feedback sliding mode design for a class of linear unmatched uncertain systems

This paper investigates the output feedback stabilization problem for a class of multi-input/multi-output (MIMO) systems with matched/unmatched uncertainties by the variable structure system (VSS) with a new sliding mode control. In dynamic systems, a new idea of a sliding sector that consists of two sets of switching surfaces is proposed. A new invariance condition is derived such that the reduced-order system in the new sliding mode is completely invariant to both matched and unmatched uncertainties. Additionally, to demonstrate the effectiveness of the proposed scheme and to reduce the drawbacks of conventional VSS design, a modified dynamic variable structure controller using only the output variables is applied to perform the sliding mode. Furthermore, a stability analysis of the overall system is also provided. Finally, an example is given to illustrate the effectiveness of the control scheme.

Sliding mode control for unmatched uncertain systems with totally invariant property and exponential stability

Abstract Some sliding mode controllers for unmatched uncertain systems are proposed. They are based on the concept of totally invariant controllers, introduced by Shyu and Hung (1997), in which the system, in the sliding mode, is invariant to the matched uncertainty over all time. In this paper, we extend this idea to a class of unmatched uncertain variable structure systems. New sliding mode controllers are derived to guarantee the existence of the sliding mode. Totally invariant property and exponential stability are assured.

Estimating stability regions for mismatched uncertain variable structure systems with bounded controllers

We address the problem of the estimation of stability regions of a class of mismatched uncertain variable structure systems with bounded controllers. The estimation of stability regions such as the practical stability region, the asymptotic stability region, and the exponential stability region are discussed. Moreover, the state transformation used in previous paper is no longer needed so that a new estimation result is directly related to the original system states without state transformation.

Decentralized Output Feedback Control for Mismatched Uncertain Large Scale Systems: An LMI Approach

In this paper, a large scale systems with matched and mismatched uncertainties is considered. Based on sliding mode techniques, a decentralized control scheme, using only output information, is presented to stabilize the system globally. In addition, appropriate linear matrix inequality (LMI) stability conditions by the Lyapunov method are derived such that each subsystem in the new sliding mode is completely invariant to both matched and mismatched uncertainties. Moreover, the stability analysis of the overall system is also provided. Finally, a numerical example is used to prove the efficacy on the method.

Decentralized dynamic output feedback controllers for interconnected systems with mismatched uncertainties using new sliding mode control

This paper presents a method for the design of decentralized output feedback controllers for an interconnected systems with mismatched uncertainties using a variable-structure control approach. A new reaching condition of the sliding mode is derived such that the reduced-order system is invariant to the mismatched uncertainties. In every subsystem, a new idea for a sliding mode that consists of two sets of switching surfaces is introduced, and a scheme of decentralized dynamic control using only output states is also proposed. This scheme can guarantee closed-loop stability of a sliding manifold of the composite system. Finally, a numerical example is given to illustrate the controller design method.