Yoshihisa Anazawa

A Two-Stage Approach to the Establishment of State-Space Formulation of 2-D Frequency Transformation

This letter proposes a two-stage approach to the open problem of establishing state-space formulation of 2D frequency transformation for 2D digital filters. In the first stage, formulation of generating a 2D state-space representation that is not in the standard form of a Roesser model will be derived, while in the second stage, the desired state-space formulation to generate a 2D Roesser state-space representation will be established based on the results obtained in the first stage by utilizing certain linear transformation. Moreover, it will be seen that the proposed formulation includes the formulation of 1D frequency transformation for 2D digital filters given by Koshita and Kawamata as a special case, and thus can be viewed as a natural generalization of their result. Numerical examples are given to illustrate the effectiveness of the proposed formulation.

Torque Analysis of HB-type Vernier Motor

A stepping motor has a concentrated stator winding and is usually driven by a pulse-shaped excitation voltage. Therefore, torque pulsation exists during rotation in principle. Meanwhile, various Vernier motors with low pulsation are being developed. For the HB-type Vernier motor, the authors derived a voltage equation and a torque formula by substituting magnetized sections with equivalent coils for analysis. This paper describes the analytical technique and compares the theoretical value of the pull-out torque with the measured value from the viewpoint of validation of the analytical technique. Using this analysis, a voltage equation and a torque formula similar to those for a general synchronous machine were obtained. To validate the analytical technique, the authors fabricated a test motor and measured its pull-out torque. It was confirmed that the calculated pull-out torque values matched the measured values quite well. Therefore, the pull-out torque can be calculated accurately by just acquiring the synchronous reactance and induced electromotive force. In a laboratory, even if only the synchronous reactance and induced electromotive force are acquired by the finite element method, the pull-out torque can still be calculated easily at high speeds and applied to the optimum design.

Revisiting the Absolutely Minimal Realization for Two-dimensional Digital Filters

The open problem of absolutely minimal state-space realization for two-dimensional (2D) digital filters is revisited. A thorough investigation is carried out for the class of first order 2D digital filters. It is found that the canonical form proposed by Kung et al. three decades ago is incomplete, probably due to an incorrect assumption, which is also pointed out for the first time in this paper. Three new canonical forms for absolutely minimal state-space realization are proposed which can realize any 2D causal digital filters of first order. Several examples are illustrated

A constructive procedure for multidimensional realization and LFR uncertainty modelling

A constructive procedure is proposed for multidimensional (nD) realization and linear fractional representation uncertainty modelling. The new realization procedure works on an nD rational matrix directly without transforming it to some nD polynomial matrices first. It is computationally more efficient and may lead to a lower order realization than existing algorithms. Furthermore, the new method is applicable to nD systems with either numerical or symbolic coefficients. Illustrative examples are presented to show the effectiveness and advantages of the proposed procedure.

A μ Approach to Robust Stability Analysis of n D Discrete Systems

This paper considers the robust stability analysis problem of multidimensional (nD) discrete systems. It is shown that the problems of stability test and stability margin computation for an nD system described by Roesser model can be recast into μ analysis problems in a unified way, thus can be solved effectively by using the commercially available software package. Several numerical examples are presented to illustrate the new methods.

Sufficient LMI conditions for H ∞ static output feedback control of 2-D systems

This paper investigates the problems of H∞ static output feedback (SOF) control of two-dimensional (2-D) discrete systems described by the Roesser model and Fornasini-Marchesini second model, respectively. By applying the 2-D Bounded Real Lemma combined with a slack variable technique, some sufficient linear matrix inequality (LMI)-based conditions for the existence of SOF controllers are established. Numerical examples are given to illustrate the effectiveness of the proposed LMI-based design method.

Output characteristics of a surface permanent magnet-type vernier motor - Comparison of test results and calculation

This paper describes a surface permanent magnet (SPM)-type vernier motor that can generate high torque at low speeds, and a simple, high-speed method for analyzing its output characteristics is proposed. In this method, if the induced electromotive force, the synchronous reactance, and the iron loss are provided by finite element analysis (FEA), the output characteristics can be calculated immediately using the voltage and torque equations on the γ and d axes. The proposed method is simpler and faster than the general method that uses FEA only. In this paper, the voltage and torque equations of the SPM-type vernier motor are derived, and the proposed analysis method using these equations is presented. Moreover, the agreement of the results calculated using this method with the measured values confirms a high degree of accuracy.

Robust adaptive control of a class of 2-D discrete systems in the presence of

Adaptive control is an effective way of controlling unknown dynamical systems. While many results on one-dimensional (1-D) adaptive control are available, little has been accomplished in the area of two-dimensional (2-D) system theory. In this paper, an indirect adaptive controller will be proposed for a class of 2-D systems in the presence of disturbances. Analyses show that the designed adaptive controller, consisting of a parameter estimator and a linear controller, can stabilize the given class of 2-D systems.

Design of surface permanent magnet-type vernier motor using Halbach array magnet

A surface permanent magnet (SPM)-type vernier motor whose rotor uses Halbach array magnet is designed in this study. Voltage and torque equations are derived, and an output calculation method and design process based on these equations are proposed. A high-output power motor and a high-power factor, high-efficiency motor are designed using the proposed design process, and the output characteristics are clarified using the proposed calculation method and finite element analysis. A high-output power motor with a maximum output of 11.9 kW is designed. A high-power factor, high-efficiency motor with a maximum output exceeding 6 kW is also designed; the power factor and efficiency of this motor at 4 kW are more than 90% and more than 85%, respectively. The proposed calculation method and the design process are shown to be very effective.

Development of Surface Permanent Magnet-type Linear Vernier Motor

A Surface Permanent Magnet-type Linear Vernier Motor (SPM-LVM) is developed, and its output characteristics are clarified by calculation in this paper. As a result, a high thrust, high power factor and high efficiency SPM-LVM with a maximum thrust of 1509N, power factor at 970N of 100.0%, and efficiency at 970N of 90.5% is obtained under the conditions that the operating voltage, frequency and synchronous speed are 100V, 50Hz and 0.942m/s, respectively.