Tsutomu Nagado

Development of low cost educational material for learning fundamentals of mechatronics

In this study, we developed low cost educational material for learning fundamentals of mechatronics by well combining Arduino, Scilab/Xcos, and hardware modules. The availability of the developed educational material is verified by a practice example.

Development of a Hall element displacement sensor with artificial neural network for magnetic levitation control

In this study, we developed a Hall element displacement sensor to control magnetic levitation (maglev) systems. This sensor is devised to achieve lower-cost maglev systems. Furthermore, in order to more accurately obtain the gap between an electromagnet and a levitated object, artificial neural network (ANN) is applied to the developed sensor. Finally, the validity of the developed Hall element displacement sensor with ANN is verified using a real-time measurement software.

Design of Adaptive Friction Control of Small-Scaled Wind Turbine System Considering the Distant Observation

The aim of this research is to reduce down the angular velocity against strong wind during the storm considering the distant observation. Our expectation of this small-scaled wind turbine is to operate continuously even in storm days. However, since the small-scaled wind turbine consists of small blade, it may exceed the limitation of angular velocity in storm condition due to the low inertia moment and consequences of centrifugal force. So it would be broken down the system. Our target is to somehow reduce down the angular velocity using the stall factor control. Stall factor control mainly used in the junction of axis of blade of wind turbines gear wheel. Subsequently, the stall factor is operated when the angular velocity exceeds the limitation. Therefore, adaptive controller is designed and in order to evaluate the angular velocity’s behavior phase space method is introduced. As consequences, the stall factor preserves the stability and angular velocity performs under desired value constantly.

Analysis of Non-linear Adaptive Friction and Pitch Angle Control of Small-Scaled Wind Turbine System

The aim of this research is toanalyze the behavior of wind turbine system for passive and adaptive resistance non-linear control. In general, the wind turbine system is generating energy from the revolution of blades. The revolution of blades is depended on the velocity of wind. So, if we have strong wind then the revolution of blade is increased and in consequently more energy will generated. Therefore, usually the wind turbine systems are located in gale area in order to generate energy efficiency. However, there are limits of the revolution of blades or the angular velocity of blades. If the angular velocity exceeds the limit then wind turbine system may breakdown. Thus in this paper, in order to avoid the malfunction of wind turbine system, adaptive and passive non-linear control of resistance is considered. As consequences, the adaptive resistance has more stable and smooth angular velocity compare to passive resistance.

Controller reduction using structurally balanced truncation method with new closed-loop structures

In this paper, we discuss controller reduction using structurally balanced truncation (SBT) method with new closed-loop structures. The most consequential disadvantage in SBT method is the problem for feasibility of Lyapunov inequalities for closed-loop systems and it still remain open to this date. The new closed-loop structures are introduced in order to relax the feasibility. Finally, a numerical example is used to verify the availability of the proposed methods.

H 2 controller reduction using the Riccati equations and the block balanced truncation

In this paper, we propose a new ℋ2 controller reduction method using the Riccati equations and the block balanced truncation. To maintain the closed-loop properties such as stability and ℋ2-norm performance, we employ the Riccati equations for controller reduction. A low-order controller is obtained by block balancing the solutions of the Riccati equations which include a full order controller. A numerical example is illustrated to show the effectiveness of our method.

Stability and performacne analysis of passive and active stall control of small-scaled wind turbine system by phase plane method

The aim of this study is to reduce the angular velocity by controlling the stall factor even in storm condition. In this paper we intend to analyze the stability of angular velocity of small-scaled-wind turbine by phase plane method. Moreover, performance of angular velocity is evaluated by phase plane method. So far in the previous researches in order to determine the stability and evaluate the performance of nonlinear system time response of long term had been observed However, since pitch angle and angular velocity are significant factors of stability and performances, observation is an inadequate approach for certain analysis. Therefore, phase plane method is proposed to increase the analysis degrees of stability and performances simultaneously. The mathematical model of small scaled wind-turbine is considered to be a non-linear differential simultaneous equation. Stall Control is applied by implementing the shock absorber in the conjunction of blade and the turbine. Moreover, axis friction control is loaded to decrease the excessive revolution. The stability and performance of turbine is examined by several condition of stall factors. Eventually, we confirm the simplification of analysis for non-linear system.

Performance and stability analysis of wireless Tele-Control system

In this paper, we intend to design a joint system of control and communication engineering which is called Tele-control system. Tele-Control system consists of control plant, controller, feedforward channel and feedback channel in the closed-loop control system. Basically, channels would be multipath channel due to the utilization of wireless communication system. The Existence of multipath channel in control systems may cause internal stability. Therefore, in order to design a suitable controller for the closed-loop system and to avoid instability, we have to consider the existence of feedforward and feedback channel. Thus, channel equalizer is proposed to implement in the closed loop system. The closed loop system consists of PID (proportional, integral and derivative) controller and channel equalizer. Channel equalizer is designed based on FIR filter and implemented in feedforward and feedback side of channel. In this paper LMS, NLMS and RLS algorithm have implemented. The control plant is set to be small-scaled wind turbine and aim to control its angular velocity from distant. The angular velocity is observed and controlled to avoid the excessive angular velocity and maintain the desire value. The evaluation of jointed system has done by step response of the closed-loop. Moreover, the performance of equalizers is evaluated by taking NMSE. Eventually, we could summarize that NLMS could perform smoother than other algorithms.

Evaluation of Internal Model Controller in Time and Frequency Domain on Application to Wind Turbine

In this paper, we aim to stabilize and improve the performance of the system which includes time-delay elements in closed-loop system and uncertainty of the wind turbine system. Time-delay will happen during the long distance communication. By observing and controlling the attitude of wind turbine system from distance, the transmitted control input and output signal will be delayed certainly. For this reason it will be an unstable system by time-delay elements. So, here we consider Internal Model Controller (IMC) method which is one of the robust controllers. IMC method is composed of optimum controller and uncertainty model of plant and time-delay elements. The optimum controller is designed by minimizing the coefficients of external disturbance of output signal by H2 norm in order to stabilize the closed loop system considering the uncertainty of plant and predicted time-delay element and at the same time minimize the effects of time-delay element in sensitivity function. In this research controlling of the angular velocity and pitch angle of blade is considered. As consequences, angular velocity had better performance in nominal case compare to non-nominal case.

Low Frequency Compensator of Multi-variable Tele-control System

The aim of this research is to compensate the multivariable Tele-control system’s performance and preserve the stability of closed loop system. Generally in Tele-control systems, it contains with 2 time-delay elements. One is input delay and the other is feedback delay. Therefore the closed loop system’s performances become poor and lose the stability due to time-delay elements. Here by using low frequency compensator, it preserves the stability and realizes a good performance of Tele-control system.