Consideration of Stretchable Dry Electrodes for Smart Shirts Aimed for Biological Signal Monitoring

Dry electrodes of a smart shirt for measuring biological signals were prepared by the additive printing method using a stretchable conductive paste with Ag fillers loading. Interfacial impedance between the electrode and skin depended on the contact pressure of electrode and the moisture of stratum corneum. When moisture of stratum corneum was more than 30%, ECG could be measured using the stretchable electrodes printed on a compression shirt. However, noise signal in the ECG signal increased when the moisture of stratum corneum was less than 30%. To solve this problem, we propose to use additional electrodes made of an electrically conductive kneaded rubber.     

MICROPROCESSOR BASED NONLINEAR EXCITATION CONTROLLER FOR SYNCHRONOUS MACHINES

ABSTRACT

The synchronous machines in power systems have the excitation systems of field winding to improve the transient stability of power systems. The synchronous machines are nonlinear systems, however, the excitation systems have been designed based on linearized systems, because the stability analysis of nonlinear systems is difficult and the generalized control method of nonlinear systems has not been developed yet.

This paper proposes a nonlinear excitation controller for synchronous machines in power systems. For the sake of simplification of the nonlinear state feedback control, this paper considers both the transient stability and the suppression of the rotor swings in transient conditions. The effect of the automatic voltage regulator (AVR) for the synchronous generator is not discussed here. This controller is designed based on Lyapunov's direct method that can directly judge the stability of nonlinear systems. The usefulness and validity of the proposed excitation controller are confirmed by numerical simulations and experiments. The microprocessor based generator excitation system that consists of a nonlinear controller, state variable detector, and PWM inverter, is constructed. The nonlinear excitation controller can improve the transient stability of synchronous machines.     

QUICK AND PRECISE POSITION CONTROL OF ULTRASONIC MOTORS WITH TWO CONTROL INPUTS

ABSTRACT

Ultrasonic motor (USM) has an excellent performance and many useful features. Since this motor is superior in holding torque and high response characteristic, it has been expected to use as position servomotor for small motors.

There have been reported some mathematical models of the ultrasonic motor. however, these models are too complex to apply for control of the motor. Therefore position controllers based on PI control or fuzzy control have been proposed in recent years. It is difficult to control the ultrasonic motor with high-performance using such controllers, thus simple and convenient mathematical model is necessary for precise control.

This paper presents a new position control scheme of ultrasonic motor, it consists of a PI controller and an adaptive controller which compensates the speed characteristic variations with online parameter identification. Moreover, this system controls both driving frequency and phase difference in order to achieve a quick and precise position control. The effectiveness of proposed control.scheme is demonstrated by experiments.