Masaya Takasaki

A tactile display using surface acoustic wave

We propose a novel method to provide human tactile sensation using surface acoustic wave (SAW). A pulse modulated driving voltage excites temporal distribution of shear force or friction shift on the surface of SAW substrates. The force/friction distribution can be perceived as tactile sensation at mechanoreceptors in the finger skin. A first prototype could express roughness successfully.

Development of a three-axis active vibration isolator using zero-power control

This paper presents the development of an active 3-degree-of-freedom (DoF) vibration isolation system using zero-power magnetic suspension. The developed system is capable to suppress direct disturbances and isolate ground vibrations of the 3-DoF motions, associated with vertical translational and rotational modes. Two categories of control strategy for the actuators are proposed, i.e., local control and mode control. The latter method allows to overcome limitations of the poor performances for rotational modes exhibited by the former. A mathematical model of the system is derived and each DoF motion is treated separately for the control system. It is demonstrated analytically that the infinite stiffness to static direct disturbances can be generated and the resonance peak due to floor vibration can effectively be suppressed for the system. Moreover, the experiments have been carried out to measure the static and dynamic responses of the isolation table to direct disturbances, and transmissibility characteristic of the isolator from the floor. The results indicate good vibration isolation and attenuation performances, and show the efficacy of the developed isolator for industrialization

A surface-acoustic-wave gyro sensor

Abstract This paper explains two novel methods to detect angular velocity by using a surface-acoustic-wave (SAW) device. In both methods, Coriolis forces, which act on the particles vibrating in the standing wave of a SAW, are applied. A novel gyro sensor is planned based on one of the two methods. For accurate fabrication, the dimensions of the electrodes are designed by using equivalent-circuit models. A SAW gyro sensor using a Rayleigh wave that propagated on a 128 ° Y -cut LiNbO 3 3 inch wafer with an operating frequency of 15 MHz has been designed and fabricated on trial.

Transparent surface acoustic wave tactile display

We have already proposed a novel method to provide human tactile sensation using surface acoustic wave (SAW). A pulse modulated driving voltage excites temporal distribution of standing SAW. The distribution generates friction shift on the surface of a SAW substrate. When the surface with the burst SAW is explored, the friction shift can be perceived as tactile sensation at mechanoreceptors in the finger skin. Controlling the burst frequency according to measured rubbing motion, reality of the displayed sensation can be enhanced. In this paper, we proposed a transparent tactile display. An experimental apparatus was fabricated on trial and controlled by using captured images. The apparatus demonstrated potentiality of the tactile display for various applications.

Control parameters for an active type SAW tactile display

We have proposed a novel method to provide human tactile sensation using surface acoustic wave (SAW). A pulse modulated driving voltage excites temporal distribution of standing SAW. The distribution generates friction shift on the surface of a SAW substrate. When the surface with burst SAW is explored, the friction shift can be perceived as tactile sensation at mechanoreceptors in the finger skin. For real reproduction of tactile sensation, the burst frequency was controlled according to measured rubbing motion. We discussed the control parameters and their arrangement. Required parameters and their tuning for the tactile display were investigated.

Optimization of slider contact face geometry for surface acoustic wave motor

An extremely large output force surface acoustic wave (SAW) motor is reported. Driving frequency of the SAW device was 9.6 MHz. Sliders were fabricated with silicon surface machining. For the contact surface, the slider had a lot of projections to control elastic contact condition. Twenty five different projection designs were tested. Using a 4/spl times/4 mm/sup 2/ silicon surface micro fabricated slider, the maximum output force was 7.6 N. Namely, it was about 0.5 N/mm/sup 2/ or 50 N/cm/sup 2/. The no-loaded speed of the motor was 0.7 m/sec in the experiment. Estimated mechanical output power of the actuator was 1 W. The mechanical output force and output power are the best of all in MEMS actuators.

Development of a three-axis active vibration isolation system using zero-power magnetic suspension

A three-axis active vibration isolation system using zero-power magnetic suspension was developed. A mathematical model of the apparatus was derived for discussing the control system. It was shown that the three motions could be treated separately and, in addition, each dynamics was represented in a similar form. The condition for the system to have infinite stiffness for direct disturbance was derived. This characteristic was confirmed experimentally. It was also demonstrated that the transmissibility characteristics from the floor to the isolation table were not worsened by introducing zero-power control.

Surface Acoustic Wave (SAW) tactile display based on properties of mechanoreceptors

The authors first analyze dynamic properties of rapidly adapting mechanoreceptors in order to derive a principle of tactile displays. It is shown that Meissner corpuscles with coiled axons and Pacinian corpuscles with layered lamellae are suited to detect equivoluminal distortion of skin. Combining these analyses with a model of a contact and a relative motion between an object and the skin, it is shown that a prerequisite for tactile displays is to generate sources of shear stress that can be spatially dispersed at the skin surface and temporally modulated with a stick-slip frequency determined by parameters of the object to be displayed. As a device that satisfies this prerequisite, we propose a tactile display using Surface Acoustic Waves (SAW). The roughness of the surface can be changed continuously by controlling the burst frequency of the SAW.

A surface acoustic wave gyro sensor

This paper explains a novel method to measure an angular velocity by using a surface acoustic wave device. Coriolis forces act on the particles vibrating in the standing wave of the surface acoustic wave, but cancel one another. Distributed cyclic perturbation masses on the surface realize detection of angular velocity. The secondary SAW, which has some coherence, can be built up in the orthogonal direction of the primary standing wave. This novel gyro sensor was planned based on this principle. The optimization of the electrode dimensions was carried out by equivalent circuit analysis. The SAW gyro sensor using the Rayleigh wave which could propagate on a 128/spl deg/ Y-cut LiNbO/sub 3/ 3-inch wafer with operating frequency of 15 MHz was designed.

Resonance Frequency Tracing System for Langevin Type Ultrasonic Transducers

This paper proposes a system to trace resonance frequencies of Langevin type ultrasonic transducers. The system consists of a microcomputer, detecting circuits and a direct digital synthesizer. Fabrication of the system is reported. Step responses are described as tracing performance. Vibration amplitude modulation using the system is also indicated as an application for mechatronics.