Takamichi Yoshimoto

Development of a Haptic Device Using a 2-DOF Linear Oscillatory Actuator

Mobile haptic devices are being studied extensively as they have a great potential to be used as information transfer devices. Amemiya and Maeda proposed a method for haptic feedback by a linear oscillator using asymmetrical drive. We have then proposed a small two degree-of-freedom oscillatory actuator for application as a haptic device. Using this actuator, we were able to reproduce asymmetric acceleration such as the one by Amemiya and Maeda. However, this waveform is dependent on the mechanical structure of the slider-crank mechanism and thus it is actually not necessary to use it for our actuator. In this paper, we propose a new waveform that is more suitable to the characteristics of our actuator. This compatibility with our actuator can be seen in the power consumption of our actuator, which is decreased by 35%.

Dynamic Characteristics of Novel Two-DOF Resonant Actuator by Vector Control

This paper proposes a two degree-of-freedom (DOF) resonant actuator and clarifies its dynamic characteristics. The feature of this two-DOF actuator is that the movement of each x- and z-axis is independently controlled by vector control. In this paper, dynamic characteristics of the actuator were confirmed through 3-D finite-element method and measurement. In single axis drive, it was found that amplitude of each x and z-axis was independently controlled by vector control. On the other hand, the amplitude of each axis is almost equal to single axis drive without mutual interference in biaxial drive. The measured results agree well with analyzed one. From these results, the effectiveness of the proposed two-DOF resonant actuator was verified.

Simplified Position Estimation Using Back-EMF for Two-DoF Linear Resonant Actuator

This paper proposes a simplified position estimation method and clarifies the dynamic characteristics of the two-degree-of-freedom (DoF) resonant actuator under sensorless control. The feature of this two-DoF actuator is that movement in the x- and z-axis can be independently controlled by vector control. In this paper, we extrapolate the mover position from the zero crossing time and amplitude of the back electromotive force. During both single and biaxial drives, it was found that the amplitude of the x- and z-axis could be independently controlled without using position sensors. The measured results agree well with the analyzed results. From these results, the effectiveness of the proposed estimation method was verified.

Optimization of asymmetric acceleration waveform for haptic device driven by 2-DOF oscillatory actuator

The asymmetric acceleration waveform shown is not necessarily the best waveform since it has not been optimized. In this paper, first, how the properties of the asymmetric acceleration properties are related to haptic perception is investigated by conducting experiments on volunteers. Then, by applying a genetic algorithm to the optimization method, an optimized asymmetric acceleration waveform is created. Finally, we verify the effectiveness of the optimized acceleration waveform is verified through 3-D finite element analysis and also experiments on volunteers.