Force Information Presentation by Vibrotactile Stimulation Combining Amplitude and Frequency Modulation

Teleoperation makes it possible to work in in-accessible environment. To do so safely and effectively, some means of force feedback is necessary. However, force feedback methods that involve a reaction force often require bulky equipment. Instead, our study has utilized force feedback using vibrotactile stimulation. Although the modulation method of force information to vibrotactile stimulation has previously been demonstrated in magnitude (AM) and frequency (FM), we propose a method called AFM that uses amplitude and frequency modulation simultaneously to improve performance. In particular, we adjusted the amplitude using the sensation level and used logarithmized frequency for the AFM. First, the vibrotactile detection threshold of participants was measured to determine the amplitude to be equivalent in the same sensation level among participants. Then, the performance of discrimination was evaluated through stair-case psychophysical experiments. The results showed that our proposal AFM method significantly improved the discrimination sensitivity for the force information as compared with AM and FM methods.