Verification of contact force estimation method for the bone-conducted sound transducer with human subjects

• Published in: Japanese Journal of Applied Physics Vol. 57; no. 7S1; pp. 7 - 12
• Main Authors: Ogiso, Satoki, Mizutani, Koichi, Zempo, Keiichi, Wakatsuki, Naoto, Maeda, Yuka
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society of Applied Physics 01.07.2018; Japanese Journal of Applied Physics
• Subjects: Contact force; Controllers; Electric contacts; Electrical impedance; Estimation; Human subjects; Neural networks; Product design; Sound transducers
• ISSN: 0021-4922; 1347-4065; 1347-4065
• DOI: 10.7567/JJAP.57.07LC11

In this study, we evaluated a method of estimating the contact force of a bone-conducted sound transducer using human subjects. The method was previously proposed and evaluated only with a human model. First, the relationship between the contact force and the electrical impedance was validated for 12 human subjects from 10 Hz to 60 kHz. The results showed that the electrical impedance shows four peaks and that the peaks change with contact force for all subjects in the same manner. A method of estimating the contact force was implemented with a three-layered neural network and evaluated with the data from 12 human subjects. The estimation results showed that 90% of the estimation error was within ±0.43 N, which shows that the estimation of contact force is possible. This result enables the estimation of contact force only from the electrical impedance and may support reproducible fitting of the bone-conducted sound transducer.