Loading can dramatically reduce the vibratory displacement and the operating frequency in vibrotactile systems implementations that use an eccentric mass motor, but this phenomenon is not well modeled or understood. In this work, we derive a dynamic model of this phenomenon and implement a system for measuring stiffness and grip force that take advantage of this phenomenon. The system is based on a non-interposed sensing approach using an eccentric mass dc motor mounted on the outside of the index finger. If the device were to be worn as a wearable sensor, it could be embedded in a ring. The basic idea is that a person could wear the ring sensor and through it measure the stiffness and grip force when squeezing various objects, without requiring the ring sensor to actually contact the object. The results show that grip force and muscle stiffness vary with motor velocity (operating frequency) and thus that the measurement of velocity can be used to infer grip force and stiffness. With the validated model, we also developed an optimization routine which computes the best design parameters for inertial load and voltage to maximize the phenomenon. This provided insight into the optimal parameters that should be used in an actual ring sensor design to achieve high performance by attaining a good trade-off between high sensor sensitivity and low level of vibration.
| Identifer | oai:union.ndltd.org:CCSD/oai:tel.archives-ouvertes.fr:tel-00807081 |
| Date | 09 November 2012 |
| Creators | Lopez, Miquel |
| Source Sets | CCSD theses-EN-ligne, France |
| Language | English |
| Detected Language | English |
| Type | PhD thesis |
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