The transfer of information using tactile aids for hearing-impaired persons is currently limited by the tactor and not by the tactile sense.
Our aim i s to design a tactor that makes full use of the tactile capability. Rather than using an external sinusoidal source to drive the tactor, we configure the transducer and the drive circuit as a self-excited electro-mechanical oscillator. The same transducer is used as a force actuator and a velocity sensor, based on inherent bi-directional properties of electromechanical transducers. The velocity signal is used to control transducer drive current, thus creating a self-excited oscillating electro-mechanical system requiring only external DC power and a control signal. Specifically, the self-oscillating drive is used with a tactor that operates in a vibrotactile mode perpendicular to the skin and also with a tactor producing a unique multimodal tactile stimulation by virtue of three different modes of vibro-tactile skin motion: compression, torsion, and indentation of the skin. Both tactors are efficient, have fast response, variable frequency of operation, large dynamic range, and provide an estimated order of magnitude improvement in information transfer capability over present tactors.
Predicted improvement in performance of new tactors should have a very significant impact on tactile system applications. The commercialization plans are based primarily on supplying existing vendors of tactile systems with new tactors. Additional uses include tactile speech perception aids, tactile feedback in devices for physically handicapped individuals, tactile feedback in virtual environment systems, cockpit feedback for pilots, and direct measurement of skin impedance for tactile research.
