Apparatus for generating a vibrational stimulus using a rotating mass motor

The present invention provides a novel implementation of a low cost eccentric mass motor vibrotactile transducer providing a point-like vibrational stimulus to the body of a user in response to an electrical input. Preferably the eccentric mass and motor form part of the transducer actuator moving mass. The actuator moving mass is constrained into vertical motion by a spring between the actuator housing and moving mass. The actuator moving mass is in contact with a skin (body) load. The actuator housing is in simultaneous contact with the body load. The body load, actuator moving mass, spring compliance and housing mass make up a moving mass resonant system. The spring compliance and system component masses can be chosen to maximize the actuator displacement and/or tailor the transducer response to a desired level. The mass of the motor/contactor assembly, mass and area of the housing, and the compliance of the spring are chosen so that the electromechanical resonance of the motional masses, when loaded by the typical mechanical impedance of the skin, are in a frequency band where the human body is most sensitive to vibrational stimuli 150-300 Hz. This configuration can be implemented as a low mass wearable vibrotactile transducer or as a transducer that is mounted within a soft material such as a seat. A particular advantage of this configuration is that the moving mass motion can be made almost independent of force loading on the transducer housing.