Vibrating muscle tendons at a range of frequencies is known to produce movement illusions in human subjects. Although there are examples in the literature on the use of vibrators to transmit simple cues such as direction information, movement illusions due to vibration have not been utilized as a method of providing illusory kinesthetic feedback. One possible main application is artificial proprioception for prosthetic devices.
Although it is relatively easy to induce the illusion, it is difficult to generate controlled sensations due to the inconsistency and instability of the illusion, differences observed among subjects, muscle configuration, and load conditions, among other reasons.
We designed and manufactured a low-cost and compact tendon vibrator with feedback controlled frequency and used it to induce elbow flexion illusions using different time-varying frequency profiles. This setup and work was demonstrated at WHC 2009 (see publications below).
Currently we are building an experimental setup that will allow us to conduct controlled experiments on improving the vividness of the illusion and evaluate feasibility of inducing the illusions in a consistent, repeatable and controllable fashion with quick onset.