Input device tracks muscle tremors

Everyone has a slight muscle tremor -- a rhythmic movement of the muscles of around 10 hertz, or cycles per second. This natural muscle tremor must be compensated for in input devices like joysticks and surgical tools.

Researchers from the National University of Ireland and the University of Glasgow in Scotland are looking to treat muscle tremor as an input mechanism rather than something that must be filtered out. Like fingerprints, muscle tremor patterns are individually distinct, depending on the structure, mass and stiffness of an arm.

The researchers have demonstrated a system made from a handheld PC that contains an accelerometer that senses the muscle tremor signal. The system mimics a pressure sensor by monitoring tremor changes from tensing, allowing a user to pump up an on-screen balloon by squeezing the device. The system also demonstrates a potential mobile telephone application; it can be set to stop ringing when a user picks it up.

The method could eventually be used for security applications that would sense individual muscle patterns, according to the researchers. It could be used as a posture recognition system because muscle tremor patterns change depending on the posture of an arm. The posture recognition capability could be used as part of an interface that allows users to store and retrieve information and programs at various points around the body, according to the researchers.

The acclerometers required by the method are becoming relatively inexpensive, and are beginning to be incorporated into mobile phones. The method could be used practically within the next two to five years, according to the researchers.

The work was presented at the User Interface Software and Technology 2004 (UIST '04) conference held October 24 through 27 in Santa Fe, New Mexico.