Stabilizing Graphically Extended Hand for Hand Tremors

Abstract

Tremors, which refer the trembling or shaking of body parts, are caused by the involuntary contractions of muscles and are one of the most common movement disorders that often reduce individuals’ the levels of the hand functions and also affect their independent body movements adversely. “Extended Hand (EH)” is an augmented body technology, which visually extends the length of a user’s arm by a spatial augmented reality. It could facilitate individuals whose reaching areas are limited by body movement disorders to interact with distant objects. However, the technology is currently limited, because any trembling of the hands contacting with the touch panel of the EH system is amplified, causing EH to shake in the physical world as well. To make EH benefit individuals whose hands and body are disabled by tremors, we proposed methods for stabilizing the movements and gestures of the EH to allow EH controlled steadily by their trembling hands. We developed a hand tremor simulator by which trembling hands interacting with EH were imitated, and investigated the effectiveness of stabilization methods by conducting a series of pointing and grasping experiments. The stabilization method composed of Kalman filter and Hysteresis was confirmed to be effective in reducing the unstable translation and unstable stationary state of EH, and the method combining the stabilization of the distances from the fingertips to their centroid and the analysis of the change in low frequency components of the touching areas effectively enable trembling hands to control the EH gestures steadily.