Compact sensing design of a hand-held active tremor compensation instrument for better ergonomics

An active physiological tremor compensation instrument has been under research and development recently. It has been shown that physiological tremor at the instrument tip can be calculated with respect to a body frame attached to the instrument. This eliminates the need to have the instrumentpsilas complete orientation information. However, kinematics used to calculate acceleration at the tip position from acceleration readings at accelerometer locations requires complete angular acceleration vector information. Resolution of angular acceleration about the instrument axis is limited by the width of the instrument. The wider the width, the higher the resolution it has. The width cannot be too big since it is of great importance that the instrument be as light and compact as possible in order not to affect natural dynamics of userpsilas hand. By placing accelerometers properly, the requirement of angular acceleration about the instrument axis is eliminated, and lesser number of accelerometers is required, thereby making the instrument compact and better in terms of ergonomics and reliability. Maximum possible errors in calculation of tremor at the tip due to inaccurate placement of accelerators are described and discussed.