Velocity-Limiting Control of an Active Handheld Micromanipulator

Abstract

Fine manipulation and precise movements are essential in any type of microsurgery. In manipulation of delicate tissue such as nerves, strain rate has been shown to be a factor in the extent of damage to tissue. Hence, there is a need to limit the maximum permitted velocity of the tool tip. Such a limitation can be enforced without losing the benefits of direct manual manipulation (e.g., tactile feedback, intuitive control, and low cost) by using an actuated handheld instrument. One such instrument is Micron, originally developed for active compensation of hand tremor during microsurgery. The current version of Micron is a six-degree-of-freedom system, with a Gough–Stewart platform manipulator for its tip. The actuators are ultrasonic linear motors (SQL-1.8-RV Squiggle motor, New Scale Technologies, Inc., Victor, NY). The device has two sets of infrared light-emitting diodes (LEDs): three on the moving platform and three fixed to the handle. The LEDs are optically tracked by a custom-built tracking system, which uses two position-sensitive detectors to triangulate each LED’s position in 3D.