"In all of these devices, control of the tool is shared between the human and the robot," Provancher and colleagues wrote. "In contrast, the Active Handrest provides ergonomic support and increased precision, but allows the user to maintain complete control of the tool. Furthermore, the Active Handrest can be used with any tool."
The Active Handrest includes a personal computer to control it. The user's wrist sits on a round wrist pad on an arm that is attached to a motorized base that can move from side to side and back and forth to re-center the hand. Under the wrist rest is a force sensor similar to a bathroom weight scale. The base also is attached to an elbow rest.
Making a Helping Handrest Better
After building a prototype, Provancher and colleagues conducted pilot studies to optimize the Active Handrest, including testing whether it is better to have the device detect a user's hand position or the force exerted by the hand. They also tested if precision could be increased by limiting the device's speed and acceleration.
The computer detects the position or force "and decides how the armrest should move," Provancher says. "With position control, the device monitors the tool motion and will reposition the handrest to follow the tool's motion."
"For force control, the device senses how you are leaning on the wrist rest. If you push forward a little bit, the handrest will move forward in response," he adds.
The pilot studies were conducted by having 12 people including the researchers perform a circle-tracing task. While using the Active Handrest, they held a stylus and traced on the top of a desk a circle appearing on a computer screen in front of them.
The researchers measured how long it
|Contact: Lee Siegel|
University of Utah