Handrest: For Precise Tasks by Surgeons

Engineers developed a computer-controlled, motorized hand and arm support that will, according to the inventors, let doctors precisely control scalpels and tools over a wider area than otherwise possible, and with less fatigue.09/03/2010

The handrest can move any direction
within a horizontal plane in response
to pressure exerted by the user;
© University of Utah

"We've invented a new device that's useful for aiding people in performing precision tasks with their hands such as surgery or other tasks that require precise control of the fingertips," says William Provancher, an assistant professor of mechanical engineering. Use of the handrest also means "less fatigue, and if you have fatigue, you are going to have tremor associated with that," meaning less precision.

A person using the handrest puts their wrist on a support that can slide horizontally in any direction. Their elbow rests on a support attached to the device. The handrest allows a person to maintain a steady hand while it senses the position of a hand-grasped tool or the force exerted by the hand, or both. Then, the device's computer software moves the handrest so it "constantly re-centres your fingertips in the center of their dexterous workspace," which Provancher says is "the range over which you can move your fingers and be very precise."

For example, if a person places their arm on a desk to write, their hand is able to move the pen about four inches in any direction, but precise writing is practical only within a one-inch wide "dexterous workspace," he says.

The prototype of the handrest lets a user move their hand precisely within a workspace of about ten by ten inches, re-centring the hand as the arm moves to reach a larger area. But future devices could allow for three-dimensional motion and even larger work areas with the same precision, Provancher says.

People often try to increase their precision when doing manual tasks by bracing their wrist or arm against a fixed object. Over the years, there have been many devices to help. "In all of these devices, control of the tool is shared between the human and the robot," Provancher and colleagues wrote. In contrast, they add, the new handrest provides ergonomic support and increased precision, but allows the user to maintain complete control of the tool.

COMPAMED.de; Source: University of Utah