NASA Jet Propulsion Laboratory, California Institute of Technology

A new robotic arm -- steadier than a surgeon's hand -promises to revolutionize the field of microsurgery and allow surgeons to perform very delicate operations of the eye and brain once it is transferred to the marketplace by scientists at NASA's Jet Propulsion Laboratory.

Working with a commercial medical partner, JPL is developing the Robot-Assisted MicroSurgery (RAMS) workstation, which will make possible new types of microsurgery procedures of the brain, eye, ear, nose, throat, face and hand, said Dr. Paul Schenker, who leads the team of JPL developers.

RAMS is being designed with the guidance of the microsurgical community, and a cooperative commercial development agreement has been signed with MicroDexterity Systems, Inc., of Memphis, Tenn. The resulting technology developments will be tested in actual clinical procedures and turned over to the private business sector through the cooperative NASA-industry venture, Schenker said.

Several different directions in medical robotics are being explored worldwide, including imaging-guided biopsies, precision joint replacements, telesurgery in which surgery is performed at a remote location and, most recently, high dexterity operations under microscopic viewing. These are all aspects of the RAMS project under way at JPL.

The primary RAMS control mode is teleoperation, in which the operator's hand motions are transferred by a sophisticated joystick-like hand controller device, and scaled down to dimensions as small as 20 to 30 microns, or 20 millionths to 30 millionths of a meter.

RAMS not only refines the physical scale of current microsurgery techniques but also enables more positive outcomes for average surgeons during typical procedures, Schenker said. That is possible because the RAMS system will include control features to enhance manual positioning and tracking and overcome involuntary jerks and hand tremors that limit most surgeons' motion skills.

The mechanical design and controls will allow relative positioning of surgical tools within 20 microns -- or 20 millionths of a meter -- while enabling the surgeon to range freely over a continuous work space as large as 20 cubic centimeters, or little more than a cubic inch. Surgeons would thus be able to scale down their hand motions as much as 5 to 10 times and perform new procedures in critical areas such as the inner eye.

The first element of the RAMS workstation, now being tested, is a six degrees-of-freedom surgical robot, or slave, made up of a torso-shoulder-elbow body with a three-axis wrist. This robot manipulator is about 25 centimeters (10 inches) long and 2.5 centimeters (1 inch) in diameter.

Each robot joint has a large continuous range of motion and the arm's base will not have to be repositioned frequently during tasks. The torso was designed with 165 degrees of motion while both the shoulder and elbow have a full 360 degrees of motion. The wrist design has 180 degrees of pitch and yaw and 540 degrees of roll. Such large motion ranges greatly reduce the chances of a joint reaching a limit during an operation and interfering with a surgeon's natural hand motion.

The work on the Robot-Assisted MicroSurgery workstation is being performed at the Jet Propulsion Laboratory under contract with NASA's Office of Space Access and Technology.

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