Ceramic Motors Enable Precision Motion in Surgical Robot

Originally Published MPMN July 2008

ENGINEERING SOLUTIONS

Ceramic Motors Enable Precision Motion in Surgical Robot

A company’s products supplied motion and precision to an MRI-compatible robot

The limitations of the human hands and eyes have challenged neurosurgeons for years. Even the most skilled and experienced doctors can only work within a limited degree of precision, and they are often visually restricted when conducting operations below the surface of the skin. While technological advances have helped improve the surgeons’ ability to see into the human body, microsurgical techniques in the MRI environment have evolved to the point where surgeons have reached their physical limits.

An international team of experts from the University of Calgary (Calgary, AB, Canada; www.ucalgary.ca) and MacDonald, Dettwiler, and Associates Ltd. (MDA; Richmond, BC, Canada; www.mdacorporation.com), a provider of advanced information products and systems, recently set out to conquer this challenge by building a machine capable of conducting microsurgical operations safely within the strong magnetic field of an MRI system.

In the past, the magnetic nature of electric motors and their metal components had banned robotic surgical applications from the MRI environment, making micromotion impossible. This limitation was well known to the team designing the neuroArm, touted as the world’s first MRI-compatible image-guided surgical robot capable of both microsurgery and stereotaxy.

To help overcome the magnetic barrier, the team sought the services of Nanomotion (Ronkonkoma, NY; www.nanomotion.com), a member of the Johnson Medtech network. Nanomotion’s experts collaborated to design and implement nonmagnetic actuators that provide the precision motion necessary to enable the neuroArm to conduct microsurgical operations.

The neuroArm utilizes 16 of Nanomotion’s HR2-1-N-3 piezo ultrasonic nonmagnetic motors, coupled with the company’s AB5 drive module. These motors cover six joints, all of which are rotary. Using the real-time visibility into the human body provided by MRI, Nanomotion actuators in the neuroArm enable surgeons to manipulate tools at a microscopic scale and conduct surgeries that were previously difficult or impossible to perform safely.

“Our design team overcame a number of challenges in building the neuroArm. One was the need for the neuroArm to operate in the strong magnetic field of MRI, and with extreme precision,” says Garnette Sutherland, professor of neurosurgery at the University of Calgary.

In addition to the nonmagnetic benefit of the ceramic motors, Nanomotion’s precision motion control products increase the granularity with which a surgeon can work. The human hand is capable of working to within an eighth of an inch while the neuroArm can function to within the width of a human hair.

“Working together with the international neuroArm design team, we have overcome the formidable challenges encountered in creating a motion device that functions in a sterile operating room, within an MRI system, and alongside medical professionals involved in surgery,” says Jim Dick, senior vice president of Johnson Electric. “The neuroArm is improving operative medicine to enable safer, more successful surgeries for patients around the world.”

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