www.servomagazine.com/index.php?/magazine/article/february2012_GeerHead
GEERHEAD
before hand tremors become an
issue.
Creator Thijs
Meenink with
the robot.
The Desire
According to Dr. Smet, younger
surgeons like the use of robotics
because it enables them to quickly
become skilled at what they’re doing.
The robot uses haptic feedback to
make it nearly impossible to cut the
retina accidentally — which, of
course, would be very bad. “The
moment you touch the retina, you
have damage,” says Dr. Smet.
The robot can also shorten the
time some surgeries take to finish.
Some retinal surgeries take a long
time because they require as many as
40 instrument changes. “When
operating on a patient who has
retinal detachments, the surgeon has to peel the
membranes and remove membranes under the surface.
These operations can last an hour or longer. A robot like
this will make such difficult work more routine,” comments
Dr. Smet.
An eye surgery robot could also enable the surgeon to
simulate the procedure before performing the operation.
Doctors could perform more sophisticated and intelligent
surgeries and learn from simulations. “It will also be possible
to operate in places in the eye where we can’t today,
perhaps underneath the retina,” says Dr. Smet. The robot
may also make it possible to bring in new layers of tissue
using stem cells or generated tissues, explains Dr. Smet.
The robot is very mobile, weighing only 30 lbs, so it
can be transported, set up, and used almost anywhere —
even in the field such as in military deployments.
How It Works
The robot filters out the surgeon’s hand tremors by
enabling instrument control through a haptic interface (HI)
which takes the form of a joystick. The forces of the
instrument are measured by a nearby force/torque sensor.
The system feeds these forces back via motors at the haptic
interface to create torque. “This helps the surgeon’s
accuracy because he will have an additional perception
where most surgical forces are below the detection limit,”
says Meenink.
Because the frame supports the HI, the physician only
needs to operate it by hand, meaning that he/she does not
have to support the weight of the HI while manipulating it.
The surgeon’s arms are supported on armrests, so he/she
can attune their full focus and energy onto the surgery.
The control software also helps dissipate any hand
tremors. Tremors are on one frequency while the intended
movements are on another frequency. Because the hand
movements of the surgeon are scaled down once they
reach the instruments — which move at only a fraction of
the measure of the hand movements — the system filters
out what is left of the unintended movements. Specifically,
the surgeon’s movements are all scaled down mechanically.
When the HI moves 18 cm, the surgical instrument’s needle
moves about 25 mm into the eye, according to Meenink.
