Surgical precision saw a major technological boost in the early 1980s when robots began accompanying doctors in the OR. In recent years, minimally invasive operations have been gaining popularity over traditional surgery because of faster post-operative recovery and less scarring.
Many of these endoscope-based surgical operations present unique risks, such as camera shake or communication difficulties between the operating surgeon and the scopist. New equipment is needed to overcome these problems. At the same time, conventional motor-driven endoscope manipulating robots are not ideal in terms of operational subtlety and delicacy. That’s why Riverfield, a Tokyo-based venture company, built EMARO—the world’s first pneumatically controlled surgical assist robot.
Launched by the Tokyo Institute of Technology and Tokyo Medical and Dental University (TMDU), EMARO resulted from more than 10 years of research on pneumatic, ultra-precision manipulation. Associate Professor Kotaro Tadano of Tokyo Tech’s Precision and Intelligence Laboratory and Professor Kenji Kawashima of TMDU’s Institute of Biomaterials and Bioengineering conducted the research.
EMARO controls the endoscope by sensing the vertical and horizontal movements of the surgeon’s head through a gyroscope that is worn on the forehead. The endoscope has four degrees of freedom for movement: forward and backward (insertion and removal), up and down, left and right, and rotation. The surgeon directs this motion by controlled movements of his head and by operating switches with his feet.
Until now, pneumatic manipulation technologies have not been able to provide the smooth and continuous movement needed for highly precise control of surgical devices. Professors Tadano and Kawashima overcame this hurdle by creating an advanced model with continuous air pressure control and an original manipulation technique. Their success owes much to Tokyo Tech Professor Toshiharu Kagawa, who has had impressive results over decades of research in the field of fluid measurement and control. Two pneumatic cylinders are used for moving EMARO forward and backward (200 mm); up and down has a -3 to 47° range of motion. For rotation and right and left movement, EMARO moves from -90 to 90°. Two rotary type pneumatic actuators are used for left and right and for rotation. All actuators are driven by a five-port, spool-type servovalve.
Pneumatic driving makes it possible for robots to move gently and smoothly. It has been used extensively in industrial robots, particularly for grasping and holding objects. Moreover, the pneumatic approach makes it possible to create a compact and lightweight design; sufficient power can be obtained by injecting or extracting air through a cylinder no larger than a standard syringe—about 10 mm in diameter.
Consequently, the operating surgeon can receive clear endoscopic images without camera shake, resulting in more precise surgeries. In addition, EMARO provides haptic feedback for the user and, taking the role of a scopist, can be useful in smaller hospitals that have a shortage of doctors, allowing more patients to undergo laparoscopic surgery.
EMARO is the first in a series of surgical assist robots that will use ultra-precision pneumatic manipulation technology. Development is now underway for a system that uses the pneumatic drive design and incorporates forceps. As its primary feature, this system will be able to detect the force exerted on the forceps through air pressure, and will feed this sensory information back to the operating surgeon. This is called force sensing.
With surgical assist robots, the surgeon sits in front of a console placed off the patient and operates the controls with both hands. While observing endoscope images, the surgeon can manipulate forceps and the endoscope. With force sensing, the surgeon will feel as if he were directly working on the patient, which is likely to help improve surgical accuracy.
There are no plans to bring EMARO stateside yet, but it’s not off the table. “We have not planed this yet, but if there is a good opportunity, we will deliver EMARO to the U.S.,” said Kawashima.