Shared-control robotic systems aid surgeons during surgery, but the human does most of the work. Unlike the other robotic systems, the surgeons must operate the surgical instruments themselves. The robotic system monitors the surgeon's performance and provides stability and support through active constraint.
Active constraint is a concept that relies on defining regions on a patient as one of four possibilities: safe, close, boundary or forbidden. Surgeons define safe regions as the main focus of a surgery. For example, in orthopedic surgery, the safe region might be a specific site on the patient's hip. Safe regions don't border soft tissues.
In orthopedic surgery, a close region is one that borders soft tissue. Since orthopedic surgical tools can do a lot of damage to soft tissue, the robot constrains the area the surgeon can operate within. It does this by providing haptic responses, also known as force feedback. As the surgeon approaches the soft tissue, the robot pushes back against the surgeon's hand.
As the surgeon gets closer to soft tissue, the instrument enters the boundary region. At this point, the robot will offer more resistance, indicating the surgeon should move away from that area. If the surgeon continues cutting toward the soft tissue, the robot locks into place. Anything from that point on is the forbidden region.
Like the other robots we've looked at, shared-control system robots don't automatically know the difference between a safe region versus a forbidden region. The surgeons must first go through the planning, registration and navigation phases with a patient. Only after inputting that information into the robot's system can the robot offer guidance.
Out of the three kinds of robot surgical systems, the telesurgical approach has received the most attention. The success of the da Vinci Surgical System caught the attention of doctors and the media alike. We may see more examples of shared-control and supervisory-controlled systems in the future.
While surgical robots offer some advantages over the human hand, we are still a long way from the day when autonomous robots will operate on people without human interaction. But, with advances in computer power and artificial intelligence, it could be that in this century scientists will design a robot that can locate abnormalities in the human body, analyze them and operate to correct those abnormalities without any human guidance.
To learn more about robots, medicine and related topics, take a look at the links on the next page.