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Puma 560
The PUMA 560 (Programmable Universal Machine for Assembly or Programmable Universal Manipulation Arm), a standard industrial robotic arm, was initially developed by an engineer at Unimation, which became a subsidiary of Westinghouse Corp.In 1985, Dr. Yik San Kwoh of Memorial Medical Center, Long Beach, CA, who developed a computer program that makes the arm work, shattered previous conceptions about robot-assisted surgery by successfully placing a needle for a human brain. -
Fig 1.
In 1985, Dr. Yik San Kwoh of Memorial Medical Center, Long Beach, CA, who developed a computer program that makes the arm work, shattered previous conceptions about robot-assisted surgery by successfully placing a needle for a human brain biopsy using Computed Tomography (CT) for guidance. This success effectively launched the “Age of Medical Robotics” around the world. The past 35 years have seen an explosion in the industry, with a global forecast of $11.4 billion by the year 2020. -
TODAY’S SURGICAL ROBOTS
The most technologically advanced surgical robot in operation today is the da Vinci Surgical System by Intuitive Surgical Inc., Sunnyvale, CA. The system consists of three main components that work together seamlessly during surgical procedures: the Vision System, which includes a high-definition 3D endoscope and a large viewing monitor: the Patient Side Cart that contains three or four robotic arms that carry out the surgeon’s commands -
how does it adjust
Permanent magnet brakes are also highly customizable, due to simple configuration and fewer parts, making them well suited for the numerous design iterations needed in order to engineer the best robotic surgery system possible. Other issues in robotic medical applications can also be resolved with the use of a PMB. PMBs are compact in size and have a low profile as well as high torque versus body size. -
how does it operate
PMB brakes operate at low voltage and have low current draw (to release). This is especially important if the equipment is portable or battery operated. PMB brakes are also environmentally friendly and UL, CSA, and RoHS compliant. -
How it worked so good
This surgical system made history by performing the first brain surgery to remove a tumor through the use of its MRI-compatible robotics as well as an intraoperative MRI. The combined use of these technologies allows an MRI scanner to move into the operating room, providing in-depth imaging during the actual procedure without having to stop the surgery to review scans as before. -
fig 4.
Previously, combining these technologies was not thought to be feasible as the magnetic field produced by the MRI equipment is in the range of 1.5 to 3 Tesla or 15,000 to 30,000 gauss (for reference the Earth’s magnetic field is only 0.50 gauss). This means anything metallic inside of this field could potentially become a dangerous projectile as well as produce artifacts on any images the doctor would use to make critical surgical decisions. -
INCREASING PATIENT SAFETY THROUGH PRECISION ROBOTICS
An inherent risk of any surgery is uncontrolled or unwarranted motion—by robot or human hand—during a procedure, where even a slight misstep can be catastrophic. A surgeon’s hand is stable to roughly 100 microns, while a surgical robot is stable to roughly 25 microns. Many medical robots today are built to both aerospace and medical standards in order to guarantee quality control. Ensuring patient safety is always the top priority in the design. -
How strong the forces is
In place of a “spring” that creates the normal force to transmit torque (as in Spring Engaged Brakes) the PMBs use Permanent Magnets to create the normal force. When the brake is energized, there is a reverse magnetic flux path created and the “return spring” disengages the braking surface, so when the power is “on” the brake is released. The “return” spring force is extremely low compared to the spring force required to transmit torque in a Spring Engaged Brake. -
ZERO BACKLASH BRAKES
New technologies are being developed to manage complementary issues that became apparent during the design and development of precision robotics. For example, one problem is the presence of backlash, or lost motion, caused by small gaps between a mechanism parts. Standard spring set power-off brakes, similar to those used in the original PUMA 560, are readily available and common in robotics, but generally have splined or hex-shaped hubs.
