MEDICAL EQUIPMENT & DEVICES PORTESCAP
Motion solution precision is key for surgical robots
The patient outcome of surgery performed by a robot is contingent on the control precision of its end effectors. Paul Schonhoff, Portescap’s subject matter expert for surgical application motion control, explains.
C
entral to this delivery is the motion performance achieved by the robot’s miniature motor system. Innovation in motion control precision has the potential to expand the array of surgical procedures that can be performed by robots. Meanwhile, for current robotic surgical applications, enhancing control precision means improved patient recovery. What steps should surgical robot designers take when specifying a motion system? Enhancing precision in surgical procedures not
potential for procedures previously deemed high- risk, greatly reducing damage to vital organs and nearby tissues. This paradigm shift in precision, driven by motion systems employed in surgical robots, promises minimally invasive techniques and quicker recovery times for patients. Central to this evolution is the motion system’s core component: the electric motor. Its zero-cogging feature, achieved through a brushless DC design and slotless structure, sets the stage for unparalleled control and responsiveness critical in robotic surgery. When coupled with considerations of power density, encoder performance, autoclavable capabilities, and customization, the standards of precision and performance for robotic surgery are
ENHANCES THE PATIENT OUTCOME The breakthrough in surgical precision advances surgical outcomes for patients across all spectrums, from pediatric to adult. The leap in precision not only has the potential to increase the effectiveness of surgery, but it could also enable procedures that were previously considered too high risk. In the future, the improvement in tool control could minimise the prospect of damage to organs and arteries in close proximity to the location of surgery. Similarly, a smaller incision also minimises the area of damage to healthy tissue. Even for robotic surgical procedures that are already considered ‘standard’, enhancing precision means improved patient recovery. The less invasive the surgery, the less time it can take to heal, and reduced scarring from a smaller incision can also minimise the potential for any future complications for the patient.
Portescap’s autoclavable encoders can be used for at least 2,000 autoclave cycles 20 August 2024 Irish Manufacturing
www.irish-manufacturing.com
THE CENTRAL ROLE OF THE MOTION SYSTEM
The ongoing search for greater precision is the trend across all types of surgical robot development. This means that exacting control of the robot’s end effectors, holding and operating tools such as blades or grinders, is critical. Central to this capability is the motion system that drives and controls the end effectors.
The motion system’s key component is the
electric motor, with its rotation controlling the position and speed of movement of the end effector. Smooth torque delivery is essential to ensure precision. To achieve this, the motor must overcome a phenomenon known as cogging, the periodic variation in torque that results in ripples during rotation.
While cogging can introduce relatively jerky
motion, it can also reduce the responsiveness of the motor to control commands. Delays in achieving the desired position or trajectory of the end effector will inhibit haptic feedback and decrease surgical control where real-time responsiveness is essential. As a result, a motor that can deliver as close to zero cogging as possible is vital to optimise precision in robotic surgery.
Central to this evolution is the motion system’s core component – the electric motor
ZERO COGGING To achieve the smooth torque delivery, a brushless DC (BLDC) motor design is preferred. A BLDC motor uses electronics to achieve commutation, the the motor’s coils to maintain continuous rotation of the rotor. Electronic commutation can also include integrated Hall sensors to optimise feedback and control of the electromagnetic circuit. This design is typically smoother than the mechanical method used by a brushed DC motor, where brushes make
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