Whether performing an intricate surgery, positioning a patient, or taking a tissue sample, today’s biomedical devices are taking advantage of advanced motion control devices to ensure accurate control and movement in biomedical applications. Robots are making it possible to perform surgical procedures not only with higher precision than before, but in less time and with less pain and suffering for the patient. Moreover, improvements in the design and packaging of motors and other control components are making it possible to shrink biomedical devices and make it easier to perform procedures in tight, confined spaces.

Fig. 1. University of Texas Southwestern Medical Center is evaluating the use of the Armeo robot to aid the recovery of a patients recovering from neurological injuries such as strokes and traumatic brain injury.
Fig. 2. Tomo Therapy’s radiation therapy system uses the DMC-2153 five-axis motion controller from Galil Motion Control to precisely position the patient table.
Robots continue to find their way into the operating room, to make difficult surgical procedures more comfortable for the patient. For instance, surgeons at the University of Illinois Medical Center at Chicago are using robots to perform minimally invasive surgery to remove the thyroid gland, without leaving an incision or scar on the patient’s neck.

Typically, removing all or part of the thyroid gland typically requires a 3- to 5- inch incision across the front of the lower neck.

“The cosmetic and psychological benefits to patients are evident immediately,” said Dr. Pier Cristoforo Giulianotti, the Lloyd M. Nyhus Professor of Surgery at UIC. “Young patients in particular are often concerned about a large visible scar, and this technique provides an alternative to traditional surgery.”

The UIC surgeons used the well-known robotic-assisted da Vinci Surgical System to remove the thyroid gland, by making one small incision under the patient’s right arm and another tiny incision in the chest. No neck incision is needed. Working from a console, the surgeon controls the movement of four robotic arms equipped with an endoscopic camera and surgical instruments. The robot provides 3-dimensional visualization, enhanced magnification and a greater range of motion to locate and remove the thyroid gland in the delicate, narrow neck space.

Fox Chase Cancer Center in Philadelphia used the ViKY® robotic holder — a technology had been developed in France by Endocontrol Medical and tested on thousands of patients in Europe — 0 to help perform the world’s first minimally invasive distal pancreatectomy. The minimally invasive distal pancreatectomy was performed on a 65-year-old man who was diagnosed with two pancreatic cysts, one of which is potentially cancerous.

Fox Chase surgeon Andrew A. Gumbs considers the robotic laparoscopic holder to be like an extra hand during surgery, adding stability and steadiness. “This system is so versatile that surgeons like me are able to use it for many different laparoscopic procedures, including those in the gastrointestinal, urologic, thoracic and gynecologic regions.” Gumbs said.

Typically, minimally invasive procedures, like a laparoscopic distal pancreatectomy require surgeons to use both hands to manipulate the surgical tools and need an assistant to manipulate the endoscope — a thin, lighted tube equipped with a camera that allows the surgeon to view the surgical field.

“The view of the surgical field is critical, so ViKY’s pinpoint accuracy helps me perform more complex procedures laparoscopically.” Unlike typical laparoscope holders, the ViKY’s system’s holder is lightweight, easy to set up and use, and takes no floor space.

Fig. 3. With the help of small motors and encoders, the SenoRx EnCor biopsy device performs non-invasive breast probing to find cancerous tissue.
Motion control advances are also paving the way to help patients rehabilitate after strokes or other injuries.

Physical therapists at University of Texas Southwestern Medical Center are evaluating a new mechanical arm that allows people recovering from neurological injuries such as strokes and traumatic brain injury to enter a virtual world where they can repeatedly practice movements needed to regain arm strength and movement.

University of Texas Southwestern Medical Center is one of fewer than a dozen sites using the Armeo robot, which provides a virtual environment and weight support system for the arm. It is trying to determine how Armeo stacks up against traditional therapies in which individuals physically pick up objects.

The Armeo robot was developed by Hocoma, the company that developed the Lokomat, a robotic therapeutic device to assist with walking. Armeo supports functional, task-specific movement therapy in a motivating and inspiring environment. Its integrated weight support reduces gravity and thus allows patients to master a wide range of movements.

Assigned tasks are based on using different muscles, and include virtual exercises such as cleaning a stove, washing a window, catching fish and capturing raindrops in a mug. The exercises also help stroke patients plan perceptually what steps they need to take. The counter-gravitational support can then be reduced over time, so the individual bears more and more weight independently. A computer then records speed and frequency of repetitions to track progress.

Precise movement of patients is also being facilitated by motion control advances. Tomo Therapy Inc., Madison, WI, developed its Hi-Art(R) treatment system, a radiation therapy device that uses 3D CT imaging to ensure accurate patient treatments. The patient lies in a table that slides into the rotating gantry for continuous 360 deg delivery of helical magnetic resonance imaging.

The patient table uses the DMC-2153 five-axis motion controller from Galil Motion Control, Rocklin, CA, to position the table with +/-1mm accuracy. Future models will have sub-millimeter accuracy. The controller accepts both incremental and SSI absolute feedback, in order to maintain the table’s position in the event of a power loss.

“We considered several motion controllers for the Hi-Art® system and Galil’s motion controller met our requirements for its Ethernet-based control of stepper and servo motors, ability to multitask, SSI feedback capability, and robust programming language,” said research engineer Graham Reitz. “It also had to be small enough to fit in our very small allowed space.”

According to Reitz, Galil customized the controller so it could easily accept all of the SSI devices for feedback. “We used lots of the I/O provided for various tasks, like machine shutdown, clutch status, and emergency stops. It also signals its embedded computer to perform motion calculations, while our system’s Linux computer calculates, coordinates, and talks directly to the Galil computer to provide redundancy and increased safety,” he said.

Miniaturization of motion control components is also making it possible to shrink the size of medical diagnostic devices to allow for more comfortable, less intrusive patient testing.

SenoRx Inc., Irvine, CA, makes a biopsy measurement device, called EnCor®. The minimally invasive, vacuum assisted breast biopsy device performs non-invasive probing of even in the most difficult locations within the breast. The device contains three motors and a sampling probe that is inserted into the patient’s breast to collect breast tissue samples to detect for the presence of cancer.

Each motor uses a tiny encoder, made by CUI Inc. of Tualatin, OR, for position feedback. “We were looking for the smallest optical encoders we could find. You need to minimize the footprint of the motor/encoder assembly,” said Martin Shabaz, Senior Staff Engineer of SenoRx.

Integrating motion control functions into manufacturing equipment is also helping companies machine precision medical devices. For example, Siemens Energy Automation, Elk Grove Village, IL, is using its integrated CNC controllers to machine orthopedic implants and knee, hip, shoulder, and other medical components. The CNC regulates the drives used in the milling, turning, and grinding functions, replacing the use of discrete machines to perform these functions, according to Ryan Legg, Product Manager for Sinumerik CNC Systems.

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Motion Control Technology Magazine

This article first appeared in the June, 2009 issue of Motion Control Technology Magazine.

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