Solved Servo Applications

Medical Motion Control for Patient Handling

servo drive motion controlled patient table

Today’s high-tech operating rooms include integrated imaging systems that give surgeons real-time feedback. Live images increase spatial awareness during procedures and provide invaluable information to precisely place implants.

Medical motion control systems abound in the modern operating room, from the overhead gantry that allows the C-arm to move out of the way when not in use, to the C-arm itself that is able to move around the patient, to the patient table that works in partnership with the imaging system.

Yes, even the patient table can have sophisticated motion control. This is because high resolution 3D imaging during medical procedures requires complex motion paths that are coordinated between the patient table and the X-ray C-arm. Tables with up to 7 axes of motion can position the patient precisely and repeatedly to ensure the best image quality and visual composition.

Customer Example – Cardiovascular X-Ray

In the case of motion controlled cardiovascular X-ray equipment the system relies on extremely precise controlled motion to allow physicians to perform accurate procedures.  As part of the integrated operating room the patient table must be capable of following and repeating complex motion paths that provide medical staff with high-resolution 3D imaging.  The table’s motion is simultaneously coordinated with the motion of the X-ray C-arm during the these procedures as well.

For this project, our customer required configurations for variations of up to 7 axes of complex and highly coordinated repeatable motion. This of course required multiple servo drives working together.  To stand out from the competition the customer's goal for the end-product was to have high performance and reliability with a focus on ease-of-installation.

The Solution

We provided a motion control solution that combined the customer's unique features with ADVANCED Motion Controls' servo drive technical know-how that exceeded medical motion standards for patient safety including:

  • Extended isolation margins of signal-to-signal and signal-to power levels
  • Exceeded IEC 60611-3
  • CISPR 11 (Class B) radiated noise emissions
Servo drive motion controlled patient table
motion controlled patient table controlled with servo drives

At the time, Ethernet-based communication in servo drives wasn’t as ubiquitous as it is today, but we were able to provide high-speed 100baseT network communications.  Additionally, we added the customer's proprietary communications with other peripheral system devices (i2C).

About the Peripheral Interface

The addition of the SPI in the servo drives was a tremendous cost-reducer because it allowed the drives to be the bridge between the controller and the peripheral devices (in general a peripheral device can be anything like a position sensor, HMI control, limit switch, position sensor, or any other device on the machine).  The SPI allowed the controller to talk to the drive and all of the peripheral devices over the 100baseT network where the drive acted as a network interface between the 100baseT network and the SPI.  The savings and increased reliability were realized by the massive reduction of wiring that would have had to go all the way back to the controller making it both easier to assemble and cost less for materials.

Custom Servo Drive for Patient Handling in Medical Motion Control Applications

ADVANCED Motion Controls' expertise for making custom products really shined through.  We began with a standard product that allowed the customer to get started on a proof-of-concept and to flesh out their requirements.  From there we built a custom servo drive starting from scratch.

  • We incorporated customer-specified system components: connectors, cabling, and pinouts. Using connectors that are compatible with the customer’s cabling saves on costs and allows them to stay true to their standardized designs.  By changing the pinouts on the drive to match with their own pinouts also saves on costly rewiring.
  • Customer specified connector locations on multiple sides of the case make it easier to route cables and make connections.
  • The servo drive was seamlessly integrated as a gateway between other peripheral devices and system host using i2C communication. This simplified the interface between the host controller and the peripheral devices to increase reliability and reduce costs.
  • The customer required “Form, Fit, Function" was achieved for this medical motion control application.
  • For added safety in medical environments the isolation between incoming high voltage power and low-level logic power was increased by 50% from 2kV to 3kV
  • We exceeded standards for noise emission with 6dB or more of extra margin across the required spectrum
  • Staying true to our core mantra of being compatible with any motor, the single model servo drive solution can operate at every axis location regardless of motor or associated loads.
digital servo drive used in motion controlled patient table

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