CT and Patient Table

A custom all-in-one brushless DC motion control module (MCM) was developed for GE’s NM (Nuclear Medicine), CT (Computed Topography), PET (Positron Emission Tomography) and Patient Table. The MCM module has replaced six separate components, fitting them in a single cost and space efficient module with a single product number for all its axes.

The Challenge

GE Healthcare was looking to develop the next generation of their Discovery 600 Series. In order to increase the lifetime of their parts, they wanted to move from brush-based technology to the more durable yet harder to control brushless technology. In addition, GE wanted to reduce their production costs, increase the accuracy and smooth operation of the system, and reduce the footprint of the control systems.

As a medical device company, GE needed a solution that would conform to strict medical EMC standards.

The Solution: All-in-one Motion Control Module (MCM)

In the previous version, GE had six separate functions in separate cards, including tilt sensors, filters, EMC, and GE Safety communication channel.
As the application was predicted to be relatively noisy, GE needed to include a set of filters. In previous versions, these filters were dispersed across the system as separate components. Servotronix consolidated all the components into a single all-in-one motion control module with a single part number.
Each module was designed to be compatible with all the system’s axes, including all the axes for the detectors and the patient’s table. By combining all the cards into a relatively low cost module, GE reduced the overall cost of the system, simplified the system operation and maintenance, while at the same time enhancing the available functionality for each axis.

Absolute dual loop feedback for collision protection or smoother operation

For enhanced control, the module connects two encoders to a single axis – a preliminary feedback control is connected to the motor, while a secondary feedback control monitors the load. On every power up, MCM sends the absolute position of each axis to the host controller for collision protection to allow smooth operation and prevent any axis backlash, by reading dual feedback as shown in the diagram below.

Conforming to medical industry standards

The control module conforms to the medical industry’s standard (Medical 60601-1-2 Class B), including conformity to electromagnetic standards (EMI/EMC).
The module features an auxiliary line to monitor safety, emergency release function, and CANopen® communications interface.