Electronic Design

Programmable Cube Controls Space Station’s COLBERT Treadmill

NASA has selected the UEIPAC Cube from United Electronic Industries (UEI) to perform an essential role in controlling the COLBERT treadmill in the new space station exercise facility. The programmable automation controller (PAC) hardware is compact and rugged, and makes efficient use of conductive cooling. As a result, the unit ideally suited for space applications.

The new treadmill was named after comedian Stephen Colbert, who won the highly publicized write-in contest for naming the new Space Station facility. However, NASA followed its long-standing policy of not using names of living people for space hardware and instead chose to name it “Tranquility” in honor of the original Apollo 11 Moon landing. In a tip of the hat to the comedian, however, NASA did decide to use the name COLBERT for the exercise treadmill to be installed in the new facility—an acronym for Combined Operational Load Bearing External Resistance Treadmill. The new treadmill is scheduled to be up and running early next year.

The astronauts need the treadmill both for exercise and for maintaining bone density in a gravity-free environment. Some of the functions monitored by the UEIPAC are characteristics of the astronaut’s gait and foot impact forces while exercising on the treadmill. This is determined by sensing data of various types from accelerometers and load cells in the treadmill and associated restraining equipment.

A novel feature of the NASA system design is the use of a finite-state-machine (FSM) software structure to control the functioning of the UEIPAC and the treadmill. The UEIPAC was a good match for this application because the Linux driver and cross compiler supplied by UEI are all compatible with the FSM structured software used for the embedded system control.

The Cube architecture is a compact (4 x 4 x 4 inches or 4 x 4 x 5.8 inches) Ethernet-based I/O platform that can be deployed in four different configurations:

  • Ethernet I/O system slaved to a host PC
  • Standalone data logger/recorder
  • Linux-based Programmable Automation Controller (UEIPAC)
  • Modbus TCP-based I/O slave

Each Cube consists of a core module (that holds the processor and network interface) along with three or six open I/O slots. Users select the deployment option that meets their requirements and match the Cube’s I/O configuration to their application by selecting the appropriate boards. The six-slot Cube provides up to 150 analog inputs, 192 analog outputs, 288 digital I/O, 48 counter or quadrature channels, 72 ARINC-429 channels, 24 Serial or CAN-bus ports, or 12 1553 communication channels.

United Electronic Industries

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