IntelliConnector System

Present in-service remote monitoring techniques utilize various sensors permanently mounted in regions of interest, such as strain gauges, thermocouples and optical fibers, however the number and location of these sensors are limited by the implied infrastructure. This includes wires for power and communication that run from each sensor to data acquisition units, which add weight, cost, complexity, and paths for potential ingress of moisture and other contaminants. Traditional data acquisition units also can become bulky and heavy as hardware components are added to accommodate all these sensors. To resolve issues MDC has developed a low-mass sensor infrastructure as part of the MEDIC system, which essentially takes the form of an intelligent connector that can digitize and process signals at the point of sensing. This IntelliConnector is a direct replacement of traditional instrumentation such as oscilloscopes and function generators. This device greatly reduces unnecessary cable weight by allowing data to be carried over a serial sensor-bus and increases signal fidelity by digitizing at the point-of-measurement to eliminate EMI. Hardware requirements are also minimized through distributed local processing.

There are presently 3 versions of the IntelliConnector: MD3, MD4 and MD7. The MD3 (presently at revision d) is the most vetted version of the device, having gone through MIL-STD-810 and DO-160 environmental airworthiness testing as well as extensive SHM validation experiments. This device is 25 mm in diameter by 80 mm in height and can facilitate 20 Vpp guided wave testing up through 150 kHz with 1MHz 16-bit data acquisition. More than 500 MD3’s have been produced. The MD4 is a wireless version of the MD3a device, using a ZibBee protocol and a lithium polymer rechargeable battery. Only a single prototype has been fabricated of this device, however it has also been successfully testing using vibration-based energy harvesting. Finally, the MD7 is the latest high-speed version of the IntelliConnector family. At 40 mm diameter and 6 mm in height, this device is capable of synchronously facilitating 20 VPP guided wave (GW), frequency response (FR) and acoustic emission (AE) testing up to 5 MHz with 50 MHz 12-bit data acquisition on 6 independent channels. There are 8 additional multiplexed channels per node for other external analog measurements with 1 Gbit of internal data buffer and 16 Mbit on-board static flash storage. More than 100 devices can be daisy-chained on a serial CAN network using unique addresses and running between 24-28 VDC. Presently MDC has produced more than 100 of the MD7 in 3 variations; MD7a with concentric PZT actuator/sensor pair, MD7b with a 7 PZT actuator/sensor vector-based locator array (patented method for eliminating dependency on wavespeed), and MD7c with 6 high-speed solder-pad break-outs.

There are several competitive advantages to IntelliConnector over competing technologies. The principal advantage is that MDC has developed a design that allows the SHM hardware to be mass-produced, using flexible software to customize the system to any application. Most rival systems require an actuator/sensor pattern that is custom designed and built for an application, adding significant cost to the system and time and risk to the vehicle manufacturing process. IntelliConnector nodes can be added to the vehicle as a final step, and the software constants would be customized and calibrated separately by MDC. Another major advantage is that the IntelliConnector can facilitate Guided wave testing, which can efficiently query a much larger area on a vehicle than any other damage detection method using only one sensor and actuator. This allows for full vehicle coverage with a much lower sensor density, reducing cost, weight, complexity and computational requirements. Finally, the IntelliConnector uses surface mounted sensors over embedded technologies, which is seen as a major advantage by most major aerospace manufacturers. Embedded sensors can initiate damage sites themselves, can prohibit repair of the structure if SHM system wires run through the damaged region, and are not able to be replaced if they fail in-situ. The MDC nodes can also be retrofitted onto existing and ageing aircraft just as easily as they can be installed on new ones. Surface mounting also allows for easy removal of the devices for structural repair.

Click here for a downloadable design specification for the Intelli-Connector SHM sensors.

Click here for a downloadable design specification for the latest Intelli-Connector HS SHM sensors.