Measurement of Angular Valve Displacement in High Vibration Environments

The United States Air Force (USAF) is experiencing high failure rates in valve position transducers that are employed in many of its testing facilities. The transducers are subjected to extreme levels of vibration-in excess of 50 gRMS over the 0-10,000 Hz band; a wide operating temperature range from -10°F to 140 °F; and other environmental influences including moisture, dirt and other contaminants. The USAF seeks a robust transducer design that can operate within these broad environmental conditions and deliver a resolution of 0.1% of maximum valve travel (~90°) with a response time of 10 milliseconds. In Phase I, Invenios, Inc. proposes to develop a retrofittable eddy current-based absolute position transducer that derives position in a Readhead that senses coil inductance variations, in quadrature, on two separate tracks of different pitch as a slotted metallic code wheel rotates overhead. The Readhead integrates a digital signal processor onto a micromachined photostructurable glass-ceramic substrate-using proprietary technology that Invenios licensed from The Aerospace Corporation- that employs an array of high-aspect ratio coil grooves filled with conductive material. The result is a first-of-its kind, "chip encoder" that achieves the USAF requirements in the smallest possible footprint.