Wire Position Sensor
 Figure: Rear-Right of the WPS2-B. Black components are cameras. A white sticker is the backlight. The green square is the source of illumination for the backlight. |
The Wire Position Sensor (WPS) measures the position of a stretched Conducting Polymer Line (CPL). The stretched CPL acts as a straight line reference for alginment. The line sags under its own weight, but this catenary we can predict to within ±10 μm over a 100-m span. Our WPS2 permits us to align objects along the span with precision 5 μm rms within its ±5 mm dynamic range. Within the WPS, an array of LEDs (light-emitting diodes) illuminates a white background attached to the interior of the cover. Two cameras view the wire as a silhouette and obtain its position by triangulation. The WPS sits on a kinematic mount consisting of three steel balls. We can mount it in any orientation. Each flash its LEDs and read out its image sensors with a LWDAQ (Long-Wire Data Acquisition) Driver. Our LWDAQ Software analyzes the images to find the wires, then applies the WPS's calibration constants to obtain the position of the wire in the coordinates of the kinematic mount. We supply Conducting Polymer Line (CPL) to deploy with the WPS. Our CPL is Dyneema braided line that coated with conducting black carbon nano-particles. The result is a black, easily-viewed line that does not accumulate electrical charge. Non-conducting line becomes charged after a while, and deviates form its predictable catenary shape. |