dje@datacube.UUCP (02/10/87)
Does anyone in net land understand or know about Gyroscopes? I have a surplus gyro, about 4" diameter and 10" long, originally hermet- ically sealed. It has a resistive (four terminal) potentiometer to pick off angle, a DC spinner motor, and solenoids and a DC motor that provide a 'reset and position' function. All functions seem to work at 12V DC. I have built an A/D and display that decodes the potentiometer output and gives a digital readout in degrees. It is very stable (no variation in angle) when sitting on a bench, and seems to work as a gyrocompass when it is moved around. It can stand about +/- 45 degrees of off axis motion (pitch, roll) before it 'loses it' and needs mechanical resetting. I will soon be testing it in my car to see if it really works. I would like to use it as a gyrocompass for boating. Here are my questions: -- Who might have made it. No documentation or labeling. -- Is it intended to readout in the horizontal plane (azimuth) or is it intended to be in the vertical plane (roll). Seems to do both. -- Is it a free gyro (stands still as the earth turns) or does it seek north? I have read Bowditch (marine navigation bible), and it says a north seeking Gyrocompass uses weights on various axes, takes lots of warmup time, and is big, expensive, and complicated. -- How is the interface to a four terminal pot normally done? -- How much error is introduced by motion. -- What about Gyros in small planes? Any and all info would be really helpful. Dave Erickson ------------------------ Datacube Inc. 4 Dearborn Rd. Peabody, Ma 01960 617-535-6644 ------------------------ ihnp4!datacube!dje
dje@datacube.UUCP (02/19/87)
This is a response to my own note. I've answered many of my own questions, so I'll post my gyro experiment results. The Gyro mounted in my car works great. Trips to and from work (20 miles) and a three hour trip on windey roads have caused essentially unmeasurable errors. Less than 2 degrees (which is the positioning error of my car in the reference driveway). So onward and upward. I'll be testing it in the boat this spring. The next step is to integrate it with the boat's distance log and to derive a single course and distance. (Given a known starting point, where am I: angle and distance?) 99% of the navigation I do is solving this problem, mostly on trips (or legs) under 100 miles, often in the fog. >-- Is it intended to readout in the horizontal plane (azimuth) or is >it intended to be in the vertical plane (roll). Seems to do both. Works fine in the H plane. That's all I need. >-- Is it a free gyro (stands still as the earth turns) or does it > seek north? It doesn't seek north. Why it doesn't stand still as the earth turns, I still don't know. Maybe magic. >-- How is the interface to a four terminal pot normally done? I have it worked out. I apply a two phased voltage to the terminals, then do two measurements to find angle to nine bits. >-- How much error is introduced by motion. Not much. Dave Erickson ------------------------ Datacube Inc. 4 Dearborn Rd. Peabody, Ma 01960 617-535-6644 ------------------------ [ihnp4 | mirror]!datacube!dje