What is meant by scale factor for gyroscopes.

[flame_m13]

hello.i'm looking at data for gyroscopes, because i need to find one that's very accurate to within a degree. there are two items that might describe it the way i see it: bias or scale factor... I'm not sure which one would tell me what I need to know. I've tried to Google for definitions, but to no avail. Could someone clear this up for me?

Thanks.

 

[schroder]

Here”s a good on-line spreadsheet for calculating most of the common parameters of gyroscopes. .[/PLAIN] [URL]http://www.gyroscopes.org/math.asp
Scale factors can be multiplied in many ways. One of the most used is to have a laser beam reflect off of a mirrored surface on the body of the gyro and on to a scale which is further away from the gyro than the laser is. This will effectively increase the scale factor.

 

[D H]

Gyroscope errors come in two basic flavors, deterministic and random. Scale factor and bias are different kinds of deterministic errors. A bias results when the gyro registers some non-zero rate when the gyro is in fact not rotating. Suppose you have compensated for the gyro bias and it reads a rates 0.11 and 0.22 radians per second when the gyro is actually rotating at 0.1 and 0.2 radians per second, respectively. That factor if 1.1 is a scale factor error. Because they are deterministic errors, both bias and scale factor errors can be assessed and compensated for, to within the gyro's random error.

There are other kinds of deterministic errors. The gyro readings can be temperature dependent, for example.

Random error is a different beast. Suppose your gyro is rotating at 0.1 radians per second. Your gyro isn't perfect; it might give a reading of 0.11 or 0.09 radians per second. These random errors make the propagated attitude drift from truth in the form of a random walk. This error is typically reported as a random walk error with units of angle/square root(time).