the gyro

[jackdawg]

team 1307 has been working on the autonomous part of the code and wanted to know if anyone out there (and there must be someone) knows how the gyro works. we have never worked with a gyro before so bear with us if we need a bit of explaining. one of my team mates even went as far as to call the company that made the gyro and they deny all knowledge of the device.

thanks for any info

Programmer Team 1307

[apalrd]

How it works? Can't tell you that..
What it does for you?
It measures how fast you are rotating. Mount it flat on your robot, and open it with a Gyro class, and it will measure how far you have rotated (angle) since you last reset.
You can use this to calibrate a turn, basically saying turn until gyro is at x angle.

[DonRotolo]

It is a rate gyro. It tells you how fast the gyro is turning, in degrees per second.

It does NOT tell you how far you have turned - you must calculate that. For example, if it says it is turning at 15 degrees per second, and you see that it has done that for exactly three seconds, then you can calculate that it has turned 45 degrees.

The "degrees per second" signal is in the form of an analog voltage. The voltage when it is standing still is 2.5 volts, and the voltage increases 10 mV per degree per second**. So 10 degrees per second clockwise gives you 2.5+0.1=2.6 volts. Counterclockwise 10 deg/sec would be 2.4 volts. Maximum reading is 250 degrees per second - turn any faster than that and the output does not increase.

**This is from memory, please review the official specifications for the milliVolts per degree per second. Thanks.

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[Tom Line]

It is a rate gyro. It tells you how fast the gyro is turning, in degrees per second.

It does NOT tell you how far you have turned - you must calculate that. For example, if it says it is turning at 15 degrees per second, and you see that it has done that for exactly three seconds, then you can calculate that it has turned 45 degrees.

The "degrees per second" signal is in the form of an analog voltage. The voltage when it is standing still is 2.5 volts, and the voltage increases 10 mV per degree per second**. So 10 degrees per second clockwise gives you 2.5+0.1=2.6 volts. Counterclockwise 10 deg/sec would be 2.4 volts. Maximum reading is 250 degrees per second - turn any faster than that and the output does not increase.

**This is from memory, please review the official specifications for the milliVolts per degree per second. Thanks.

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That's not precisely true. The gyro outputs angular rate, however the WPI folks were nice enough to provide a current "heading" of your robot (obtained by integrating the angular rate value). Turn left and it decreases, turn right and it increases.

[Phoenix Spud]

Did you check the Sensor Manual? I found it very helpful last year when I was learning about gyros. Also, there (should) be a bit in the WPIlib documentation on the gyro class.

[furiousgeorge]

i was wondering about this same topic, is there a wiring diagram somewhere showing how to connect the gyro to the analog breakouts of the cRIO? we have never used a gyro before either and any information would be a big help.

[emersont49]

i was wondering about this same topic, is there a wiring diagram somewhere showing how to connect the gyro to the analog breakouts of the cRIO? we have never used a gyro before either and any information would be a big help.

If you are using Labview, the gyro example code has a wiring diagram included. That code will give you current heading as well as yaw rate.

[jackdawg]

thanks all! great info.