Got Gyro?

I was planning on using a gyro again this year, but I just noticed that there wasn’t one included in the 2007 KOP.

Then I saw the rule about not using special FIRST custom circuits from prior years.

Is there an “approved” gyro board available this year?
Anyone have a part number?

If not, is it permitted to use the one from last year?
(I don’t know if it was custom or COTS)

Thanks
Phil

Your primary contact should have gotten an e-mail that tells you how to request the gyro and accelerometer at no extra cost.

Here is a link to the original email that stated how to order the Gyros and Accelerometers

Here you go:

http://www.sparkfun.com/commerce/product_info.php?products_id=395

This is the Gyro we use.

It’s pricey but it works great.

Thanks everyone. The email will go out tomorrow…

So much to read, so little time :slight_smile:

Phil

I’ll second this. The turn rate of the kit gyro is too easy to hit. We used the ADXRS300 last year as well, although we wired up the eval board. The SparkFun one looks a bit easier to wire up.

We’re using a gyro this year as well, it was really nice when the students rigged up a PID loop to keep the robot driving perfectly straight.

Hey Folks,
I submitted a request for the gyro and the accelerometer on 1/6 and still haven’t received anything. Has anyone received theirs?

No. We have not recieved ours either.

Team 95 received ours late last week.

Thanks Mike and kaszeta, I usually buy the adxrs300eb right from analog devices, but they are out of stock 'till 6/07 and digikey is out until 4/07. =/ SparkFun didn’t even come up on a google search. I was looking at piezo sensor yaw rate controllers for r/c helicopters, but we 'd have to hack one and I couldn’t find the sensitivity (300deg/sec) we need anyway.
The SparkFun website says that their stock is down to under 20, so order one quick :wink:

Thanks
EricS

We haven’t received ours yet either, and i ordered it the week after the kickoff.

I’m convinced that somewhere, the various inventory control guys at Digi-key, Newark, and Sparkfun all wonder why every January there is a run on ADXRS300 gyros, Grayhill 63R128 encoders, and the other various components many 'bots use that I can easily buy the rest of the year, but suddenly become out of stock during the build season.

Hah, yeah, yet another reason we tend to purchase hard-to-find items during the off-season. We see FIRST like Christmas, do all your shopping for things you know you need or that you’re low in stock of in order to beat the Christmas rush.

Ho Ho Ho.
-Danny

That sounds interesting. I wouldn’t mind learning more about this technique.

/Jason

Our robot is basically a tank drive (left side and right side wheels centered on the robot), driven by a single joystick:

  1. p1_y determines the speed of the robot. Set both L and R motors to this speed.
  2. p1_x adjusts the desired heading of the robot.
  3. Every time through the loop, you look at your current heading, and the
    desired heading, and use the error between the two in a PID control loop
    to set the amount you’re adding to one side and subtracting from the other
    to turn the robot to correct the heading.

This allows us to correct for motor biases and different traction between left and right and drive in a straight heading.

We’ve also used this same approach with a omnidirectional drive system, although we’ve never gone to competition with it.

On 1014 we used a gyro drive very successfully last year. On the night before ship the mechanical teams accidentally estroyed the last of our encoders, so we had to scrap our encoder-PID drive. Since our drivetrain was fairly difficult to control as it was, we decided to work out something with our only remaining working sensor, the gyro.
Our algorithm was essentially like the descirption above. It took us about 45 minutes to code and tune. After it was done, our robot could easily be driven by almost anyone who wanted too. Even with the PID drive on the encoders, only a few people on the team were coordinated enough to not hit things. When the coding was done I was able to drive it on my own and chase the person who killed our last encoder around the room shooting balls at him. (That was fun.)
We got our camera working Saturday so that we can chase a green light on a cart around the school with a PI loop, and now are reimplementing the same gyro algorithm as last year to try to approach the cart without waffling side to side as much. Since the robot doesn’t have encoders installed yet, the only feedback currently is from the camera.
I don’t know how much experience you have programming for FRC, but if you need some help, I can talk to my programming team and get some code samples.

Kyle W
Engineering Director, Team 1014

Very interesting. Did you start with Kevin’s code? We’re going to be trying this this year- assuming we ever get the Gyro offering.

We are thinking about using the provided gyro this year. Does anyone have instructions as to how to connect it to the FRC controller?

Thanks, TEAM 203

You’ll want to use the three left-most connection holes labeled
G 5 T
B R W

T stands for “twist” and is your signal wire.
5 stands for your 5 volt power wire
G is ground

See http://www2.usfirst.org/2007comp/other/2007%20FRC%20Sensor%20Manual.pdf