The Science of Shaking One's Moneymaker

You can't really tell from this photo, but we've added a motor onto our trailer hitch.

By this, I mean that instead of just letting the trailer drag behind the main robot, we've got a motor over the hitch point that - in theory - should let us swing the trailer left and right, or straighten it out behind us. This will all depend on Stev3's pulling power, of course.

Will it be useful? Not sure yet. But it seemed like a good idea today.

By the way, don't pretend you haven't noticed he's got two gyro sensors on board. (you can see one in front of Stev3's face and the other on the tail)

I originally bought the second gyro when we were talking about the rack & pinion steering design. Lego motors are really drifty and inaccurate. There are features that allow you to set the angle or position of a rotating motor but Lego is pretty lax about pinpoint precision.

You say: BP.set_motor_position(hitch, 90)

They say: Meh, shrug, that's about 90, give or take 45. Good luck dude!

So when we tried to get the pinion steering working, the steering pivot never quite knew whether they were pointing straight, and the answer was they were NEVER pointing straight.

Question:

How can we help the robot know that its wheels are aligned?

Theory:

If we put one gyro on the main robot, and a second gyro on the steering mechanism, then we could get several pieces of information:

1. If both gyros are pointing the same way, then the wheels must be aligned and the bot will travel in a straight line.

2. If we are constantly reading both gyros, we would get better accuracy for staying on a heading because it could check the reading from two gyros.

3. If we want to turn a predictable angle (i.e. 90 degrees), we would:

   1. take a reading from both gyros

   2. tell the steering gyro to turn 90 (or Max if less than 90)

   3. start driving

   4. as soon as the steering gyro is pointed in the right heading, tell it to straighten out and stay pointed at 90

   5. Continue to drive forward until the main gyro is ALSO pointed at 90.

Hypothesis:

A second gyro is an essential purchase.

Observation:

Then we ditched the steering mechanism, so everything above doesn't matter anymore. But hey, we have this second gyro now.

Result:

Maybe we can stick it on the trailer instead? We can still double up the readings if we need to, and maybe we can use it to point the trailer at a specific angle if that's useful to us.

Conclusion:

Who cares about science when Stev3 can wag his little tail like a wee pupper doggo!