Let's Make Robots!

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Crazyrabbit's picture

Thanks for your intrest. I found with 1 wheel turns (one wheel not turning) I guessed about 45 degrees for the back wheel and 2 wheel turns about 90 degrees for the back wheel. As you can see by the video, a little more tweeking for the movement wheels can be done or mabe when I get better encoders would correct the drift. That is a simple servo test program I use on my new robots. As I mentioned, this one can carry some weight on most kinds of surfaces from shag carpet to cracked up sidewalks. Work still in progress until I learn the prop more.

ignoblegnome's picture

It looks like you did a pretty good job just by trial and error. You are correct that for a two wheel turn (drive wheels in opposite directions and same speed) your steered wheel should be at 90 degrees.

For Why Tri, I purposely placed the center point of the three wheels in an equilateral triangle to make the math easier. So for your one wheel turn, you'll need to determine the angle specific to your platform. For an equilateral triangle, this is 60 degrees.

ignoblegnome's picture

Hey, another robot with both differential drive and a steered wheel. How have you dealt with getting the angle of the steered wheel to match the relative speeds of the two drive wheels while turning?

I have a blog about this type of steering, Why Tri? A stupid way to steer. Don't take offence from the title; I have learned a lot trying this way to steer. I'm curious what you have learned.