Why don't I ever see robots that steer like a car

[robostangs548]

I really think that it would, that is why we just might be doing it

[bman]

We figured out how to do a system that is four wheel drive and four wheel steer with a diff in the middle and rack and pinion steering

[mattotters]

Originally Posted by robostangs548

I really think that it would, that is why we just might be doing it

is that pot i smell? and thats pretty sweet really sweet

[robostangs548]

Originally Posted by mattotters

is that pot i smell? and thats pretty sweet really sweet

Why thanks, we will have a vid up in the next 2 hours or so...

[robostangs548]

Video is up!
http://robostangs.tonch.com/asdf.html

[bmusser]

Ackerman drives can theoretically keep the front wheels locked straight and have a tank steer mode to turn in place if you needed a smaller turning radius.

[fnsnet]

Back in 2001 competition my School Team (616) had Rack and pinion steering. It worked well (though we bought a trillion limit switches).
As a few other's have posted, the turning radius is what kills you. If you're off track at all (read: pulling into a parking space all jacked up), you almost always have to backup and try again. Building and programming the system was awesome though (back when we programmed in P-Basic.)

Perhaps when the fields get a little larger, and traveling around the (larger) field has more importance in the game, rack and pinion steering will come to the forefront. Right now though, manuverability is what's important.

Matt

[robostangs548]

Originally Posted by fnsnet

Back in 2001 competition my School Team (616) had Rack and pinion steering. It worked well (though we bought a trillion limit switches).
As a few other's have posted, the turning radius is what kills you. If you're off track at all (read: pulling into a parking space all jacked up), you almost always have to backup and try again. Building and programming the system was awesome though (back when we programmed in P-Basic.)

Perhaps when the fields get a little larger, and traveling around the (larger) field has more importance in the game, rack and pinion steering will come to the forefront. Right now though, manuverability is what's important.

Matt

That is why with a quadrasteer design, you can crab walk a 45 degree

[FIRSTMa2104]

Originally Posted by robostangs548

I really think that it would, that is why we just might be doing it

Funny, we are using the same motor to steer.

[Ed Sparks]

Team 34 has an Ackerman steering system this year with a limited slip differential.

Here's the front end (without bumpers) ......




Top view of the front end .......



Here's an overall view of the rear end .....



A close up of the drive train ......



A close up of the diff .......




I took these pictures before we attached our lift. We'll be at the Peachtree & Bayou regionals. See ya' soon.

[Blue_Mist]

Interesting tread. Spray paint? If so, I anticipate blue streaks all across the carpet...

[EricH]

Originally Posted by Blue_Mist

Interesting tread. Spray paint? If so, I anticipate blue streaks all across the carpet...

Nah, blue nitrile I think it's called. It's a traction material that comes blue--no streaks on the carpet.

[Ed Sparks]

Originally Posted by Blue_Mist

Interesting tread. Spray paint? If so, I anticipate blue streaks all across the carpet...

Nope. It's Nitrile roughtop rubber belting available from McMaster-Carr.

[StevenB]

Team 34, that is a beautiful and impressive drivetrain. Out of curiosity, why did you choose to go with a differential rather than have one motor for each side and vary their speeds as you turn? It seems to me that if you lose traction on one wheel, you lose about half your power either way.
For video of an Ackerman-steering robot in action, look here:
http://www.chiefdelphi.com/forums/sh...ad.php?t=64389

[Ed Sparks]

Originally Posted by StevenB

Team 34, that is a beautiful and impressive drivetrain. Out of curiosity, why did you choose to go with a differential rather than have one motor for each side and vary their speeds as you turn? It seems to me that if you lose traction on one wheel, you lose about half your power either way.

1. We don't believe there is a great need for 'brute force' this year. One two speed gearbox should do it. High speed for getting around the track in a hurry, and low speed for pushing our way out of a jam. We have plenty of speed and power in high to move out in a hurry and the CG is so low we can take a corner at full speed. The turn radius is about 3 feet.

2. Our system utilizes a clutch to provide torque transfer in the event of one wheel loosing traction. That metalic device just behind the blue diff is an adjustable clutch. We can adjust this clutch to whatever torque we want so we have in effect created a "Limited-Slip" differential system. In general, we set the torque high enough so we can still move in the event one wheel looses traction but not so high that the rear axle acts as a solid axle during cornering.

3. Weight. It weights less than a system that has independent gear boxes. We wanted to be sure that we had weight to use for our lift. As it turns out, the base you see pictured weighs only 42 lbs which gave us plenty of room for lift development. The whole robot only weights less than 100 lbs.

4. We wanted to use a CIM on our lift and I'm glad we did. It's ultra fast and smooth as silk.

5. Simple. It looks complex but this thing is actually easy to maintain. The software was easy, it avoids any issue with two gearboxes stuck in an undesireable condition, and it's layed out well.