12-01-2008 12:51

Jeff K.

Re: pic: FRC 1726 Steering Prototype

Did you get go-kart turning spindles and modify them? They look pretty good.

12-01-2008 12:53

MrForbes

Re: pic: FRC 1726 Steering Prototype

No, we made our own, from some 1/2" bolts, square tubing, and flat stock.

Not much to it, really. We spent about an hour or so.

Anyone want to guess the weight?

12-01-2008 13:07

AdamHeard

Re: pic: FRC 1726 Steering Prototype

So, the wheel rides on that bold, and the whole assembly is rotated on that hole in the tubing via that "arm"?

12-01-2008 13:10

GUI

Re: pic: FRC 1726 Steering Prototype

Yes.

12-01-2008 13:11

MrForbes

Re: pic: FRC 1726 Steering Prototype

You can almost see them in this picture, where I'm explaning the geometry to some of the new students.

http://photos.project1726.org/displa...lbum=25&pos=15

12-01-2008 13:43

Kat Kononov

Re: pic: FRC 1726 Steering Prototype

My team wants to use Ackerman steering, but they also want four-wheel drive. What would you recommend? please?

12-01-2008 13:48

MrForbes

Re: pic: FRC 1726 Steering Prototype

I would recommend that you put two wheels next to each other on the rear of the robot on each side, in the fashion of a school bus (dualies), and then you'll have a 6 wheel robot with 4 wheel drive and easy to build Ackermann steering.

We plan on trying to set up the steering so the robot can turn very sharply, sort of like a forklift (but with front/rear reversed from a forklift), and making it turn that sharply pretty much rules out having shaft drive to the center of the front wheels like normal 4x4 trucks use. Instead, you want to make it work like a "crab drive" or "swerve" robot, and then it would not really make sense to bother with the Ackermann geometry.

also with a 2wd Ackermann system with very tight steering angles, it might be very helpful to have a programmed "differential" that drives the motors opposite directions to make the robot spin about the rear wheel center axis. We haven't figured this out yet, though.

12-01-2008 14:08

Kat Kononov

Re: pic: FRC 1726 Steering Prototype

haha that's a clever solution. Unfortunately, it didn't fly with anyone. Thanks though.

12-01-2008 20:30

Tytus Gerrish

Re: pic: FRC 1726 Steering Prototype

that looks like the steering knuckle on my go-cart that broke and made me crash

12-01-2008 20:39

=Martin=Taylor=

Re: pic: FRC 1726 Steering Prototype

I don't want to sound overly harsh.... But what if any is the benefit of car steering?

I mean, you realize that this game isn't really as simple as "Go straight and turn left" it will take a great deal of maneuvering to pick up and hurdle a track ball (which I assume you are trying to do).

Just imagine trying to make a five-point turn every time you want to pick up your ball

I don't think this game will really resemble a race, I think it will look more like a game of "territories" with robot progressing through the "territories" in a counterclockwise direction.

12-01-2008 20:59

falconmaster

Re: pic: FRC 1726 Steering Prototype

Looks Great NERDS! Keep it up! Looking forward to alliancing with you all!

12-01-2008 21:07

Enigma's puzzle

Re: pic: FRC 1726 Steering Prototype

2075 is going for the ackerman system, even though I don't agree with it.
I think we are over thinking it. Were hoping to an engineering award with the rest of our drivetrain though.

12-01-2008 21:07

MrForbes

Re: pic: FRC 1726 Steering Prototype

We are well aware of the difference in close maneuvering with the car type steering, and have a back up plan to build the drivetrain as 6wd if we feel it won't perform well enough.

At the same time, we are working hard to make it easy to pick up and hurdle the ball, and hopefully to catch it on the bounce. And if the ball stuff doesn't work as planned, we will have a fast lapper

That is quite possible. Predicting how the game will play out is a risky business!

(and thanks for the encouragement Fredi, should be fun having you at both regionals this year!)

12-01-2008 21:14

s_forbes

Re: pic: FRC 1726 Steering Prototype

For the sake of knowing, in what way did it break?

12-01-2008 21:21

GUI

Re: pic: FRC 1726 Steering Prototype

Another advantage squirrel forgot to mention was how easy to control this system is. Unlike a tank drive (we were comparing to our 6wd chassis from last year) which can be finicky to keep going straight and easy to over/under shoot when turning, the ackermann style drivebase goes exactly where you tell it too.