Questions about crab/swerve drive.

[big1boom]

Might as wel preface this saying that I only have 1 year (this year) experience with crab/swerve

Originally Posted by BenX02

1) The design I came up with has six CIMs, one for each wheel module, and one for each side to turn the modules. My only concern with this design is that it will be heavy. Can someone show me some designs or CADs (or just explain your design) for your designs. Don't worry, I won't rip them off, I just want to get insperation.

http://www.chiefdelphi.com/media/photos/33181
This is our swerve. My brother posted images of his CAD's later in the thread.


This year we went with 1 CIM total, but for a normal year I would recommend going 1 CIM for each side (r/l) The main problem with this setup is that you have to be exact for the bevel gears, otherwise the will not mesh correctly.
We used globe motors to turn our wheel modules. I have seen other teams use FP motors, or window motors.

Originally Posted by BenX02

2) This is going to sound like a dumb question, but I have heard that a water jet/computerized mill is necessary for building a crab drive system, may I ask why? The machine shop our team meets at has one, but in the past they have not let us use it.

It is not necessary to have a computerized mill, although it does make everything easier.

We had our boxes cut out by an old CNC, then we drill pressed all the holes, then had them welded.

Originally Posted by BenX02

3) As a driver, I have been wondering about the different ways you can drive a crab/swerve. I have seen teams do a tank style with two joy sticks, where it acts like tank drive but if you move the sticks sideways your robot moves sideways ect. I have also seen with one stick and a throttle, and a stick with a Z axis. But which would you say is the best?

This year we went with 1 Joystick controlling throttle, one joystick with twist controlling translation (strafing) and rotation.

Originally Posted by BenX02

4) I know you need lots of sensors, but what kind and where might I get them?

I didn't have involvement in sensors other than mounting them, but I know that we mounted a magnet onto a sensor sprocket shaft, then put the sensor right above it, no contact. This sensor then outputs a voltage that corresponds to an angle. According to our team's programmer, he has to round the values otherwise it will crash/slow down the cRIO.

If you have any more questions, please post here, or PM someone. Most people are more than willing to help