Re: The Hardest Drive System To Program:
 

Welcome to CD. Your enthusiasm and self-confidence are admirable, but as you get older and gain experience you will find that those absolute statements have many shades of gray.

A software problem need not involve advanced math to be complex. It may involve just algebra, geometry, and trig... but require considerable skill and experience to set the problem up properly.

In the real world, many software people get paid to rewrite already working code, be it to make it more efficient, make it more maintainable, make it more re-usable, make it conform to a new customer-required (or company-required) coding standard or language, take advantage of the unique characteristics of a new processor, avoid royalties, or migrate away from a legacy language.

Rewriting library code just to be "elitist" is immature and counterproductive. But assuming that learning is the motivation, at least one good reason to re-write library code is to learn. Some people learn best by doing. Understanding and analyzing an already-solved problem and designing and coding a working solution is one way to do this. Comparing your solution to someone else's can be rewarding and provide deeper insight. It goes without saying that this learning process should not be allowed to jeopardize the project.

Re: The Hardest Drive System To Program:
 

Reading through this thread, I do have a question.

Assuming a robot has a crab drive, how would turning of the actually base fair? I would think that since turning would pretty much be comparable to a 4WD, it wouldn't so hot, but my knowledge of swerve/crab isn't whole.

Can anyone confirm this?

Re: The Hardest Drive System To Program:
 

The way our swerve drive turns would be to turn the wheels in so that it actually doesn't skid. I know 1717 does this and it is very effective as far as I can tell.
If they didn't turn inward it would be rather difficult to turn I think.

Re: The Hardest Drive System To Program:
 

I think he was asking specifically about crab drive (which is a subset of swerve), where all four wheels are driven and steered in the same direction.

With high-traction wheels and a long wheelbase, yes.

Re: The Hardest Drive System To Program:
 

Now, this might sound ridiculous, but has anyone thought of putting a "turret". So the Drive train would be a separate system than the turret like a tank.

Re: The Hardest Drive System To Program:
 

I believe this has been done.

Re: The Hardest Drive System To Program:
 

This Robot comes to mind. So do a few others by team 118.

Re: The Hardest Drive System To Program:
 

Re: The Hardest Drive System To Program:
 

:eek: How stable was it? Are you aware if it broke down often or at all?

Re: The Hardest Drive System To Program:
 

If you crab a long/narrow wheelbase sideways, it becomes a short/wide wheelbase.

Re: The Hardest Drive System To Program:
 

Of course.

If the vehicle is mechanically limited to crab operation that may be your only option.

If not, it could be argued that it would be easier overall to replace crab software with something more flexible.

Re: The Hardest Drive System To Program:
 

Short answer: Swerve drive with 4 independently controlled wheels.

Long answer: Swerve drive with 4 independently controlled wheels that have a limited range of motion. This forces the programmer to limit how the wheels will be pointed as to not tear out the wires leading to the motor powering the wheel (CIM motor in most cases.) It also requires the wheels taking a specific path in order to do this. This path is not necessarily the shortest and most direct, but it should be no more than 180 degrees of travel. An example of this is the attached picture, a portion of team 2421's creation this year. If someone wants to see the code for it, it is available here. Feel free to PM me with any questions you may have

Re: The Hardest Drive System To Program:
 

From what I can see, you only need 90 degrees of rotation. Personally, from the context of this competition, having 4 independently rotated wheels are too much weight. The swerve system it self is quite heavy, adding unnecessary weight should be avoided. I really see no advantage with 4 independent wheels compared to the "crab" drive. At least the negatives far outweigh the positives.

Re: The Hardest Drive System To Program:
 

I agree with david on this one. While i do see the merit in four independently controlled swerve modules, i think the weight and the limited motors outweigh the benefits of the control. For the case of FRC i think that the crab is more than sufficient.

Re: The Hardest Drive System To Program:
 

I disagree.

Many teams are capable of making such a drive lighter than most teams invest in traditional drivetrains. They then achieve full omnidirectional motion without the drawbacks of a robot sitting on rollers.