Swerve Drive with Servos

[bharrison6]

We were looking into making a swerve drive if not for this year then next year and I seen where you can use any commercially available servo up to a certain limit on power. (I think 4w at 6vdc) I was thinking servo's would be awesome for a steer motor since you can just tell it what angle you want it to turn to. Is there some reason people don't do this? Is it because the max size servo allowed is not strong or fast enough to turn a swerve drive? Also what is the reasoning behind not letting in stepper motors? They seem to be the best option if they were allowed.

[wilful]

The reason most teams do not use servos in swerve drive is because of the lack of power.

Consider a robot using such a system driving in a straight line, and then being hit by a defending robot. The lack of power in the servos causes them to be back reducing the amount of power the defending robot actually needs to push the swerve robot, as the swerve modules now act as powered caster wheels.

While one could drive and steer with them, if someone pushes this robot, it is now stuck driving either directly into, or directly away from the defender.

This, coupled with a slow module turning speed leads to a poorly implemented drive system.

That being said, if anyone has run a servo steer swerve drive successfully, please correct me.

[Redo91]

I have never seen a swerve drive that has the wheel axis in a different plane than the axis the module rotates about(I think that is an appropriate description). This keeps swerves from having that effect of turning when hit from the side by another robot because no moment is generated around the axis of rotation for the module.

As wilful said, for FRC, legal servos aren't quite powerful for an effective swerve drive.

And now for the usual "DON'T DO IT" comment. Whle swerve is a super cool drive system, if this is your first time doing it, and you are thinking of doing it for this season, DON'T DO IT. From the way it sounds, your team is still deciding on what drivetrain to do. Hopefully you are not still trying to do that this late in the season.

[Electronica1]

It has been done before. However that was on a low friction field. So you might need something stronger to turn it.

[bharrison6]

We already have a drive setup for our competition robot. We are just considering what we need to make this happen next year. We already have a wooden chassis setup for the swerve though and we were going to experiment and see if we can make it work when we get time.

[Wren Hensgen]

As part of a team that created a FTC-legal swerve, I would heavily advise against it. The limits on servos reduce the power you have available, and even in FTC, we didn't have enough power to turn our modules.