Team 2471 swerve drives

[Bryce2471]

Also, doesn't swerve have a high latency? As of what I know, holonomic drive can have very little latency

I'm confident that this swerve will not have latency problems. The modules can turn at around 120 rpm and still have enough torque to spin the wheel under load. the wheels will never have to turn more than a quarter turn, so the most you could wait to drive is .5 seconds. In practice it turns out to be much less than that. When driving it, the latency is not even noticeable.

There are a few teams that have the resources and ability to pursue swerve or other complex drives. The poster appears to have the capability and commitment to do swerve. The rewards can be big. Putting aside the competition aspect of swerve and think how much knowledge and skill a swerve project can give students.

Thank you, It's cool to here someone that has done this several times has confidence in us. I agree, even if this project never gets used on a final FRC season robot, there will have been a lot of benefit to the team from what we have already done.

[bobcroucher]

Originally Posted by Bryce2471

I'm confident that this swerve will not have latency problems. The modules can turn at around 120 rpm and still have enough torque to spin the wheel under load. the wheels will never have to turn more than a quarter turn, so the most you could wait to drive is .5 seconds. In practice it turns out to be much less than that. When driving it, the latency is not even noticeable.

At 120 rpm, a 90 degree rotation only takes 1/8 second. That's probably why it feels like less than 1/2 second.

[AdamHeard]

Originally Posted by bobcroucher

At 120 rpm, a 90 degree rotation only takes 1/8 second. That's probably why it feels like less than 1/2 second.

Based on our swerve and 1717's, I'd say you can gear your turning faster. Easily in the 180-200 rpm range and get a responsiveness gain.

[Bryce2471]

Originally Posted by AdamHeard

Based on our swerve and 1717's, I'd say you can gear your turning faster. Easily in the 180-200 rpm range and get a responsiveness gain.

I believe the current gear ratio is faster than 1717's. Our current ratio is about 87:1. The number 120 was just a number I chose because it's in the middle of the motor's range. Thanks for the suggestion though.


On a side note, here is a render of a future frame I CAD'd. It is built with a 110" perimeter. The swerves are 3" wide and 9.375" long. Sorry for the low quality render, but it was my first time trying to making a render.

[AdamHeard]

Originally Posted by Bryce2471

I believe the current gear ratio is faster than 1717's. Our current ratio is about 87:1. The number 120 was just a number I chose because it's in the middle of the motor's range. Thanks for the suggestion though.


On a side note, here is a render of a future frame I CAD'd. It is built with a 110" perimeter. The swerves are 3" wide and 9.375" long. Sorry for the low quality render, but it was my first time trying to making a render.

Ah, I assumed you were quoting free speed. Yes, you are geared faster then.

[s_forbes]

Very impressive drive system. Now that you have one iteration done and currently testing, you can continue to develop and make improvements to put yourselves further ahead than a large majority of teams for the 2014 season (assuming that a swerve drivetrain is beneficial next year...) Abuse it until you find what breaks!

I am curious about the Black and Decker gearboxes you used. Do you have more details on what model you purchased and what modifications you needed to make? I'm a fan of cheap off the shelf components like this.

Originally Posted by yash101

I'm not trying to grief here, but 28 pounds for the drivetrain sounds horrendous! I do not know how much our mecanum drivetrain weighed, but I know that it is well under 28 pounds!

I don't believe that I've ever helped construct a FIRST robot with a drivetrain that weighed less than 35 pounds. I would argue that reducing the weight of the upper structure of the robot is much more important. If you have a 28 pound drivetrain and 92 pounds worth of other mechanisms/components, then the drivetrain is not the part that needs to be redesigned.

[brianbond]

Awesome design! Question for ya, have you had any problems with plastic gears?

[yash101]

After comparing the "~37lbs" to other drivetrains, THAT IS VERY LIGHT FOR A SWERVE DRIVETRAIN (I think I needed those caps ). I think that that may be around how heavy the KOP chassey should be! Good work Bryce and Team 2471!

[Tyler2517]

Originally Posted by brianbond

Awesome design! Question for ya, have you had any problems with plastic gears?

If i remember correctly their plastic gears are for the encoders only, they have timing/gate belts for the drive loads.

On a side not the pocketing on then modules for the encoders was an amazing idea. The weight of the swerve is the lightest I have ever seen and will only be getting litter by the time of next season.