Drive Systems

[Skooks]

I've been noticing the many different styles of drive systems, such as tank, mecanum, H-drive, and swerve. I was wondering what other people have seen and built for there robots.

[PowerfulKitty]

Tank is the basic and, in my opinion, the best drive for most teams. It is simple and effective. I believe that even in RR tank is superior. This is most often a 6 wheel, dropped center. Sometimes you will see an 8 wheel dropped center. It provides the best traction so you get pushing power and acceleration.
The main disadvantage of tank is the inability to move sideways.

Mecanum is often used to move sideways. I am not a programmer, but from what I understand it requires rather complex programming. When done well, it is easy to use, but can be easily messed up. It provides poor tration and is easily pushed around.

H drive uses omni wheels mounted perpendicular to each other. Omni wheels hame small rollers that allow them to slide sideways, so there is a set of wheels for each direction. It has the same low traction as mecanum.

Swerve is often considered the best overall drive. It has great traction and has sideways/diagonal/any direction movement. Each wheel is mounted on a pivot so it turns beneath the bot. These are very difficult to build but are very versatile.

One of the most interesting drives I have driven is one developed by team 967. This 9 wheel drive used an 8 wheel dropped center base, with one wheel mounted perpendicular and on a piston. When the piston is activated the wheel is forced down and the back end of the bot lifts off the ground, so it is supported by the two front wheels and the 9th wheel in the center of the bot. This allows great traction in regular tank mode and the ability to move sideways. I believe in 2014 Team Titanium utilized this concept in their drive base.

What else is out there?

[thatprogrammer]

1114 is using kiwi drive this year. Three omnis set in a triangle.

[lcoreyl]

Originally Posted by PowerfulKitty

Tank is the basic and, in my opinion, the best drive for most teams. It is simple and effective. I believe that even in RR tank is superior. This is most often a 6 wheel, dropped center. Sometimes you will see an 8 wheel dropped center. It provides the best traction so you get pushing power and acceleration.
The main disadvantage of tank is the inability to move sideways.

Mecanum is often used to move sideways. I am not a programmer, but from what I understand it requires rather complex programming. When done well, it is easy to use, but can be easily messed up. It provides poor tration and is easily pushed around.

H drive uses omni wheels mounted perpendicular to each other. Omni wheels hame small rollers that allow them to slide sideways, so there is a set of wheels for each direction. It has the same low traction as mecanum.

Swerve is often considered the best overall drive. It has great traction and has sideways/diagonal/any direction movement. Each wheel is mounted on a pivot so it turns beneath the bot. These are very difficult to build but are very versatile.

One of the most interesting drives I have driven is one developed by team 967. This 9 wheel drive used an 8 wheel dropped center base, with one wheel mounted perpendicular and on a piston. When the piston is activated the wheel is forced down and the back end of the bot lifts off the ground, so it is supported by the two front wheels and the 9th wheel in the center of the bot. This allows great traction in regular tank mode and the ability to move sideways. I believe in 2014 Team Titanium utilized this concept in their drive base.

What else is out there?

lots of incorrect and exaggerated information in here. since the OP wasn't asking about each drive and rather what is out there, I won't turn this into thread 8,398 like this.

There were a few Killough (4 wheel omni). Here's one

At least one octocanum.

And don't forget the... kiwi swerve? not sure what overclocked is calling this.

[SJaladi]

Team 1923 built a custom drivetrain this year that incorporates some of the best qualities of different variations of tank drive. It is constructed with C-channel like a standard tank drive, but similarly to a WCD one wheel on each side is direct driven by the gearbox allowing for us to drive to some extent even if all the chains fail. Additionally to prevent damage to the chain we run all the chain within the c-channel. The drivetrain has 5 wheels on each side (3 colsons in the center and 2 omnis out at the ends). It does not use a drop center but rather relies on the omnis out at the ends to facilitate turning with minimal scrub. We chose to use 5 wheels on each side so that we could use 4" wheels and still maintain complete control while crossing over and driving on the scoring platform.

Because we lack extensive machining resources we designed this drivetrain to be built using only a drill press and a band saw through extensive usage of VexPro VersaFrame.

[TikiTech]

Here is what we call the HI Drop Drive.

The pneumatic actuated center wheels allow us enough clearance to drive over the bump and will center the robot while driving the length for ease of scoring..

Depending on how you look at it, it is either an "H" or "I", since we are from Hawaii we went with it..

This is an early picture of the system.
http://www.chiefdelphi.com/media/img...4205589a_l.jpg

More to come as the media team gets it to me..

Good luck to everyone.

Aloha!

[dradel]

We did something similar on our drive this year as well.

[Ether]

Originally Posted by dradel

We did something similar on our drive this year

Do those center wheels scrub a lot when you rotate?

[dradel]

Nope look at the pic closer... Air cylinders lift them off the floor. We weren't sure how it would work during competition, but got us to finals last weekend in Waterbury.

[Boltman]

We did Omni H with center suspension (Early pic while figuring suspension..which makes a huge difference took us 4 weeks to figure it out)

https://fbcdn-sphotos-a-a.akamaihd.n...a0e94dd5d6f547

[Andrew Schreiber]

Originally Posted by lcoreyl

And don't forget the... kiwi swerve? not sure what overclocked is calling this.

It's just a 3 wheel swerve. There've been a lot of them. (67 - 05, 148 - 08, 16 - Many years)

[g_sawchuk]

I saw some hexagonal robots last year (mainly vacumn bots for some reason). Those were interesting to say the least. My favourite drive this year so far is 1114's kiwi/crab drive.

[DarkRune]

Originally Posted by lcoreyl

At least one octocanum.

Hey! Don't forget us. Don't have a video of it on the actual bot, just the drive train for now.

[asid61]

We've used a 6WD and a 4WD successfully in my time. The year before I joined they made a robot with an 8WD and 8020, which still runs today.
Over the summer we may experiment with swerve drives if we get the necessary manufacturing resources to make a good one.

[GeeTwo]

I put together a lesson on drive systems for our (boreal) summer 2014 "robocamp". Trying to classify drives, I came up with something like:

• Skid-steer/tank (2n+4 wheels, drop center when n>0, optional shifter)
• Linkage drives
  • Two-wheel steering (automotive style, rarely if ever seen in FRC, but I wanted to cover it in the camp if only to explain why it is rarely used.)
  • Crab drive (all wheels drive same direction and speed)
  • X drive (I made up this name, but it has 4 wheels, left-rear and right-front rotate together and mirror left-front and right-rear)
  • Fire truck steering (independent 2-wheel steering on front and rear wheels, again rarely used)
• Holonomic wheel drives (I focused here on the wheels with rollers, not whether it was truly holonomic)
  • Omni tank (a 4-wheel skid steer with omni wheels)
  • H-drive (omni tank plus a transverse-mounted strafe wheel)
  • Killough (that is 4 omni wheels in a diamond configuration, not Killough's drive)
  • Mecanum
  • Kiwi (3 omni wheels whose axle lines cross at the CoG, a lot closer to Killough's drive)
• Swerve drives (I described 3 and 4 wheel setups, and explained that other configurations were possible)
• Articulated drives
  • Holonomic wheel hybrids
    • Octanum (includes butterfly and grasshopper)
    • Nonanum
  • Crab/lobster (dual skid/steer - alternate drive is transverse to main drive)
  • Articulated shifter (different size wheels or gear ratios on different drive wheels)
  • Ladder drive (as shown above, though I did not include it this past summer, but will add this year)

I did not include a monobot, or what I've personally called a "dizzy drive" (crab with a big steerable lazy susan for the "upper robot"). I'm sure there are other possibilities.