holonomic drives

[Max Lobovsky]

Even though this season is not yet over, i have been thinking about a chasis and drive train that my team could build for practice and preparation for next year. I have a lot of questions about holonomic drives, so if anyone with experience (programming, mechanical, or anything) I'd be very interested. Most importantly, I'd like to know about sources or ways to build effective omniwheels. If you could list contact info, that would be great.

[Ryan M.]

I don't have any actual expertice, but I'll just say that those are hard to build, but tons of fun to see in action.

I have done some programming for something I constructed out of LEGO Mindstorms once, so I might be able to offer some advice if you have something specific. Feel free to PM me, the worst that could happen is I don't know and have to yell at you cover my lack of knowledge.

P.S. Mindstorms is great. Check out my avatar for some of the cool things you can do. And I got it to Mars with less than those NASA guys.

[George1902]

Originally Posted by Texan

I'll just say that those are hard to build

Actually, it's not much harder than any other FIRST bot unless you decide to machine your own omniwheels. The toughest part is independently powering all 4 wheels, but some teams do this anyway on their 4-wheel drive bots.

[NotQuiteFree]

Sorry for being ignorant, but what exactly is a holonomic drive?

[Solace]

technically, a holonomic drive is a drive that allows you to move in three axis at once (i.e., going forward, left, and rotating). examples of a holonomic drive are 857's kiwi drive (killough platform) or the technocats ball drive.

a swerve drive is not truely holonomic, but for FIRST robot purposes it is close enough. a swerve drive has the wheels rotating seperately from the robot orientation.

[George1902]

Omniwheel.com is where we got ours this year. We used their 4000 series transwheel on our prototype and the Omni 2.538 on our actual bot. In our next incarnation, we will probably machine our own, but that just wasn't within our capabilities this year.

The most popular holonomic platform has 3 wheels at 120 degree intervals around a circle. For a FIRST robot, we decided that 4 wheels at 90 degree intervals was the best configuration to maximize our footprint.

I didn't have much input on the programming aspect of this year's bot, but I know we used shaft encoders to monitor and adjust the speed of each wheel. This is vital to a well-behaved robot.