Vex Holonomic Drive

[8osuwari8sit8]

i have a question for recreating this kind of robot. im using vex as well. how difficult is it to drive, and what channels did you plus the motors into on the microcontroller?

[ajosmer]

I'd like to let you know that this video is what first got me interested in holonomic drive trains, and the omni-drive type in particular. Since I saw this video, I've done quite a bit of work with both the mechanics, and mostly the code aspect, and I'd like to thank you for the inspiration!

[natpie1]

I was similary inspired by a video. I had never herd of holonomic drives before I saw one by accadent. Be sure to post your results too!

[wheagy]

Hi...I have something similar with 3 wheels arranged tangent to the center. Any suggestion on an algorithm to control this thing? Having trouble locating tri-wheel control algorithms. Thanks.

[natpie1]

Your probably going to end up doing some vector math. I've seen a few tri-wheel bots but haven't read anything on the subject. I have been thinking about building this bot again and adding a compass module and using vectors to set an alignment platform for the controls that do not change. It may make it a bit easier to control, but I haven't sat down to try it out yet.

[Mayanstudios]

It would have to have the third wheel stopped most of the time, and only used when turning. Maybe a bunch of if statements would work for you

[tjhynson]

My works just like that except (go back, forth, and turn) how did you program it to go on a diagonal?

[xDevix]

Just put all the wheels diagonally so then it can spin and go back and forth freely.

[natpie1]

I didn't do anything special. All the wheels are assigned a value directly related to two axis on the remote. Then and offset is applied to allow it to turn (There are a lot of conditionals in the turning offsets to keep the wheels from reversing directions when min or max values are reached). So one stick controls forward/back and Left/Right. If I want to go diagonally i just move the stick diagonally. The other stick allows it to turn.

[deadlyfalcon89]

Actually if you mount the video camera to an extra servo so you can look up and down that can be even more fun.

[deadlyfalcon89]

Sweeeet. I need to figure out an omni system, that looks like insane fun.  Not to mention the 2.4GHz camera attached, that's possibly my favorite thing to do with Vex even though it's not very complicated.

[Roboticianists]

yup, i've used the smaller omni directional. its too small, it doesn't work as well on rougher surfaces. (carpet, etc.)

[12Apostle]

Pretty sick. You need omni directional whees for that huh?

[natpie1]

Yes. Vex has releaseed some new ones that look beter, but I haven't seen them yet. The previous ones didn't slide sideways as easiliy as I would have liked them to.

[robotman71]

this video is cool.....i have vex too... i have made this kind of robot!! its great!!

[octanetripledax]

i have 4 standard motors and 1 servo motor. i have 1 remote, like you, but i only know how to control 2 motors at the same time! tell me how! please!

[natpie1]

Sorry I haven't checked my mail i a while.

If you just have the basic kit you probably cant do it. The trick to the holonomic bot is not the design as much as the software. I wrote cusom code to be able to drive it the way you see it in the video.

If you have a programing kit the software isn't too tricky. Oringanaly planed on doing some vector math to make it work but ultimatly just added ans subtracted some offsets based on other input.

[octanetripledax]

hey, i was wondering(because i have vex too) how do you control 4 motors with 1 remote?

[ghostinside]

Are thos standard vex wheels or something custom?

[natpie1]

They are the standard Omni directional Wheels from vex.

They have some new larger ones I may need to try.

[KartMan250]

thats very interesting! i should go get a few more motors!

[soccr500]

wow. thats amazing! great idea

[Mattersmatter]

WOW WOW WOW WOW WOW WOW that is awesome...you should gear it to go faster though, it's kiinda boring to watch because it's so slow