Question about an X drive

VEX V5 General Discussion General Forum
1

Hello again everyone,
*
I have a question about this x drive, I have never built one before and I don’t know if I did it properly. I was wondering if someone with experience or just knows about them could tell me if I’m the right path :smiley: or if it needs more work.
*when you evaluate the base/drive assume:

  • All the appropriate screws are in place
  • More stability will be applied

http://http://i.imgur.com/ScxnYfd.png

Thank you.

2

here is an overhead view

3

This looks good as far as I can tell. I’m in the process of developing some really neat code for holonomic/x-drive chassises. I plan to release it early during the school year, when I can finish building one :smiley:

4

Looks great, very similar to ours which works perfectly. You will want more tan the 1 piece of angle on top, but otherwise you are on the right track.

5

I will be looking forward to that reveal because programming an X drive is also new for me but I’m sure my team will figure it out ;).

sbdrobotics thanks for the input, it was actually the debate on your reveal thread that made me rethink my original 6 wheel drive, because I thought that it couldn’t go over the bump, I was proven wrong :smiley: which was good news.

https://vexforum.com/t/4080-teaser-reveal/23372/1&page=4 → sbdrobotics’s reveal thread

6

Are you using RobotC or Easy C? Also are you planning on tank or arcade controls? The sample program for mecanums in RobotC will work for an X drive with arcade control, if you need tank control code for RobotC let me know.

7

How exactly would one control X-drive with a tank control style? You’d have left side on left y-channel, right side on right y-channel, and what would be your rotation and strafe channels?

8 
   //Remote Control Commands
    motor[frontRight] = vexRT[Ch2] - vexRT[Ch1];
    motor[backRight] =  vexRT[Ch2] + vexRT[Ch1];
    motor[backLeft] = vexRT[Ch3] - vexRT[Ch4];
    motor[frontLeft] =  vexRT[Ch3] + vexRT[Ch4];
9

Hmm… I’ve never seen that one before.

10

Here is what you can expect bump wise.

11

Looks great, except for 2 things:

  1. Have you checked to make sure this is within the 18" size limit? It looks like it’s 17.5" wide, but also it looks a little longer than it is wide.

  2. I notice that your chassis isn’t elevated over 2". This might cause problems going over the bump (you’d have to test it to be sure though).

X-drive is a good choice, good luck!

12

Counting the holes I can tell you it is 17.5" both directions, and if you notice the cross member (there needs to be more than one) is on top of the chassis giving them around 2-1/4" to travel over the bump sideways with.

13

Doesn’t it matter that the C-Channels scrape the bump? We haven’t tested an un-elevated chassis yet.

14

https://vexforum.com/t/answered-can-license-plates-be-oriented-sideways/27784/1

We (some of the best here) worked on getting the most optimized, fastest, easiest to read and complete X-holo code for ROBOTC in that (somewhat legendary) thread.

It’s old so I’m posting the link here.

Also the (also old) video explains holo drives extremely well, if you have questions watch it.

As for the holo, it looks good, but be sure to pay special attention to getting it square. -Cody

15

I plan on using arcade just simply because it is my preferd type of driving :). Using RobotC
*
Thanks sbdrobotics for that video on crossing the bump it helped prove a few points about crossing it.

  • yes I have more angles attached now that my tower/ arm is on
  • there are now more supports :wink:
16

Sbdrobotics is right is is about 17.5 both ways :).

The chassis not being over 2" tall might pose a problem however it should be able to pick up those 3 Bucky balls on the bump with no problem.

It had crossed my mind that I might hit the bump while going over. I haven’t tested it with An X drive but at a robotics camp im volenteering at, a tank style 4 wheel drive got over fine with the same spacing As me but agin this is an X so ill have to find out. I can’t actually build until just before school starts so I haven’t tested it with the 2" clearance.

Thanks Cody for the forum link it was **very **helpful on holomonics, thanks !
_
Thanks everyone who gave me some input on how to improve it a little and offered some advice :slight_smile:

17

No prob. That video and the code I came up with in it has helped a ton of people who were interested in X drives. I’ve been thinking of redoing it but haven’t gotten around to it. Please do note that the good optimized code is at the end of the thread, the stuff with the video is crap.

-Cody