View unanswered posts | View active topics It is currently Wed Oct 22, 2014 8:18 am






Reply to topic  [ 9 posts ] 
Vex mecanum help 
Author Message
Rookie

Joined: Fri Nov 23, 2012 2:59 am
Posts: 5
Post Vex mecanum help
Hey guys,

I'm new to vex robotics.

I wanted to try to build this vex robot: http://www.robotc.net/blog/2011/11/22/v ... ng-robotc/

I know that it's not the best robot to start with, but I have some experience with robotics in general, so I can learn while building.

The thing is though, I don't know all the specific vex robotics components. So, is it possible for you guys to give me a list of the components
used on that robot? I know the mecanum wheels, motors (not sure what specific type), gears, shafts, micro-controller, ultrasonic sensor, the lcd screen and the aluminum chassis parts. But I'm not sure about the other ones.

Thanks in advance!


Fri Nov 23, 2012 3:09 am
Profile
Site Admin
Site Admin

Joined: Thu May 24, 2012 12:15 pm
Posts: 592
Post Re: Vex mecanum help
The program showcased for that particular robot (highlighting the VEX Mecanum wheels) is actually only using three main parts; the robot itself, the Mecanum wheels, and the Cortex connected to a VEXNet system; everything else on the robot (all of the other sensors) were used in other projects.

From the look of things, it appears that robot also had an accelerometer (the black board on the standoffs, near the LCD screen), four quadrature encoders (one on each shaft), an ultrasonic sensor (front bar of the robot), a potentiometer (with the gear attached, near the LCD screen).

_________________
Check out our Blog! And our Facebook page!
Need help? Take a look at our Wiki and our Forums.

I just met you,
And this is crazy,
But here's my code now,
So fix it, maybe?
~ Carly Rae Jepsen parody


Tue Nov 27, 2012 1:04 pm
Profile
Rookie

Joined: Fri Nov 23, 2012 2:59 am
Posts: 5
Post Re: Vex mecanum help
Thank you for your reply!

I'm planning to have a remote-controlled robot. Therefore, do you think that I'll need the encoders and accelerometer?


Tue Nov 27, 2012 3:33 pm
Profile
Site Admin
Site Admin

Joined: Thu May 24, 2012 12:15 pm
Posts: 592
Post Re: Vex mecanum help
If you are doing strict remote control, then no, the encoders and accelerometer (as well as most other sensors) will not be needed. However, they can be used in custom tele-op code (for instance, coding bumper switches to stop the robot from moving in one direction if it has hit an obstacle) to create unique, custom code. In this particular case, you can use the encoders to help match and scale the four motors in case one motor runs faster or slower than the other three.

_________________
Check out our Blog! And our Facebook page!
Need help? Take a look at our Wiki and our Forums.

I just met you,
And this is crazy,
But here's my code now,
So fix it, maybe?
~ Carly Rae Jepsen parody


Tue Nov 27, 2012 4:16 pm
Profile
Moderator
Moderator
User avatar

Joined: Tue Sep 14, 2010 9:19 pm
Posts: 496
Post Re: Vex mecanum help
I know that the ROBOTC blog has code posted already, but if you'd like a little bit more in depth explanation of a very simple mecanum teleop code, I made a video about a year ago: http://www.youtube.com/watch?v=v7CujEW0wgc

_________________
sudo rm -rf /


Tue Nov 27, 2012 5:06 pm
Profile
Rookie

Joined: Fri Nov 23, 2012 2:59 am
Posts: 5
Post Re: Vex mecanum help
Thanks so much guys for your replies. The video was really helpful too.

Just out of curiosity, has any one of you used the vex mecanums and vex motors with an arduino before?


Wed Nov 28, 2012 11:40 pm
Profile
Rookie

Joined: Fri Nov 23, 2012 2:59 am
Posts: 5
Post Re: Vex mecanum help
I need an advice, guys.

I have this project whereby I have to have a robot to navigate through a flat area of 5 meters by 7 meters. Within this area, there will be obstacles (the size and placement are not defined).
There's a guarantee that there will always be a path that will not be severely restricted, but since the dimension for the maximum restriction isn't given, it's up to us to design our robot to be a bit small while at the same, complete the mission (picking up a few things and pushing a button) in the shortest time. The obstacles won't be moved around to accommodate big robots. Also, speed is important but not as important as finishing all the missions.

I was thinking of using the vex mecanum wheels, but having not used it before, I'm a bit skeptical that I'll be able to build a small robotic platform using these wheels because of their size. Creating my own wheels is out of the question because I want to focus more on other things.

The reason why I want to use the mecanum wheels is primarily because of the maneuverability that it provides, enabling the robot to stay in one orientation for most of the parts. The coolness is also a bonus :D

So, for those who are familiar with the mecanum wheels, what do you think? Do you think the robot base is going to be too large? Or do you recommend that I use a different wheel altogether?

Thanks in advance!


Thu Dec 27, 2012 6:23 am
Profile
Guru
User avatar

Joined: Sun Nov 15, 2009 5:46 am
Posts: 1347
Post Re: Vex mecanum help
As an alternative option, you can achieve the same mecanum drive effect by using 4 Omni wheels oriented in a diamond formation. The mecanum drive code will work the same way.


Thu Dec 27, 2012 4:38 pm
Profile
Rookie

Joined: Fri Nov 23, 2012 2:59 am
Posts: 5
Post Re: Vex mecanum help
Thanks :) I will look into that.


Sat Dec 29, 2012 10:36 am
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 9 posts ] 

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  



Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by ST Software for PTF.