Vex Vs. Edubot Vs. RCX Vs. NXT

[Matt Krass]

Originally Posted by Mike

If you want to get nitty gritty with the electronics/programming aspect of it, I'd recommend not using any. Build your own solution with the AVR ATMega chip series. You can get the development board (STK500) for about $80, and it includes pretty much everything to get things started off for you.

Gotta disagree with you here, the STK500 is great, but none of the DIP packaged AVR chips have more than a few timers/PWM generators, so that limits your motor output options.

[Ryan Dognaux]

A VEX kit would be giving you the most bang for your buck here and it's the closest thing to building an actual FRC robot that you can/could buy locally. Seems that Radioshack's online store has permanantly slashed prices in half and they still have the kits in stock Right Here.

However, I do have to say, if it comes down to getting an RCX or an NXT, go for the gold and get the NXT. In my opinion, it's going leaps and bounds beyond the old mindstorms kit and any team who utilizies its functions will have a pretty decent advantage over those with the old Mindstorms kit.

[Nitroxextreme]

I would have to also side on the side of Vex...

When compared to any of the other alternatives you provided, it just blows them away. Also I would act soon...because without a 50% discount at Radioshack they can get expensive very quickly.

[Rich Wong]

[quote=Ryan Dognaux]A VEX kit would be giving you the most bang for your buck here and it's the closest thing to building an actual FRC robot that you can/could buy locally. Seems that Radioshack's online store has permanantly slashed prices in half and they still have the kits in stock Right Here.

QUOTE]
I agreed!

Even though I have 3 or 5 RCX units (not really sure because of my kids keep using them for different projects) and one VEX at home, I preferred the VEX. The options for the VEX is growing day by day and it is closer to the FRC world. Definitely try to visit the local RadioShacks for bargain parts!

I found that Home Depot supplies a variety of metal decking brackets that makes great custom parts for my VEX projects. They are easy to cut, bend, shape and drill.

[MattD]

Last weekend I actually went out to RadioShack and bought some Vex stuff after learning that it was still in stock, and still at half price. It's better to buy it now while you can still get it at the lowered price.

Here's a picture of it all:



Shown in this picture is:
1 Starter Kit
1 Programming Kit
1 Hardware and Metal Kit
1 Tank Tread Kit
2 Servo Kits
2 Motor Kits
2 Light Sensor Kits
1 Ultrasonic Range Finder Kit

Since they didn't have any of the battery kits in stock, I bought some rechargable NiMH batteries. I just wish I had enough for the transmitter, because the cheap batteries I used for that died out within 5 minutes of use. Now I'm just playing around with autonomous and plan on making a robot that has the same characteristics as myself (i.e. hates the light and always travels towards darkness) until I get some more batteries.

[EHaskins]

I think it depends on what you want do with the kit. First the vex costs less and does more than an EDU, and the NXT does more than an RCX.

If you want to use different/custom parts the vex is the way to go. If you want to something to that's fast and simple to use LEGO is the way to go.

[David55]

Guys, just a point to think about, in Israel we don't have "locol Radio Shacks and Home Depots".

In my opinion vex is the best system from the above list, although to really build a cool robot you need to buy a lot of expansion packs and it can get fairly expensive. I was lucky and was able to bring a lot of vex stuff to Israel, so Leav if you have a way to do so then get vex.

[Leav]

Thanks guys, you really helped me make up my mind.

I will go with the VEX for a couple of reasons:
-cheaper (kit and body parts) and easier to expand with scrap stuff (scrap computer cases etc.)
-More expandability and better standard compliance.

I already know I will only get the VEX kit if i manage to get the prototype programming kit. (so i can program in real C)

so now I have two questions:
-is there any other way to get the prototype programming kit not from the vexlabs? because the phone method is a bit tricky for me... (I live in israel).

-Where can I get more sensors for the Kit? what kind of sensors do i need?
for starters I would like a ultrasonic range sensor and a rotation sensor with a good resoultion (accurate at 6 degrees).

Thanks alot guys!
-Leav

[Tom Bottiglieri]

Originally Posted by Leav

-is there any other way to get the prototype programming kit not from the vexlabs? because the phone method is a bit tricky for me... (I live in israel).

-Where can I get more sensors for the Kit? what kind of sensors do i need?
for starters I would like a ultrasonic range sensor and a rotation sensor with a good resoultion (accurate at 6 degrees).

Vexlabs sells a pretty decent ultrasonic range sensor. The way it works is very comparable to Parallax PINGs and other similar brandings, but Vex went out of the way to provide pins for I/O signals. This is very helpful when using a preconfigured control board, like a FRC or Vex controller.

As for a rotation sensor, it depends on what kind of rotation yo are trying to measure. I will assume you would like to sense the rotation of a joint. You should have no problem wiring up a potentiometer or encoder. There's been numerous discussions here on which resistance pot to use and wiring techniques.

Vexlabs sells a 90 ppr encoder. It's non-quadrature, so you'll have to cook up some way to keep track of direction. I'd start off with that and then put those good old problem solving skills to the test. (I mean thats half the fun, isn't it? )

[EHaskins]

For an ultrasonic senor check this out you just solder a PWM cable to the vcc, gnd, and analog pins. It is fairly accurate (about an inch) up to 20'.

Hope this helps.

[David55]

Leav I am currently in the US and if you want I will be able to stop at Radio Shack and pick some stuff up for you (small things like sensors and programming pack, not a kit).

[Leav]

Originally Posted by David55

Leav I am currently in the US and if you want I will be able to stop at Radio Shack and pick some stuff up for you (small things like sensors and programming pack, not a kit).

Hi thanks David... but I wouldn't want to hassle you with all that... I have a friend who's coming over from the states soon, so i'm buying it all online and shipping to him... (hope he remembers to bring it...)


My only real problem is the prototype programming kit. i sent them an e-mail and called but it was like 19:00 at texas when i called so they probably stopped working...

the whole VEX thing hinges on the prototype programming kit - i want to program like a big boy!

if anyonecould help me with that i would appreciate it...

thanks again!
-Leav

p.s.
the rotation sensor is for a lock picking robot (combination lock) which usualy have 60 points per rev. so i will need something that can find the angle accuratley time after time.

-Leav

[Ben Piecuch]

You can always gear up/down the VEX potentiometers to get the resolution you need. Typically it's the sampling rate (and the lack of quadrature) that limits the possibilities with the VEX pots... Sounds like a very interesting project.

BEN

[JaneYoung]

Where in Texas?
Jane

[artdutra04]

Originally Posted by Leav

My only real problem is the prototype programming kit. i sent them an e-mail and called but it was like 19:00 at texas when i called so they probably stopped working...

Leav, you can use the official Vex Programming module and still program in real C (as in MPLAB). All you do is when you buy the Vex Programming Module you only install the USB-Serial driver, and ignore installing EasyC. The prototype and the official Vex modules are both the same price at $99 USD, so I'd just go with non-prototype one.