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View Full Version : bot carts. need info!


1075master
01-05-2006, 05:22 PM
yes i know i'll get yelled at because theres already posts on this but there are so many and they are long and i'm having difficulty finiding what i am looking for.
i am trying to come up with an idea of how to build a simple cart driven by 2 motors. i am planning on using the rc and oi from a previous year to control it.
it needs to be small but be able to get over bumps and somehow raise the bot to a good working height that we like.(about 3 feet from ground).
if anyone has any plans or ideas they can give me post them here or you can email me here (blackness_light_psycho_child@hotmail.com).

once again yes i know i'm repeating posts from before but they tend to be on carts in general. if someone knows of a thread with the info i'm looking for tell me and i'll close down this thread. thanks!

viking1902
01-05-2006, 05:34 PM
two years ago 1083 just purchased a Radio Flyer wagon that had big pneumatic tires. it worked fine for traversing those power cable protector things around the field. it was simple and got our robot around. the top of the wagon was a bit low so something to raise the top up might be good.

EricH
01-05-2006, 05:39 PM
I have no experience with powered driving carts. However, here's some of the obstacles you will need to worry about: Wire guards (the main one; usually about 1-3 inches high and close to a foot long) and the occaisional ramp. And, of course, crowds. Assuming tank steering, you may want casters. For raising the bot, you can raise the whole cart (which doesn't work too well) or use a scissors lift.

KenWittlief
01-05-2006, 05:45 PM
some (most?) regionals do not allow powered carts, scooters or other motorized vehicles in the pit area or along side the playfield.

During a competition the pit area and the paths to the playfield are often filled shoulder to shoulder with teams and crews trying to get to or from the playfield, along with spectators who want to see whats going on in the pits.

Having a motorized cart would be awesome, but I think in this case the risks outweight the cool-factor.

Look at it this way: FIRST requires plexiglass shields, steel railings all around the playfield, and for all students and refs near the field to wear safety glasses in order to drive a well specified and inspected robot during the event. Why would they then allow the same students to drive an experimental robot cart around in the pit area, right next to students and spectators, with no restrictions, inspections, or safety measures of any kind?

Kyle Love
01-05-2006, 05:51 PM
I would say, don't use motors and don't make it complicated. A simple cart will be better in the long run. Sure, at The Championships it will be handy to have one with massive storage, but the rest of the time its just in the way. KEEP IT SIMPLE! :]

jdhawg
01-05-2006, 05:55 PM
Last year our Seniors built a motorized cart out of Diamond Plate and an old Electric Wheelchair. Quite a nice ride for our robot, to be sure. The only semi-complaint (more of a warning) was when we first arrived at the Lone Star Regional someone told us to keep the stereo they had installed turned down so as not to become a distraction to teams working on their 'bots.

Ian Curtis
01-05-2006, 06:09 PM
I would say, don't use motors and don't make it complicated. A simple cart will be better in the long run. Sure, at The Championships it will be handy to have one with massive storage, but the rest of the time its just in the way. KEEP IT SIMPLE! :]

At the championships? I'd prefer to have the space at a regional as well. Even when your pit is a modest 300 feet away, it still seems to take an awful long time to get there and back when you need stuff and all you have is 10 minutes until your next elimination match! :ahh:

And does it really have to be motorized? Just give it big pneumatic tires, a handle, and storage space and you'll be waayyyyyy ahead of many teams.

PS Do not put small hard plastic wheels on your cart! You will have to pick it up over the wire covers and it will be a big pain in the neck.

lukevanoort
01-05-2006, 06:53 PM
Look at it this way: FIRST requires plexiglass shields, steel railings all around the playfield, and for all students and refs near the field to wear safety glasses in order to drive a well specified and inspected robot during the event. Why would they then allow the same students to drive an experimental robot cart around in the pit area, right next to students and spectators, with no restrictions, inspections, or safety measures of any kind?
Well they allow the robot to be driven on a tether, and if they mount their OI in the cart and the RC as well connecting the two via tether it should be okay, although this is in the realm of the legality depending on the people at a given competition.

Bcahn836
01-05-2006, 07:09 PM
Team 836 last year used a motorized cart using 2 wheel chair motors, an electrical car battery, an OI from 2002 and spare motor controllers and spikes from 03,04. It worked quite well, it had enough clearance to fit through a doorway and enough ground clearance for bumps. It also doubled as a shipping crate for all of our tools and spare parts. If you would like some pics i am sure i can find some.

Andy B
01-05-2006, 07:15 PM
Whatever you do, use good, strong durable wheels.

If you use cheap wheels, they will most likely break on you at the most inopportune time as ours did last year at the Championships. Because we could only go in once on the first night to get all our stuff in, we loaded everything on our cart together. Before we made it 6", the front two castor wheels broke.

We bought another pair of cheap castor wheels the next day and they broke again, so we broke 4 wheels just at the championship event.

So, USE STRONG WHEELS!

1075master
01-05-2006, 07:17 PM
our regional does allow the use of motorized carts. a team last year made one in the design of forklift and they had no problem with the staff. up here in toronto the attendance isn't as great as in the states. umm and a pics would be great

sburro
01-05-2006, 07:19 PM
yes i know i'll get yelled at because theres already posts on this but there are so many and they are long and i'm having difficulty finiding what i am looking for.
i am trying to come up with an idea of how to build a simple cart driven by 2 motors. i am planning on using the rc and oi from a previous year to control it.
it needs to be small but be able to get over bumps and somehow raise the bot to a good working height that we like.(about 3 feet from ground).
if anyone has any plans or ideas they can give me post them here or you can email me here (blackness_light_psycho_child@hotmail.com).

once again yes i know i'm repeating posts from before but they tend to be on carts in general. if someone knows of a thread with the info i'm looking for tell me and i'll close down this thread. thanks!

Just make sure you read the documents that just came out. There are NEW rules for carts.

1075master
01-05-2006, 07:22 PM
all i can find are 05 docs where did u get this info??

sburro
01-05-2006, 07:27 PM
all i can find are 05 docs where did u get this info??


http://www.usfirst.org/robotics/doc_updt.htm

I just read it somewher let me find it

1075master
01-05-2006, 07:27 PM
found it but all i see is that u can't put a stereo and what not...

sburro
01-05-2006, 07:28 PM
all i can find are 05 docs where did u get this info??


http://www.usfirst.org/robotics/doc_updt.htm

section 7.3.5

To make sure your team members are safe when they are going from the Pit to the competition area, bring some type of cart to transport your heavy robot. The carts must remain in the team pit area when not in use for robot transportation. All carts should fit through a standard 30-inch door. Cart wheels must not damage site
flooring.

1075master
01-05-2006, 07:31 PM
ha but its not on that page u can't get to it u can only get '05 info u have to go here (http://www.usfirst.org/robotics/2006/frcdocs.htm#Section0)

aaeamdar
01-05-2006, 08:21 PM
Concurring with a lot of people here. Go with a simple thing with a handle. Make /sure/ it can support 130 pounds though.

Just my 2cp

generalbrando
01-06-2006, 08:57 AM
Building something is great and my team would love to do it if we had the time and resources.

However, what I've also seen a lot is teams mod'ing carts that you can buy which already do what you described. Buzz has a cart with a medium sized tool chest on it. Personally, I don't care for having a driven cart. I'm more interested in having nice big wheels and being able to lift the robot to working level. To accomplish this, check out industrial suppliers like MSC for mobile lift tables. The name varies from supplier to supplier. Depending on the size and features, you can get one for as little as $400 or as much as $10k. That's a hefty price for many teams, but if you can afford it, it's probably worth it.

scott
01-06-2006, 09:58 AM
I'd like to stress a simple cart again. In 2004, we (447) had a cart with AirRide on board. It was nice to raise the robot to work on, but the added weight made it a pain to steer. We asked our local Lowe's for one of their old beat-up flatbed carts for the Flower Section. Fixed it up, did a little bit of welding and added a little pan under it for storage, and it works great!

Peter Matteson
01-06-2006, 10:40 AM
I just wanted to throw out a reminder weight can equal painful shipping costs. We looked at using a surplused electrified lift cart from my company. Only the lift was electric but the weight of the cart was so great the shipping cost would have been outrageous to get it to nats. Also it was not easy to load in and out of a vehicle so we went another way.

DUCKIE
01-06-2006, 10:49 AM
As a queuer with 2 years experience... I also concur that it is best to keep it simple... but not too small or too big.

The biggest pain to move carts seemed to be the large motorized ones
(as many were not too hot on the turning thing... or it took them a little while to get it powered up to move... when we needed them to move quickly so they could move down a narrow walkway to the other end of the field before the next match started.)

and the really small/cheep dolly carts... that were like 1' x 1' with the dinky caster wheels. (always a pain to move over cable protectors... and i was not too keen to be putting my hand under a 130 lb. robot that could easily slide off of it... and onto my hand.)

I also recommend that you keep the center of gravity of the robot and cart... somewhat low... at least durring transport... tippy robots/carts = bad!

---------------------------

If you have the time / want to design and build your own cart...

-think about having the robot supported on the cart by it's chassis and not it's wheels. (that way... it will not roll off the top of the cart (VERY BAD!) and you can also run/test your drive system in the pits without even taking it off the cart.)
-"easy transport / packing" (ours is made of bosch... and itsn't too hard to disassemble/reassemble)
-locking wheels (for those occasional inclines)
-storage/shelving (good to be able to carry at least some basic tools and a tether in case you need to reset quickly)

dhitchco
01-06-2006, 12:04 PM
When you think about a robot cart, consider the "bigger picture".

1) How can you construct a robot cart that is lightweight and easily transportable from the school to the regional and possibly to the championship. Shipping & transportation of the bot cart should be part of your consideration.

2) Think about the various heights at which your bot cart should be able to "elevate". You may want the bot cart to be able to rise/lower itself to different heights when working on the upper or lower parts of your robot.

3) Think about safetly when you are putting the robot on and off of the cart. Namely, how can the cart be lowered so you can safely lift (or ramp-up) the robot without straining your backs? The same holds true when "delivering" the robot onto the playing field. How can you design a cart that makes it easier and safer than two people tripping over the field side rails when enering/exiting the arena (yeah, i know they also have removable panels.....but I've seen many players almost drop the robot when moving it)

4) A motorized bot cart may be nice for the long haul tunnel in Atlanta, but as other have stated, many of the regionals have short walks to/from the pit area, and the "traffic" often comes to a quick stop.....can your motorized cart do that safely?

Donut
01-06-2006, 08:51 PM
You might want to also consider, regardless of whether it is motorized or not, making a cart that can be partially or completely disassembled. The cart our team had 2 years ago was a large slab of wood with short sides and casters, and was rather wide to fit in cars and through some doors. The new cart we have is designed so that we can adjust the height of the rails the robot rests on and the entire cart can be taken apart and fit in a very small, narrow area. A cart that can be taken apart is extremely easy to transport and tends to be pretty light.

You might also want to ask sponsors/mentors for help with your cart. One of our mentors asked our main sponsor about help for building a new cart, they asked him what we wanted it to do, and they came up with a design for it and sent it to us.

KenWittlief
01-06-2006, 10:15 PM
another requirement for your cart design. It will also be used to move the bot, and probabally other stuff as well, from your bus across a parking lot to the regional pit (maybe a long distance - in the rain or snow) and you might want to use it to make several trips to move tool boxes and team buttons and cases of drinking water

it would be a real drag if you had to get your cart across a parking lot in the pouring rain, and it would only go 2.5mph, or the batterys die in the parking lot on the 5th trip

and consider other events too, local off season competitions, when you may not have a coachline bus to carry your cart?

Donut
01-06-2006, 11:16 PM
To build off the last comment, if you intend on using your cart to move materials from outside to the regional pit, make sure anything built on it can withstand the elements, we don't carts shorting out from rain in the parking lots!