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jeremy56763
12-22-2009, 11:54 AM
There are a few ways to make a carrying devise from pit station to game area you can go motorized or manual. What I would like to know is what is the better way to go.

Vikesrock
12-22-2009, 12:16 PM
Welcome to Chief Delphi

It's good to see that you and your teammates have found your way here to the forums.

I recommend you familiarize yourself with the search function here on the forums (spread the message to your teammates too!).

I also recommend checking out these two threads for some general info/advice on posting here on the forums:
http://www.chiefdelphi.com/forums/showthread.php?t=78869
http://www.chiefdelphi.com/forums/showthread.php?t=50532

The first one is a freebie. I believe the the device you are talking about is what is commonly referred to as a "pit cart" or "robot cart". A small number of teams have designed motorized carts, but most of us find high school students make good motors.

Here's a good thread about carts. (http://www.chiefdelphi.com/forums/showthread.php?t=72450&highlight=cart)
Many pictures of carts can be found here (http://www.chiefdelphi.com/media/search/results/535856?page=1)
Here's a motorized cart (http://www.chiefdelphi.com/media/photos/31195)

My personal opinion is that a motorized cart is a waste of time. A motorized cart will likely be much larger than a non-motorized one. There are also significant safety concerns that must be addressed with a motorized cart (see the description of the picture I posted above). If you're looking for an offseason project I think playing around with different drivetrains or designing a demo robot is more useful than a motorized cart.

Daniel_LaFleur
12-22-2009, 12:18 PM
There are a few ways to make a carrying devise from pit station to game area you can go motorized or manual. What I would like to know is what is the better way to go.

I second what Vikesrock said.

In addition, remember that the pit area is 10'x10' (max, some are smaller), so make sure that you can fit it (and your robot) into the pits.

DonRotolo
12-22-2009, 03:15 PM
In addition, remember that the pit area is 10'x10' (max, some are smaller), so make sure that you can fit it (and your robot) into the pits.
...and your tools, and your battery charging area, and the people who will work on the robot, and EVERYthing else you bring....that isn't in the stands cheering the team and/or scouting.

In other words: The pits are a lot smaller than you might prefer.

Many teams use their pit cart as their work table for when they work on the robot. Some have a lift mechanism, some sit on small stools as they work.

Others have a pit table that stays there all the time, and they just put the small pit cart somewhere out of the way...

Karibou
12-22-2009, 03:30 PM
Welcome to Chief Delphi!


In other words: The pits are a lot smaller than you might prefer.

Many teams use their pit cart as their work table for when they work on the robot. Some have a lift mechanism, some sit on small stools as they work.

Others have a pit table that stays there all the time, and they just put the small pit cart somewhere out of the way...
Our cart is just an off-the-shelf metal hand cart, with a hydraulic lift system. All we did was add some brackets to it to help fit the robot onto it. We choose to store our tools, batteries, etc. in the pit, but with the brackets that we have, there is a little space underneath the robot to store small things if need be.
The only part of the cart that extends outside of the bumper perimeter is the handle. When we bring our robot back to the pit, it usually just stays on the cart. Even with our gigantic pit tables, the fact that the cart is the same length and width as the robot means that we don't lose any space to the cart. The cart provides some elevation, too, which is useful when making repairs to the chassis.
If we need to take the robot off the cart for some reason, the small size makes it easy to shove into a corner of the pit.

(This picture (http://gpgearheads.org/gallery/Kettering/DSC01574) gives a decent shot of the cart with the robot in the pit, even though half the team appears to be present also)

Oh, and make sure that the cart will fit through a standard-sized door. You might have more than few problems if it doesn't.

Koko Ed
12-22-2009, 04:05 PM
There are a few ways to make a carrying devise from pit station to game area you can go motorized or manual. What I would like to know is what is the better way to go.

Working que the past few years it stuns me the amount of teams that go all out to build a fancy tricked out motorized cart (which then I have to move to the right place after they loaded their robot onto the field and they forgot all about it) but build a mediocre robot.
Build a manual cart that gets the robot and important things like batteries and tools to the field and spend more time on focusing on building a more competitive robot.
You'll be better for it in the long run.

BrendanB
12-22-2009, 05:16 PM
Working que the past few years it stuns me the amount of teams that go all out to build a fancy tricked out motorized cart (which then I have to move to the right place after they loaded their robot onto the field and they forgot all about it) but build a mediocre robot.
Build a manual cart that gets the robot and important things like batteries and tools to the field and spend more time on focusing on building a more competitive robot.
You'll be better for it in the long run.

I agree with what Ed has said. Happens a little too much where a "sick" cart carries a mediocre to "what the heck does it do" robots.

However, building carts like this can be a good learning experience. Designing and building a motorized cart can be a useful tool when bringing new students onto the team as you can introduce CAD and other methods of the team into the process. But don't make it such a huge priority that other items get side tracked all for the precious cart! ;)

Our team has a simple garden cart from the hardware store with some rails to support the robot, along with a rack in the front to hold some batteries other items of use when your out on the field, (tether, some tools, etc...). We have found that it works really well as it has large tires making it easy to traverse over uneven ground without rocking the bot too much.

Good luck with whatever you end up creating.

GaryVoshol
12-22-2009, 05:17 PM
And put your team number on the cart, so Ed knows who to yell at (er, speak to gently) to get it into the proper parking spot.

Ian Curtis
12-22-2009, 05:58 PM
Our team has a simple garden cart from the hardware store with some rails to support the robot, along with a rack in the front to hold some batteries other items of use when your out on the field, (tether, some tools, etc...). We have found that it works really well as it has large tires making it easy to traverse over uneven ground without rocking the bot too much.

Good luck with whatever you end up creating.

Agreed. We had a garden cart with 2x8s around edge that was spray painted red. Robot sat on the top of the 2x6s, and the area underneath was great for batteries and zip ties. We used it for five seasons, but it was definitely a little worse for wear at the end of last year.

We had a ground level cart on casters in 2004 that was a real pain. You definitely want to be able to pull it from a normal height.

Koko Ed
12-22-2009, 06:07 PM
And put your team number on the cart, so Ed knows who to yell at (er, speak to gently) to get it into the proper parking spot.

Ask the Florida teams, I no longer yell at them to get their carts.
Now I just hide them.

sanddrag
12-22-2009, 07:38 PM
It is possible the robot may be geared in such a way, and the wheels and tread have sufficient characteristics that you may not need a cart at all. If you do need a cart, I would most definitely recommend free-wheeling (human powered) over motorized. Fewer problems, easily variable speed and maneuvering, less weight.

Al Skierkiewicz
12-23-2009, 06:47 AM
Remember that whatever you build will need to be shipped. The combined wisdom of the above posters taken together would imply something that is light, human powered, collapses for travel (or easily fits in the robot crate) and can do double duty as a work platform and a transport for pit tools and accessories.

Andy Baker
12-23-2009, 07:43 AM
This (http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200365546_200365546) is what I suggest using as a robot cart (or something similar):

http://www.northerntool.com/images/product/images/143654_lg.gif

Andy B.

RoboMom
12-23-2009, 02:04 PM
And make sure it fits through a normal size doorway because, trust me, you will be on the other side of that doorway at some point, late for a presentation.
I have fond memories of gentle inquiries about the size of a spanking new customized cart and was reassured they had that taken care of.
Oops. Not quite. They were off by ....

Chris is me
12-23-2009, 02:18 PM
As someone who had to push around a robot cart for four events last year, a few things:

1. Big wheels (pneumatic tires or rubber) make going over gaps and wiring sections on the floor much easier. 3 inches of ground clearance in the middle is perfect, less requires some work.

2. A solid handle is significantly better than a rope handle.

3. 2 fixed, 2 omni / swivel casters works well for maneuverability; four casters is a little harder to control with just one person.

4. Storage for stuff like the driver station is nice, not required but your drivers will thank you if they have a spot to throw the controller. (Some robots have room on them for this kind of stuff).

5. Some events (cough 10,000 Lakes cough) have only 32 inches of clearance for your cart. Long way forward and no wider than your robot is the best solution, or at least a way you can shrink it.

,4lex S.
12-23-2009, 02:26 PM
The cart Andy suggested is basically what my team has used the past few years. They are available from a ton of manufacturers, and are customizable to your own needs. Last year, we mounted a plywood deck for the robot to sit on. If you choose to do this, ensure it is strong enough to handle the robot (If it isn't, injuries will occur).

Also, you should consider your robot's center of gravity in whatever you build (we almost dumped our robot off the side of the cart a few times last year).

Flashy carts are usually a waste of money, I would much rather have a flashy robot :D.

Ted Weisse
12-23-2009, 10:08 PM
This (http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200365546_200365546) is what I suggest using as a robot cart (or something similar):

http://www.northerntool.com/images/product/images/143654_lg.gif

Andy B.

On sale, with coupon for $89.99 until 1/14/10 at Harbor Freight.

artdutra04
12-23-2009, 11:20 PM
Chris has some great points, but here's some additional information (shown in red) that 228 has learned from about a half dozen different iterations of homemade robot carts over the past twelve seasons. We've learned all nine points the hard way at one point or another.

As someone who had to push around a robot cart for four events last year, a few things:

1. Big wheels (pneumatic tires or rubber) make going over gaps and wiring sections on the floor much easier. 3 inches of ground clearance in the middle is perfect, less requires some work.

2. A solid removable handle is significantly better than a rope handle.Nothing is more annoying (or a potential safety hazard) than having a solid, non-removable handle. Having an easy to remove solid handle allows you to remove the handle to work on the robot and make it easier to lift the robot onto/off of the cart. This can be something as simple a bent or welded piece of aluminum tubing than can slide into a slot in the cart.

3. 2 (at the end of the cart opposite of the fixed handle) and 2 omni / swivel casters (at the end with the handle) works well for maneuverability; four casters is a little harder to control with just one person.When you put the casters at the end opposite the handle, you'll have a large rotational moment when trying to turn the cart. If you put the casters at the same end as the handle, it'll be much easier to rotate the cart.

4. If you are going to build your own cart, while storage for stuff like the driver station is nice (not required), storage space for spare batteries and bottled water should be provided. but your drivers will thank you if they have a spot to throw the controller. (Some robots have room on them for this kind of stuff).Having storage space for batteries will save you from running to the pits, and having storage space for ample bottled water will literally save you. We once had a member of our drive team collapse during the elimination rounds five or six years ago from dehydration. Since then we've taken aggressive measures to always have ample bottled water (or Nalgenes+drinking fountain) at all times.

5. Some events (cough 10,000 Lakes cough) have only 32 inches of clearance for your cart. Long way forward and no wider than your robot is the best solution, or at least a way you can shrink it.Standard doorways are between 30-32 inches wide, so this should be a universal standard.

6. Most FRC robots are a maximum of five feet tall. Remember this when building a cart. The maximum height of a robot on top of the cart should be less than the maximum clearance height of the lowest doorway you'll encounter.

7. Your robot will change every year, but when you finally build a cart, build it once. Therefore, design in an easy to change method for holding the robot every year. One good solution is to mount blocks on pieces of 80/20 (or other similar extrusion), to slide to new positions every year.

8. If you have a giant flat surface, put a lip on it. There will be times where you'll have loose hardware from a mechanism on the cart that's still being assembled as you rush back to the field. Having lips on the cart will prevent that loose hardware from getting hopelessly lost.

9. Make your cart lightweight. Don't make it motorized, don't put on surround speakers, don't have permanently attached toolboxes, etc. Make it carry the robot, carry spare batteries, and potentially carry the operator interface. Anything else should stay in the pits.


Here's a photo of the homemade (wood) cart 228 has been using since 2006, which incorporates all of the above features:

http://www.team228.org/gallery/108/slideshow/frc-championship-2009_5c198-a4b89.jpg (http://www.team228.org/media/pictures/view/5236)

with handle removed:
http://www.team228.org/gallery/106/slideshow/connecticut-regional_c904b-e4f91.jpg (http://www.team228.org/media/pictures/view/5099)