motorized robot carts
 

Two friends and I on my robotic team have been assigned to make one for our team. All we have to work with is an electric wheel chair and basic robtics components in our shop. If your team has made one could you post pictures of them and how you guys made them any help is nice thanks.

Re: motorized robot carts
 

While I don't have any pictures, I can give you a basic description of the one I worked on a few years ago.

It was a very basic unit, we made a simple rectangular frame, the front had castors and was covered with a big sheet of diamond plate. At the rear there was a bump over the two drive wheels. It was setup like a basic tank drive robot using all old KOP components.

It worked decently well, one could ride on it with the robot, though we never brought it to competition as the legality was a bit sketchy, and we lacked the room to transport it. There are obvious drawbacks to a tank drive steering on a car, but it was still moderately maneuverable.

Re: motorized robot carts
 

We've had various proposals and sketches over the years. I thought one concept was pretty good: build a small "tractor" to pull a more typical non-motorized cart. Given sufficient power, that might also give you the option of adding an additional trailer for tools or batteries, or even seats for the drive team.

Re: motorized robot carts
 

As far as I have see, there are two main configurations. There is the afore mentioned tractor/trailer. This provides good stability, however driving the thing is a little bit more difficult, as the trailer doesn't follow the tractor's path exactly. A great advantage to this design is that you can make the tractor detachable. That way, if you run out of battery, you can just pull the tractor portion yourself.
The second configuration is a platform directly on top of the base. I saw one of these at the oregon regional. I seemed a little top heavy, so if you do this, beware of bumps. The platform for the robot was also really high up (approx 48 in), so lifting the robot may get a little awkward.

Re: motorized robot carts
 

Talk to T3 about it, I'm sure there is someone from their team lurking around here.

Re: motorized robot carts
 

While I don't have any specs on building one, you might want to try and get in touch with Team 1806, SWAT Team. They've had a motorized cart for some time now and it works pretty well. It's a regular cart with a segway-like attachment directly on the back. No joint inbetween, and they use a joystick/pedal to drive it.

Re: motorized robot carts
 

We have a motorized cart which is built on top of a motorized golf bag caddie. Unfortunately, the extra batteries needed take up a bit too much space so generally it is just pushed, which is no issue if one is going forwards, but it has an anti-rollback feature that makes backing up a slight issue. It is low to the ground and stable. The design allows for a couple of extra batteries to be stored in the bottom of the cart since the batteries are about the same height as the caddie's motor housing.

Re: motorized robot carts
 

Talk to 1075 about the coolest motorized robot cart ever.

Re: motorized robot carts
 

1899 built one for Logomotion. Wheelchair-based... A few pictures here:

http://www.flickr.com/photos/saintsr...57626693671452
http://www.flickr.com/photos/saintsr...57626693671452
http://www.flickr.com/photos/saintsr...57626693671452

I'll ping our mentor who worked on it... he has all the design details.

Re: motorized robot carts
 

Agreed 1075's cart is amazing, however, i believe it is extremely UNsafe. the drier has a hard time seeing it looks like. And having somthing like that in the pits seems very unsafe when there is a big crowd

Re: motorized robot carts
 

We took the motors and joystick off of an electric wheel chair, two car batteries, and a wooden table top the raises from about 18 inches to about 3 and a half feet off the ground. The rear two wheels are powered and the front two are casters. It has room for one person to ride. I'll put some pictures up later tomorrow.

Re: motorized robot carts
 

1293 modified a robot for parade duty in 2005, and it ended with me having to push around 200 pounds of robot and spare batteries mounted onboard for a half-mile to the parade end (including resistance from one of the gearboxes that was still engaged with its wheel). I had a lot of great memories with 1293...that was not one of them.

When your cart breaks*, what is your contingency for making sure the drive team can get the robot there safely and without exhausting themselves?

Something to consider.

*I'm not questioning your fabrication skills, but you know what will happen if you design with the assumption that it won't break....

Re: motorized robot carts
 

As someone who works team que at several events may I make a request on behalf of all field volunteers everywhere and ask you to please don't make one?
I know alot of teams think it's so cool to roll up tot he field in some tricked out cart pumping jams out of your expensive sound system and flashing lights but have you considered how tight the space is around the field and the pits, the amount of spectators milling around (especially children) and unless your team number is 67, 1114 or a 469 wouldn't that brainstorming be better served building a better robot (last I heard a team has never been picked because they had a cool robot cart but I wouldn't be surprise if a team wasn't picked because other teams found their cart annoying and their robot underwhelming)?
I know I'm being a big mean ol' jerk because of this but all I ask is you please think about this before you do this. It's one thing to make a cart that bring tools and batteries to the field but do you really need all that other stuff?

Re: motorized robot carts
 

I'm with Ed on this one. Yeah, they look cool, but is pushing/pulling a robot that difficult? Unless you can make one that is as small and can turn as tight as a normal cart, it probably not worth wasting your time on it.

And please don't be that team that blasts music from your cart. Its annoying and the rule book prohibits it.

Re: motorized robot carts
 

I completely agree, that is why this is an OFF SEASON project only. Its a great way to get your brain thinking before kickoff. We built ours in between regionals in 2008 as a present from our mentors for winning our first regional.

Re: motorized robot carts
 

Playing music from the cart in your pit is one thing, but playing your music while on your way to field is another. Besides, by the field they have music going pretty loud, so why do you need to have music playing from your cart too? It'll just annoy the volunteers and other teams around you. Now if you're going to be playing music in your pit anyway then I would say it is ok to have it coming from your cart as long as you don't play it while going to and from the field. Having some kind of stero system on the cart would also benefit a team for something like a demo where you would be playing music.

I don't see a reason why you would need to drive the robot. You're going to be walking right next to it anyways, so why not jsut push it.

I don't really see what problems lights would cause on a robot cart.

Re: motorized robot carts
 

Ed stole my GOM thunder.

Please keep in mind the queuing and field personnel when making your cart. I have seen motorized and non-motorized carts become a nightmare for these hard working volunteers. They must be able to easily and quickly move the cart without power. It's can easily become a safety problem.

It's a great project to do to exercise some creative juices or have when you are doing demo's but please when it come's to competition time leave it at home.

Re: motorized robot carts
 

To be blunt: how many motorized carts do you see parked on the side of Einstein?

Re: motorized robot carts
 

The overall dimensions are 71" x 32", and the platform/table top is 48" x 32". When the table is in the transport position, down, it sits 11" off the ground, when the table is in the pits, the working position, it sits about 34" off of the ground. I hope this helps.

Our chart is quick, easily moved, and is not inconvenient for queuing I've asked the volunteers.

Re: motorized robot carts
 

For all of the Queuing and Field crew members I've worked with in my almost 10 years volunteering I must say
PLEASE do not bring motorized and/or poorly-maneuverable carts to competition. They might look cool, but they slow down queuing-flow, load-on, and load-off immensely.

Re: motorized robot carts
 

Ed and Sam-

I usually agree with you guys, but I can't on this issue.

While many of your concerns are valid, it doesn't mean its a guaranteed issue for every single team. I've seen plenty of carts that are a danger because of their size/maneuverability, etc that are nothing more than a modified handtruck. I'm not in favor of motorized carts necessarily, but I feel if you are going through the effort of designing an effective cart, you ARE spending time wisely.


If you are going motorized you can go through a drivetrain cycle thats outside the typical scope for FRC drives.

I guess my point is a motorized cart doesn't necessarily mean a big obstruction that will do nothing but get in the way.


As for the music issue on carts, I realize it tends to be very polarizing. For me, I'm totally for it and here's why: It's by far the most effective method of clearing a path through a crowd of people I've seen. People hear music and assume its just extra noise a team is creating. However, I find people and teams who walk through the pits screaming "ROBOT!" to be far more intrusive. Obviously there needs to be a certain level of maturity and respect level for other teams for a team who has music on their cart. Again, I feel its just a few bad apples that have ruined the perception for many.

-Brando

Re: motorized robot carts
 

Man, I never thought I'd have to cite a rule during the offseason.

(emphasis mine)

Re: motorized robot carts
 

No it isn't
Going to the field and blasting your music to compete with the loud music already playing is annoying and if I must say so disrespectful.

Re: motorized robot carts
 

Agreed. Like I said before, if you want to have music capability on your cart for in the pit purposes and separate demo events, then that's fine. But don't create unnecessary noise that no one wants to hear by the field.

As far as motorized carts: again, you're already walking next to it anyways. Just put some caster's on there and push the darn thing. That way it's safe and you can get out of the way of something quickly as opposed to accidentally running the cat into someone.

-Nick

Re: motorized robot carts
 

It's certainly an interesting engineering exercise. You don't have the very same size and weight constraints you always have, and your results have long term benefit. I think it could be a very rewarding project if done correctly and if the designer makes for queueing friendly features (a neutral gear for wheeling around, small size to make it less noticeable)

Sound shouldn't be played on the field.

Re: motorized robot carts
 

to the guys who are against it i can understand your concern but this cart is being made either way me and my friends who are working on it will make it modest we won't make this a "look how much better than you, we are" project it will be as little as possible easy to manuever and not playload music while flashing lights. If the job is given to another kid on our team who we were told would be given that he will try for the most showoffish design he can make.
otherwise thanks for the concern.

Re: motorized robot carts
 

There's a right way to do it and a wrong way to do it. I'm sure everyone's familiar with the "wrong way". I however have seen teams be very respectful with their music and actually make for a more pleasant competition experience.

What's the difference though? It's against the rules...

Brando

Re: motorized robot carts
 

When I was a Freshman someone on my team half jokingly said it would be cool to have a noise canceling system on a robot cart.

But back to the issue at hand, If a sound system is desired for demonstration purposes, It could be designed as part of a modular system. At competitions the sound system could simply be lifted out and replaced with a box to hold some basic tools, A battery holder, and/or an off-board compressor, just to name a few possible options. That way you won't have to push around the dead weight of a sound system that you can't even use at competitions, and you will have a place to put things that you might actually need.

Re: motorized robot carts
 

Our team has had this wheelchair based cart for 7 years now. Any questions just ask me. :)

http://www.flickr.com/photos/66721945@N04/

Re: motorized robot carts
 

Is it safe? It looks like the robot can roll off anytime

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Yes its really safe. Theres a lip all the way around and I hold onto the robot while driving. Drives like butter on flat ground, like a snake on angled.

Re: motorized robot carts
 

hmm, I've never driven a snake before, care to elaborate?

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Strait line speed is slow unless zig-zagging is pleasurable O.o

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I am working on CAD-ing a mecanum drive cart for production during our preseason. :D Shall use old robots electronics. Photos when done.

Re: motorized robot carts
 

Question regarding any carts in general. We had a less than stellar cart last year and we had trouble going over the bumps that covered the wires on the ground. How did you guys overcome that problem?

Re: motorized robot carts
 

1. Make sure you have ample ground clearance (4+ in.)
2. Bigger tires go over bumps easier, so having a relatively large wheel size helps.
3. To go along with 2, a tire with some give also makes the transition over a bump less severe, so pneumatic tires work extremely well for that.

McMaster P/N# 22925T71 also comes in a rigid form factor that allows you to use the ideal steering setup of 2 casters and 2 fixed wheels.

Hope it helps.

-Brando

Re: motorized robot carts
 

Probably a bad idea on non-flat terrain. And there's just enough non-flat terrain at a FIRST event to make this troublesome—cable raceways, floor protection panels, small ramps, etc.. I suppose it wouldn't be a huge deal if you can just push it to overcome those obstacles.

Re: motorized robot carts
 

I thought of that and our mec's have large enough rollers and a sufficent diameter for wires. We also will use a pnematic suspension on the rear two wheels to accomidate non flat surfaces. But in the end our 4 super cims should power through the bumps ;)

And we have no problem going over 4 inch bumps on our wheelchair powered cart. Ground clearence, grippy/large tires and way to much power is key.

Re: motorized robot carts
 

Sorry I didn't see this thread earlier. Please be advised that due to insurance regulations at various venues, you may be asked to remove a powered cart or to at least disable it's drive while at that event. Insurance for an event like ours is pretty hard to write especially with all of the students and volunteers present. Adding a power driven cart to the mix when it will be used in tight places and dark areas is just too much to ask. Others have weighed in on the sound system but let me add, that often alliances are discussing strategy and assisting other with software rewrites in the Queue. With the sound coming from the field, additional sound is counter-productive and as Kara has pointed out a violation of the rules.
Again, you may be asked to remove or disable a powered cart, be prepared.

Re: motorized robot carts
 

We've drove our wheelchair cart for 7 years with no problems. Besides we always bring a push cart just in case our cart fails.

The mecanum drive is more manuverable than tank drive and gobs safer.