Hi all! My team and I are trying to decide on a non-motorized cart for our robot to bring onto the field. We were thinking about building on fro scratch, however we do not know how to approach it.
you are going to want to think of all the things you want. Do you want waterbottle holders for the drive team? maybe a drawer to store tools/towels/lights? do you want bars to hold the robot up by the chassis so it doesn’t fall or so its easier to do maintenance. or you can go super simple like 971 and just have a super small wooden dolly made to fit each robots chassis with a rope for pulling. Design it just like you would your robot so you don’t have to come back and re-do it another year. save yourself the time now.
PSA: please dont use the large “cafeteria cart” because they are fairly top heavy and tall making it harder to move your robot on and off and easier for it to fall off
This is what 5811 decided to do last year. It is a simple super structure made out of 1x2 box tube with 1/8” walls and gusset plates with diamond plate on top and 8in castor wheels on the bottom. The skis were added later so we could run the robot on the cart. It took us almost the entire off season to build because we machined and painted all of the box tube in house. The thing is a beast and can pretty much hold anything we put on it, including team members. Very heavy though.
Let’s start with one thing I have in experience being Technician and using the cart often, please, please do not build anything larger than the robot, you can make it as wide and as long but if you build it any bigger it will start to become an issue with how much it would weigh (based on what we use) and how big it is. Since you guys are coming at it with a similar approach, non-motorized, from scratch, etc. try to build the frame out of 80/20, you can stack it, use pieces 2-however many feet you need it and brace the 80/20 with another row of it to keep it strong, try to use the biggest pieces you have and even use full lengths of 80/20, it’s not the best idea to use scraps and pieces around the shop but I wouldn’t do what I did using scraps, just simply use full lengths to brace each other and then bolt perhaps plywood or metal something of strength, plywood will be just fine even if you have to split it up as in a row of boards, then apply on the top, to the bottom so that you can store toolboxes, bumpers, what-have-you in the bottom. Also a cool thing to do is make a sign and add lights, teams love seeing that cool stuff, even if they are cheap christmas rope lights from the neighbors trash that still work.
Another problem we ran across is what type of wheel to use, should we use 2 casting wheels, or 4 casting wheels?
Use 2 swivel casters in the back and 2 regular casters in the front, it will be easy to turn and control
Another thing I should add, Put a permanent lift or set of boards like @WhoeverYouLike has in their cart so that your robot does not roll off if you come to a sudden stop or hit an object, it’s a shame for me to say this but I killed last years blue alliance bumpers because we did not have the robot stopped or held by anything when I hit a large post base something simple like two 2x4s should do the trick
Overall what Im pretty much talking about is in their picture If you can’t get those some materials you can make a box out of 80/20, wood on top wood on bottom and handlebar don’t forget to run supports for the 80/20
This really helped with our decision making, thanks so much.
If you aren’t competing this weekend you could try and send a couple people to a competition and look at carts that teams are using there. If they aren’t busy I’m sure they’d also be willing to rattle off a feature list of things they wish their cart had.
I’ll reiterate that some type of feature to keep the robot from rolling off the cart when accelerating/going on slopes is important. Whether that be depressions for the wheels, or pegs that the bumpers run into, or whatever else; having a mechanism break because you dropped the robot off your cart feels really dumb.
We used 80/20, built a rectangle, attacked wheels to the corners (front two spin, just like a shopping cart), and put a handle on the back with a slot for a spare battery and two L-brackets our driver station board thing attaches to.
Or rookie year we just threw some wooden plants together, painted them red, attached some wheels to the bottom, and had two loops of rope through the front and the back end. It was janky, but it got us through the year.
This is they cart we built last year and I think we’re re-building it similarly this year. I highly recommend.
We haven’t built another one since our upgrade from wood. I definitely recommend building a cart you think will handle any future design.
For robot carts, do you guys usually design something to hold driverstation?
some really useful features we have on our cart is a winch that can bring the robot up and down the arms of the cart can move in and out to fit the size of that years robot and there is a lot of storage space underneath the robot and in the back of the cart where we keep batteries extra bumper hardware a few tools for bumper mounting and basic fixes a ethernet cable battery beak and we hang our drum harness on that we use for our driver station on it
This is our first year so we don’t really know this stuff.
This was pretty similar to the idea that we wanted to go for. Is there any way you could give us some recommendations on how to build it? That would be greatly appreciated!
Also make sure you use large casters and make it as light as possible. The cart will need to be able to easily traverse soft foam tiles, ramps of various sizes and conditions, and cable guards for the AV crew at regular integrals (about 3 inches tall) , and you don’t want it to be a pain every time you encounter something like that, also make sure it is narrow enough to fit though a regular assessibilty door, not all venues will have enough space to have an open pathway or double open doors to get to que and certain pit areas.
I know I’m echoing some other advice, but our team has kept it simple for years
- piece of plywood, with edging for roll-off. Wide enough for robot, narrow enough for doorways.
- a custom holder for the robot out of 2x4 to go on top (so robot doesn’t roll. good for pit testing too)
- fixed wheels in the back
- swivel casters in the front (no-roll locking)
- snow shovel handle for pulling, bolted with butterfly net thru C-channel to top of plywood
- Wheels are large to go over bumps easy (door frames, small curbs, snowy roads, etc)
End product is something like a mesh deck wagon at Harbor Freight or a garden center.
Alternate,if you search Amazon for a " Wagon Undercarriage", you just need to add the plywood and you are done in 60 minutes or less, depending on how many times the students need to remeasure.
The ability to transport this in the back of car/SUV is key. Removing the handle makes it safe in pits (trip hazard) and to/from events in vehicles. It is ungainly to steer sometimes, but it depends on the student driving the platform.
While I am envious of the larger carts that hold everything, it takes a village to move this, so if your team is logistically challenged, keep it simple. Now, if we ever get a trailer…
As a rookie team, I wouldn’t go too fancy with your robot cart. Just get a dolly with decent-sized wheels, little red wagon, or garden-type cart. Maybe a hand truck that can be used as a cart. Remember that you’ll probably have to go over cable protectors at some point (or other tough terrain). Add a couple of rails (2x4s) to raise the robot up for testing the drive/access underneath.
This will give you something that you can compare against and work with right away… Do the cart as an after-season project, based on what you see that you like at your event(s).