building a robot transport

[Bcahn836]

Originally Posted by bskll

my team is interested in building a motorized cart that help us transport our heavy robot.

the total amount of weight that the motors has to support is about 130 pounds for the robot and about 20-30 pounds for the cart it self.

we are planning to drive it with a simple drive system of two motors each individually connecting to a chain and then the chain will connect to 1 wheel each.

what gear ratio do you guys suggest? we don't need it to be fast here. we just need to help move along the robot.

thanks for any suggestion.

P.S. this is my first post.

What kind of motor do u plan on using? We are using two wheel chair motors and their rated load is 200lbs each.

[bskll]

we are using the bosch motors that came with the 2004 kit.

it is the best thing that we have so far.

and we are not working on top of the cart during the competition. we are just transporting tools and the robot. we're probably not going to ship it along with the robot.

the new estimate is about 130 pounds for robot. 30 pounds for the cart itself plus motors. and i guess two spare batteries will add up to about 50 pounds. plus 40-60 punds for other tools.

so a total of about 250-270 pounds.

[oreocookeee]

i have been working on a cart design for the past two years but i havnt been able to make it happen due to lacking funds. i figure that if you are going out of the way to transport it to the competitions, it should be worth the effort. the cart that i have in mind is motorized and collapsible so that it could easily be transported in the crate. it is somewhat modular: it is designed to fit various types of platforms, tables, etc. the coolest feature that i had in mind was a leadscrew-driven scissor lift so that the platform could raise or lower to any height. all i have so far are rough sketches, but i plan on transfering them to inventor eventually. if i can figure out how to put it together entirely with old parts, maybe my team will be able to show it off at this year's competitions.

[phrontist]

Hmm... this thread has given me an idea! Imagine a cart that you could actually get up on and pedal, in a really low gear. Just kind of cruise to the comp and back. Make it with old bike components...

[Stephen Kowski]

i don't about being motorized, but my old team (312) and the took a lift table and welded it to a cart. That way they really never take it off of there unless it is going on the field. in the pits they simply jack it up and lock the wheels in place and it makes everything simple to work on. The get called for a match so they lower the thing down and don't have any doorway problems that I often see teams have.

[Wetzel]

Stephen has reminded me of a rather important point.

Made sure you can fit through a standard door way. That means a 36" wide footprint at most (ADA requires 36") I have seen teams that have had to take their robot off their cart to finagle their cart through the door at the Georgia Dome. Not fun.

Another consideration that teams seem to neglect is the little plastic ramps that contain the AV wires. You've seen them, they are about 4 inches tall with slopes on either side. Teams with small caster wheels have great difficulty surmounting these simple obstacles.

Good luck!


Wetzel

[Darkshining]

Originally Posted by oreocookeee

i have been working on a cart design for the past two years but i havnt been able to make it happen...

that's almost like me, people in the robotics team keeps on coming up with new designs and ask me for dimentions... how the heck am i suppose to know.
bskll, just measure the R.P.M, then calculate both motors and then find out the ratio you want. test them out first to see if it works, nothing is definite.

[greencactus3]

Originally Posted by Wetzel

Another consideration that teams seem to neglect is the little plastic ramps that contain the AV wires. You've seen them, they are about 4 inches tall with slopes on either side. Teams with small caster wheels have great difficulty surmounting these simple obstacles.

ahh yes. definitly need to watch out for those. our casters last year was teeny and had trouble getting over even a door ledge. if your space allows, bigger wheels are definitly better. and as for getting through the door, well if you have to take the robot off for it to go through, screw the cart, or shave it down. or if you're really fancy you can go through another door that might be wider too