frc 4592 pit carts

HI my name is jaleel from frc team 4592 and WE Would like to actuate our pits up and down does anybody have any suggestion of doing this?http://nebula.wsimg.com/731dae12a8ff309c33aaaf539069bac3?AccessKeyId=28F0BAAA468E816BA370&disposition=0&alloworigin=1

If you are going for minor actuation you might want to look at drop down casters. Just out of curiosity why do you want to actuate your pit?

What part(s) of the pit cart do you want to actuate up and down (whole cart from floor onto wheels; workbench relative to base; overhead storage relative to workbench; something else) and why? Both the stroke length and required force will drive the solution pretty heavily.

we want to actuate the overhead where the storage bins are up and down because at recent competition we had to manually bring it up and down. and also we want to do a drive systen for our carts instead of manually pushing them. any idea of a drive and control system for this?

For the overhead activation, the first thing I would do is put the overhead units on some sort of spring or counterweight so that your motor or cylinder will not have to dead lift the unit, greatly reducing the size and power needed. By the time you’ve done that, you may decide that there’s no need for an actuator to do the small remaining amount of lift. Don’t forget to take the weight of the contents of those bins into account when selecting springs.

As for motorizing the cart, this should be doable with standard FRC motors, wheels, and gearboxes. Note that you do not need to drive all of the wheels for this application as you would for a robot, because you don’t really WANT this thing to accelerate at 30+ ft/s/s. A single driven wheel (or better yet, swerve module) below the CoG of the cart with a defined suspension force (spring, weight, or pneumatic cylinder) would probably do the trick. If you DO motorize the cart, include a “dead man switch”. That is, require that a person be gripping a handle or similar control in order for the motor to run, similar to a lawn mower built in the past few decades, and put the drive motor controller(s) in brake mode - you don’t want anything this heavy actively running away from you.

To elaborate more, place the shelves on vertical tracks. Balance the empty shelves with a constant force springs. You can purchase those from mcmaster. Put your stuff in them, and then use a fish scale or other tool to find the force required to lift it. I’d use a simple rope and pulley system to lift it myself.

If you balance the shelves with things in them, you’ll have to fight to get them down if they aren’t full. That can be a problem. Especially since if they are large shelves you may be talking about hundreds of pounds. A rope and pulley system can lower that to whatever weight you want to deal with.