Re: Robot Lifting
 

After considering all situations that could happen in the last 20-30 seconds when handing will be attempted i came to the conclusion that it is best if 2 robots hang and one continues to score. This is simply because there will be potentially ungarded goals and more then likely 2+ balls in the scoring end, or a ton in the middle. If you have a good kicker it may be best to score even if you could hang. 2 teamates can easily hang off of the tower, any more and you have to hang off eachother. I think this will be a challenge and not all teams will be able to do this quickly. So if two teams hang off the tower and the third scores the team will have 4+(i would guess anywhere from 2-5 points) The other team will have from 6-8 if there whole team hangs. If 2 of the opposing team hangs then its even. If you run through all the senarios and make some assumptions you will see what i am saying. I think, but i may be wrong, that scoring with no deffender will be easy in the last 20-30 seconds (depending on when the enemy has to start hanging) and therfore it will be benifical to build the best kicker you can because if teams realize this they will want you.

Of course if no one builds a hanging bot then this doesn't matter.

My team is focusing on our kicker now and if we finish with time left we will build a hanging mechanism. This will give us time to practce while we build the hanging mechanism and then attach it on in the end if we decide to. I think this strategy will be great because we will then have a ton of driving practice, and the ability to do any task.

Re: Robot Lifting
 

We've looked into a system much like this; the trouble we're having is limiting degrees of freedom while elevating.

Re: Robot Lifting
 

Here is an idea that our team came up with that we believe would work and is outside the norm of lifting a robot that others may not think of. I was extremely proud of all of the ideas that the students generated this year for lifting. Besides this idea, they also came up with a great idea for lifting using the vertical bars. For the record, we are not using either idea. We are using the KISS method (Keep It Simple Students) and believe that we will have a lifting robot that can do the job quickly, efficiently and is simple.

I include this diagram within the spirit of Gracious Professionalism

Re: Robot Lifting
 

Neat idea! did anyone calculate the load on the winch? that low angle will make it pretty tough.

Re: Robot Lifting
 

That is a quite awesome idea.

I hope you guys make it work.

Re: Robot Lifting
 

That's a pretty sweet idea, i have to say.

There are some simple ways to get up the vertical bars (for example, clamp onto it with a wheel on each side, and spin the wheels. They'll naturally tighten onto the bar while they pull you up) - the problem we saw with using them is the amount of precision needed to get your mechanism arranged on the bar. I'm sure some team or teams out there will figure out a great way to take care of the precision problem... but we wanted to keep it simpler and fool proof.

So like many others here, we're going with a winch - it's simple, strong, and automatically locks to prevent being back driven. The innovative, and really cool, part is getting the hook up to the horizontal bar - that part takes under 1 second and needs, at most, a servo (we may be able to get the winch motor to work with it, eliminating the servo) in our prototype. It'd be nice to improve that on the real robot :)

Re: Robot Lifting
 

If the point about which your robot rotates up into place is within your FRAME PERIMETER, this does not work. The 3.25" bumpers will project through and below an imaginary plane at 20".

The idea is sound, but the implementation is tricky.

Re: Robot Lifting
 

I love it. Though I wonder how you get yourself pulled up so your bumpers don't break the plane of the PLATFORM, I guess I'll find out after Wisconsin. Good thinking!

Re: Robot Lifting
 

Has anyone managed to lift 120lbs with a 2.5" CIM Motor & 12.76:1 gearbox (TOUGHBOX)?
By my calculations it should be able to do the job. However, in a test I made, it managed to lift only about 55lbs...

Re: Robot Lifting
 

How did you try to lift with it? did you use a winch to wind up cable? if so, how big is the size of the spool that the cable winds on?

If it is too big diameter you will not have enough leverage.

Re: Robot Lifting
 

Yes, I have. the diameter of the spool was 1.5" by what I remember.

Btw, I'm asking if anyone managed to do that in order to be sure whether it's the motor's fault, or mine for not building the mechanism frictionless enough

Re: Robot Lifting
 

You'll need to lift 150 pounds factoring in bumpers and stuff.

I think your reduction is a little low... (i.e. not reduced enough)

Re: Robot Lifting
 

If you have some flat nylon strap you could try winding it on the toughbox output shaft to see if it can lift the weight. You might want to put another bearing on the other end of the shaft to support it though!

Re: Robot Lifting
 

That's exactly what I've done when I made that test.
But I did it with a piece of metal with a hole, that the spool goes in it. which may have created unnecessary friction.

Btw, thanks a lot for the quick replies. :)

Re: Robot Lifting
 

Well, in order to lift the robot you'll actually have to accelerate its mass, so you'll need more than 150 lbs. of force.

Also keep in mind that you'll need to calculate the output of the reduction at 1/3 the CIM's stall torque for max power. A CIM at stall will not lift your robot :)

You could add a chain or compound pulley reduction off of your T-Box to get enough force.

We found that a 70:1 reduction with a 2" dia pulley lifted the robot without tripping the breakers.