The afterthought bridge manipulator
 

After our first regional this year, our team has learned a lot about this game.
One thing we (and quite a few other teams) didn't see coming was the difficulty of lowering those bridges.
Our bridge arm was the last system to be designed, and was not given enough weight/space allotment. For that reason, we ended up having a "you lower it and we'l follow you up there" robot. We tried at least two different designs both powered by a window motor, to no avail. Then again, with 5 pounds of weight to spare for a manipulator, what can you expect?

I'm curious as to who else was in this boat, and if they found a way to overcome this problem. It would be interesting to discuss last ditch bridge manipulator implementations, and their effectiveness.

Re: The afterthought bridge manipulator
 

Every year there is always an aspect of the game that people underestimate that in the end cost them the opportunity to win the game. The ability to negotiate the bumps and manipulate the bridges is this year's bugaboo. I have seen plenty of robots helplessly paw at the bridge for the endgame and I have seen robots get stopped cold at the bump as if they hit a brick wall. I think teams figured scoring balls were more important and while it can make you dominant the ability to consistently make it on the bridge (especially the Coopertition Bridge during Qualification matches) is practically invaluable.

Re: The afterthought bridge manipulator
 

We were in the same boat, and it hurt.. a lot...

For off season I am thinking of just strapping a 1.5inch bore Pneumatic cylinder on the side of the robot and using that to push the bridge down.

Re: The afterthought bridge manipulator
 

We had this same idea, we do not run a compressor on the robot though so this would be tough, UNLESS we charged our air before each match and never charged it on the field :eek:
Plausible?

I agree that bridge manipulation is invaluable, it's unfortunate that many of us cannot yet do it.

Re: The afterthought bridge manipulator
 

From our last year experiences, think 2inch bore x 24 inch cylinder, we found it best to run a compressor on board for anything bigger then .75inches; your mileage may differ.
The biggest problem without running a compressor is tiny leaks, we per-charged this year and then by the time we got onto the field we found we lost already 15PSI.

Re: The afterthought bridge manipulator
 

I watched a lot of teams (both veterans and rookies) struggle with this over the weekend. I'm not sure if the issue was more geometry or providing enough torque to the bridge to lower it.

One of the most clever methods I've seen is team 103, who has two curved pieces of tubing that flip down and so when they drive up to the bridge the natural motion of their forward momentum causes the bridge to tilt and allowed for them to get up pretty easily. It was a pretty effective, light weight and passive way of lowering the ramp without having to stop and wait for some other mechanism to push the bridge down. If I can find a pic I'll post it.

Or you could try the 25 method: bump the bridge, pop a wheelie and then get on. Seemed to work well for them :rolleyes:

Re: The afterthought bridge manipulator
 

Our regional is next week. After watching weeks 1 & 2 we're scrambling to make a bridge manipulator:
Andymark gearmotor (KOP) on a length of c-channel with a small wheel on the end.
This is untested and will not get a chance until Thursday.
Fingers crossed!

Re: The afterthought bridge manipulator
 

Gear that down. A LOT. Make it go slower than molasses with gearing. You'll need he torque

Re: The afterthought bridge manipulator
 

We had the same problem in Smoky Mountains. Our bridge manipulator turned out to be the worst part of our robot. We tried to fix it but it eventually became this

So after the regional I started designing. I had 10 pounds to work with, 5 from the old one and then we sacrificed the angle changer on our shooter and will change the speed instead, which gave another 5 ish pounds.

This is what i designed
Down
Up

Current weight is about 6 pounds. We dont have to add any electronics because the old electronics are still there.

Though for us depending on another robot for a bridge manipulator worked! We are undefeated right now, and won Smoky Mountains. :D

Re: The afterthought bridge manipulator
 

Nice design! Are you running a window motor to power that?

Re: The afterthought bridge manipulator
 

NO! lol sorry PLEASE DO NO USE A WINDOW MOTOR!!!!!!!!!! Im putting on a fisher price motor. The gearbox is there in the picture :P The old Bridge manipulator was a window motor, but it doesnt have nearly enough torque to push the bridge down.

Re: The afterthought bridge manipulator
 

Word. ;)

But we shouldn't have this dependency in Wisconsin.

Re: The afterthought bridge manipulator
 

We will definitely need a bridge manipulator if we want to be competitive against 1114, 2056 and 188 in GTR West.

Re: The afterthought bridge manipulator
 

We had originally designed our cannon to have a barrel extension which extended the length of the cannon when in the firing position, but realized the cannon was just barely long enough to get the bridge down. During build week 5, we reversed the extender to extend the cannon when it was in the down position, making it very easy to put the bridge down.

Re: The afterthought bridge manipulator
 

We haven't attended a regional yet (we are week four), but we have spent enough time going up/down bridges with our robot to comment here...

Our team prototyped a bridge manipulator that would push the bridge down, and like some of the other posters figured out that using an arm to do all the pushing was not as simple as some thought. The moment we thought we should change designs was when our robot ran over our bridge manipulator...

In the end, we created an mechanism that acts as a ramp, and uses the power of our drivetrain to lower the bridge. When approaching the bridge, the driver will lower the mechanism out over our bumpers, and hit the bridge. The lip of the bridge will slide down the ramp (like so: -evil bridge lip-\[robot here]). When the bridge's lip reaches the bottom the the ramp, the wheels will be able to roll onto the bridge.