Does anyone have any ideas to get onto the ramps, preferably by attaching something to your robot frame?
Our team came up with an idea; attach a piece of wood to the frame and run it into the ramp, therefore pushing the ramp down.
Suggestions?
angle idea.bmp (442 KB)
angle idea.bmp (442 KB)
That idea could work, but I think you’ll find it’ll be difficult with bumpers. My team actually has an arm, about 1.5’ long, with a small wheel at the end. It’s slow moving but it has enough torque to push the ramp down to the floor (alternatively raise it up to lower the other side for an alliance partner). It also doubles as a way to lift our frame up and over the barrier.
Main take-away: I’d suggest doing as much as possible with active control as opposed to passive control.
We’re mainly looking for ideas too attach something to the frame, without deploying anything off of the robot.
You’d have to get the ramp just about below your bumpers for that to work properly (below the bumpers, you can just have an angle down towards the drivetrain). Let’s do some rules/field work here:
The bridge settles at 12" off the floor. Bumpers, by rule, must have their bottom between 2" and 5" off the floor (due to the bumper zone). So, whatever angle you use must go beyond the bumpers far enough to lower the bridge by 7" or more.
Per [R02-E], unless the appendage exemption ([R02-D]) is used, nothing can go beyond the vertical projection of the frame perimeter, which is defined in the Bumper Zone. Therefore, you must have an appendage. If a part of the robot, specifically an angle like you want, is stationary, I doubt that you could classify it as an appendage (particularly because [G01] forces all appendages to be within the frame perimeter to start the match). Translation: It needs to be able to move from inside the frame perimeter to outside the frame perimeter.
Now, to some math. You will need to extend out beyond the frame perimeter a minimum of 3" to get the appendage clear of the bumpers. You’ll need to be able to drop the bridge 7-10", and of your 14" extension, you have 11" left (due to the 3" clearance of bumpers). This is very doable with a 45* angle. But, you’ll need to keep the appendage extended while putting the bridge down. That’s the hard part, and ways to do it are left as an exercise to the reader.
Short version: What you want to do (drop the bridge without deploying anything) is not possible without being in violation of [R02]. There are ways to have a simple deployment that would then act as part of the robot once deployed; technically, those would be very difficult to find illegal. However, you’d need to be careful about contacting other robots with the appendage, as there is a risk that some of the gameplay rules could be violated.
As mentioned above, there probably isn’t anything you can do that can rigidly attach to your frame and not be deployed. That doesn’t mean you can’t use your idea and try to find a way to deploy it. I’d really suggest trying to make a quick prototype out of cardboard to see how you can deploy it, and just run with it. If you can’t find a solution in the next few days, then move onto the next idea. Time is a precious commodity at this point of the season, and you can’t afford to spend too much of it on an idea with a dead end.
Thats what my team is doing
http://www.youtube.com/user/RenaissanceRobotics?feature=mhee#p/u/5/Gc-bCIJxjcg
Thats what my team is planning on doing
http://www.youtube.com/user/RenaissanceRobotics?feature=mhee#p/u/5/Gc-bCIJxjcg
I found the golden ratio. :] :]
If you are indeed using a pneumatic cylinder to drive that linkage as shown in this diagram, you will probably find this linkage geometry will not work the way you intend. Right now the pneumatic cylinder and linkage pivot points pass the linkage’s kinematic singularity point* during some point in the middle of its intended transition. This means that the linkage can toggle between either its intended geometry of rotating out and down or trying to rotate into itself/the robot.
Use one motor and a arm. like this: http://www.youtube.com/watch?v=BQ1mGk50OFc&feature=youtu.be
You can use it to lift the ramp, pull the ramp down or level yourself when there are two or more on the bridge.
@artudutra: It’s hard to tell but the piston stroke stops before it can pass that singularity point. My concern is enough force. We selected a 12mm wide piston from FESTO (DSNU-12-125-PPV). The competition bridge requires 30lb at 30 from the first fulcrum to tip it. Our test bridge has no where near this resistance and so I hope we are able to bash the bridge.
@Mike: Is your bridge to spec? If so, what motors are you using?
This was an idea we were testing and our final bot will have a similar mechanism to the one posted, but with one single appendage rather than two, and will actually be slightly recessed into the frame when in the upright position. It shows a passive approach to bringing down the ramp.
