Hypothetical Situation - Stairs

some people interpret the game hint Little Eva - locomotion - Robotic Locomotion http://en.wikipedia.org/wiki/Robot_locomotion

The point of this is not to discus the game hint, there are 500 other posts about that. This is a fun mental exercise that can challenge us for the next week.

I assume that for the sake of rookies the kit drive-train would have to be able to play the game so perhaps a bonus obstacle close to the driver station such as the ramp in 06.

So here is my Hypothetical Situation:

4 steps each 6 inches high, spaced 6 inches apart. At the top of the stairs there is a platform 2 feet tall, 3 feet wide, 8 feet long. At the end of the match each robot on the platform scores 50 points.

don’t actually build a robot just describe you strategy and how you would attempt to mechanically solve this challenge.

Look at robots from 2004. They climbed steps very well.

A couple of highlights:
our robot (33):
The entire top piece (the big refrigerator-box) moved by window motors, and had wheels on the front. It would tip back, and get the wheels onto the platform, then move down (lifting the robot, but the back two wheels remained on the ground). Then it would drive up. Almost all of the weight of the robot was in the chassis (it was full weight, 130lbs with battery, and the entire top piece weighed around 10lbs), so it wouldn’t tip over easily.

Simbotics (1114): They had four wheel pods (two crab pods and two casters) each with a pneumatic piston. They would lift all of the pistons, then run into the platform. Sensors on each pod would lift it as it hit the platform.

that was a different challenge. The steps I was thinking of are much larger than 04, but similar concepts should work

I know this doesn’t address the OP’s original question, but to add on to what was said here

We had a similar solution, except it was just front and back instead of 4 independent modules like they did. We had 8 light sensors that we used to detect where the robot was relative to the platform and raised/lowered the modules accordingly. It worked great, but in practice the time that it took to raise the modules wasn’t as fast as we had hoped (the goal was to be able to drive on without slowing down)

Check out our Encore promo video from that year to see more details.

Again, that was a different challenge with only a single step to deal with.

As a mentor of one of those rookie teams who will most likely be using the kit frame unless CADed otherwise, I would recommend designs such as 190’s 2004 robot. Or I would really like to try 1276’s off-season prototype.

Just in case there are stairs this year, would it be best to have tracks or what ever they are call ed, like on tanks. ??? unlesss we have to use legs i mean. and Where can i find some or purhase them???

If I remember the game correctly, WPI (Team 190) had a great platform climber, went around a goal obstruction, and hung on a bar, all autonomously. Can’t wait to see the new game. Speculation is generally fruitless, but can be fun for some.

They went up the 2" stairs, and intentionally built narrow to go around the goal. I remember that part of their robot was a piece of laminated paper to reach over a line and “straddle” it so they’d be in position for the stairs.

I might try 330’s approach: oversized rear pneumatic tires (12") with an angled front and 6" wheels to lead up the step.

Tank tracks: Outback Manufacturing has a kit for those, but most teams make their own with varying degrees of success (the Triplets in 2006) and unsuccess (any robot that throws more than one or two in a season). They’ll work for stairs, but I wouldn’t recommend them for flat floors necessarily.

I’d probably approach the 6" stairs with a tank tread design as well. Perhaps only to climb - wheels could provide the regular movement.

A very fast and exciting way would be for a robot that had the ability to shift is CG very high (approximatley 3feet or higher), and then take a run at the platform and let the physics of momentum do the work.
Of course this strategy could literally turn into a trainwreck…

id try to create a design that could some how also get the other robots up, maybe a modified ramp bot like 08. Or after it climbs flips down a ramp so the other bots can get up easier

I just had to complete a stair climbing challenge for RPI’s Intro to Engineering Design class. Here’s what my team learned with a tracked Vex robot.

The key to going up - and down - stairs with a tracked system is CG. Your left-right CG should be centered so that you track as straight as possible. You will want to move your CG around going up and down steps, however. If your tracks span more than one step, you’ll want your CG more forward than aft. On the way down, you’ll want it more aft than forward to prevent rolling right down the stairs. Of course, with all CG problems lower is always better, and a low CG means you have to displace your CG less.

The other tricky part of stairs can be climbing the vertical face of the step (the “first step problem”). With enough traction, you can “roll” up the side of the stairs, and if you lack the traction you’ll need to find other means to “pop up”…

http://www.vexforum.com/gallery/files/3/1/6/5/img_0798.jpg

I did some researching on my own of stair-climbing a few months ago and I found some very interesting things.

This one is personally my favorite, and if the modules were made larger, they could potentially climb much larger stairs:

Even something like this is possible in the FRC:

The most interesting thing I found was something like this:

But that would be pretty out of the question for FIRST.

But something like this would be extremely interesting to see:

I even did some small mental experiments with the mechanics that go into climbing stairs and came up with some pretty interesting ideas.

This tank tread system worked very well for us in climbing the platform in 2004 - our arm tilted in the direction of the climb to give us CG advantage when climbing. When climbing down, we kept the arm in the same position and drove in the opposite direction. Very stable.

Game rules (bumper design requirements, ability of appendages to leave base footprint, etc.) may prevent the use of such a method in future “step” games. There are also nagging little weight, cost, and reliability of tread factors associated with this and similar treaded designs.

You shouldn’t be buying*, building, or designing anything to be used on your final robot before Kickoff.

*with the probable exception of tools, supplies, raw materials, etc.

Why not? I would love to be prototyping a tank drive in the off-season even though it is almost over. Off-season is THE time for prototyping new ideas or mechanisms you are unfamiliar with so come build season you have knowledge that you can build off of.

The 190 robot also had across it, 4 sets of wheels, instead of just two. As it climbed up, parts of the robot were over hanging off the platform, and the robot could be supported by wheels in the center of the robot.

Also, this design worked well when it was able to get up on the platform in auto. I saw a few matches they were in where they did not make it up onto the platform. This posed a problem, as the robot could not turn well.

Just remember, many great designs have also had a major drawback.

A perfect example of this is finals match 2 from the championship of 2002. SPAM 180 beat 71 to the center goal, and knocked them out of the way. Without the goals secured to itself, not all that much they could do. http://www.thebluealliance.net/tbatv/match/2002cmp_f1m2

Not to move this off topic, but just remember there are always tradeoffs to be made. How you deal with the game elements and field is up to you.

Edited my post to clarify.

prototyping that kind of drive train would even be useful for that fabled water game

also, for those wanting a real challenge, try this method:

:yikes:

Although we were relatively successful with both the complex wheel pods of Simbot Simon in 2004 and the tank treads of Simbot Beckham in 2006, neither solution was chosen for pure climbing ability.

In 2004, the reason we went with with the independent lifting wheel pods was because we felt it was the best way to climb a 6" step, while using a swerve drive. If we weren’t already committed to swerve drive, there’s no way we would have gone down this road. This was just way too complex of a solution for a problem that could be handled in a much more conventional way.

In 2006, our use of tank treads had very little to do with climbing the ramps that were on the field. We went with the treads because we felt we could get more traction by taking advantage of the longer contact patch between the tread and the carpet. Granted, this does seem a bit odd considering the equation for traction has no surface area component. When you’re dealing with two surfaces that interlock in the way carpet and roughtop tread do, the traditional model for evaluating traction doesn’t exactly apply. Regardless, we chose treads because we wanted that robot to be immovable, the benefit of climbing the ramp was an added bonus. Again, the complexity, maintenance and cost could not have been justified just for climbing when a much simpler solution could have sufficed.

So, I don’t have any groundbreaking suggestions for innovative stair climbing devices. However, I can say this: If you are going to go with a complex design like the ones discussed above, you better make sure the extreme design costs are justified by the game benefits. Typically the best way to justify these costs for a function is to make sure you get multiple points of utility out of them.

(And if you didn’t bother reading all of that, here’s the synopsis: Keep it simple!)