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#1
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Re: Hypothetical Situation - Stairs
1. The wheels you speak of are probably the 8" AndyMark wheels, either the FIRST, FIRST slick, Plaction, etc. and the 8" IFI wheels
2. The IFI wheels use the same tread as the AndyMark Plaction wheels (Actually, they can use either, the difference is minor between wedgetop and roughtop, and you can get both from AndyMark or IFI, but the Roughtop tends to have more usable life). 3. Why not just use 8 Plaction wheels (or other wheels with roughtop tread) in a dropped center 8wd? |
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#2
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Also, keep in mind, that you could modify some snowmobile treads. Team 1091 did that, last season, and we had some excellent success with traction and manueverability. We could easily navigate over the bumps, and by gearing down, we lost some speed, but we weren't pushed around.
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#3
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Re: Hypothetical Situation - Stairs
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#4
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Re: Hypothetical Situation - Stairs
I have a question: what kind of legal servos are able to support a 100+ lb robot? Would pneumatics or other parts be necessary to support such a robot?
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#6
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Re: Hypothetical Situation - Stairs
I don't understand your question. What kind of application are you using to use them in? Which robot are you referring to?
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#7
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Re: Hypothetical Situation - Stairs
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ANY If you gear it enough But id be faster if you used a more powerful motor such as a CIM or Fisher-Price. |
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#8
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Re: Hypothetical Situation - Stairs
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You could use a ratchet device to support the robot most of the time, only releasing it when you want to change postion. |
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#9
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Re: Hypothetical Situation - Stairs
Or a worm gear. That would probably provide all of the reduction you would need.
I would probably mix a pair of encoders, a gyro (maybe) and an inclinometer. The encoders would determine wheel speed and distance, the gyro would (as usual) determine rotational velocity (Although you might have to do some stuff to keep it sensing correctly, or just use it when in a known orientation), and the inclinometer would detect the ground. An accelerometer *might* work but would be affected by the robot's forward velocity. A weight on a pot would work as well, but would have weight to it (and weight is always a bad thing). David - about servos - They are weak motors with built-in logic to steer to a certain position, and work the same as a motor, Victor, and pot. Except they are weak. With a CIM or Fisher-Price as the motor, you have significantly more power, which with gearing means you can drive whatever load you must drive faster. Any motor can move the load, but a more powerful (not necessarily a higher/lower free speed or stall torque, but output power, measured in Watts) motor can perform the task faster. |
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#10
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Re: Hypothetical Situation - Stairs
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http://www.chiefdelphi.com/forums/sh...94&postcount=5 My the end of the season we had the belt trapped so it couldn't find a way to slide off. Unfortunately this really cut down our efficiency so our robot was slower than we hoped. Definitely not an ideal situation. |
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#11
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Re: Hypothetical Situation - Stairs
In 2004 we happened upon a simple, robust, and fast method for climbing the stair. We put drop down ramps made of UHMW plastic on the front of the robot and had 4 large knobby pneumatic tires. The ramps would start the match folded up and would drop down and latch into place, giving the front face of the robot a sloped leading edge that would be just above the top of the step, sort of like an amphibious car.
To climb the stair the driver would simple turn the robot to face the stair and apply throttle. The ramps would lift the nose and when the front tire hit the stair’s edge it would climb onto it. Because the robot would high center between the wheels, we put UHMW plastic strips on the frame so we could glide across until the rear wheels would engage. To get down from the platform we would just drive off and bounce a bit. It was not a finesse move and required the robot to tip about 30-45 degrees, so you needed a relatively low CG. I don’t think we ever tried, but I think we could have climbed multiple stairs if there was a good edge to bite into like in 2004. This method served us very well and was very KISS, perhaps the KISSiest Jay |
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#12
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Re: Hypothetical Situation - Stairs
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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. |
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#13
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Re: Hypothetical Situation - Stairs
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#14
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Re: Hypothetical Situation - Stairs
I'd probably approach the 6" stairs with a tank tread design as well. Perhaps only to climb - wheels could provide the regular movement.
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#15
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Re: Hypothetical Situation - Stairs
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... |
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