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#16
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Re: H-Drive Strafing issues
We also used a pneumatic cylinder as a "spring" on our H-drive setup in 2015. We put the cylinder on its own air circuit and tuned the pressure to the point where we got the max down-force without lifting the "normal" wheels too much. ("too much" being a technical term meaning the point where things don't work correctly
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#17
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Re: H-Drive Strafing issues
What chassis did you use?
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#18
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Re: H-Drive Strafing issues
We've modified and built atop the AM14U2 for three years (2015-2017). Does it matter?
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#19
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Re: H-Drive Strafing issues
What we did in 2015 is have 2 pneumatic pistons on either side of axle, to push down when needed with a single trigger pull.
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#20
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Re: H-Drive Strafing issues
I think it might.... we are using Vex, so it may be more reliable (since it is a kit)
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#21
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Re: H-Drive Strafing issues
We used a copy of 148's design in 2015. https://www.youtube.com/watch?v=uL-NnuZzOkU It is the easiest way to accomplish H drive... - no springs, no pneumatics, no extra controls, and it accommodates changes in floor height seamlessly. I wish I had invented it.
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#22
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Re: H-Drive Strafing issues
Quote:
I don't get your gist. OBTW, the AM14U2/3 is also a kit. Possibly not germane, but our off-season pneumatic strafe had a number of variables really screwed up because we were using what we had vice what was best for the application, but it worked first try. Barring further findings, I cannot and will not recommend anything other than some definite control over the applied force of the strafe wheel to the carpet, whether spring or pneumatics or synthetic muscle or cosmic pressure. Last edited by GeeTwo : 08-02-2017 at 22:47. |
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#23
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Re: H-Drive Strafing issues
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At this point, though, if you want to delay it further, then continue to deliberate. But you've only got a couple weeks left, and if you want this thing driving well by the end of build, you're going to need to either order the parts you need very quickly and get it done, or just switch to a basic 2+2 or 6-wheel tank drive. |
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#24
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Re: H-Drive Strafing issues
Quote:
https://content.vexrobotics.com/vexp...-top-trans.png And andymark has a H drive kit?? |
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#25
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Re: H-Drive Strafing issues
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Anyways, you'll probably want to use that Robowranglers method of actuating the strafing wheels. Or switch to a tank drive. Given that you have your wheels in the corners, a 2+2 (2 traction in front, 2 omni in back) would probably work alright. |
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#26
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Re: H-Drive Strafing issues
It is possible to make a ridged mounted H-Drive work, but not work well.
In 2015 we gave H-Drive a try without realizing the need for the center wheel to be articulated, by the time we were done we had offset the center wheel 1/16"-1/8" below all the other wheels on the robot, this resulted in some very odd rocking in the chassis and the strafe only worked about 75% of the time (because the carpet floors are never perfectly flat). It wasn't accurate enough to use during autonomous, but driving it manually it worked ok. If I had to build an H-Drive again though I would definitely put it on a suspension. |
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#27
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Re: H-Drive Strafing issues
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Getting the strafe wheel at the same height as the other four is NOT what you need. Even when we had about 1/16" of a drop on ours relative to the corners, it did not provide enough traction to move the robot well. By the time we got the drop deep enough to produce consistent strafing, we had problems driving in forward and reverse. There just is no right height for a rigid mount. |
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#28
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Re: H-Drive Strafing issues
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All in all I would definitely take a look at 148's robots both their 2010 and 2014 strafe wheel assemblies. |
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#29
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Re: H-Drive Strafing issues
I hate to go off topic, but in all seriousness how did this drive not self-destruct immediately? We've used solid 3/8" polycarbonate plates for our drive system for several years and it barely holds up (it tends to crack a lot). We keep using it because of the weight savings but we have to be very careful with it.
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#30
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Re: H-Drive Strafing issues
Quote:
Quote:
Last edited by GeeTwo : 09-02-2017 at 10:17. Reason: Moved equation up, added link. |
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