Quote:
Originally Posted by jeremylee
Any basis for this conclusion? I was thinking without blue nitrile, this was a good starting point.
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It's a colson wheel, so the COF is only slightly lower than that of blue nitrile. A pushing match gets the cims up to 60+ amps acording to JVN design calc, so if the drive is really mired down, that's not good.
Quote:
Originally Posted by Bryce2471
Very cool! I was also planing on doing a belt shifting version of this as well. I have a couple questions though.
What is the second white pulley on the lower belt for?
Are you worried about it being cantilevered off of a single plate?
Why did you float the drive encoder in the air?
Is the steering encoder absolute?
If so, how do you plan on determining the exact angle of the caster with the gear ratio?
How do you plan on adjusting the belt tension if necessary?
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The second white pulley was for tensioning the larger/ lower belt, but I just updated the model and now instead am using a plain bearing to tension the lower belt.
The drive encoder is not floating. It's held in place by some standoffs on a Vex mounting plate.
The steering encoder is absolute. Although it's geared down, there are still ways to ensure that the angle it's reading is correct. I'm thinking of hooking up an XMOS or some other lightning fast microcontroller to keep track of the angles and rotations and make it seem like the encoder is directly on the module. Essentially, you count the rotations the encoder undergoes from the start of the match and add add the partial rotation the encoder is at presently, and apply the gear ratio to determine the "true angle" of the module. I could use some 3D printed gears in the empty space above the module instead, but that would add quite a bit of weight and complexity.
Belt tensioning is in two steps. The top pulley is tensioned via a sliding the cim, and the bottom one is tensioned by moving unconnected pulley in and out. The newer model uses a plan bearing instead of a pulley for this.
EDIT: The cantaliever on the drive plate is solved by adding a partial ring made of delrin aroud the main module. It's not in the picture, but it's there in the cad. It keeps the module from rocking around.