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Originally Posted by Sam Skoglund
Thank you so much for the detailed feedback Cothron Theiss! I will talk about your topics one by one here. If you or anyone else could answer some more questions I have that would be great!
Speed: Our team has a history of building speedy drivetrains, so my view of an "average" speed is most likely skewed. If you think that I have geared it too fast, what speeds would you recommend?
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Nope, your speeds are fine. 15 ft/s is fine if you're viewing it as a high gear. 20 ft/s is getting a little risky.
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Cylinder Actuation: I agree fully that I need to revise the attachment of the cylinders to the wheel modules. Mounting them as you suggested seems like the best option. Would it work to keep them mounted as they are and connect them to the wheel module plates with a small linkage that pivots on both contact points?
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If you can make it work, it'll work. Not meaning to be asinine, but you'll just have to play around with the design and see. One issue you might run into with using a linkage like you described is making sure the distances are always the exact same. You wouldn't want to increase the pressure of your cylinders and have the height change.
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Hex Shaft Collars and Sprockets: My team is addicted to these. I may eliminate some and opt for threaded shafts, but only if it means easier production and or a better final product. Price is not a factor, as we already own well over 32 of these! The extra sprockets are there because we already own that many and if one strips, the chains could be rearranged to new sprockets without disassembling the entire gearbox.
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Yup, I understand that. I've used a gear as a spacer just because it's what I had on hand and because Week 6 is insanity. But 80 pounds for a drivetrain is WAY too much in my opinion, so I'd be looking for any and every way to cut down on weight that you can. Also, a screw and washer is a more robust solution in many situations.
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Strafing Wheel: In terms of a pushing match, I don't think it would be a bad thing to have the strafing wheel constantly pushing on the ground. The talons controlling the strafing motors could be programmed to enter brake mode whenever the drivetrain is in traction mode, so that when hit from the side, the strafing wheel would act as a brake or could even be driven to push back slightly. I think the actuation would be something to consider if the field is uneven.
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Yup, it's probably a bad thing to have the strafing wheel exerting force against the ground. Driving the strafing wheel or setting its controller to brake mode will only help when you're being pushed from the side, and you aren't going to win any pushing matches with just one wheel. You'll want to evade and outmaneuver in that situation, not push. If you're being pushed from the front, you'll most likely lose.
Any force your strafing wheel exerts on the ground is weight not being translated into normal force onto your driving wheels. The normal force on the driving wheels and the co-efficient of friction between your driving wheels and the carpet are the two major factors of how much traction you have. If you want to win pushing matches, you need to maximize those two factors.
Chassis: I assumed that the sheet metal bottom would provide enough rigidity, is this not correct?
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Battery: Yes that is the battery. The routing of the battery wires, motor wires, and pneumatic tubing is something I have actually planned out. The battery cables will rest above the strafing module to reach the PDP. There is enough room between the strafing module and the upper sheet metal panel to do this. The pneumatic tubing and motor wires will route through a hole in the main tubing and through the drive chains (will have to protect the from shredding) to get to the electronics.
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Good on you.