Hey! From lesson’s learned last year, or experience in general, has anyone dropped their robot on their swerve drive train (really interested in SDS)? Our team wants to prepare some spare parts for competitions, but don’t want to be wasteful with money or material.
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we dropped our bot from the bar last year onto mk3s and had no issues. i would guess it fell around 1.5 feet.
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did it land like a cat? or land on a single wheel?
Have you done any back-of-the-envelope force analysis? Figure out how much energy is in a falling robot from height h, then figure out what over timescale that energy needs to be dissipated in order for the parts not to see forces near their yield strength.
Sure, but as you noted you cannot assume that the energy is absorbed in 0.0 seconds or 0.0 inches of distance (impact of completely rigid objects) as the forces produced by such a theoretical impact would be infinite.
So, in order to do that back of the envelope analysis, you need to know a lot about two key links in the chain of the time and/or distance over which these forces are produced which are the carpet and the wheel tread. In addition, the robot itself is going to be reasonably flexible (compared to a perfectly rigid object) and will absorb a lot of that energy through elastic deformations such that the forces through the bearing of the swerve module are going to be significantly reduced. I’m just not sure that this back of the envelope calculation is going to provide much insight based on the level of unknowns involved.
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I figure:
If the timescale has to be on the order of 10ms, you’re probably fine.
If the timescale has to be on the order of 10s, you’re probably in trouble.
It gets fuzzy between those, but that’s still a three-order-of-magnitude window to work with. A lot better than nothing.
landed on the back 2 wheels first, then the front 2.
it might be important to point out our entire chassis is made with baltic birch laser cut and tabbed together, so it absorbed some of the impact through deformation of the chassis.
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that sounds fancy? pics?
Naive dimensional analysis gives a minimum timescale of ~5ms for a 1/8’’ square of 6061 aluminum to avoid yielding from the energy of a 2’ fall. The equivalent distance scale is about half an inch.
This seems…rather encouraging?
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