Quote:
Originally Posted by craigboez
Care to share your calculations? And how do you determine the magnitude of the load you'll expect to see at a corner wheel?
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It was quick and dirty, but here's what I did:
A worst case scenario of running into a robot at full speed with a high COG could lift the back 4 wheels off the ground. I chose this as starting point. Assuming a full weight robot with bumpers and a battery (~150lbs), that means we've got about 75lbs on each of the two wheels still contacting the ground.
I happen to be designing a
very similar drivetrain, so I took my most cantilevered wheel and did my analysis on that. My colsons are cantilevered such that there's a 1 inch gap. I then threw all of this into SolidWorks SimulationExpress and came up with a minimum factor of safety of 3.074 right next to the bearing where you'd expect them the shaft to shear.
The above was done with 7075-T6 Aluminum. If a FoS of 3 still leaves you uncomfortable, you could easily go with steel shafts and never have to worry about them breaking.
Quote:
Originally Posted by craigboez
Another aspect of this design that is still TBD is the way the bumpers integrate. I'd like to incorporate a latch like 971 and 254 and Spectrum have shown. The Skunks posted another variation of this a few days ago using a different type of latch. Making a solid connection on the "wing" area is my biggest concern. Any good ideas on this?
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I followed the 971 method of bumper attachment, though it's not 100% fleshed out yet. The important part is to have a well constructed, single piece bumper.
Here's what I have so far.