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Unread 08-06-2014, 17:40
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asid61 asid61 is offline
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AKA: Anand Rajamani
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Re: The in-wheel swerve shifter!

Quote:
Originally Posted by Chris is me View Post
It can't shift on the fly because even if the output direction doesn't change, reversing the CIM will still slow the drive down to zero and then go back up to speed. The motor has to fight the inertia of the drive system when reversing input direction, and this takes time at which point you aren't moving.
Like I said, the motor only fights against the drive shaft. That's just a couple miter gears, two 3" shafts, 2 sprockets and a gear. The CIM will instantly reverse unloaded, so even with the above it's not a lot of inertia.
That would be something that would be debugged and found in testing.

Quote:
Originally Posted by Jared View Post
This looks really cool. It looks like it could work well on a 2013 climber, where you'd want to deploy quickly, but raise the robot with lots of torque.

What happens if you're going slowly and somebody pushes your robot from behind? Instead of the wheels driving the motor to go faster, the dog will back out, but it won't engage with the other side because it's going the wrong way, so the dog will be bouncing off the two sides until you speed up the motor or reverse direction.
Interesting example. If a fast robot pushed you, the dog would instantly lock into the other gear, be it low or high. Then as you said, it would probably bounce around. I would want to test this too to see for myself the ramifications.
You would have to have code to debug this situation, probably with current sensors to see if the current gets too low, signifying a robot is pushing you. Then the cim would reverse direction.
In any case, then you could just shut down the cims if it continues (it would be a pretty obvious strategy) and you're going in the direction you want to anyway, but faster. So that situation would be useless for the other robot.

Last edited by asid61 : 08-06-2014 at 17:47.
 


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