[OCCRA]: OCCRA 2010 VEX Workshop OSTC-NE 06Oct10

Competition OCCRA
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Here are some updated presentations that were given at the OCCRA 2010 VEX Workshop held at Oakland Schools Technical Campus - NE on October 06, 2010.

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Here are some updated instructions on how to update the Firmware into the new, VEX Cortex, microcontroller and joystick.
The IFI Firmware update is run from outside the EasyC V4 Cortex programming environment

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  1. I wasn’t at the workshop this year. I went last year, and assumed I was good.

  2. I read the PDF’s you posted. You did some math on speed and torque. JVN has a really really nice design spreadsheet for rotary mechanisms (See JVN’s Design Calculator http://www.chiefdelphi.com/media/papers/2059). I first calculated the aprox. needed gear ratios by hand, and punched them into the calculator. I assumed the weight of the mechanism was neutral because of counterforce (notice I didn’t say counterweight?) and the motor would only have to drive the ball. I over-estimated the arm length since I hadn’t actually built it yet, and it said with a BIG motor (which does around 17 n-m of torque, BTW, the JVN calc needs numbers in n-m’s). It said it would work quite well, and gave me the loaded output speed and motor current draw. I built it. It works well. The numbers say I can go a little bit faster, but then it would be uncontrollably fast (And I am trying to do the feedback with only P if possible, but I might need D).

Just a friendly reminder to OCCRA teams: Do the math! Just because a mechanism is large does not mean it will move slowly! With bungee you can do it easily!