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#16
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Re: 2809 - Traction Control Demo
that robot looks a whole lot better than my team's rookie bot
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#17
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Re: 2809 - Traction Control Demo
Does your ystem work for acceleration as well, or just shoving? It would be nice to see a comparison of acceleration with and without TC. The pushing thing--it looks nice, but have you collected more empirical data than "he stumbles back more with traction control on"?
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#18
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Re: 2809 - Traction Control Demo
Really impressive - I'm really looking forward to watching these bots in action! In what language did you implement the traction code?
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#19
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Re: 2809 - Traction Control Demo
Quote:
Not sure why you'd need encoders with that setup... hmmm.... perhaps rather than measuring current, you are measuring voltage across the motors and comparing it to motor speed. It looks like Ontario has spawned another great team. Good luck at Hershey Centre, GTR is a great tournament. Jason |
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#20
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Re: 2809 - Traction Control Demo
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#21
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Re: 2809 - Traction Control Demo
Yep, the robot is just pushing, and will even compensate when you push back on it. The issue we found is that once you start slipping, it's really easy to move you around.
Hopefully we can get another video up when we test on the playing surface tomorrow. |
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#22
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Re: 2809 - Traction Control Demo
Quote:
My only other idea would be attaching a free-swinging pendulum to the robot. An encoder or Gyro attached to the axel of this device could then be used exactly the same as an accelerometer but without the noise. This does seem like a lot of work though. Does anyone else have a simpler solution to detecting speed? |
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#23
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Re: 2809 - Traction Control Demo
Quote:
I assume 2809 is probably doing what we're doing this year. More details to come on Monday (if it works). |
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#24
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Re: 2809 - Traction Control Demo
Quote:
I don't know if this is how you are doing it, I am guessing, but that is what we are doing. |
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#25
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Re: 2809 - Traction Control Demo
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#26
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Re: 2809 - Traction Control Demo
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#27
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Re: 2809 - Traction Control Demo
Quote:
Anyway, it turns out the torque a DC motor produces is related only to the voltage (effective) you are sending it and the rpm of the motor. We measure the rpm of the motor with the encoder, plug that into the equation, and get back the maximum voltage we can send without causing enough torque to slip. The beauty of the system is that it involves no PID loops, no tuning, no trial-and-error. We have about 15 measureable constants and 2 measureable variables (battery voltage and motor rpm), but nothing needs to be manually tuned. Yay for physics. |
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#28
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Re: 2809 - Traction Control Demo
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#29
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Re: 2809 - Traction Control Demo
Quote:
And no PID? Are you just doing direct drive with a variable cap? (To hold the torque.) |
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#30
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Re: 2809 - Traction Control Demo
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We found follower wheels to be the optimal solution. It may not have the best results, but its a simple system thats easy to integrate and works good enough. |
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