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#16
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Re: Need help programming our swerve with feedback?
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#17
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Re: Need help programming our swerve with feedback?
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At Silicon Valley, we found our potentiometer working fine, but instead, our speed was messed up, and often our wheels were going in the wrong direction entirely. Obviously, this was not good, and we ended up reverting to simple manual drive. Thanks for all the help everyone. Last edited by Grommit : 08-04-2004 at 21:35. |
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#18
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if you want some real help keep in contact with my team team 1011 team crush. we used swerve this is our second year and we made it to the semi finals but i would say look for brian on team 1011 or eric on team 1011 or korbin on team 1011
good luck at nats niick brown ![]() |
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#19
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Re: Need help programming our swerve with feedback?
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. I will post the documentation about the drive and code soon. thanks again |
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#20
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Re: Need help programming our swerve with feedback?
the documentation and code is really long, so there will be a link soon on monta vista's website: www.mvrt.com. id like to thank everyone again for his or her help. the swerve was working perfectly by the end of friday, so we were swerving on saturday and in finals. the speed function wasnt working because i was trying to use the greater of |p1_x | and |p1_y| so the robot would move the fastest sideways and straight. however, near 45 degrees the handoff wasnt smooth. anywas, check out the website if u are interested, or email me at rebecca@mvrt.com. thanks
rebecca electrical officer mvrt 115 |
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#21
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Re: Need help programming our swerve with feedback?
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about the set point. The oscillation is a natural consequence of the linear force, much in the same manner that a mass bounces back and forth when suspended by a spring. You can reduce the finickyness by adding a damping term that operates much as a shock does on a car. This is done by adding a force that is proportional to, in this case the rotational, velocity and in opposition to the travel. This is easily done in he code by remembering the arm position from the prior poll with the computer, or interrupt as the case may be, and subtracting the current value. If you do this, you will find that you can increase the constant of proportionality for power to the drive motor, tightening up control, while preventing oscillation. There is a value for the damping, referred to as critically damped in physics terms if I remember correctly, that is somewhat magic in behavior. We used this form of damping on 1280s arm at the SanJose regional, and it was quite effective... |
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#22
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Re: Need help programming our swerve with feedback?
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If you were at SVR you probably saw our arm. A lot of programming went into keeping that monster controllable. |
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#23
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Re: Need help programming our swerve with feedback?
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http://hyperphysics.phy-astr.gsu.edu/hbase/oscda.html by using an electrical damping term, not depending on mechanical damping, you can get improved speed and control, subject to any slop in the mechanism, of course. |
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#24
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Re: Need help programming our swerve with feedback?
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We had a setup like the one I think you're describing. We did:-Pot hooked to motor -Operator set target w/ another pot -use absdif (a function I wrote and used quite frequently) to find the difference between pot and target -if difference < variance then stop the arm -if pot < target then go up/out -if pot > target then go down/in no scaling velocities, remembering values, just find the diference and point it in the right direction. |
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#25
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Re: Need help programming our swerve with feedback?
That would work, but only on a very basic level. If your motor value is too high you'll overshoot and oscillate, if it's too low, you will be really really slow, and any impediment (or heavier arm, do you carry the yellow balls around?) will stop it from working. For an arm like ours where we don't know what the torque on it is going to be, or whether its going to have a ball or not, a control system that can handle all the different situations by itself is much more important.
Last edited by 10intheCrunch : 12-04-2004 at 13:49. |
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#26
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Re: Need help programming our swerve with feedback?
We solved the problem by having a dial for speed.
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