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Unread 10-11-2018, 08:48 PM
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Sudden movements at the start of autonomous

When we are testing autos, sometimes when we enable, our robot shows some sporadic movements in some of its subsystems (our elevator lift is one of them). It seems like it is trying to finish a previous command given in the previous auto test run. It does these odd motions then goes back to intended position and runs the correct auto movements. Has anyone had this problem or maybe a solution?
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Unread 10-11-2018, 09:23 PM
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Re: Sudden movements at the start of autonomous

It is hard to diagnose these sort of issues without seeing your code? Do you have a copy online? A github repo perhaps?
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Unread 10-12-2018, 12:30 AM
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Re: Sudden movements at the start of autonomous

We have had this happen due to there being an aluminum chip in the Rio where our elevator encoder plugged in causing a short. Upon enable, the elevator would shoot up and then pull it's self back down.
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Unread 10-12-2018, 12:33 AM
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Re: Sudden movements at the start of autonomous

This can also happen if you are not commanding anything during disabled mode. The FPGA latches the last PWM output values, and they enable before the first iteration of robot code after enable. So its likely your robot is using the last value when enabled, which causes the jumps. This is one of the reasons I always recommend actually setting motors to 0 explicitly when disabled.
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Unread 10-12-2018, 08:34 AM
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Re: Sudden movements at the start of autonomous

We had an issue where we would run our autonomous routine, then disable it at some point. Since we weren't resetting our encoder counters and the position the elevator was supposed to go to, when we immediately tried our autonomous routine again it would try to go back to that position. I'm not sure if we solved it by resetting the values in the disabled init routine or the autonomous init routine.
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Unread 10-12-2018, 02:05 PM
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Re: Sudden movements at the start of autonomous

Thank you all for your help. I set the motors to 0 during disabled mode and that works now.
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