90 microseconds sampling and max motor speed


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    Default 90 microseconds sampling and max motor speed

    please explain to me. I have a yaskawa sgmah motor with a maximum speed of 3000 rpm and an encoder of 2048, which gives 8192 pulses per revolution. The KFLop sampling the axes every 90 microseconds, respectively, at this time 36 pulses pass. Does this mean I can not use the maximum speed otherwise the response of the KFlop will be delayed? I also noticed that at long distances and maximum speeds, the Kflop sometimes goes mad and does not stop at the end of the path and does not react to the end-of-track sensor . How can this be avoided?

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    Default Re: 90 microseconds sampling and max motor speed

    Although the servo sample/update time is 90uS, the encoders are connected to hardware encoder counters, which work at a far higher speed (up to the 1MHz limit, which is over 7300RPM for your motors)
    It's those counters that the servo loop reads every 90uS.

    What do you mean by goes mad?
    Have you implemented soft limits?



  3. #3
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    Default Re: 90 microseconds sampling and max motor speed

    Hi bouseman,

    As m_c describes the encoders can count up to 1 million quadrature counts/second without any delay or issue. But this assumes your encoder and cabling provides a clean signal at the encoder input.

    Regarding going "mad":You might check if the encoder is counting correctly. Regardless of what happens (as long as you don't exceed 7300 RPM) the encoder should always track the position correctly. This should be true even if you crash, axis goes unstable, disable, or anything. So if you zero the Encoder at some specific place then whenever you return to that place the count should be zero (or very close to zero). If it is not, then the encoder did not count correctly. What type of encoder do you have? Is it differential? How is it connected? How long is the cable? Do you have any termination?

    If you set a small following error then sudden loss of counts and such should trigger a following error and immediately disable the axis.

    What is your end-of-track signal? How is it interfaced? Is the Axis configured to monitor it in the Limits options?

    Regards

    TK
    http://dynomotion.com


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90 microseconds sampling and max motor speed

90 microseconds sampling and max motor speed