• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 82 subscribers
  • Views 1046 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CCS/LAUNCHXL-F28069M: how to calculate the speed from angle theta of sine cosine resolver?

SHAMEER N
Intellectual 280 points

Part Number: LAUNCHXL-F28069M
Other Parts Discussed in Thread: CONTROLSUITE

Tool/software: Code Composer Studio

Hi,

I have a resolver in my motor,the output of the resolver is sine and cosine waveform.I have calculated the angle using arctan function.How can I measure the speed from these two inputs?

I found speed fr module in controlSUITE\libs\app_libs\motor_control\math_blocks. But I am not able to understand the full logic behind the speed calculation.How can i measure the speed from angle input??

Thank you in advance.

Shameer

  • 0
    TI__Mastermind 27200 points

    Hi Shameer,

    I'm assuming you have a resolver, as opposed to a "sincos" transducer.

    In order to compute shaft speed you will need to introduce time into the calculation.  The TI resolver library does this using a pair of data structures in which sample time is a user parameter.  The result is stored in an element in the "RESOLVER_OUTPUT" data structure ("rpsObs").

    If you're not using the resolver library, you could simply take the difference between two consecutive angle measurements.  This is what the "speed_fr" function is doing, except that it applies a low-pass filter to the result.

    If you are actually using a sincos transducer, there is a separate library but it does not deliver speed information.  In that case you would need to compare two angle measurements as above, or extract the speed information from the QEP.

    Please let me know if this doesn't completely answer your question.

    Regards,

    Richard