Quote:
Originally Posted by Cem8301
Can you explain this? Is there an equation we can use to determine how the the duty cycle determines the speed? Or would we just have to read one of those motor graph charts?
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At constant load, the speed varies approximately linearly with duty cycle.
The windage of a spinning wheel varies with speed, so the load is not constant. So the speed vs duty cycle is less linear.
You could do this empirically. Run different duty cycles and observe the effect of motor speed on your launch distance. Put the data in a table in your software.
The problem with that approach is that the voltage delivered to the motor at a given duty cycle varies with the bus (supply) voltage. If you are using CAN, you can use the "voltage" mode rather than the "%Vbus" mode, and it will compensate for changes in bus voltage.
Finally, you could put an encoder on your spinner and use rate feedback to control the speed.