One really nice thing about this setup is that both motors are actively controlled by a single microcontroller, which is also performing all of the data collection. After a reset, the microcontroller waits for a computer to connect and open up serial communication (via a data collection script written in python), after which it will start the test and run it to completion autonomously. Then the data is written to a CSV and plots like the one above can be generated, all of which happens without user intervention.
It would be fair to say that those peak values are the only really useful bits of data generated here, but I would argue that given how frequently open loops steppers are used, there are valuable insights to be had below that interpolated line. For example, if driving an electric vehicle with an open loop stepper (not recommended), this data informs us about the power consumption headroom we have by switching to a closed loop system (you don't get to choose torque demand for some commutation speed when driving on a road). For a closed loop motor, this data becomes much more relevant, which will be a good future direction to take the project. Several things to note from looking at the graph above:
- All of the efficiencies at RPM = 0 are dark blue, or 0%. This makes sense considering we are doing 0 work at 0 RPM, and the product of (0 RPM x some torque = 0).
