Commit 3e2cc054 authored by David Preiss's avatar David Preiss
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Update images/dyno/currentSweep.png, README.md, images/dyno/23HS30_2804S.png files

parent 3fb2f137
# Dynamometer
## Week 5 - 4/1/21
This week I took a first stab at one of the initial motivations for building the dynamometer, but that I've neglected so far. That is looking at stepper motor torque limits as we approach saturation and thermal limits for the motor. The plot below illustrates this by sweeping through increasing current chopping setpoints (remember that open loop stepper motors are driven as constant current devices). What we see is a surprisingly linear response in peak holding torque (keep in mind these tests are conducted at 0 rpm).
![currentSweep.png](./images/dyno/currentSweep.png)
[Here's a link to the stepper that I am testing.](https://www.omc-stepperonline.com/nema-23-bipolar-1-8deg-1-9nm-269oz-in-2-8a-3-2v-57x57x76mm-4-wires.html) It's one of the more commonly used NEMA23 steppers used for DIY applications, rated for 1.9Nm at 2800mA. Fortunately this lines up extremelyt well with our own tests! At 2500mA we acheive a peak torque of 195N*cm. Below is an image of stepperonline's speed torque curve (you can disregard the 36V vs 48V difference as this has minimal impact at 0 RPM).
![23HS30_2804S.png](./images/dyno/23HS30_2804S.png)
## Week 4 - 3/25/21
This week I focused on improving data analysis (see the nicely interpolated speed-torque curves below), speeding up test times, and slogging through the endless process of finding bugs and improving repeatability.
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