[help needed] electronic DIY shock dyno

[kb1gtt]

For a low cost linear measurement, you could try digital calipers. They typically have a serial port out the top side.
https://www.aliexpress.com/item/200mm-8-Inch-Digital-Caliper-Electronic-Carbon-Fiber-Vernier-Gauge-LCD-Screen-Micrometer-Measuring-Tools/32868362949.html?spm=2114.search0204.8.77.79e32c57dZqF8h

Brief overview of the serial interface found here. It notes the 1.5V signal levels, so with the STM32, I think we are OK with our 3.3V supply. No need for those external level shifting transistors. Just wires between this and the STM32.
http://nut-bolt.nl/2012/reading-digital-calipers-with-an-arduino/

The above article references this article, which gets into more detail. I recall there were 2X different protocols for these. This one is the most common, but beware there is another one that could be obtained. AKA get the plastic that looks like these, not those other ones with more fancy looking plastic.
http://robocombo.blogspot.com/2010/12/using-tis-launchpad-to-interface.html

This trick also tends to work with these DRO devices.
https://www.aliexpress.com/item/shahe-0-150-mm-linear-scale-dro-remote-digital-readout-linear-scale/32826807324.html?spm=2114.search0204.8.5.456612d3s2qULN

[deezums]

I made a DIY dyno based off the Honda forum post a while back. I used a 1,000kg load cell and linear potentiometer from injection molding machines.

It more or less worked, matches up with what I would expect a stock miata bilstein to look like. I never actually tried changing any valves, or rebuilding any shocks.

If I recall, the HX711 was way too slow. I bought some dev board for a fancy Analog devices ADC and got it up and running at very high speed instead. Ringing doesn't much seem to be an issue, but slop in joints on changes of direction are, so I filter those results out.

Noise on the potentiometer was always an issue, I looked into LDVTs and some other encoders and more or less left it there.



And some data, sorry for the lack of units and wacky scaling and no visibility. Pretty sure the last two are the software's fault and not my own.

https://imgur.com/a/bTfKXoD

[AndreyB]

I made a DIY dyno based off the Honda forum post a while back.

where are you located?!

[deezums]

Near the middle of Kansas, more or less.

[AndreyB]

Near the middle of Kansas, more or less.

Important thing we are in the same country Can I please borrow it from you in 2022?

[deezums]

Haha, not a problem! I probably won't build my own set of shocks before then anyway.

Just as a fair warning, it's a bit of a workout!