Compliant mechanisms

Have some feature requests, feedback, cool stuff to share, or want to know where FreeCAD is going? This is the place.
Forum rules
Be nice to others! Read the FreeCAD code of conduct!
cox
Posts: 963
Joined: Wed Nov 26, 2014 11:37 pm

Compliant mechanisms

Postby cox » Sat Mar 30, 2019 10:49 am

I found this interesting, and thought it might be for others on here.

https://www.youtube.com/watch?v=97t7Xj_iBv0
Need help? Feel free to ask, but please read the guidelines first
User avatar
DeepSOIC
Posts: 6871
Joined: Fri Aug 29, 2014 12:45 am
Location: Saint-Petersburg, Russia

Re: Compliant mechanisms

Postby DeepSOIC » Sat Mar 30, 2019 12:04 pm

One of the most fascinating compliant mechanism I ever touched was one in a precision balance.
It's a lever system, probably EDM-machined from a single block of ?bronze?.
WP_20141224_22_06_25_Pro_reduce.jpg
WP_20141224_22_06_25_Pro_reduce.jpg (553.25 KiB) Viewed 227 times
balance closeup.jpg
balance closeup.jpg (584 KiB) Viewed 227 times
mlampert
Posts: 1277
Joined: Fri Sep 16, 2016 9:28 pm

Re: Compliant mechanisms

Postby mlampert » Sat Mar 30, 2019 5:21 pm

Came across compliant mechanisms a few weeks ago and am massively fascinated by them. Would you know how this balancer works?
User avatar
DeepSOIC
Posts: 6871
Joined: Fri Aug 29, 2014 12:45 am
Location: Saint-Petersburg, Russia

Re: Compliant mechanisms

Postby DeepSOIC » Sat Mar 30, 2019 5:47 pm

mlampert wrote:
Sat Mar 30, 2019 5:21 pm
Would you know how this balancer works?
Of course I do.

Here's a crude animation of the lever movement.
balance-compliant-lever.gif
balance-compliant-lever.gif (372.24 KiB) Viewed 194 times
The weight to be weighed is put onto the slowly moving group on the right. There is a voice coil motor on the end of the long lever (on the left side). And an optical position sensor. The motor and the sensor are tied in a feedback loop, so the lever never moves (the motor compensates the force created by weight being measured). ADC samples the current flowing through the motor, and converts it into a displayed value.
mlampert
Posts: 1277
Joined: Fri Sep 16, 2016 9:28 pm

Re: Compliant mechanisms

Postby mlampert » Sat Mar 30, 2019 6:53 pm

Awesome - thanks a lot!