The mention of rotary encoders made me think of the optical rotary encoder in the trackball I use. I don't know how many pulses per revolution it produces but it is driven from the trackball through a high ratio friction drive. I think the same mechanism is, or used to be in some mice. There is very little friction in the trackball....R
Not while it's moving/flying.
BTW the aircraft in question is technically a 'model' aircraft, but it has a 30 meter wingspan (about 90ft if you're american) and weighs 35kg
You get a lot of atmosphere induced accelerations in a Boeing 747
We used LVDTs at the refinery I worked at prior to retirement. The largest covered a 12" stroke on a large hydraulically controlled 56" butterfly control value under PID control. They can be made to work very accurately but for long strokes it's difficult/complex/expensive to compensate for ambient thermo changes and effects. But given the proper electronic support circuitry a LVDT can give very good accuracy and reliability, but being a limited/specialty market I've never seen hobbyist affordable offerings.
But what you don't know is has it moved from 5 degrees to 5 and a half degrees, or from 70 degrees to 70 and a half.also, they're not particularly cheap.
QuoteYou get a lot of atmosphere induced accelerations in a Boeing 747Yea, at 950km/h speed and against 300km/h jet stream..
Another idea for a high accuracy low friction method would be to use something like this or this they both use non contact measurement so should be low friction and I don't think there is much magnetic drag.
What's the best way to measure very small mechanical movements very accurately?I'd like to make an instrument to measure the angle of attack that a planes wing makes with the air. Mechanically it's very simple, I attach a freely rotating vane to the front of the aircraft and measure the angle this vanes makes relative to the airflow.
Option three - same as option two but using hall switches instead. Disadvantages - all the same disadvantages as for option 2, and costs a lot more.