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Topic: Need help timing two servos (linear actuators) 25 bucks! (Read 1 time) previous topic - next topic

ajohri

I'm driving two actuonix PQ12-R linear actuators with an Uno board and I can't get the timing down so I thought I'd put it up on the Gigs forum.

Pseudo code:

actuator 1 extends to 180 degrees
shortly after 1 begins its stroke, actuator 2 gets sent to 180 degrees (full stroke)
right after actuator 1 extends all the way, it retracts to ~150 degrees
shortly after actuator 1 begins retraction, actuator 2 hits its full stroke of 180 degrees
actuator 2 now begins to retract while actuator 1 is being driven to 180 degrees again
...
so on and so forth.

The actuators are mounted perpendicular to each other (as pictured), so the desired result produces a 2 axis rotation once the actuators are in sync. Please follow up with any questions or anything I was unclear about. This is my first time on this forum so I'm not sure how gigs work, but I'm sure we'll figure it out.


cedarlakeinstruments

While it's a nice idea to state what your budget is, many providers on this site have minimum charges in excess of $25. Just something to be aware of if you don't get any takers.

Anyway, what you need may not work very well unless you can put sensors on the actuators. That's because the feedback on RC servos is internal, so the controlling program has no idea when it gets to the end of travel.
However, if you're going to put an external sensor on the actuator, you may as well close the control loop in software yourself.

Without that, we have to rely on timing. Timing can work but there can be lags between one motor ending and the other one starting so depending on how tight you want that timing to be, you may or may not be disappointed.
Electronics and firmware/software design and assistance. No project too small


DH12043

Do you have a button or a sensor of sorts like a hull effect or encoder of some sort that could be used for this? It is important to know what we have to work with when writing a program.

 -- DH

justone

Quote
so the desired result produces a 2 axis rotation
What is a 2 axis rotation?

WOW, $70 apiece for those actuators!

I can't see how this will cause any kind of rotation.

Any kind of animation or a series of simple drawings to illustrate this process?


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