Linear Position when Arduino Started

Other Hardware Motors, Mechanics, Power and CNC
1

Sorry for this basic question, I've seen some good articles with various resources on this, but not touching on my overall basic question here.

I have an arduino with a adafruit motor controller running steppers but looking to move to operating linears due to my project requirement here.

Does an arduino know the linear's current location when it starts up? I think this is a basic question, but say I have 4 linears all at different spots from my last session using, can it retain or keep those positions when powered off and back on?

I was looking at saving positions and I think it depends on the linear used here perhaps? Actuonix L12-I Micro Linear Actuators With Internal Position Controller These seem like arduino compatible linears with position control and analog position output? Not sure if that is how they work.

2

If a linear actuator has position feedback (most often, an analog potentiometer), then the current extension can be read out at startup.

Many don't have feedback, other than limit switches which open the motor connection at either end of the travel. Often, that is all one needs.

There are a few actuators that behave like servos, and are Arduino compatible. But with those you can't read out the current extension, only set it.

3

That actuator works like a servo and has the same problem, the Arduino never knows where it is, only where it was sent on the last command. If you save the last commanded position in EEPROM before shutdown, then you can retrieve that position and set it on next startup.