I started wondering if car door lock actuators would be a possibility in projects requiring a linear actuator. They are cheap and plentiful.... there must be a catch!
There are probably a few hundred others on the forum who have already done it, so I hope for an answer to the following:
Are they all just "a DC motor and some gears" or are there more complex systems like "real" linear motors? Some have just two wires, other have quite a few, indicating sensors of some sort.
Are there any "servo like properties" to them, IE is there some sort of position control, or does the car's electronics just power it for long enough to be sure it has done it's thing.
If it is "powered for long enough" with no other control, is the motor then just stalled in the end position, or can it free wheel at the end of the stroke?
Are they only good for a few actuations and then need time to cool off, or can they be operated continuously with a moderate load?
Apart from using them in the regular door mode to pull or release a latch, I like the idea of a rowing boat robot.
Hi Peter_I, did you have any luck with your questions about the actuator? I have the same questions. Is it ok to leave them powered at the end stops? Do they need to cool? Did you drive them with 12V or less?
No it is not OK to drive them hard into the stops for unlimited time. The control circuitry in the car applies 12V to the door locks for only a second, or less. If you do it for longer, they will probably overheat. I think they may even have a limit of 60 actuations in 1 minute must be followed by 5 minutes rest. Datasheets for this must exist but they probably aren't available to you unless your surname is "Ford."
I have had some luck adding feedback to the door locks from Jaycar. The 'master' lock has simple switches on it to detect full travel. The slave door locks can fit a 50mm linear potentiometer inside for analog feedback and total proportional control.
