Thank you, Max. Two follow up questions:
1) how is the "norm" determined? when door starts opening it probably draws very little current because the door is still vertical (relatively), as opposed to when it extends up towards horizontal position it would impose much heavier load to the motor. We would have a similar situation (canopy moves from horizontal to a vertical position) where the load/current will vary across the motion range.
2) Any suggestions about how to implement this? what the schematic may look like for this type of circuit and what components to use? I am relatively newbie at this and any guidance would help.
1) Torque = Current * k
Max torque = max current , occurs at start or braking stop = stall Current rating or "locked rotor " =5x~8x rated current
Motion induced back EMF voltage counteracts stall current
Rated voltage/ rated current = Zo. = 5~8x Coil Resistance which determines start/stop current peak.
2) motor sensing current shunts are chosen to drop very little voltage e.g. <100mV Max
Motor protected polyfuse PTC do the same and are cheap protection.
Normally current shunts with Differential amplifiers can be made or combined in an IC.
Normally current * time limit by timer is measured to detect a fault condition, so an RC value is typical method with a threshold to detect the criteria.
Recovery can be many choices, like toggle reverse door.
As always ,
write a spec with testable values before design is started to be part of your Design Verification Test (DVT) plan , point form is OK, but list as much as you expect in function and parameters. This is key to any good design, even DIY.