I want to position-control an axis combining the action of two DC servomotors - one of them alone is not powerful enough; I had those available and preferred not to buy a new one.
I have not the possibility to measure the output axis position directly, so I must rely on the integrated position, speed or torque feedback control logic built in my actuators.
Long story short, the two motors will transmit power to the output axis through gears (a separate gearbox for each one).
Now I am approaching the design of the control system and I realized that using the built-in position-control logic for both actuators might not be a recommendable choice, the reason being that it will be practically impossible to calibrate them with the exact same zero reference, meaning that a small misalignment in the motors' output positions will arise, leaving during operation just a single one of them in actual contact with the respective geartrain, sustaining all the load, and the other unloaded.
The only alternative approach I can think about is the following one: to control one of the two motors (let's call it 1) in position, while controlling the other one (call it 2) in torque by feeding it, as setpoint, the torque corresponding to the current absorption measured on motor 1.
This way motor 2 should provide power until it reaches the same torque motor 1 is providing, thus sharing the load without introducing uncertainty on what position setpoint is being followed.
I would like to know if this approach could be likely to succeed, if there are some precedents and/or if there exists any better solution.