I have a linear ball screw control by a simple stepper motor. Mounted on the platform of the linear ball screw is a mechanism to grip a small wire. At one end of the ball screw there is another mounted grip that remains stationary. The stationary grip is attached to a load cell so that as the mobile grip moves backward, the wire pulls on the stationary grip and the load is measured. I need to control this motor so that there remains a constant load on the load cell. Basically, I need to speed up/slow down the screw if the load drops below or rises above a certain value input by the user. My motor has a "velocity mode" so that the speed can be changed on the fly. Any thoughts on how to do this? The system cannot easily be modeled by control theory because there are too many unknowns.
Matt is correct, we definitely need to know what hardware we're dealing with, as well as what software you have (LabVIEW version, NI-Motion version would be good).
Doesn't sound like it's impossible to do with control theory. You need a model of your system and your feedback could be the force which you can convert into control signals to the motor.
