I a modelling an actuator which works in the following way: a leadscrew and a spring are connected in series. The input is a motor torque which makes the nut translate on the leadscrew, which pushes the spring where a force sensor is implemented. Another input is at the other end of the spring, where a user can input a force which compresses the spring and increases the force. The actuator is force controlled. I would like to have some insight on what I have done until now, and how to proceed from here on, as I would like to implement the friction component which I have extracted from the real actuator during data collection.