I have a basic question because I'm trying to understand right now a concept that I thought it was obvious. Looking at this video he is going to feedback the variable state x with the input of the system, which is a force f.
Now, if I'm correct it is only possibile to feedback variables which share the same units, so I expect to drive a meter through an input variable which is a meter and the difference will be then feed into the PID. Is the example in the video just to show up how to use simulink? Or I m wrong?