2. Study of force feedback

The number of applications for force feedback is increasing. We shall confine ourselves here to proposing a few general ideas drawn from recent studies and experiments with such equipment.

First of all, and considering only electrohydraulic servo-controls, we need to distinguish two main families of force servo-controls:

• pressure servo valve drives, i.e. servo valves whose internal arrangement is such that an electrical input command corresponds to a pressure in the output line 4