1. Position control study

The subject is approached through a simplified approach to the calculation of a position servo with mechanical input and translational output (cylinder). This approach provides information on the response speed of the servo system, but does not allow us to predict the instability often encountered in practice.

The same servo is then studied again, taking into account the fluid's compressibility, using the classical linear method (Laplace transform); this method provides us with stability conditions. The results obtained are then extended to electrohydraulic and rotary motor position feedback.

The next two paragraphs are devoted to studying the influence of interface parameters (such as anchor stiffness) and component non-linearities (such as servo valve threshold), which are at the root of most of the tuning difficulties encountered in practice....