Machine automation is often equipped with hydraulic systems. In the hydraulic controls there is also a distinction between “Open Loop” and “Closed Loop”. An example of a typical “closed loop” control is a control with proportional hydraulic valve. The application area is usually on a position controlled tool with absolute positioning, for example in a punch or press unit.
The control circuit is very similar to a servo drive:
- Position control
- Amplifier
- Actuator
As position control we often use digital position controller of Bosch Rexroth, coupled to an absolute measuring device with SSI bus as feedback to the controller. Closed-loop position control.