Among the numerous possible controller functions for constant those involving basic transfer elements (transfer elements) are the broadest. These include:
- P-controller [P-controller]: Each control difference (control deviation) is allocated a certain value of the correcting variable.
- I-controller [I-controller]: Each control difference is allocated a certain correcting speed. The change of the correcting variable is therefore the time integral of the control difference.
- D-controller [D-controller]: Each change speed of the control difference is allocated a certain value of the correcting variable.
- PI-controller [PI-controller]: The correcting variable is equal to the sum of the output variables of a P-controller and an I-controller.
- PD-controller [PD-controller]: The correcting variable is equal to the sum of the output variables of a P-controller and a D-controller.
- PID-controller [PID-controller]: The correcting variable is equal to the sum of the output variables of a P-controller, I-controller and a D-controller.
- P-T1-controller [PT1-controller]: P-controller with
- P-T2-controller [PT2-controller]: P-controller with 2nd order time delay.
These controllers work consistently in a single loop and are not sufficient for higher demands in terms of . Therefore, in electro-hydraulic control technology, they are enhanced by secondary minor loops for cascaded (multi loop) control systems or state controllers, which can lead to considerably more efficient drive characteristics (Figure R 22).
Figure R 22: Comparison of the drive characteristics of different controller concepts