According to DIN 19 225, controllers are divided according to their tasks and properties.
Designation according to tasks distinguishes
- between the type of the controlled variable, such as the location, speed, rotation speed control, etc. or
- controller function (synchroniser, limit value controller, amongst others) or
- reference variable (fixed value, sequence, master controllers, amongst others).
For designation according to properties, a distinction is made
- by order: 1st, 2nd order system, etc.,
- by signal form: analogue or digital controller,
- by construction: single loop controllers, cascade controllers, state controllers,
- by the degree of complexity: linear controllers, non-linear controllers, status monitors, adaptive controllers. (Figure R 21).
Figure R 21: Classification of controller types