State control
A state control is a control loop that controls the controlled variable based on the state space representation . In this case - in contrast to traditional regulation - not (only) the controlled variable is returned , but (also) the internal state of the controlled system (in terms of state variables ). This is why the method is also called control through state feedback .
Multi-loop state controllers are widely used. Several state variables are fed back, each resulting from the integration of the previous state variable. An example of this is the position control of a cylinder drive, in which not only the position of the cylinder piston is fed back, but also the speed and acceleration, from which the position results from (twice) integration.
The prerequisite for the use of a state controller is that the system can be controlled . A popular method in connection with state controllers is the pole specification .
application
State controls are used in systems for which a calculation of the controller in the frequency domain cannot be used or only with difficulty. These are primarily non-linear systems (which can not or can only be linearized with difficulty around operating points ) and time-variant systems, as well as multi-variable systems . State controls are mainly used when fast controls with high control quality are required.
Determination of the state variables
The feedback , which forms the control loop together with the controlled system, takes place in the state control via a measuring device and the actual state controller. The latter is also called the feedback matrix. That is why a state controller is always a proportional controller .
Because the measurement of state variables is very complex (and therefore expensive) or even technically impossible, the measuring device is often replaced in practice by an observer who tries to follow the controlled system. Analogous to the controlled system, the observer consists of an observer-state differential equation , an observer output equation and the observation vector . The output of the observer is compared with the output of the controlled system; the difference acts on the observer-state-DGL via the observation vector.
See also
- State space representation #Regelung_im_Zustandsraum
- Controller #State controller
- Control system #Control system in the state space
literature
- Holger Lutz, Wolfgang Wendt: Pocket book of control engineering with MATLAB and Simulink , 11th edition, Verlag Europa-Lehrmittel, 2019, ISBN = 978-3-8085-5869-0.
