Control task

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Control task

 

In the control of discrete systems, which will be dealt with here, a control algorithm is sought for a given discrete system with input NeuesElement256and output NeuesElement255as well as a control target. The algorithm should select the input sequence NeuesElement254 depending on the output sequenceNeuesElement253  in such a way that the control goal can be achieved.

 

The following objectives can be specified for the control system:

 

 

Specified end state: The control path is to be transferred to the end state  NeuesElement252or the output sequence is to end with the value NeuesElement251.

Specified sequence: The control path is to run through a predefined sequence NeuesElement250 of states.

Forbidden states: The control path may not assume the states  NeuesElement249of the specified set.

Forbidden state transitions: The control path must not execute the state transitions (events) of a given set NeuesElement248.

 

 

These control goals, put into a formalism, are called the formal specification of control. In the illustration, the controlling system is the control device and the actuators, sensors and the process to be controlled are the control path.

 

 

 

 

 

The control device determines the input NeuesElement246of the control path depending on the outputNeuesElement245 , so that the operation of the control algorithm NeuesElement244can be described by a function.

 

 

NeuesElement243

 

If no dynamic element is included, the following relationship applies for each point NeuesElement242 in time 

 

NeuesElement241

 

This type of control is called logic control because the current input to the control path depends solely on the last output of the control path.

If the control contains dynamic elements, then the following applies:

 

NeuesElement240

 

The sequence of the last NeuesElement239-output stored in the control algorithm can be interpreted as the stateNeuesElement238 of the control system, then the following applies

 

 

NeuesElement237

 

and we speak of a sequence control. Cf. (Lunze, 2003, p. 409)