Design of an Automatic Control Algorithm for Energy-Efficient ...

6 The optimiser: an evolutionary algorithm approach 66
point, for example when the windscreen is fogged or iced and cannot be defogged in the
time � �������. Then solutions going in the “wrong direction” are likely to be preferred
because the saturated objective is equal for all and will be not influence the decision. In
this case a solution with only little cool air blown to the feet could be chosen as control
in the fogged window example. In such a case it would help to modify the predicted
time span. That would lead to increased (and varying!) computation time, which is not
desirable. In addition, one could imagine a situation where this would lead to extreme,
if not infinite periods which have to be simulated. Therefore, another method has been
implemented here.
Each objective has its limit assigned which has already been used for the ranking. If
this limit is exceeded it is usually close to saturation or in a state where counter measures
have to be taken. Thus, for each objective a special control output is defined which is
aimed at helping the controller to find a way to a secure state. If several limits are exceed
at a time, an ordering (�) gives an indication which to handle first. The weights used for
the ranking can be applied for this purpose as well.
handler.
If the chosen individual is above a limit, the output will replaced with a panic
� ������ �
�
��
��
� ������� for � ��� �������� � � � � � ������ ���
� �������
for � ��� �������� �� � � � � � � � ����� ���� � �� ��� �������� �� ��
(6.8)
This solution allows deterministic computation time since no change to the simulation is
made. It also allows the control to handle extreme situations.
6.3.11 Final thoughts on the algorithm
The described methods were chosen with the information found in different publications.
However, the optimisation of the algorithm and its parameters would go beyond the scope
of this thesis.
The main drawback of the choice of a genetic algorithm is that the quality of the
found solution cannot be guaranteed, but with the introduction of the replacement signals
through panic handlers safe outputs are given at each time step. The deterministic run-