Overview
Control systems may control perceptions that have no direct representation in reality, but instead are constructed from combinations of sensed environmental variables. In this demonstration, three systems simultaneously attempt to control their own perceptions, each of which consists of a different weighted combination of the same three environmental variables. By changing the reference values associated with each of these systems and the disturbances aplied to each of the enviornmental variables(click and drag to the left to decrease, to the right to increase), you can see how they respond to changes.
Each control system receives input from each of the three environmental variables (labeled EV 1, EV 2, and EV 3 in the diagram), multiplies each input by a given input weight (shown in the windows where the environmental variables connect to the control system, dashed lines), and then adds the resulting weighted variables together to produce Qi, the input quantity. On the output side of the control system, the output quantity, Qo, is multiplied separately by three different weights, and each resulting weighted output action is applied to a different one of the three environmental variables to close the negative feedback loop.
In the demonstration, the input weights, which range potentially between values of plus one and minus one, are chosen at random. Each output weight is then set equal to the corresponding input weight. This arrangement guarantees that the feedback to each environmental variable will be negative, as it must be in a control system. If you click on the "Change weights" button, new random input weight will be generated.
What To Do
Try adjusting the reference levels and disturbances while paying attention to the match between each reference level and its corresponding perceptual level (P) as the three systems approach their stable values. Note also the magnitudes of the outputs (Qo) being generated in an effort to oppose the effects of the disturbances.
In a few cases, rather large discrepancies will remain between the reference values and the corresponding perceptions, owing to interactions occurring between the three systems as they act upon the same three environmental variables. In those cases the systems are to some degree in conflict and may be producing large outputs in an effort to overcome the effects of the other systems as they attempt to control their own perceptions. You can observe the effects of different weightings of the environmental variables on the abilities of the three systems to control their own constructs by repeatedly selecting new sets of weights (by clicking on the “Change weights” button).