Search results
Results from the WOW.Com Content Network
Living control systems differ from those specified by Engineering control theory (a thermostat is a simple example), for which the reference value (setpoint) for control is specified outside the system by what is called the controller, [6] whereas in living systems the reference variable for each feedback control loop in a control hierarchy [7 ...
Perceptual control theory (PCT) is a model of behavior based on the properties of negative feedback control loops. A control loop maintains a sensed variable at or near a reference value by means of the effects of its outputs upon that variable, as mediated by physical properties of the environment.
In general, feedback systems can have many signals fed back and the feedback loop frequently contain mixtures of positive and negative feedback where positive and negative feedback can dominate at different frequencies or different points in the state space of a system. The term bipolar feedback has been coined to refer to biological systems ...
Controllability is an important property of a control system and plays a crucial role in many control problems, such as stabilization of unstable systems by feedback, or optimal control. Controllability and observability are dual aspects of the same problem.
The root locus of a feedback system is the graphical representation in the complex s-plane of the possible locations of its closed-loop poles for varying values of a certain system parameter. The points that are part of the root locus satisfy the angle condition.
Control systems that include some sensing of the results they are trying to achieve are making use of feedback and can adapt to varying circumstances to some extent. Open-loop control systems do not make use of feedback, and run only in pre-arranged ways. Closed-loop controllers have the following advantages over open-loop controllers:
A pure feed-forward system is different from a homeostatic control system, which has the function of keeping the body's internal environment 'steady' or in a 'prolonged steady state of readiness.' A homeostatic control system relies mainly on feedback (especially negative), in addition to the feedforward elements of the system.
A key insight of PCT is that the controlled variable is not the output of the system (the behavioral actions), but its input, "perception". The theory came to be known as "perceptual control theory" to distinguish from those control theorists that assert or assume that it is the system's output that is controlled.