any one of the relative gradations of sets of control elements in an integrated system, grouped and separated according to the hierarchical principle of control. The control elements of various levels are interconnected and strictly subordinated.
In hierarchical control systems, each subdivision, or subsystem, solves only problems of its own level; the original information for decision-making and developing control signals is transmitted from lower to higher levels, and the control information or signal is transmitted from higher to lower levels. In a digital computer, for example, the operation of the individual units, such as memories, printers, and the like, is coordinated according to the specific computer program by a central unit, in which one link is the computer’s control console (at the highest control level). Local controls (at the lowest control level) are commanded by the central control unit; they generate signals to execute individual operations according to their own operating algorithm, and the aggregate of these operations constitutes the computational process.
In automated production control systems, the automatic controllers that control actuating mechanisms and machine functions, together with the measuring transducers (sensors) that monitor the progress of the production process, constitute the lowest control level. Monitoring and measuring information from the sensors is fed to a dispatcher’s control panel or to a control computer (the highest level), which evaluates the accuracy with which operations are being executed and then generates commands to be fed to elements at the lowest control level. In more complex systems, such as automated control systems for an industry branch or an enterprise or integrated power grids, there may be three or more separate control levels.
The separation of control functions by control level in integrated systems makes it possible to restrict the range of problems solved by each subdivision, regulate the distribution of information among control elements, simplify accounting and reduce the number of documents required, and improve the quality of decisions made.