science

Supervisory control

Supervisory control is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Supervisory control rather than just read about it. In short: Supervisory control is a general term for control of many individual controllers or control loops, such as within a distributed control system. It refers to a high level of overall monitoring of individual process controllers, which is not necessary for the operation of each controller, but gives the operator an overall plant process view, and allows integration of operation between controllers.

Key takeaways

Supervisory control belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Supervisory control to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Supervisory control from memory before moving on to harder problems.

Reference excerpt

Supervisory control is a general term for control of many individual controllers or control loops, such as within a distributed control system. It refers to a high level of overall monitoring of individual process controllers, which is not necessary for the operation of each controller, but gives the operator an overall plant process view, and allows integration of operation between controllers. A more specific use of the term is for a Supervisory Control and Data Acquisition system or SCADA, which refers to a specific class of system for use in process control, often on fairly small and remote applications such as a pipeline transport, water distribution, or wastewater utility system station.

Forms

Supervisory control often takes one of two forms. In one, the controlled machine or process continues autonomously. It is observed from time to time by a human who, when deeming it necessary, intervenes to modify the control algorithm in some way. In the other, the process accepts an instruction, carries it out autonomously, reports the results and awaits further commands. With manual control, the operator interacts directly with a controlled process or task using switches, levers, screws, valves etc., to control actuators. This concept was incorporated in the earliest machines which sought to extend the physical capabilities of man. In contrast, with automatic control, the machine adapts to changing circumstances and makes decisions in pursuit of some goal which can be as simple as switching a heating system on and off to maintain a room temperature within a specified range. Sheridan defines supervisory control as follows: "in the strictest sense, supervisory control means that one or more human operators are intermittently programming and continually receiving information from a computer that itself closes an autonomous control loop through artificial effectors to the controlled process or task environment."

Other points Robotics applications have traditionally aimed for automatic control. Automatic control requires sensing and responding appropriately to all combinations of circumstances which can present problems of overwhelming complexity. A supervisory control scheme offers the prospect of solving the automation problem incrementally and leaving those problems unsolved to be handled by the human supervisor. Communications delay does not have the same impact on this control scheme. All time critical feedback occurs at the slave where the delays are negligible. Instability is thus avoided without modifying the feedback loop. Communications delay, in this case, slows the rate at which an operator can assign tasks to the slave and determine whether those tasks have been successfully carried out.

See also Human reliability and human factors for more on human supervisory control Thomas B. Sheridan, a researcher of supervisory control and other subjects and professor of mechanical engineering at MIT Supervisory control theory – Method for automatically synthesizing supervisors that restrict the behavior of a plant

References: Human Supervisory Control Amalberti, R. and Deblon, F (1992). Cognitive Modelling of Fighter Aircraft Process Control: A Step Towards an Intelligent On-Board Assistance System. International Journal of Man-Machine Studies, 36, 639-671. Hollnagel, E., Mancini, G. and Woods, D. (Eds.) (1986). Intelligent decision support in process environments. New York: Academic Press. Jones, P. M. and Jasek, C. A. (1997). Intelligent support for activity management (ISAM): An architecture to support distributed supervisory control. IEEE Transactions on Systems, Man, and Cybernetics, Special issue on Human Interaction in Complex Systems, Vol. 27, No. 3, May 1997, 274-288. Jones, P. M. and Mitchell, C. M. (1995). Human-computer cooperative problem solving: Theory, design, and evaluation of an intelligent associate system for supervisory control. IEEE Transactions on Systems, Man, and Cybernetics, 25, 7, July 1995, 1039-1053. Mailin, J. T., Schreckenghost, D. L., Woods, D. D., Potter, S. S., Johannsen, L., Holloway, M. and Forbus, K. D. (1991). Making intelligent systems team players: Case studies and design issues. Volume 1: Human-computer interaction design. NASA Technical Memorandum 104738, NASA Johnson Space Center. Mitchell, C. M. (1999). Model-based design of human interaction with complex systems. In A. P. Sage and W. B. Rouse (Eds.), Handbook of systems engineering and management (pp. 745 – 810). Wiley. Rasmussen, J., Pejtersen, A. and Goodstein, L. (1994). Cognitive systems engineering. New York: Wiley. Sarter, N. and Amalberti, R. (Eds.) (2000). Cognitive engineering in the aviation domain. Lawrence Erlbaum Associates. Sheridan, T. B. (1992). Telerobotics, automation, and human supervisory control. MIT Press. Sheridan, T. B. (2002). Humans and automation: System design and research issues. Wiley. Sheridan, T. B. (Ed.) (1976). Monitoring behavior and supervisory control. Springer. Woods, D. D. and Roth, E. M. (1988). Cognitive engineering: Human problem solving with tools. Human Factors, 30, 4, 415-430.

Citations

Worked examples

Example 1 — a first encounter with Supervisory control

Start with the simplest possible case. Write down what Supervisory control claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Supervisory control before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Supervisory control ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Supervisory control

In research: Supervisory control appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Supervisory control in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Supervisory control is common in secondary-school and first-year university syllabi. It links to neighbouring topics Control theory, so understanding it makes those chapters shorter.
In everyday life: Look for Supervisory control outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Supervisory control in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Supervisory control means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Supervisory control out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Supervisory control in simple terms?

Why does Supervisory control matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Supervisory control?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Supervisory control.