Supervisory control
Encyclopedia
Supervisory control is a general term for control of many individual controller
s or control loops, whether by a human or an automatic control system, although almost every real system is a combination of both. A more specific use of the term is for a SCADA
system, or Supervisory Control and Data Acquisition system, which refers to a specific class of system that can be purchased, usually for use on fairly small remote locations such as a pipeline transport
, water distribution, or wastewater
utility system station.
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."
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.
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
Controller (control theory)
In control theory, a controller is a device which monitors and affects the operational conditions of a given dynamical system. The operational conditions are typically referred to as output variables of the system which can be affected by adjusting certain input variables...
s or control loops, whether by a human or an automatic control system, although almost every real system is a combination of both. A more specific use of the term is for a SCADA
SCADA
SCADA generally refers to industrial control systems : computer systems that monitor and control industrial, infrastructure, or facility-based processes, as described below:...
system, or Supervisory Control and Data Acquisition system, which refers to a specific class of system that can be purchased, usually for use on fairly small remote locations such as a pipeline transport
Pipeline transport
Pipeline transport is the transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used....
, water distribution, or wastewater
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
utility system station.
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."
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 reliabilityHuman reliability
Human reliability is related to the field of human factors engineering and ergonomics, and refers to the reliability of humans in fields such as manufacturing, transportation, the military, or medicine...
and Human factors
Human factors
Human factors science or human factors technologies is a multidisciplinary field incorporating contributions from psychology, engineering, industrial design, statistics, operations research and anthropometry...
, for more on human supervisory control
Thomas B. Sheridan
Thomas B. Sheridan
Thomas B. Sheridan is American professor of mechanical engineering and Applied Psychology Emeritus at the Massachusetts Institute of Technology. He is a pioneer of robotics and remote control technology.- Biography :...
, a researcher of supervisory control and other subjects and professor of mechanical engineering at MIT