process control

Fuzzy control system-feedback controller

System – A set of connected things or parts forming a complex whole, in particular. A set of things working together as parts of a mechanism or an interconnecting network.

Systems can be any size – from microelectromechanical (tiny) to enormous (power generating plants)

Systems engineering – about the whole process of a project


  • uncontrolled – settlement pond

Process controls – statistics and engineering discipline that deals with the mechanism, architectures, and algorithms for controlling a process. Some examples of controlled processes are:

  • Controlling the temperature of a water stream by controlling the amount of steam added to the shell of a heat exchanger.
  • Operating a jacketed reactor isothermally by controlling the mixture of cold water and steam that flows through the jacket of a jacketed reactor.
  • Maintaining a set ratio of reactants to be added to a reactor by controlling their flow rates.
  • Controlling the height of fluid in a tank to ensure that it does not overflow.

Control systems – control via an embedded system.

How stuff works – System dynamics, the study of the behavior of complex systems

  • the behavior of complex systems over time
  • internal feedback loops and time delays that affect the behavior of the entire system
  • stocks and flows

These elements help describe how even seemingly simple systems display baffling nonlinearity.

Control systems – device, or set of devices, that manages, commands, directs or regulates the behavior of other device(s) or system(s).

  • airplane autopilot
  • oil refinery
  • home heating thermostat
  • car engine cooling

There are of course other ways of controlling a system, such as designing it to mechanically self-regulate. While mechanical regulation is definitely a method of controlling a system, it often isn’t lumped in with “control systems”.

ASME Systems & Design

  • Computers & Information Engineering
  • Design Engineering
  • Dynamic Systems & Control
  • Electronic & Photonic Packaging
  • Fluid Power Systems & Technology
  • Information Storage & Processing Systems
  • Microelectromechanical Systems

Failures in Process Control – Catastrophic failures in process control remind us of the importance of control systems and engineering. Bhopal, India Disaster, Three Mile Island Disaster, Texas City Disaster

Sensors and Actuators

  • Control Systems: Measurement devices
  • Temperature sensors
  • Pressure sensors
  • Level sensors
  • Flow sensors
  • Composition sensors
  • pH and viscosity sensors
  • Miscellaneous sensors
  • Valves: types, kinds, and selection
  • Valves: modeling dynamics

modeling systems, analysis

  • Simulink
  • Modelica – open, free library – model mechanical (1D/3D), electrical (analog, digital, machines), thermal, fluid, control systems and hierarchical state machines.

Engineering ideas

  • system components, comparator, controller, plant, sensor, variable, input, output, complexity, behavior, predict, signals, flow
  • control effort, measured output, error signal, closed loop system
  • proportional control, integral control, and combinations of proportional and integral (plus derivative?) control
  • mathematical techniques that involve differential equation solution
  • linear system, transfer function
  • xogenious

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