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1. The Excitement of Control Engineering

1.6 Summary

  • Control Engineering is present in virtually all modern engineering systems.
  • Control is often the hidden technology, as its very success removes it from view.
  • Control is a key enabling technology with respect to
    • enhanced product quality,
    • waste and emission minimization,
    • environmental protection,
    • greater throughput for a given installed capacity,
    • greater yield,
    • deferring costly plant upgrades, and
    • higher safety margins.
  • Examples of controlled systems include the following:

    Controlled outputs include
    Desired performance includes
    Aircraft Course, pitch, roll, yaw Autopilot Maintain flight path on a safe and smooth trajectory
    Furnace Temperature Temperature controller Follow warm-up temperature profile, then maintain temperature
    Wastewater treatment pH value of effluent pH controller Neutralize effluent to specified accuracy
    Automobile Speed Cruise controller Attain, then maintain selected speed without undue fuel consumption

  • Control is a multidisciplinary subject that includes
    • sensors,
    • actuators,
    • communications,
    • computing,
    • architectures and interfacing, and
    • algorithms.
  • Control design aims to achieve a desired level of performance in the face of disturbances and uncertainty.
  • Examples of disturbances and uncertainty include the following:

    Aircraft Throttle servo, rudder and flap actuators, etc. Navigation instruments Wind, air pockets, etc. Weight, exact aerodynamics, etc.
    Furnace Burner valve actuator Thermocouples, heat sensors Temperature of incoming objects, etc. Exact thermodynamics, temperature distribution
    Wastewater treatment Control acid valve servo pH sensor Inflow concentration pH gain curve, measurement errors
    Automobile Throttle positioning Tachometer Hills Weight, exact dynamics