L01 - Control Systems Fundamentals

Objectives:

Analyze behavior of dynamical systems
Define and study feedback control system performance
Design control devices

Concepts

Plant - System to be controlled (e.g: A car)

Controlled Output - Physical variable under control (e.g: The car speed or safety distance)

Control Input - Manipulable variable acting on the plant (e.g: Force needed to accelerate/decelerate car)

Reference Signal - Prescribed values of controlled output (e.g: The desired car speed)

Controller - Device that produces control input

Disturbance input - Disturbance that affects the plant, cannot be manipulated, hinders control

Open and Closed-loop controllers

Open-loop controllers (feed-forward)

Provide input signal to plant depending on past and present values of reference signal only.

No access to any information about the plant except for maybe some possible prior information (e.g. what is known before the control signal is applied)
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Closed-loop controllers (feedback)

Exploit information about the plant through the feedback of the measured output , obtained by one or more sensors.

Sensor - A device that measures a physical quantity and converts it into an electrical signal which can be processed by instruments. (e.g radars)

Sensor Noise - Affects measured output, disturbance in sensor measurement.

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Closed-loop controllers provide control input based on past and present values of both reference signal AND measured output.

More powerful than open-loop since it's able to withstand and compensate for disturbances and uncertainty/variations.

Actuators

An actuator is a part of the system that makes the control action possible (e.g: a pump, motor, etc..)