Control Systems: Block Diagrams

• A Control System manages and directs the behavior of devices/systems.
• Residential applications include HVAC systems, smart home automation, and security systems.
• Commercial applications include industrial automation, traffic light control, and medical devices.

Block Diagrams

• A block diagram is a visual representation of a system's component interactions.
• The steps to create a block diagram consist of identifying inputs, defining the process/controller, finding the outputs, including a feedback loop if needed, and connecting components with arrows.

Liquid Level Controller

• The controller determines when to open or close the valve of a tank.
• If water is below the level specified by the controller, the float notifies the controller to keep the valve open.
• Once the specified level is reached, the controller closes the valve.
• If water flows out, decreasing float position, the controller reopens the valve.
• The controller continuously monitors the float position, sending signals to the valve accordingly.
• The float acts as feedback to the water level control system.

Summing and Take-off Points

• The summing point is where multiple signals are compared in a block diagram.
• The take-off point in a closed-loop system feeds part of the output back to the input for feedback.

Control System Types

• Closed-Loop Control Systems use feedback, thermostats, and cruise control in cars.
• Open-Loop Control Systems lack feedback, washing machines, and microwaves.

Process Control Terms

• Standard defines the reference for calibration.
• Calibration adjusts sensors to match a standard.
• Accuracy measures how close a measurement is to the true value.
• Precision is the repeatability of measurements.
• Sensors detect environmental changes.
• Transducers convert energy forms from one sensor to another.

Measuring Electrical Properties

• Voltage is the electrical potential difference, measured in Volts.
• Current is the flow of charge in a circuit, measured in Amperes.
• Resistance is the opposition to current flow, measured in Ohms.
• Voltage measurements are taken across a power supply.
• Current measurements are taken in a circuit, such as a motor or LED.
• Resistance measurements are taken across a resistor.

Circuit Testing

• Voltage Testing checks power levels.
• Current Testing ensures correct current flow.
• Continuity Testing checks for wiring breaks.