Cyber Physical Systems Lecture 4

Overview of Cyber-Physical Systems

• Cyber-Physical Systems (CPS) integrate computation, networking, and physical processes.
• The seamless communication between sensors and actuators ensures machines perceive, interpret, and react to their environments.

Sensors

• Sensors convert physical or environmental changes into electrical signals.
• Essential for data collection, allowing machines to interact with their surroundings.

Types of Sensors

• Thermocouples: Generate voltage in response to temperature changes.

• Temperature Sensors:

  • RTDs: Change resistance with temperature variations.
  • Thermistors: Resistance decreases as temperature increases.
  • Infrared Sensors: Measure temperature based on emitted infrared radiation.

• Pressure Sensors:

  • Strain Gauge Sensors: Measure pressure-induced deformation.
  • Capacitive Sensors: Detect pressure changes via capacitance variations.
  • Piezoelectric Sensors: Generate electrical charges in response to pressure.
  • Piezoresistive Sensors: Change resistance based on applied pressure.

• Motion Sensors:

  • Accelerometers: Measure acceleration forces on multiple axes.
  • Gyroscopes: Detect angular velocity and orientation.
  • Infrared Sensors: Monitor motion using infrared radiation.
  • Ultrasonic Sensors: Detect objects and motion through sound waves.

• Light Sensors:

  • Photodiodes: Convert light into electrical current.
  • Phototransistors: Amplify current based on light intensity.
  • Light Dependent Resistors (LDRs): Resistance changes with light levels.

• Humidity Sensors:

  • Resistive Sensors: Change resistance based on humidity.
  • Capacitive Sensors: Measure capacitance changes linked to humidity.

Actuators

• Actuators convert electrical signals into mechanical motion, executing commands in the real world.

Types of Actuators

• Motors:

  • DC Motors: Provide variable speed control, ideal for precise movement.
  • AC Motors: Suitable for high-speed, high-torque applications in industry.
  • Stepper Motors: Allow fine control over position and rotation, used in robotics.
  • Servo Motors: Offer precise control of angular position, speed, and acceleration, crucial for high accuracy tasks.

• Hydraulic Actuators:

  • Hydraulic Cylinders: Convert hydraulic pressure into linear motion, used in heavy machinery.
  • Hydraulic Motors: Produce rotary motion from hydraulic pressure, used in excavators.

• Pneumatic Actuators:

  • Pneumatic Cylinders: Convert compressed air into linear motion, widely utilized in automation.
  • Pneumatic Motors: Generate rotary motion using compressed air for tools and machinery.

• Thermal Actuators:

  • Bimetallic Actuators: Use the thermal expansion of two different metals to initiate movement.
  • Shape Memory Alloys (SMAs): Change shape in response to temperature, enabling small, precise movements.

• Electromagnetic Actuators:

  • Solenoids: Convert electrical energy into linear motion, often used in locks and valves.
  • Voice Coil Actuators: Employ electromagnetic forces for precision positioning systems.