Mechatronics Engineering Lecture 3

Mechatronics Engineering (OFRME200) - Lecture 3

• Course: Mechatronics Engineering (OFRME200)
• Level: 2
• Semester: Fall
• Instructor: Walaa Shoeib
• Faculty: Electronic Engineering, Menoufia University

Overview of Output Signals in Mechatronic Systems

• Signal Type: Output signals can be analog, digital, or pulse signals. These signals control actuators and other system components.
• Signal Format: Output signals can be transmitted in various formats, including voltage, current, frequency, and pulse width. The format choice depends on the specific actuator and requirements.
• Signal Interpretation: Actuators interpret received signals and translate them into mechanical motion or physical property changes.

Introduction to Output Actuators

• Mechanical Components: Actuators contain mechanical parts like gears, shafts, and linkages that convert energy (electrical or fluid) into motion.
• Control Systems: Actuators often have internal control systems regulating speed, position, or force based on input signals.
• Output Mechanisms: Actuator output can be linear (straight line movement) or rotary (circular movement), depending on the application.

Hydraulic Actuators

• Working Principle: Hydraulic actuators use hydraulic fluid and pressure to create force and motion. Pressure is controlled by hydraulic pumps and valves.
• Advantages: High force output, smooth and precise motion, relative ease of control.
• Applications: Construction equipment, heavy machinery, and aerospace systems frequently use hydraulic actuators.

Pneumatic Actuators

• Power Source: Pneumatic actuators use compressed air as their power source. Compressed air is supplied by compressors and controlled by valves.
• Speed: Pneumatic actuators are known for their fast response time and quick movement ability.
• Cleanliness: Air is a clean and relatively safe medium, making pneumatic actuators suitable for environments where contamination is a concern.
• Applications: Automation assembly lines, packaging machinery, and robotics frequently use pneumatic actuators.

Electric Actuators

• Power Source: Motors convert electrical energy into rotational or linear motion. Electric actuators use electric motors.
• Control Electronics: Control electronics manage motor speed, torque, and direction for precise control.
• Applications: Automation, robotics, and consumer products commonly use electric actuators due to precision, efficiency, and low maintenance.

Chapter 2: Sensors & Transducers

• Topic: Sensors and Transducers
• Course: Electronic Measurements
• Instructor: Walaa Shoeib

Introduction to Sensors

• Functionality: Sensors are essential components of modern technology. They detect and measure physical quantities from the environment, converting them into electrical signals.

Types of Sensors

• Temperature Sensors: Measure the temperature of an object or environment.
• Pressure Sensors: Measure the force per unit area applied to a surface.
• Motion Sensors: Detect movement or changes in position.
• Light Sensors: Measure the intensity or color of light.

Sensor Technology Fundamentals

• Transduction: The process of converting physical quantities into electrical signals.
• Signal Conditioning: Amplifying, filtering, and formatting electrical signals for use.
• Data Processing: Analyzing and interpreting sensor data.

Sensing Principles

• Resistive Sensing: Resistance changes based on the measured quantity.
• Capacitive Sensing: Capacitance changes based on the measured quantity.
• Inductive Sensing: Inductance changes based on the measured quantity.

Passive Transducers - Resistance

• Potentiometer: A variable resistor used to measure or change voltage or resistance.
• Strain Gauge: Measures strain/deformation.
• Thermistor: A temperature-sensitive resistor.
• Thermocouple: Measures temperature using a junction of two dissimilar metals.

Potentiometers

• Rotary Potentiometer: Consists of a resistive element and a wiper connected between terminals.
• Linear Potentiometer: A slider with a wiper that slides along a resistive element, providing a visual indication of position. Includes elements like graphite, wire, carbon, ceramic, or metal mixture.

Membrane Potentiometer

• Functionality: A very thin, linear variable potentiometer with resistance changing linearly based on pressing on various parts of the strip.
• Applications: Precise position indicators for CNC machines, or variable user input (volume level).

Strain Gauge

• Functionality: Converts mechanical strain into an electrical signal.
• Mechanism: Uses a wire or foil patterned in a zig-zag shape attached to a material. Deformation changes resistance.
• Applications: Measuring strain in various applications involving stress (load cells, torque meters, diaphragms, accelerometers, flow meters). Measurements are proportional to the applied strain.

Strain Gauge Measurement

• Formula: GF = (ΔR/R) / (ΔL/L) = (ΔR/R) / ε (Gauge Factor Formula) Where:
  • GF = Gauge Factor
  • ΔR = Change in resistance
  • R = Original resistance
  • ΔL = Change in length
  • L = Original length
  • ε = Strain

Problems

• Includes worked examples calculation problems on resistance strain gauge.