MECHENG 201 Part 2: Electronics, Sensors and Actuators

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MECHENG 201 Part 2: Electronics, Sensors and Actuators por Mind Map: MECHENG 201  Part 2: Electronics, Sensors and Actuators

1. Electronics: Diodes

1.1. Introduction

1.1.1. Active

1.1.2. Passive

1.1.3. Electro-mechanic

1.2. Diodes

1.2.1. a two-terminal electronic component that conducts primarily in one direction

1.2.1.1. Role: allow current to pass in forward direction, block current in reverse direction

1.2.1.2. Analogous example: Check Valve

1.2.1.3. First Diode: Thermionic Diode

1.2.1.3.1. Edison Effect: when hot, the cathode releases electrons into the vacuum

1.2.1.4. Types:

1.2.1.4.1. Diode

1.2.1.4.2. LED

1.2.1.4.3. Photodiode

1.2.1.4.4. Zener Diode

1.2.1.4.5. Schottky Diode

1.2.1.4.6. Transient-voltage-suppression Diode (TVS)

1.2.1.4.7. Tunnel Diode

1.2.1.4.8. Varicap

1.2.1.5. Ideal Diode:

1.2.1.5.1. Forward Biased

1.2.1.5.2. Reverse Biased

1.2.1.5.3. NO Break down region

1.2.1.6. Real Diode:

1.2.1.6.1. Forward Biased

1.2.1.6.2. Reverse Biased

1.2.1.6.3. Breakdown

1.2.1.7. Other Functions:

1.2.1.7.1. Unidirectional behaviour = Rectification: - convert AC to DC - detect AM radio signals

1.2.1.7.2. - voltage drop is a function of temperature = use as a temperature sensor or voltage reference

1.2.1.7.3. Avalanche Diode: protect circuits from high voltage

1.2.1.7.4. Varactor Diode: tune radio and TV receivers

1.2.1.7.5. Tunnel, Gunn and IMPATT Diode: - generate radio frequency oscillations - create microwave and switching circuits

1.2.1.8. Diode + Inductors:

1.2.1.8.1. current stopped = 0 --> stored energy creates reverse voltage spike (flyback) that can damage switch

1.2.1.9. Diode-Resistor Logic (DRL):

1.2.1.9.1. OR Gate

1.2.1.9.2. AND Gate

1.3. Integrated Circuit

1.3.1. a set of electronic circuits on one small chip (semiconductor material e.g silicon

2. Sensors

2.1. never used by themselves!

2.2. = element that produces a signal relating to the quantity being measured

2.3. Transducer:

2.3.1. = device that converts energy from one form to another

2.4. Absolute & Incremental Sensors

2.4.1. Absolute:

2.4.1.1. detect a unique position - not power dependent

2.4.2. Incremental:

2.4.2.1. measure a relative position - depends on a prior position or last power on/off

2.5. Analog & Digital Sensors

2.5.1. Analogue:

2.5.1.1. continuous output signal or voltage

2.5.1.2. proportional to quantity being measured

2.5.1.2.1. e.g voltage measured by potentiometer is proportional to the angle it is measuring

2.5.1.3. Example: Thermocouple

2.5.1.4. Measurement:

2.5.1.4.1. 1. Linear

2.5.1.4.2. 2. Polynomial

2.5.1.4.3. 3. Exponential

2.5.1.4.4. y = measurement x = sensor output signal

2.5.2. Digital:

2.5.2.1. discrete digital output signal or voltage - step response

2.5.2.2. binary output signal

2.5.2.2.1. Signal conditioning

2.5.2.3. Example: Light Sensor

2.6. Selecting a Sensor:

2.6.1. 1. Nature of measurement required

2.6.1.1. nominal value of variable

2.6.1.2. range of values

2.6.1.3. accuracy required

2.6.1.4. required speed of measurement

2.6.1.5. reliability required

2.6.2. 2. Nature of output required from sensor

2.6.3. 3. Factors of the sensor

2.6.3.1. range

2.6.3.2. accuracy

2.6.3.3. linearity

2.6.3.4. speed of response

2.6.3.5. reliability

2.6.3.6. life

2.6.3.7. power supply requirements

2.6.3.8. cost

2.6.3.9. size

3. Sensors: Examples

3.1. Strain Gauge Pressure Sensor

3.1.1. change in R/R = G.E E = strain G = proportionality factor

3.2. Pressure Sensor

3.2.1. pressure measurements of gases or liquids

3.2.1.1. produces proportional output voltage

3.2.2. can indirectly measure volume or alititude

3.3. Barometric Sensors

3.3.1. detect atmospheric pressure

3.3.2. Tactile Sensors

3.4. Potentiometer

3.4.1. example of an encoder

3.4.2. absolute analog sensor that measures angular position

3.4.2.1. after a few revolutions, it will reset to zero

3.4.2.2. it works like a variable resistor

3.4.2.2.1. turning the shaft changes the resistance

3.5. Radar Sensor

3.5.1. "Radio detection and ranging"

3.5.1.1. emits very small wavelength radio frequency signals

3.5.1.1.1. detect - moving objects (planes) - shape of land

3.5.2. radio waves

3.6. Sonar

3.6.1. "Sound navigation and ranging"

3.6.1.1. generates ultrasonic waves and the receiver captures waves that bounce back from the target

3.6.1.1.1. timer calculates how long it takes for signal to return

3.6.1.1.2. using speed of sound in the air

3.6.1.2. long range poor resolution

3.6.2. sound waves

3.7. Infrared Sensor

3.7.1. accurate, medium range, non contact position measurement

3.7.2. small maximum range better resolution compared to Sonar sensor

3.8. Optical Position Sensor

3.8.1. measure position of a target

3.8.1.1. infrared emitting diode + NPN infrared silicon phototransistor

3.8.1.1.1. used in assembly lines, machine automation, edge detection

4. Sensors: Types

4.1. Types:

4.1.1. Displacement, Position & Proximity Sensors (either contact or non-contact)

4.1.1.1. Displacement Sensors focus on measuring how much the object has moved

4.1.1.2. Position Sensors focus on the position of the object to a reference point

4.1.1.3. Proximity Sensors are position sensors that sense whether the object has moved within a critical distance = give ON/OFF outputs

4.1.2. Velocity & Motion

4.1.2.1. monitor linear and angular velocity and detect motion

4.1.2.1.1. e.g security systems cash machine screens

4.1.3. Force Sensors

4.1.3.1. focus on measuring forces applied on them

4.1.3.1.1. e.g spring balance - displacement is a measure of force

4.1.4. Fluid Pressure & Level

4.1.4.1. Fluid Pressure

4.1.4.1.1. monitors fluid pressure

4.1.4.2. Fluid Level

4.1.4.2.1. Directly

4.1.4.2.2. Indirectly

4.1.4.3. Pressure Sensing Technologies

4.1.4.3.1. Force Collector Types

4.1.4.3.2. Other Types

4.1.5. Environmental Sensors

4.1.5.1. Temperature Sensors

4.1.5.1.1. changes commonly used are - expansion/contraction of solids/liquids/gases - change in resistance of conductors

4.1.5.2. Light Sensors

4.1.5.2.1. measure intensity of light

4.1.5.3. Humidity Sensors

4.1.5.4. Wind Sensors

5. Sensors: Characteristics

5.1. Characteristics

5.1.1. Performance

5.1.1.1. 1. Range

5.1.1.1.1. the limits between which the input can vary

5.1.1.2. 2. Span

5.1.1.2.1. maximum value - minimum value input

5.1.1.3. 3. Error

5.1.1.3.1. Error = measured value - true value

5.1.1.4. 4. Accuracy

5.1.1.4.1. extent to which the value might be wrong

5.1.1.5. 5. Sensitivity

5.1.1.5.1. how much output there is per unit input = output/input

5.1.1.6. 6. Hysteresis Error

5.1.1.6.1. same point being measured, different outputs, due to continuously increasing or decreasing change

5.1.1.7. 7. Repeatability

5.1.1.7.1. ability to give the same output for repeated applications of the same input value

5.1.1.7.2. Repeatability = (max - min values given)/full range x 100%

5.1.1.8. 8. Stability and Drift

5.1.1.8.1. Stability

5.1.1.8.2. Drift

5.1.1.8.3. Zero Drift

5.1.1.9. 9. Dead Band

5.1.1.9.1. Dead Band or Dead Space

5.1.1.9.2. Dead Time

5.1.1.10. 10. Resolution

5.1.1.10.1. the smallest change in the input value that will produce an observable change in output

5.1.1.11. 11. Output Impedance

5.1.1.11.1. electrical output is interfaced with an electronic circuit = there will be output impedance

5.1.1.11.2. having a sensor that reads the output impedance can modify the behavior of the system

5.1.2. Static VS Dynamic

5.1.2.1. Static Characteristics

5.1.2.1.1. values given when steady-state conditions occur

5.1.2.2. Dynamic Characteristics

5.1.2.2.1. behavior of the sensor between the time that the input value changes and the time that the value given by the sensor settles down to steady-state.

5.1.2.3. Response Time

5.1.2.4. Time Constant

5.1.2.5. Rise Time

5.1.2.6. Settling Time

6. Actuators

6.1. part of the machine that moves or controls something

6.1.1. Types:

6.1.1.1. 1. Mechanical

6.1.1.1.1. conversion of rotary motion to linear motion

6.1.1.2. 2. Electric

6.1.1.3. 3. Electro-mechanic

6.1.1.3.1. like mechanical actuators but control knob/handle is replaced with electric motor

6.1.1.3.2. rotary motion converted to linear displacement

6.1.1.4. 4. Piezoelectric

6.1.1.4.1. very short range of motion

6.1.1.4.2. very high voltages = tiny expansions

6.1.1.5. 5. Hydraulic

6.1.1.5.1. converts hydraulic pressure + flow into torque + angular displacement (rotation)

6.1.1.6. 6. Pneumatic

6.1.1.6.1. air

6.1.1.7. 7. Thermal

6.1.1.7.1. material in actuator changes from solid <--> liquid

6.1.1.7.2. narrow temperature range = precise control

6.1.1.8. 8. Magnetic

6.1.2. Types of Motion:

6.1.2.1. Linear

6.1.2.2. Rotary/Circular

6.1.3. Performance Metrics:

6.1.3.1. Force

6.1.3.2. Speed

6.1.3.3. Operating conditions

6.1.3.4. Durability

6.1.4. Electric Motors

6.1.4.1. DC Motors

6.1.4.1.1. continuous movement, speed of rotation easily controlled

6.1.4.2. AC Motors

6.1.4.2.1. outside Stator/inside Rotor/ Permanent Magnets or electrical windings

6.1.4.3. Stepper Motors

6.1.4.3.1. electromechanical

6.1.4.4. Solenoids

6.1.4.4.1. coil of electrical wire with an armature

6.1.4.4.2. electromagnet and plunger inside coil

6.1.5. Smart Motors:

6.1.5.1. in a Single Servo Model:

6.1.5.1.1. DC Motor

6.1.5.1.2. Reduction Gearhead

6.1.5.1.3. Encoder + Controller + Driver

6.1.5.1.4. Communications

7. Electronics: Microcontrollers and Microprocessors

7.1. Microcontrollers and Microprocessors

7.1.1. Microprocessor

7.1.1.1. heart of a computer CPU complete computation engine

7.1.1.1.1. General/personal purpose use

7.1.1.1.2. Example: Raspberry Pi

7.1.2. Microcontroller

7.1.2.1. MCU small computer on one IC one or more CPUs

7.1.2.1.1. Embedded applications

7.1.2.1.2. Example: Arduino

7.1.2.1.3. Selecting a Microcontroller:

7.1.3. Microprocessor Systems

7.1.3.1. 1. Central Processing Unit (CPU) or Microprocessor

7.1.3.1.1. Roles:

7.1.3.1.2. Parts:

7.1.3.2. 2. Memory

7.1.3.2.1. stores binary data

7.1.3.2.2. Size: depends on number of wires in the address bus

7.1.3.3. 3. Input and Output Interfaces

7.1.3.3.1. transfer of data between the microprocessor and the external world

7.1.3.4. 4. Buses

7.1.3.4.1. Data Bus

7.1.3.4.2. Address Bus

7.1.3.4.3. Control Bus

7.1.4. Microcontroller VS Microprocessor System

7.1.4.1. Microprocessor systems have an external peripheral Microcontrollers have RAM, ROM, EEPROM embedded internally

7.1.4.2. Microcontrollers = all on ONE CHIP Microprocessor Systems = many chips

7.1.4.3. Microcontrollers = cheaper Microprocessor Systems = expensive

7.1.4.4. Microcontrollers = lower processing speed (8 to 50MHz) Microprocessor Systems = high processing speed (>1GHz)

7.1.4.5. Microcontrollers = simpler tasks Microprocessor Systems = more complex tasks

7.1.5. Computer

7.1.5.1. Structure:

7.1.5.1.1. 1. Input devices

7.1.5.1.2. 2. Processor

7.1.5.1.3. 3. Main memory

7.1.5.1.4. 4. Output devices

7.1.5.1.5. 5. Backing storage

7.1.5.2. Classification:

7.1.5.2.1. Structure

7.1.5.2.2. Type

7.1.5.2.3. Size

8. Electronics: Filters

8.1. Filters

8.1.1. Signal Processing

8.1.1.1. a device or process that removes some unwanted components or features from a signal

8.1.2. Electronics

8.1.2.1. a circuit designed to pass inputs in a certain frequency range while blocking other inputs

8.1.3. Classes:

8.1.3.1. Linear or Nonlinear

8.1.3.2. Time invariant or Time variant

8.1.3.3. Causal or Not causal

8.1.3.4. Active or Passive

8.1.3.4.1. Active

8.1.3.4.2. Passive

8.1.3.5. Analog or Digital

8.1.3.6. Discrete time (sampled) or Continuous Time

8.1.3.7. Infinite Impulse Response (IIR) or Finite Impulse Response (FIR)

8.1.4. Types:

8.1.4.1. Low-Pass Filter

8.1.4.1.1. "High-cut"

8.1.4.2. High-Pass Filter

8.1.4.2.1. "Low-cut"

8.1.4.3. Band-Pass Filter

8.1.4.3.1. based on a frequency range

8.1.4.4. Band-Stop Filter

8.1.4.4.1. "Band-reject"

9. Electronics: 555 Timer

9.1. Timer 555

9.1.1. an integrated circuit used in a variety of timer, pulse generation, and oscillator applications

9.1.1.1. Structure:

9.1.1.1.1. a SR Flip-flop

9.1.1.1.2. 2 comparators (OPAMPS)

9.1.1.1.3. transistor Q1 = switch

9.1.1.2. Modes of Operation:

9.1.1.2.1. 1. Monostable

9.1.1.2.2. 2. Astable

9.1.1.2.3. 3. Bistable

9.1.1.3. Pulse Width Modulation (PWM)

9.1.1.3.1. modulation = changing

9.1.1.3.2. allow the control of power supplied to electrical devices

10. Electronics: OPAMPS

10.1. OPAMP

10.1.1. a high-gain electronic voltage amplifier with a differential input and a single-ended output

10.1.1.1. Used in:

10.1.1.1.1. 1. Signal conditioning

10.1.1.1.2. 2. Filtering

10.1.1.1.3. 3. Perform math operations

10.1.1.2. Symbols:

10.1.1.2.1. V+

10.1.1.2.2. V-

10.1.1.2.3. Vout

10.1.1.2.4. Vs+

10.1.1.2.5. Vs-

10.1.1.3. Structure:

10.1.1.3.1. 20 BJT transistors

10.1.1.3.2. 11 resistors

10.1.1.3.3. 1 capacitor

10.1.1.4. Types:

10.1.1.4.1. Comparator

10.1.1.4.2. Inverting amplifier

10.1.1.4.3. Non-inverting amplifier

10.1.1.4.4. Differential amplifier

10.1.1.4.5. Summing amplifier

10.1.1.4.6. Differentiator

10.1.1.4.7. Integrator

10.1.1.4.8. Instrumentation amplifer

10.1.1.5. Ideal OPAMP:

10.1.1.5.1. Open-loop gain (AOL) = infinite

10.1.1.5.2. zero gain for common mode signal (only has gain when there is a voltage difference)

10.1.1.5.3. infinite input impedence

10.1.1.5.4. zero output impedence

10.1.1.5.5. infinite bandwith

10.1.1.6. Real OPAMP:

10.1.1.6.1. Bandwidth Considerations

10.1.1.6.2. Non Linear Limitations

10.1.1.6.3. Slew Rate

10.1.1.6.4. DC Imperfections

10.1.1.7. Summing Point Constraint

10.1.1.8. Negative Feedback Loop

11. Electronics: Transistors

11.1. Transistor

11.1.1. a semiconductor device used to amplify or switch electronic signals and electronic power

11.1.1.1. made from semiconductor material (silicone) through DOPING

11.1.1.1.1. Triode

11.1.1.1.2. Doping

11.1.1.2. Advantages

11.1.1.2.1. 1. no cathode heater

11.1.1.2.2. 2. very small size and weight

11.1.1.2.3. 3. lots of transistors can be made on one IC

11.1.1.2.4. 4. low operating Voltage

11.1.1.2.5. 5. physically robust

11.1.1.2.6. 6. no maintenance

11.1.1.3. Limitations

11.1.1.3.1. 1. silicon can age and fail

11.1.1.3.2. 2. high power/frequency operation better suited for vacuum tubes where e- can move better

11.1.1.3.3. 3. sensitive to radiation and cosmic rays

11.1.1.4. Types:

11.1.1.4.1. FETS Field-effect Transistors

11.1.1.4.2. BJTS Bipolar junction Transistors

11.1.1.5. Categories:

11.1.1.5.1. Semiconductor Material

11.1.1.5.2. Structure

11.1.1.5.3. Electrical Polarity

11.1.1.5.4. Maximum power rating

11.1.1.5.5. Maximum operating frequency

11.1.1.5.6. Application

11.1.1.5.7. Physical Packaging

11.1.1.5.8. Amplification Factor

11.1.1.6. Operation Modes:

11.1.1.6.1. 1. Saturation

11.1.1.6.2. 2. Cut off

11.1.1.6.3. 3. Active

11.1.1.6.4. 4. Reverse Active

11.1.1.7. Transistor as Switches

11.1.1.7.1. making use of cutoff and saturation states

11.1.1.7.2. Advantages of TRANSISTORS

11.1.1.7.3. Advantages of RELAY SWITCHES (a substitute)

12. Sensors: Encoders

12.1. capture position or orientation

12.1.1. Rotary Encoder

12.1.1.1. electro-mechanical device

12.1.1.2. converts angular position/motion to analog/digital signal

12.1.2. Linear Encoder

12.1.2.1. paired with a scale which the encoder reads from

12.1.2.1.1. converts encoded position to analog/digital signal

12.2. Absolute

12.2.1. unambiguous position (doesn't depend on previous position)

12.2.1.1. robust to interruptions

12.3. Incremental

12.3.1. cyclical, ambiguous (counting of cycles)

13. Switches

13.1. Microswitch

13.2. Push Button

13.3. Optical Switch

13.3.1. photo-micro sensor non-contact triggering

13.3.1.1. triggers when object comes between components