1. Sensors
1.1. never used by themselves!
1.2. = element that produces a signal relating to the quantity being measured
1.3. Transducer:
1.3.1. = device that converts energy from one form to another
1.4. Absolute & Incremental Sensors
1.4.1. Absolute:
1.4.1.1. detect a unique position - not power dependent
1.4.2. Incremental:
1.4.2.1. measure a relative position - depends on a prior position or last power on/off
1.5. Analog & Digital Sensors
1.5.1. Analogue:
1.5.1.1. continuous output signal or voltage
1.5.1.2. proportional to quantity being measured
1.5.1.2.1. e.g voltage measured by potentiometer is proportional to the angle it is measuring
1.5.1.3. Example: Thermocouple
1.5.1.4. Measurement:
1.5.1.4.1. 1. Linear
1.5.1.4.2. 2. Polynomial
1.5.1.4.3. 3. Exponential
1.5.1.4.4. y = measurement x = sensor output signal
1.5.2. Digital:
1.5.2.1. discrete digital output signal or voltage - step response
1.5.2.2. binary output signal
1.5.2.2.1. Signal conditioning
1.5.2.3. Example: Light Sensor
1.6. Selecting a Sensor:
1.6.1. 1. Nature of measurement required
1.6.1.1. nominal value of variable
1.6.1.2. range of values
1.6.1.3. accuracy required
1.6.1.4. required speed of measurement
1.6.1.5. reliability required
1.6.2. 2. Nature of output required from sensor
1.6.3. 3. Factors of the sensor
1.6.3.1. range
1.6.3.2. accuracy
1.6.3.3. linearity
1.6.3.4. speed of response
1.6.3.5. reliability
1.6.3.6. life
1.6.3.7. power supply requirements
1.6.3.8. cost
1.6.3.9. size
2. Sensors: Examples
2.1. Strain Gauge Pressure Sensor
2.1.1. change in R/R = G.E E = strain G = proportionality factor
2.2. Pressure Sensor
2.2.1. pressure measurements of gases or liquids
2.2.1.1. produces proportional output voltage
2.2.2. can indirectly measure volume or alititude
2.3. Barometric Sensors
2.3.1. detect atmospheric pressure
2.3.2. Tactile Sensors
2.4. Potentiometer
2.4.1. example of an encoder
2.4.2. absolute analog sensor that measures angular position
2.4.2.1. after a few revolutions, it will reset to zero
2.4.2.2. it works like a variable resistor
2.4.2.2.1. turning the shaft changes the resistance
2.5. Radar Sensor
2.5.1. "Radio detection and ranging"
2.5.1.1. emits very small wavelength radio frequency signals
2.5.1.1.1. detect - moving objects (planes) - shape of land
2.5.2. radio waves
2.6. Sonar
2.6.1. "Sound navigation and ranging"
2.6.1.1. generates ultrasonic waves and the receiver captures waves that bounce back from the target
2.6.1.1.1. timer calculates how long it takes for signal to return
2.6.1.1.2. using speed of sound in the air
2.6.1.2. long range poor resolution
2.6.2. sound waves
2.7. Infrared Sensor
2.7.1. accurate, medium range, non contact position measurement
2.7.2. small maximum range better resolution compared to Sonar sensor
2.8. Optical Position Sensor
2.8.1. measure position of a target
2.8.1.1. infrared emitting diode + NPN infrared silicon phototransistor
2.8.1.1.1. used in assembly lines, machine automation, edge detection
3. Sensors: Types
3.1. Types:
3.1.1. Displacement, Position & Proximity Sensors (either contact or non-contact)
3.1.1.1. Displacement Sensors focus on measuring how much the object has moved
3.1.1.2. Position Sensors focus on the position of the object to a reference point
3.1.1.3. Proximity Sensors are position sensors that sense whether the object has moved within a critical distance = give ON/OFF outputs
3.1.2. Velocity & Motion
3.1.2.1. monitor linear and angular velocity and detect motion
3.1.2.1.1. e.g security systems cash machine screens
3.1.3. Force Sensors
3.1.3.1. focus on measuring forces applied on them
3.1.3.1.1. e.g spring balance - displacement is a measure of force
3.1.4. Fluid Pressure & Level
3.1.4.1. Fluid Pressure
3.1.4.1.1. monitors fluid pressure
3.1.4.2. Fluid Level
3.1.4.2.1. Directly
3.1.4.2.2. Indirectly
3.1.4.3. Pressure Sensing Technologies
3.1.4.3.1. Force Collector Types
3.1.4.3.2. Other Types
3.1.5. Environmental Sensors
3.1.5.1. Temperature Sensors
3.1.5.1.1. changes commonly used are - expansion/contraction of solids/liquids/gases - change in resistance of conductors
3.1.5.2. Light Sensors
3.1.5.2.1. measure intensity of light
3.1.5.3. Humidity Sensors
3.1.5.4. Wind Sensors
4. Sensors: Characteristics
4.1. Characteristics
4.1.1. Performance
4.1.1.1. 1. Range
4.1.1.1.1. the limits between which the input can vary
4.1.1.2. 2. Span
4.1.1.2.1. maximum value - minimum value input
4.1.1.3. 3. Error
4.1.1.3.1. Error = measured value - true value
4.1.1.4. 4. Accuracy
4.1.1.4.1. extent to which the value might be wrong
4.1.1.5. 5. Sensitivity
4.1.1.5.1. how much output there is per unit input = output/input
4.1.1.6. 6. Hysteresis Error
4.1.1.6.1. same point being measured, different outputs, due to continuously increasing or decreasing change
4.1.1.7. 7. Repeatability
4.1.1.7.1. ability to give the same output for repeated applications of the same input value
4.1.1.7.2. Repeatability = (max - min values given)/full range x 100%
4.1.1.8. 8. Stability and Drift
4.1.1.8.1. Stability
4.1.1.8.2. Drift
4.1.1.8.3. Zero Drift
4.1.1.9. 9. Dead Band
4.1.1.9.1. Dead Band or Dead Space
4.1.1.9.2. Dead Time
4.1.1.10. 10. Resolution
4.1.1.10.1. the smallest change in the input value that will produce an observable change in output
4.1.1.11. 11. Output Impedance
4.1.1.11.1. electrical output is interfaced with an electronic circuit = there will be output impedance
4.1.1.11.2. having a sensor that reads the output impedance can modify the behavior of the system
4.1.2. Static VS Dynamic
4.1.2.1. Static Characteristics
4.1.2.1.1. values given when steady-state conditions occur
4.1.2.2. Dynamic Characteristics
4.1.2.2.1. 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.
4.1.2.3. Response Time
4.1.2.4. Time Constant
4.1.2.5. Rise Time
4.1.2.6. Settling Time
5. Electronics: Filters
5.1. Filters
5.1.1. Signal Processing
5.1.1.1. a device or process that removes some unwanted components or features from a signal
5.1.2. Electronics
5.1.2.1. a circuit designed to pass inputs in a certain frequency range while blocking other inputs
5.1.3. Classes:
5.1.3.1. Linear or Nonlinear
5.1.3.2. Time invariant or Time variant
5.1.3.3. Causal or Not causal
5.1.3.4. Active or Passive
5.1.3.4.1. Active
5.1.3.4.2. Passive
5.1.3.5. Analog or Digital
5.1.3.6. Discrete time (sampled) or Continuous Time
5.1.3.7. Infinite Impulse Response (IIR) or Finite Impulse Response (FIR)
5.1.4. Types:
5.1.4.1. Low-Pass Filter
5.1.4.1.1. "High-cut"
5.1.4.2. High-Pass Filter
5.1.4.2.1. "Low-cut"
5.1.4.3. Band-Pass Filter
5.1.4.3.1. based on a frequency range
5.1.4.4. Band-Stop Filter
5.1.4.4.1. "Band-reject"
6. Sensors: Encoders
6.1. capture position or orientation
6.1.1. Rotary Encoder
6.1.1.1. electro-mechanical device
6.1.1.2. converts angular position/motion to analog/digital signal
6.1.2. Linear Encoder
6.1.2.1. paired with a scale which the encoder reads from
6.1.2.1.1. converts encoded position to analog/digital signal
6.2. Absolute
6.2.1. unambiguous position (doesn't depend on previous position)
6.2.1.1. robust to interruptions
6.3. Incremental
6.3.1. cyclical, ambiguous (counting of cycles)
7. Switches
7.1. Microswitch
7.2. Push Button
7.3. Optical Switch
7.3.1. photo-micro sensor non-contact triggering
7.3.1.1. triggers when object comes between components
8. Electronics: Diodes
8.1. Introduction
8.1.1. Active
8.1.2. Passive
8.1.3. Electro-mechanic
8.2. Diodes
8.2.1. a two-terminal electronic component that conducts primarily in one direction
8.2.1.1. Role: allow current to pass in forward direction, block current in reverse direction
8.2.1.2. Analogous example: Check Valve
8.2.1.3. First Diode: Thermionic Diode
8.2.1.3.1. Edison Effect: when hot, the cathode releases electrons into the vacuum
8.2.1.4. Types:
8.2.1.4.1. Diode
8.2.1.4.2. LED
8.2.1.4.3. Photodiode
8.2.1.4.4. Zener Diode
8.2.1.4.5. Schottky Diode
8.2.1.4.6. Transient-voltage-suppression Diode (TVS)
8.2.1.4.7. Tunnel Diode
8.2.1.4.8. Varicap
8.2.1.5. Ideal Diode:
8.2.1.5.1. Forward Biased
8.2.1.5.2. Reverse Biased
8.2.1.5.3. NO Break down region
8.2.1.6. Real Diode:
8.2.1.6.1. Forward Biased
8.2.1.6.2. Reverse Biased
8.2.1.6.3. Breakdown
8.2.1.7. Other Functions:
8.2.1.7.1. Unidirectional behaviour = Rectification: - convert AC to DC - detect AM radio signals
8.2.1.7.2. - voltage drop is a function of temperature = use as a temperature sensor or voltage reference
8.2.1.7.3. Avalanche Diode: protect circuits from high voltage
8.2.1.7.4. Varactor Diode: tune radio and TV receivers
8.2.1.7.5. Tunnel, Gunn and IMPATT Diode: - generate radio frequency oscillations - create microwave and switching circuits
8.2.1.8. Diode + Inductors:
8.2.1.8.1. current stopped = 0 --> stored energy creates reverse voltage spike (flyback) that can damage switch
8.2.1.9. Diode-Resistor Logic (DRL):
8.2.1.9.1. OR Gate
8.2.1.9.2. AND Gate
8.3. Integrated Circuit
8.3.1. a set of electronic circuits on one small chip (semiconductor material e.g silicon
9. Actuators
9.1. part of the machine that moves or controls something
9.1.1. Types:
9.1.1.1. 1. Mechanical
9.1.1.1.1. conversion of rotary motion to linear motion
9.1.1.2. 2. Electric
9.1.1.3. 3. Electro-mechanic
9.1.1.3.1. like mechanical actuators but control knob/handle is replaced with electric motor
9.1.1.3.2. rotary motion converted to linear displacement
9.1.1.4. 4. Piezoelectric
9.1.1.4.1. very short range of motion
9.1.1.4.2. very high voltages = tiny expansions
9.1.1.5. 5. Hydraulic
9.1.1.5.1. converts hydraulic pressure + flow into torque + angular displacement (rotation)
9.1.1.6. 6. Pneumatic
9.1.1.6.1. air
9.1.1.7. 7. Thermal
9.1.1.7.1. material in actuator changes from solid <--> liquid
9.1.1.7.2. narrow temperature range = precise control
9.1.1.8. 8. Magnetic
9.1.2. Types of Motion:
9.1.2.1. Linear
9.1.2.2. Rotary/Circular
9.1.3. Performance Metrics:
9.1.3.1. Force
9.1.3.2. Speed
9.1.3.3. Operating conditions
9.1.3.4. Durability
9.1.4. Electric Motors
9.1.4.1. DC Motors
9.1.4.1.1. continuous movement, speed of rotation easily controlled
9.1.4.2. AC Motors
9.1.4.2.1. outside Stator/inside Rotor/ Permanent Magnets or electrical windings
9.1.4.3. Stepper Motors
9.1.4.3.1. electromechanical
9.1.4.4. Solenoids
9.1.4.4.1. coil of electrical wire with an armature
9.1.4.4.2. electromagnet and plunger inside coil
9.1.5. Smart Motors:
9.1.5.1. in a Single Servo Model:
9.1.5.1.1. DC Motor
9.1.5.1.2. Reduction Gearhead
9.1.5.1.3. Encoder + Controller + Driver
9.1.5.1.4. Communications
10. Electronics: Microcontrollers and Microprocessors
10.1. Microcontrollers and Microprocessors
10.1.1. Microprocessor
10.1.1.1. heart of a computer CPU complete computation engine
10.1.1.1.1. General/personal purpose use
10.1.1.1.2. Example: Raspberry Pi
10.1.2. Microcontroller
10.1.2.1. MCU small computer on one IC one or more CPUs
10.1.2.1.1. Embedded applications
10.1.2.1.2. Example: Arduino
10.1.2.1.3. Selecting a Microcontroller:
10.1.3. Microprocessor Systems
10.1.3.1. 1. Central Processing Unit (CPU) or Microprocessor
10.1.3.1.1. Roles:
10.1.3.1.2. Parts:
10.1.3.2. 2. Memory
10.1.3.2.1. stores binary data
10.1.3.2.2. Size: depends on number of wires in the address bus
10.1.3.3. 3. Input and Output Interfaces
10.1.3.3.1. transfer of data between the microprocessor and the external world
10.1.3.4. 4. Buses
10.1.3.4.1. Data Bus
10.1.3.4.2. Address Bus
10.1.3.4.3. Control Bus
10.1.4. Microcontroller VS Microprocessor System
10.1.4.1. Microprocessor systems have an external peripheral Microcontrollers have RAM, ROM, EEPROM embedded internally
10.1.4.2. Microcontrollers = all on ONE CHIP Microprocessor Systems = many chips
10.1.4.3. Microcontrollers = cheaper Microprocessor Systems = expensive
10.1.4.4. Microcontrollers = lower processing speed (8 to 50MHz) Microprocessor Systems = high processing speed (>1GHz)
10.1.4.5. Microcontrollers = simpler tasks Microprocessor Systems = more complex tasks
10.1.5. Computer
10.1.5.1. Structure:
10.1.5.1.1. 1. Input devices
10.1.5.1.2. 2. Processor
10.1.5.1.3. 3. Main memory
10.1.5.1.4. 4. Output devices
10.1.5.1.5. 5. Backing storage
10.1.5.2. Classification:
10.1.5.2.1. Structure
10.1.5.2.2. Type
10.1.5.2.3. Size
11. Electronics: 555 Timer
11.1. Timer 555
11.1.1. an integrated circuit used in a variety of timer, pulse generation, and oscillator applications
11.1.1.1. Structure:
11.1.1.1.1. a SR Flip-flop
11.1.1.1.2. 2 comparators (OPAMPS)
11.1.1.1.3. transistor Q1 = switch
11.1.1.2. Modes of Operation:
11.1.1.2.1. 1. Monostable
11.1.1.2.2. 2. Astable
11.1.1.2.3. 3. Bistable
11.1.1.3. Pulse Width Modulation (PWM)
11.1.1.3.1. modulation = changing
11.1.1.3.2. allow the control of power supplied to electrical devices
12. Electronics: OPAMPS
12.1. OPAMP
12.1.1. a high-gain electronic voltage amplifier with a differential input and a single-ended output
12.1.1.1. Used in:
12.1.1.1.1. 1. Signal conditioning
12.1.1.1.2. 2. Filtering
12.1.1.1.3. 3. Perform math operations
12.1.1.2. Symbols:
12.1.1.2.1. V+
12.1.1.2.2. V-
12.1.1.2.3. Vout
12.1.1.2.4. Vs+
12.1.1.2.5. Vs-
12.1.1.3. Structure:
12.1.1.3.1. 20 BJT transistors
12.1.1.3.2. 11 resistors
12.1.1.3.3. 1 capacitor
12.1.1.4. Types:
12.1.1.4.1. Comparator
12.1.1.4.2. Inverting amplifier
12.1.1.4.3. Non-inverting amplifier
12.1.1.4.4. Differential amplifier
12.1.1.4.5. Summing amplifier
12.1.1.4.6. Differentiator
12.1.1.4.7. Integrator
12.1.1.4.8. Instrumentation amplifer
12.1.1.5. Ideal OPAMP:
12.1.1.5.1. Open-loop gain (AOL) = infinite
12.1.1.5.2. zero gain for common mode signal (only has gain when there is a voltage difference)
12.1.1.5.3. infinite input impedence
12.1.1.5.4. zero output impedence
12.1.1.5.5. infinite bandwith
12.1.1.6. Real OPAMP:
12.1.1.6.1. Bandwidth Considerations
12.1.1.6.2. Non Linear Limitations
12.1.1.6.3. Slew Rate
12.1.1.6.4. DC Imperfections
12.1.1.7. Summing Point Constraint
12.1.1.8. Negative Feedback Loop
13. Electronics: Transistors
13.1. Transistor
13.1.1. a semiconductor device used to amplify or switch electronic signals and electronic power
13.1.1.1. made from semiconductor material (silicone) through DOPING
13.1.1.1.1. Triode
13.1.1.1.2. Doping
13.1.1.2. Advantages
13.1.1.2.1. 1. no cathode heater
13.1.1.2.2. 2. very small size and weight
13.1.1.2.3. 3. lots of transistors can be made on one IC
13.1.1.2.4. 4. low operating Voltage
13.1.1.2.5. 5. physically robust
13.1.1.2.6. 6. no maintenance
13.1.1.3. Limitations
13.1.1.3.1. 1. silicon can age and fail
13.1.1.3.2. 2. high power/frequency operation better suited for vacuum tubes where e- can move better
13.1.1.3.3. 3. sensitive to radiation and cosmic rays
13.1.1.4. Types:
13.1.1.4.1. FETS Field-effect Transistors
13.1.1.4.2. BJTS Bipolar junction Transistors
13.1.1.5. Categories:
13.1.1.5.1. Semiconductor Material
13.1.1.5.2. Structure
13.1.1.5.3. Electrical Polarity
13.1.1.5.4. Maximum power rating
13.1.1.5.5. Maximum operating frequency
13.1.1.5.6. Application
13.1.1.5.7. Physical Packaging
13.1.1.5.8. Amplification Factor
13.1.1.6. Operation Modes:
13.1.1.6.1. 1. Saturation
13.1.1.6.2. 2. Cut off
13.1.1.6.3. 3. Active
13.1.1.6.4. 4. Reverse Active
13.1.1.7. Transistor as Switches
13.1.1.7.1. making use of cutoff and saturation states
13.1.1.7.2. Advantages of TRANSISTORS
13.1.1.7.3. Advantages of RELAY SWITCHES (a substitute)