Sensors

ME5410 Lesson 7

penway
Last updated on Oct 17, 2023 1 min read Course Notes, ME5410

Transducer: A device that converts one form of energy to another. Can be used as a sensor or actuator.

Sensor: sense a physical quantity and convert it to an measurable (usually electrical) signal. One or more transducers.

Classification

  1. By Measured: Temperature, Position, Pressure, Force, Flow, Level, Gas(Chemical)
  2. By Tech: Electrical, Optical, Magnetic, Mechanical
  3. contact vs non-contact; passive vs active; analog vs digital

Sensor Characteristics

  1. Transfer Function
  2. Range: min and max values
  3. Saturation: max-out
  4. Deadband: range where no output, usually around zero
  5. Hyteresis: difference between up and down
  6. Linearity: deviation from line
  7. SNR
  8. Error: systematic(bias), precision(random)
  9. Accuracy: how close to true value
  10. Precision(Repeatibility): how close each measurement
  11. Resolution: smallest change that can be reliably detected
  12. Stability: keep characteristics over time
  13. Zero Offset: output when input is zero
  14. Zero Drift: Zero Offset changes over time
  15. Response Time
  16. Operating Temperature

X. Calibration: determine transfer function X. Calibration Cycle: up and down (for hysteresis)

Sensor in Robotics

  1. Extroception vs Proprioception: external vs internal
  2. Position and Proximity Sensors
    • potentiometer: 电位器
    • capacitive proximity sensor: 电容接近传感器，可用于非金属测量距离
    • hall effect sensor: 霍尔传感器
    • ultrasonic sensor
  3. Touch Sensors
    • Contact sensor
    • Tactile sensor: pizeoresistive, capacitive,
    • Force sensor
  4. Vision Sensors
    • CCD and CMOS
    • Infrared 红外
    • ToF: time of flight, 通过测量光的往返时间来测量距离, 但是精度不高，但是便宜
    • LiDAR: light detection and ranging, 通过测量光的往返时间来测量距离, 精度高，但是贵
    • Radar: radio detection and ranging