TRC3500: Sensors and Artificial Perception
Week 1: Introduction to Sensing and Measurement
Key Concepts:
1. Sensors as Transducers:
o Convert physical phenomena (temperature, pressure, motion) into
electrical signals.
o A sensing module includes all hardware and embedded systems needed
to support the sensor and capture data.
2. Perception as Inference:
o Combines raw data with prior knowledge to construct a model of the
environment.
o Must manage variation and uncertainty to estimate the most likely
interpretation of noisy inputs.
3. Sensing and Transduction:
o Transduction: Conversion of one form of energy (mechanical, thermal)
into another (electrical signals).
o Input Modality: Type of stimulus (light, force, chemical composition).
o Output Modality: Resulting electrical signals (voltage, current).
4. Categories of Sensors:
o Direct Sensors: Produce electrical signals directly from the stimulus
(e.g., photodiode, piezoelectric sensor).
o Hybrid Sensors: Involve intermediate conversion steps (e.g., chemical
sensors generating heat).
o Passive Sensors: Do not require external power (e.g., thermocouples).
o Active Sensors: Require external power (e.g., thermistors).
Measurement and Evidence:
• Measurement Techniques:
o Direct: Explicitly obtain a value (e.g., ruler, thermometer).
, o Indirect: Relate to other measurable variables (e.g., thermistor resistance
converted to temperature).
o Null: Compare unknown quantity to a known reference (e.g., Wheatstone
Bridge).
• Measurement Quality:
o Validity: Measures the correct parameter without confounding variables.
o Reliability: Consistency across repeated trials.
o Accuracy: Closeness to the true value.
o Precision: Consistency of repeated measurements.
o Resolution: Smallest detectable change.
• Errors:
o Theoretical: Model assumptions fail.
o Static: Steady-state inaccuracies (e.g., parallax errors).
o Environmental: External factors (temperature, humidity).
o Dynamic: Sensor response lag.
o Insertion Errors: Device perturbs the system.
Standards in Measurement:
• Hierarchy:
o International Reference Standards (most reliable).
o National Primary Standards.
o Transfer Standards.
o Working Standards (least reliable).
Week 1: Introduction to Sensing and Measurement
Key Concepts:
1. Sensors as Transducers:
o Convert physical phenomena (temperature, pressure, motion) into
electrical signals.
o A sensing module includes all hardware and embedded systems needed
to support the sensor and capture data.
2. Perception as Inference:
o Combines raw data with prior knowledge to construct a model of the
environment.
o Must manage variation and uncertainty to estimate the most likely
interpretation of noisy inputs.
3. Sensing and Transduction:
o Transduction: Conversion of one form of energy (mechanical, thermal)
into another (electrical signals).
o Input Modality: Type of stimulus (light, force, chemical composition).
o Output Modality: Resulting electrical signals (voltage, current).
4. Categories of Sensors:
o Direct Sensors: Produce electrical signals directly from the stimulus
(e.g., photodiode, piezoelectric sensor).
o Hybrid Sensors: Involve intermediate conversion steps (e.g., chemical
sensors generating heat).
o Passive Sensors: Do not require external power (e.g., thermocouples).
o Active Sensors: Require external power (e.g., thermistors).
Measurement and Evidence:
• Measurement Techniques:
o Direct: Explicitly obtain a value (e.g., ruler, thermometer).
, o Indirect: Relate to other measurable variables (e.g., thermistor resistance
converted to temperature).
o Null: Compare unknown quantity to a known reference (e.g., Wheatstone
Bridge).
• Measurement Quality:
o Validity: Measures the correct parameter without confounding variables.
o Reliability: Consistency across repeated trials.
o Accuracy: Closeness to the true value.
o Precision: Consistency of repeated measurements.
o Resolution: Smallest detectable change.
• Errors:
o Theoretical: Model assumptions fail.
o Static: Steady-state inaccuracies (e.g., parallax errors).
o Environmental: External factors (temperature, humidity).
o Dynamic: Sensor response lag.
o Insertion Errors: Device perturbs the system.
Standards in Measurement:
• Hierarchy:
o International Reference Standards (most reliable).
o National Primary Standards.
o Transfer Standards.
o Working Standards (least reliable).
