Sensors for Robots - Nyu

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2 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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Sensors

Definition


Sensor: A device which provides
information

about the physical world.

Transducers


Convert of energy from one form to another.



e.g. microphone and speakers convert
between

acoustic and electrical energy.



Many transducers are bidirectional.



Some sensors
are

transducers; almost all
involve transduction.

What can be sensed?


Direct Transduction
: e.g., electric and
magnetic fields, mechanical strain,
temperature, electromagnetic energy...



Derived quantities
: e.g. distance, human
presence, heading, air flow, molecular
concentrations, air pressure, color...

Common Animal Sensors

Sensor

Phenomena

Eye

Electromagnetic waves in
some

sub
-
spectrum

Ear

Pressure waves between about 10 hz and
100kHz (animal
-
dependent)

Nose

Concentration of airborne molecules

Tongue

Concentration of dissolved molecules, etc.

Skin

Pattern of pressure on animal's surface

Proprioceptive
system

Pattern of nerve impulses from muscles

Unusual Animal Sensors


Magnetoreceptor: Sensing of earth’s magnetic
field. Seen in newts, birds, rats and maybe
humans.



Electric field sensing: Seen in a variety of fish.



Cerci: Cockroach airflow sensors



Body as eye: Brittlestar covered with optically
perfect lenses

Biological Rotation Sensor


semicircular canals

detect angular
acceleration




3 canals: one per plane



inertia of fluid causes deflection of sensory element

Robot design as creature design


Animal sensory systems adapted to
functional needs and environment.



Robots can use non
-
biological sensors
which suit them to their ‘ecosystems’



e.g., neutron
-
sniffing robodog, UAV with
weather radar, etc.



Sensors for dead reckoning



Typical sensor:
optical encoder



One type found in
standard computer
mouse



Quadrature encoding

Sensors for orientation/heading


Use:
orientation/heading



Options: gyroscope,
geomagnetic sensors



Issues: gyro drift, B
-
field distortion

Sensors for obstacle detection


e.g., where are walls?



Options: ultrasonic
TOF, lateral
-
effect
photodiode (PSD)


Sensors for detecting humans


Options: computer vision,
pyroelectric sensor



pyroelectric sensors detect far
-
IR
radiation



can also detect heat, fire



standard alarm sensor (cheap)