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Sensor And Gesture
Inside Smart Phone
BHAVYA K SHAH - 375
• What is Sensing?
• What is Motion Sensing?
• Types of Sensors.
• Sensor benefits.
• What is Gesture?
• Benefit of Gesture.
• Traditional mobile sensing-based applications use extra equipments
which are unrealistic for most users. Smartphone’s develop in a
rapid speed in recent years, and they are becoming indispensable
carry-on of daily life. The sensors embedded in them provide various
possibilities for mobile applications, and these applications are
helping and changing the way of our living
• Bell may be the first generation of sensors; people tie up a bell to
a string so that when there is a vibration on the string, the bell will
ring. Bell is a very powerful and effective sensor; it contains two
parts: detection and processing. When a bell detects a vibration, it
will generate a period of ringing and the volume of the ringing is
proportional to the amplitude of the vibration
• A sensor (also called detector) is a converter that measures a
physical quantity and converts it into a signal which can be read
by an electronic instrument an observer or by.
• A sense is a physiological capacity of organisms that provides
data for perception.
• A sensor is a device which receives and responds to a signal
• In physics, motion is a change in position of an object with respect
to time and its reference point.
• The term ‘Motion sensors’ can be used to refer to any kind of sensing
system which is used to detect motion; motion of any object or
motion of human beings.
• Motion sensors also called as motion detector.
• An accelerometer measures proper acceleration, which is the
acceleration it experiences relative to free fall and is the acceleration
felt by people and objects. To put it another way, at any point in
space-time the equivalence principle guarantees the existence of a
local inertial frame, and an accelerometer measures the acceleration
relative to that frame. Such accelerations are popularly measured in
terms of g-force..
• Units: m/s2 or g
• Accelerometer is good at measuring the displacement of an object;
however, it is inaccurate to measure the spin movement of the
device, which is an easy thing for gyroscope.
• A gyroscope is a device for measuring or maintaining orientation,
based on the principles of angular momentum. Mechanically, a
gyroscope is a spinning wheel or disk in which the axle is free to
assume any orientation.
• A magnetometer is a measuring instrument used to measure the
strength and perhaps the direction of magnetic fields. Accelerometer
and gyroscope are able to detect the direction of a movement;
however, the direction is a relative direction; it obeys the coordinate
system that a Smartphone uses. Sometimes, different Smartphone
need to synchronize their directions; therefore, a magnetometer is
needed to get an absolute direction (the direction obeys the
coordinate system of earth).
• proximity sensor, which is comprised of an infrared LED and an IR
light detector. It is placed near the earpiece of a phone, and for a
good reason – when you place the handset up to your ear, the sensor
lets the system know that you're most probably in a call and that the
screen has to be turned off. The sensor works by shining a beam of
invisible to humans infrared light which is reflected from a nearby
object and picked up by the IR detector.
• light sensor is what measures how bright the ambient light is. The
phone's software uses this data to adjust the display's brightness
automatically – when ambient light is plentiful, the screen's
brightness is pumped up, and when it is dark, the display is dimmed
down. An interesting fact is that high-end Samsung Galaxy phones
use an advanced light sensor that can measure white, red, green,
and blue light independently.
• Barometer – a sensor that can measure atmospheric pressure. Data
measured by it is used to determine how high the device is above sea
level, which in turn results in improved GPS accuracy. On a related
note, the Motorola XOOM and the Samsung Galaxy Nexus were
among the first Android devices to feature this sensor.
• Thermometer for measuring ambient temperature. However, there's
a thermometer in pretty much any Smartphone, and some handsets
might have more than one of them. The difference is that they're
used to monitor the temperature inside the device and its battery. If
a component is detected to be overheating, the system shuts itself
down to prevent damage. And speaking of the Galaxy S4, it
pioneered the use of an air humidity sensor in a Smartphone. Data
provided by it was used in the S Health application to tell whether or
not the user was in their "Comfort Zone" – one with optimal air
temperature and humidity.
• We must also mention the fingerprint sensors built into a number of
smartphones, including the iPhone 5s, the Samsung Galaxy S5, and
the HTC One Max. Of these, the 5s has the sensor most convenient
to use as it does not require swiping in order to read fingerprint
data. Fingerprint scanners are most often used as an extra layer of
security – as a substitute for a lock screen password.
• The Science behind it ? that it uses your phone’s camera instead of a separate heart
rate sensor. As your heart beats, the capillaries in your fingers contract and dilate
causing a change in the way they reflect light. The process is called
Photoplethysmography if you want to read about it.
• How it works in phones? If you shine a bright light like, say, your phone’s LED
flash, on your index, its thin skin becomes slightly transparent making the capillaries
and their pulsing detectable. Now if you have a camera nearby, you can take a video
of your finger and use a smart algorithm to distinguish the pulses and hence calculate
the heart rate.
• How accurate is this? Very accurate. In my own comparisons against manual heart
rate measurement, a heart rate chest belt, and a Blood Pressure monitor that also
displays the heart rate
Type of Active Where Sensor Used
Sensor hubs maximize sensor benefits
Advantage of Sensors
1. It avoids a lot of wiring
2. It can accommodate new devices at any time
3. It's flexible to go through physical partitions
4. It can be accessed through a centralized monitor
5. Sensors networks allow a system to be extended from
one with basic functions to one that can receive and act
on data about the environment it operates in.
6. Sensors such as PIR detectors are relatively cheap if
using wired versions.
Disadvantage of Sensors
1. A sensor that you wouldn't expect to find on a
Smartphone is one capable of detecting harmful
radiation. Yet there's a phone that sports one – the
Sharp Pantone 5. Released only in Japan, it features a
dedicated button which launches an app used to
measure the current radiation level in the area.
2. it as we cant control propagation of waves
3. Comparatively low speed of communication
4. Gets distracted by various elements like Blue-tooth
Still Costly at large
• Gesture recognition enables humans to interface with the machine
and interact naturally without any mechanical devices.
• Using the Concept of Gesture Reorganization. It is possible to point a
finger at the computer screen so that the cursor wills move
• Gesture recognition can be conducted with techniques from
computer vision and image processing
Common Multi-Touch Gesture
Tap Double Tap Long Press Scroll Pan
Flick Two Finger Tap Two Finger Scroll Pinch Two hand Pinch
Two hand rotate
Benefit of Gesture
• Replace Keypad of phone
• Pointing Gesture
• Navigate in a virtual environment
• Pick up and manipulate virtual object
• Interact with the 3D world
• No physical contact with computer
• Communicate at distance
• No training is required
• Simple fast, and easy to implement. Can be applied on real system
and play game
• The system successfully recognized static and dynamic gesture.
Could be applied on a mobile robot control.
Disadvantage of Gesture
• Irrelevant object might overlap with the hand. Wrong object
extraction appeared if the object large than the hand.
• Performance recognition algorithm decreases when the
distance is greater than 1.5 meters between the user and the
• System limitation restrictions restrict the applications such
as the arm must be vertical, the palm is facing the camera
and the finger colour must be basic colour such as either red
or green or blue.
• Ambient light affects the colour detection threshold.