This lecture is the first in the series which introduces the different types of sensors used in Robotics

1. Sensors for Robotics
UEEE210
Dr. Hema C.R.
Lecture 1

2. Road Map
• Introduction to Robotics
•History
•Robot Sensors
•Desirable features
• Need for Sensors
•Classification of Sensors.
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3. Introduction
• Robotics is an interdisciplinary field that
involves design, construction, operation,
and use of robots.
• The goal of robotics is to design machines
that can help and assist humans.
• Robot is derived from the Czech word
Robota meaning ‘A worker of forced labor’.
The word first appeared in a 1921 play
“R.U.R” (“Rossum's Universal Robots”) by a
Czech playwright Karel Capek
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4. Introduction
• Robots find applications in many areas such as
• Manufacturing and Assembly,
• Service,
• Military,
• Domestic,
• Hospitals etc.,
• They all share three basic similarities when it comes to
their construction:
• All Robots have some kind of mechanical construction, a
frame, form or shape designed to achieve a particular task.
• Robots have electrical components that power and control
the machinery.
• All robots contain some level of computer coding for
navigation and movement. There are three different types of
robotic programs: remote control, artificial intelligence and
hybrid.
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5. Classification by JIRA
Japanese Industrial Robot Association (JIRA) :
“A device with degrees of freedom that can
be controlled.”
•Class 1 : Manual handling device
•Class 2 : Fixed sequence robot
•Class 3 : Variable sequence robot
•Class 4 : Playback robot
•Class 5 : Numerical control robot
•Class 6 : Intelligent robot
Ref: https://en.wikipedia.org/wiki/Japan_Robot_Association
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6. Robot manipulators
Mobile Robots
Mobile manipulators
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7. Four Legged Military Robot
Six Legged Robot
Two Legged Robot
Eight Legged Robot
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8. Robotic Sensing
• Robotic sensing is a branch of robotics science
intended to give robots sensing capabilities, so that
robots are more human-like.
• Robotic sensing mainly gives robots the ability to see,
touch, hear and move and uses algorithms that
require environmental feedback.
• The use of sensors in robots has taken them into the
next level of creativity. Most importantly, the sensors
have increased the performance of robots to a large
extent. It also allows the robots to perform several
functions like a human being.
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9. •Sensors are devices that responds to a physical
stimulus heat, light, sound, pressure, magnetism,
motion, etc. and convert that into an electrical signal.
They perform an input function.
•Actuators are devices which perform an output
function and are used to control some external device,
for example movement. Coverts electrical energy to
mechanical movement (motors)
•Both sensors and actuators are collectively known as
Transducers.
•Transducers are devices used to convert energy of one
kind into energy of another kind.
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10. Robot Sensors
• Robotic sensors are used to estimate a robot's
condition and environment. These signals are passed
to a controller to enable appropriate behavior.
• They sense and measure geometric and physical
properties of robots and the surrounding
environment
• Position, orientation, velocity, acceleration
• Distance, size
• Force, moment
• Temperature, Luminance,
• Sensors in robots are based on the functions of
human sensory organs.
• Robots require extensive information about their
environment in order to function effectively.
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12. Desirable features of Sensors
1. Accuracy: Accuracy should be high. How close output
to the true value is the accuracy of the device.
2. Precision :There should not be any variations in the
sensed output over a period of time precision of the
sensor should be high.
3. Operating Range: Sensor should have wide range of
operation and should be accurate and precise over
this entire range.
4. Speed of Response: Should be capable of responding
to the changes in the sensed variable in minimum
time.
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13. Desirable features of Sensors
5. Calibration: Sensor should be easy to calibrate, time
and trouble required to calibrate should be
minimum. It should not require frequent
recalibration.
6. Reliability: It should have high reliability. Frequent
failure should not happen.
7. Cost and Ease of operation :Cost should be as low
as possible, installation, operation and maintenance
should be easy and should not required skilled or
highly trained persons.
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14. Need for Sensors
• Sensors are needed in robotics in order to make
them automated.
• Without sensors, a robot is, in essence, blind and
deaf.
• Sensors allow a robot to collect information from the
surrounding environment, in order to interact with it.
• Humanoid robots need a multitude of these sensors
in order to mimic the capabilities of their living
counterparts (human).
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15. Need for Sensors
•Sensors are important in creating robots which are
efficient in their appointed purpose.
•The inclusion of sensors is imperative to their
automation. however, developers need to take care
when choosing which sensors to incorporate in the
design.
•Sensor type, sensitivity, accuracy, and position are
all important factors for the success of the robot.
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16. •Industrial manufacturing robots need sensors
in order to allow them to operate efficiently for
pick and place of objects without crushing or
dropping them.
•They use torque sensors which monitor and
control rotational forces.
Torque Sensor
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17. • Acoustical and piezoelectric sensors allow
robots to identify prominent sounds, such as
commands, in an area with background
noise.
• Robots can incorporate pre-programmed
outputs based upon the commands heard.
This could be especially useful for field work,
or robots in noisy environments.
Acoustic proximity sensors
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18. • The simplest sensors are switch sensors. There
are three types of switch sensor; contact, limit
and shaft encoder sensors.
• All of these sensors work without processing.
The most useful type of switch sensor is the so-
called “bump switch” which allows a robot to
‘feel’ when it has impacted into an object,
although it a simple concept, but it can be
implemented in many different types of robots.
Bump switch
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19. • Light sensors can also be used in multiple ways.
They give a robot the ability to see.
• Light sensors allow robots to measure light
intensity, differential intensity, and break-beam,
i.e. the sudden reduction of intensity.
• These light sensors can be applied in different
positions and directions depending on the
robot’s intended purpose.
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20. Classification of Sensors
• There are a wide variety of sensors used in robots
• Sensors can be classified using two important functional
axes
• Proprioceptive / exteroceptive (internal/external)
• passive/active.
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21. Classification of Sensors
Proprioceptive sensors measure values
internal to the robot; for example,
• motor speed,
• wheel load,
• robot arm joint angles, and
• battery voltage.
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22. Classification of Sensors
Exteroceptive sensors acquire information
from the robot’s environment; for example,
• distance measurements,
• light intensity, and
• sound amplitude.
• Hence, exteroceptive sensor measurements
are interpreted by the robot in order to extract
meaningful environmental features.
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23. Classification of Sensors
Passive sensors measure ambient
environment energy entering the sensor.
Examples of passive sensors include
• temperature probes,
• microphones, and
• CCD or CMOS cameras.
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24. Active Sensors
• They emit energy into the environment, and then
measure the environmental reaction.
•As active sensors can manage more controlled
interactions with the environment, they often achieve
superior performance.
•However, active sensing includes several risks: the
outbound energy may affect the very characteristics
that the sensor is attempting to measure.
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25. •An active sensor may suffer from interference
between its signal and those beyond its
control.
•For example, signals emitted by other
nearby robots, or similar sensors on the
same robot may influence the resulting
measurements.
•Examples of active sensors include
•wheel quadrature encoders,
•ultrasonic sensors, and
•laser range finders.
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26. Q and A