Transcript What is a sensor?

Project Overview
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Introduction & Product Analysis
Drawing & communication
Sensing abilities in robots
Programming Robots
Mechanisms and Systems
Designing new products & Packaging
Presentation and Rendering
Biomimicry
Concept Modelling
Concept presentations
LESSON 03
LESSON 3 STARTER
Learning objective: Learn about sensors, sensing within robots, and their application in
industry. Learn ways of establishing the sensing ability of robots. Develop new ideas for robots
using different sensors.
LEARNING ABOUT SENSORS
What is a sensor?
A sensor (also known as a detector) is a device that measures a physical quantity and
converts that measurement into a signal that can be read electronically.
Robots use sensors for a number of reasons. Sometimes robots need to acknowledge the
presence of something (a product) before they can carry out a job. So a robot packaging
boxes with chocolate bars needs to first know that the box is ready in front of it.
A sensor replaces the human ability to use our fives common senses. What are they?
New words: sensor
Sensing Abilities of robots
How can a robot sense?
Discussion with your peers
Why would a robot car want to sense it surroundings?
“Cars are driven by humans. During a driving test and in order to pass, a human will need to
use a sense of sight to see hazards, a sense of hearing to acknowledge hazards that are not
immediately visible, a sense of touch to operate controls of the car, a sense of smell to
identify potential fuel or fire hazards, and perhaps only a sense of taste is not required.”
In order for a robot car to operate as a human does with the same level of safety, it would
need to be able to employ the same sensing abilities. Though we have the sensors needed to
achieve this, why do we not have robot cars on our roads (as we see in the futuristic
movies?)
Sensing Abilities of robots
VEX Robotics Sensors
VEX is a robotics design system for educational use that secondary schools can offer to help
students like you to design and build robots. To help students learn how to design industry
standard robot solutions, VEX provides a range of sensors. Here are some and what they do…
A Light Sensor
This sensor detects different levels of light and
darkness. The robot receives a signal from the sensor
and interprets it as a voltage. This voltage can be used
by a robot to trigger a response, which might be to
stop moving (when it finds darkness) or move
towards a light.
New words: voltage
Sensing Abilities of robots
VEX Sensors
Ultrasonic range finder
Much like a bat flies through the air avoiding
obstacles in the pitch black, an ultrasonic range finder
sends out a sound signal which bounces off an object
and returns to the sensor informing the robot how
close it is getting to an obstacle as it moves.
A bump switch
This bump switch is a very simple sensor which allows
the robot to “crash” into obstacles, hitting the bumper
surface, which closes an electrical circuit. As it closes, a
electronic signal travels to the robot informing it a
collision has occurred, allowing the robot to respond.
New words: switch, signal
Sensing Abilities of robots
VEX Sensors
Limit switch
Similar to a bump switch, a limit switch closes a
circuit which triggered. The only difference is that the
sensor acknowledges very small delicate “touches”
rather than collisions. This allows the robot to sense
very small or fine movements and respond.
Shaft encoders
The sensors detect rotational movement. They
would be fitted in pairs to the axel of a robot
vehicle (through the hole) and record the
rotation of the axel as a robot moved. They
allow a robot to “know” exactly where it is.
New words: shaft is also known as an axel on vehicles
Sensing Abilities of robots
VEX Sensors
Line follower
These three sensors are very useful in detecting a
changing surface. By pointing all three sensors down
onto the ground under a robot, and lining each
alongside one another, the robot can detect changing
signals between each sensor. If a signal changes from
a sensor (which would be caused by the surface of
the floor changing colour) then the robot could
receive this signal and change how it is behaving.
These sensors allow robots to follow lines on the
floor.
Sensing Abilities of robots
Human Senses
Of the five human senses, which can be replicated (or imitated) in VEX sensors and with
which sensor.
Task:
Complete the table below on your hand-out.
EXAMPLE
Y/N
SENSE
Touch
Bump switch or Limit switch
Smell
Sight
Light sensor and line sensors
Hearing
Ultrasonic range finder
Taste
Sensing Abilities of robots
Hexbug Sensing abilities
Task:
You are going to employ a range of “tests” to decipher and prove that a Hexbug can sense.
Cup your hands over the
Hexbug
Does it stop moving?
Clap your hands loudly
over the Hexbug
Does it change direction?
Touch the antenna on the
Hexbug head
Does it change direction?
Put obstacles in the way of
the Hexbug
Does it avoid them?
Yes = It senses light.
Yes = It senses sound.
Yes = It senses touch.
Yes = It senses infra red light.
Sensing Abilities of robots
Hexbug Sensing abilities
Results. Which Hexbug was able to sense what?
The crab sensed…
The original sensed…
The larva sensed…
The ant sensed…
The scarab sensed…
How can you prove it? How can you prove it?
How can you prove it?
How can you prove it?
How can you prove it?
Where is the sensor?
Where is the sensor?
Where is the sensor?
Where is the sensor?
Where is the sensor?
Sensing Abilities of robots
Hexbug ideas
Ideas Task: Consider what senses have not been achieved in a Hexbug so far.
Smell & Taste
What insect or creature could the Hexbug be?
What would it do?
Why would it sense this (what would be it’s purpose?)
LESSON 3 PLENARY
As a class, let us consider the following questions?
A. Why do robots sense things?
B. What sensors can be applied and in which situations?
C. How could a robot be blinded?
D. What animals in nature have similar sensing abilities?
Summary
Learning objective: Learn about sensors, sensing within robots, and their application in
industry. Learn ways of establishing the sensing ability of robots. Develop new ideas for robots
using different sensors.
Today you have:
 Learnt what different sensors can be applied in the field of robotics
 Developed methods of testing the ability of robot sensors
 Developed ideas for new robots using sensors