SECTION 3: FUNCTION OF ROBOTS, SENSING DEVICES AND ACTUATORS
1.
What is
meant by 'Degrees of freedom'? Ensure you include a diagram to highlight your
understanding. (p. 253)
‘Degrees of
freedom’ is meant by the number of different ways an appendage can pivot with
the term relating to the amount of movement is built and utilised within the
nature design. An example of this is below in this robotic arm with the base of
the robot (moving mechanism) having the ability to move remotely in any
direction and for the arm mechanism to rotate its arm 360 degrees.
2.
There are 5 general input devices used in
robotics. List them below. (p. 254)
1.
Digital camera
2.
Keyboard
3.
Light pen
4.
Mouse
5.
Microphones
3.
Sensors are a common input device on
robotics. Complete the following table (see p. 254 to 255)
Sensor Name
|
Description
|
Examples of use
|
Potential Issues
|
Thermostat
|
Switch that opens at a set
temperature and stays open while the temperature remains at that level or
higher.
|
Ovens, hot water services
|
Cheap but not as accurate/responsive
as other senses.
|
Thermistor
|
Measures temperature continually as
resistance: when the temperature increases the resistance drops.
|
Microwave ovens and air conditioners
|
Cheap and also similar to thermostat.
|
Semiconductor
|
Are sensor materials that have
electrical conductivity to a degree between a conductor and an insulator.
|
Transistors, solar cells and LED
lights.
|
Expensive but efficient.
|
Light
|
Detect changes in the level of light.
They collect data related to the intensity of light of an image and then
convert it to a digital form.
|
Barcode scanners, burglar alarm
|
It is harder to convert more
complicated images into digital form.
|
Position
|
A sensor used to monitor and track
the relative position of objects around it.
|
Ultrasonic sensor and proximity
sensor
|
The machine operates to a very
accurate extent but the machine could fail. A repair of a position sensor is
not easy.
|
Potentiometers
|
Sensors that are used to determine
rotation measuring electrical resistance with a meter showing the amount of
voltage at a particular point.
|
A video game joystick and a remote
control
|
Overheating and wrong readings.
Environment could have an effect on the reading. For e.g. Wind and rain.
|
Sonar
|
Sonar sensors are used to detect
sound underwater to discover the position of an object in the water.
|
Submarines and boats.
|
Can have some harm to marine mammals
such as whales.
|
4.
Define and compare an Actuator to a Sensor
A sensor is a device that converts input from
the environment into a signal that can be communicated to a control system. An
actuator however is a specialised hardware device which, under control, comes
out as mechanical actions. The differences between a actuator and a sensor is a
sensor controls the input into a robotic system however the actuator then
receives the input and then creates the appropriate output responses. Actuators work on performing the work from
the measured inputs by powering the system such as electrical and hydraulic
power however sensors focus on measuring the data from its environment such as
temperature, light, touch, sound etc. Actuators also produce mechanical actions
but sensors focus on converting an input into a signal that then leads to an
output, carried out by the actuator.
18. Actuators are
a common output device on robotics. Complete the following table (see p. 256)
Output devices
|
Description and main feature
|
Advantage
|
Disadvantage
|
Speakers
|
Is an external hardware that produces
sound from a computer through a 3.5mm stereo jack. The main feature is the
speaker’s volume control.
|
Normal speech rather than synthesized
speech is possible
|
Require extra hardware e.g. sound
cards
|
Display (CRT or LCD)
|
Is an output surface that projects
mechanisms that show text, images, animations etc. The main feature of an LCD
display is that they are available for many applications.
|
No waste of paper and instead can be
interactive or display animations.
|
No hard copy (ie. printed page)
|
Solenoids
(an actuator)
|
A cylindrical coil of wire acting as an electromagnet when carrying
electric current. It uses the electromagnet to move an arm or plunger through
a small movement.
|
High reliability and limited pressure
drop.
|
Control signal must stay on while in
operation.
|
Stepping motors
(an actuator)
|
A motor that moves and rotates in
small, discrete steps. It also uses electromagnets with it utilizing a shaft
that makes the motor turn.
|
Needs no feedback
|
Has low efficiency.
|
19.
Define Primary Storage and provides examples
(p. 257)
Primary storage is a device that holds data
for processing, processed data waiting for output and instructing for
processing. Primary storage is found in the motherboard where it is linked to
the processing parts of the computer such as the CPU and GPU. Some examples of
primary storage are ROM and RAM.
20.
Define Secondary Storage and provide examples
Secondary storage is any storage device that
is located outside of the CPU (central processing unit). This type of storage
is not essential to the operation of the computer but is used as a peripheral
to hold information and store data that can be accessed from the computer.
Secondary storage also is not the main memory of the computer. Some examples of
secondary storage are hard disk drives, DVD’s and portable flash drives.
21.
Using the following diagram, write below what
each letter represents. You will find an overview of this motherboard at http://www.build-your-own-computer.net/motherboard-diagram.html
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