2. Learning Objectives
The aim of this lecture is to understand the brief
introductions to robotics, actuators and sensors,
and manipulators:
• Introduction to Robotics
– History of robotics
– Application of robotics
• Actuators and sensors
• Manipulators
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3. Reference textbooks
1. P. Corke (2017). Robotics, Vision and Control (Second Edition).
2. B. Siciliano, L. Sciavicco, L. Villani, G. Oriolo (2010). Robotics: Modelling,
Planning and Control.
3. John J. Craig (2005). Introduction to Robotics: Mechanics and Control
(Third Edition).
4. R. Siegwart, I. R. Nourbakhsh, D. Scaramuzza (2011). Introduction to
Autonomous Mobile Robots (Second Edition).
5. B. Sciliano, O. Khatib (2008). Springer Handbook of Robotics.
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https://moodle.glos.ac.uk/course/view.php?id=48366
4. 1.0: Robot Definition
The term robot was first introduced by the Czech playwright Karel Capek in his
1921 play Rossum’s Universal Robots (the word robota being the Czech word for
worker). The term automaton had been used since ancient Greek times.
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Two common definitions are:
• An industrial robot is a reprogrammable, multifunctional manipulator designed
to move parts, tools or special devices through variable programmed motions
for the performance of a variety of tasks.
• A robot is an artificial physical agent that perceives its environment through
sensors and acts upon that environment through actuators.
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5. 1.1: Brief History of Automatons
• 1,000 BC Yan Shi (China) creates a humanoid automaton (sing and dance)
• 400 BC Archytas of Tarentum (Greece) designed a mechanical bird, "The
Pigeon“, which was propelled by steam.
• 322 BC Homer's Iliad, Aristotle speculated (Politics book 1, part 4) that
automatons could bring about human equality by the abolishing slavery.
• 1206 Al-Jazari’s humanoid robot. A boat with four automatic musicians. It
had a programmable drum machine with pegs that bump into little levers that
operate the percussion. The drummer could play different rhythms and drum
patterns by moving the pegs.
• 1464 Leonardo Da Vinci’s warrior. Humanoid automaton was dressed in
medieval armour, capable of some human-like movements. It was able to sit,
wave its arms and move its head and jaw.
• 1737 Jacques de Vaucanson’s Digesting Duck. Powered by weights, it
could flap its wings (each wing has over 400 parts), eat & digest grain, and
defecate by excreting matter stored in a hidden compartment.
• 1868 Zadoc P. Dederick's Steam Man inspired many walking machines, and
(science) fictional stories (patented, google patents). Robot was designed to
pull a cart.
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6. 1.1: Brief History of Robotics
• 1921 The term "robot" was first used in a play published by the Czech Karel Čapek.
• 1938 World’s Fair, New York: “Electro” and “Sparko” (Westinghouse Electric Corporation). It could walk
by voice command, speak about 700 words, smoke cigarettes, blow up balloons, and move his head
and arms.
• 1940-45 Small radio-controlled robot tanks in World War 2 (Goliath & teletanks)
• 1962 First industrial arm robot (Unimate) installed on a General Motor’s assembly line. Unimation
becomes profitable in 1975.
• 1966 Stanford “Shakey” first general purpose mobile robot with vision system
• 1968 General Electric “walking truck” for the US army. Movements are slaved to an operator.
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7. 1.1: Brief History of Robotics
• 1968 Hydraulic Minsky-Bennett arm developed by Marvin Minsky. (Twelve joints)
• 1969 Victor Scheinman (Stanford) created the Stanford Arm
• 1970 The Stanford Cart which can follow lines and controlled via radio
• 1977 Asea produce a microcomputer controlled range of arms. These will go on to become ABB
• 1979 SCARA robot
• 1979 Stanford Cart rebuilt to include vision which permits 3D mapping
• 1981 Takeo Kanade builds the direct drive arm which is the first to have motors installed directly
into the arm joints.
• 1986 Honda start a research programme which leads to ASIMO
• 1988 Lego and MIT collaborate to create LEGO Logo
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8. 1.1: Brief History of Robotics
• 1992 John Adler developed Cyber Knife which takes x-rays (tumour) and delivers a dose of
radiation
• 1993 Dante (8 legged walking robot) developed at CMU (falls into a crater in the Antarctic)
• 2000 ASIMO unveiled by Honda
• 2001 Lego Mindstorms released
• 2001 Candaarm2 on the ISS (International Space Station)
• 2002 Roomba released by iRobot
• 2003 Mars rovers Spirit and Opportunity land
• 2006 Big dog (and petman) developed by Boston Dynamics (google)
• 2007 HyQ was developed by iit (Italian Institute of Technology)
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10. 1.2 Current Robotic Application
Sectors
• Manufacturing
• Surgical
• Service
• Military
• Healthcare
• Home
• Space
• Farming
• Security/surveillance
• Rescue
• Extreme Environments
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11. Activity
You are given 15 minutes to search some content
related with robots or their applications, then come
back to discuss your findings with classmates.
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12. 2.1 Actuators
Three commonly used actuator types:
• Electromagnetic
– The most common types of actuators
• Hydraulic
• Pneumatic
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13. 2.1.1 Electromagnetic Actuators
Brushed DC Motor
• Current flowing through armature generates a magnetic field and
permanent magnets torque the armature
– Advantages: provides variable speeds, low-cost
– Disadvantages: Brush wear out, low precision
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14. 2.1.1 Electromagnetic Actuators
Brushless DC Motor
• Armature is fixed, and permanent magnets rotate
– Advantages: Efficiency, Low noise, Cooling, Water-resistant
– Disadvantages: low precision, costly
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15. 2.1.1 Electromagnetic Actuators
Stepper Motor
• Brushless, synchronous motor that moves in
discrete steps
– Advantage: Precise, quantized control without
feedback
– Drawback: Slow and moves in discrete steps,
expensive
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16. 2.1.2 Hydraulic Actuators
Cylinders (linear actuators):
• Advantages:
– Very powerful that offer very large
force capability, but expensive
– High power-to-weight ratio
• Drawbacks:
– Their power supplies are bulky and
heavy
– Oil leakage
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17. 2.1.2 Hydraulic Actuators
Cylinders (linear actuators):
• Force, F, calculation extend & retract:
– Cylinder bore diameter: 25 mm
– Cylinder rod diameter: 16 mm
– Max pressure, P= 21 MPa (210 bar)
F = P * A
Calculate force for extending the rod with max P:
A = π R2 = 490.625 mm2
F = 21 x 490.625 = 10,303 N
Retract the rod:
A = A1 – A2 =π R2 = 289.665 mm2
F = 21 x 289.665 = 6,083 N
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A
P
A1
A2
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21. Question 1
• What types of actuators have you ever used?
• Why have you chosen to use it or them?
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22. 2.2 Sensors
• Motivation, why do robots need sensors?
• Robotic sensor classification
• Various sensors overview
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23. 2.2.1 Motivation
• A robot would be easily controlled if a complete model of the
environment was available for the robot, and if its actuators could
execute motion commands perfectly relative to this model.
• Sensors only measure a physical quantity
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24. 2.2.2 Robotic sensor classification
• Proprioceptive
– Internal state of the robot
– Measures values e.g. wheels position, joint angle, battery level,
etc
• Exteroceptive
– External state of the system
– Observing environment, detecting objects, etc.
• Active
– Emits energy (e.g. radar)
• Passive
– Receives energy, e.g. camera
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25. 2.2.2 Robotic sensor classification
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Application Sensors PC/EC A/P
Tactile sensors (physical contacts, distance
estimation etc)
Bumpers, contact switches
Optical barrier
Proximity sensors
EC
EC
EC
P
A
A
Wheels and Motors sensors
Detecting speeds and position
Brush encoders
Potentiometers
Optical, magnetic, inductive
capacitive encoders
PC
PC
PC
P
P
A
Heading Sensors
Orientation of robot and alignment
Compass
Gyroscopes
Inclinometer
EC
PC
EC
P
P
A/P
Ground based beacons (localisation)
GPS
RF, ultrasonic, reflective beacons
EC
EC
A
A
Active ranging (reflectivity, time-of-flight,
geometric triangulation)
Ultrasonic, laser, reflective sensors
Optical triangulation (1D)
Structured light (2D)
EC
EC
EC
A
A
A
Motion and speed sensors (relative to a fix
or moving object)
Doppler radar
Doppler sound
EC
EC
A
A
Vision-based sensors (visual ranging,
segmentation, object detection etc)
CCD/CMOS cameras
(ranging, tracking, etc packages)
EC P
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26. 2.2.2 Robotic sensor classification
• Real-world Characteristics of sensors
– Sensitivity: Ratio of output change to input change.
– Error/Accuracy: Difference between the sensor’s output and the true
value.
• Systematic/Deterministic Error: Caused by factors that can be
modelled (in theory), e.g., calibration of a laser sensor.
• Random Error: e.g., hue instability of camera, black level noise of
camera.
– Reproducibility: Reproducibility of sensor results.
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30. 2.2.3 Various sensors overview
• Thermal sensor
• Thermal resistor
• Temperature sensors
– Analogue
– Digital
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31. 2.2.3 Various sensors overview
• Proximity sensors
• Non-contact
• Devices that can be used in areas
that are near to an object to be
sensed
• Different types of Proximity
Sensors:
– Infrared
– Ultrasonic
– Inductive
– Capacitive
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32. 2.2.3 Various sensors overview
Position Sensors (for angle)
• Potentiometer
• Resolver
• Optical Encoders
– Relative position
– Absolute position
Measure position, speed, direction of revolution of the wheel.
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33. 2.2.3 Various sensors overview
Heading sensors:
• Heading sensors can be proprioceptive (gyroscope, inclinometer) or exteroceptive
(compass).
• Used to determine the robots orientation and inclination
Compass
• The magnetic compass was invented by Chinese (more than 2000 years ago),
suspended a piece of natural magnetite from a silk thread and used it to guide a chariot
over land.
• Absolute measure for orientation based on Earth magnetic field
o Mechanical magnetic compass
o Direct measure of the magnetic field, Hall-effect
Drawbacks:
Easily disturbed by magnetic objects or other sources
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34. 2.2.3 Various sensors overview
• Accelerometer
• Acceleration is the change in velocity over time, based
on Newton’s 2nd law (F = ma) a sensor may be made to
sense acceleration by simply measuring the force on a
mass.
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35. 2.2.3 Various sensors overview
Gyroscope
• Heading sensors for measuring
and to keep the orientation to a
fixed frame
• Two methods:
– Mechanical (flywheel)
– Electronic
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Gyroscope was invented by Jean Bernard
Léon Foucault, a French physicist, in 1852.
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36. Question 2
• What types of sensors have you ever used?
• Why have you chosen to use it or them?
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37. Components used for Manipulators
• Components in a joint:
– Motors (electric or hydraulic)
– Motor Encoders
• Angle (joint angle)
• Displacement sensor
– Gearbox
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38. 3.1: Robotic Manipulators
A wide range of robotic manipulators exist. Typically, all manipulators represent
a different price, performance & capability trade-off.
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39. 3.1: Manipulator Application
(before)
Benefits in repetitive operation:
• Increase volume / capacity
• Improve quality and consistency
• Untouched by human hand
• Reduce wastage
• “Up skilling” of work force
A Return On Investment (ROI) study would be performed to quantify these
factors and justify the investment in a bespoke robotics solution.
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40. 3.1: Manipulator Application
(after)
• Pancakes are delicate (use a blown air end effector to grasp)
• Require high (variable) volume, fast turn around, minimum waste,
• 4 FlexPickers (delta robots) with cameras are used
• Stacks ~100 each minute
• Increased capacity / reduced costs eliminated the competition
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41. 3.2 Joints
• Different types of joints:
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Revolute Joint
(R)
Prismatic Joint
(P)
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42. Joints
• Different types of joints:
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Cylindrical Joint Spherical Joint
Universal Joint
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47. Manipulator
• Links:
– n moving link(s)
– 1 fixed link
• Joints
– Revolute (1 DOF)
– Prismatic (1 DOF)
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Base
Revolute
Joints
End effector
Link i
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48. Position Parameters
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Position parameters describe the full configuration of the
system
Generalised coordinates:
A set of independent configuration parameters
Degree of Freedom:
Number of generalised coordinates
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49. Position Parameters
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• We need 6 DOF to have access to 3D space
3 DOF : Position
3 DOF : Orientation
Revolute and prismatic joints have 1 DOF
How about Cylindrical joint?
How about Spherical joint?
Revolute Joint
Prismatic Joint
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50. Generalised coordinates:
• A set of independent configuration parameters
• Each rigid body needs 6 parameters to be described
– 3 positions
– 3 orientations
• For n rigid body, we need 6n parameters
• Constrains must be applied:
– Each joint has 1DOF, so 5 constrains
will be introduced.
n moving links 6n parameters
n joints 5n constrains
How many DOF?
6n – 5n = n DOF
This is for manipulator with fixed base
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6 parameters
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51. End effector configuration
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End effector is the last rigid-body and it has all the freedom from
previous links.
A set of parameters describing position and orientation of the end
effector: (x1, , x2 , x3 , ...., xm) with respect to {0}
On+1 : is operational coordinates (task coordinates)
A set of x1, , x2 , x3 , ...., xmo
of mo independent configuration parameters
mo is number of DOF of the end effector,
max 6 DOF
{0}
On+1
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52. End effector, Joint coordinate:
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Joint space (configuration space) is the space that a manipulator is represented
as a point.
(x,y) is a vector for position of end effector
α defines orientation (angle) of end effector
Defines:
operational coordinates Operational space
θ
θ1
θ2 θ3
θ1
θ2
θ3
(x,y)
α
End effector
x
y
α
Robot in configuration space
End effector in operational space
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53. Redundancy
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A manipulator is redundant if
n m
n number of DOF of the manipulator
m number of DOF of the end effector (operational space)
Degree of redundancy: n - m
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54. General Manipulator Videos
• Where it all began (in the 70s)
http://www.youtube.com/watch?v=2xNgQhLAPyI
• Precise motion control
http://www.youtube.com/watch?v=SOESSCXGhFo
• 10 application areas for robotics
http://www.youtube.com/watch?v=fH4VwTgfyrQ
• Programming robots
http://www.youtube.com/watch?v=acJ3WDnoDCM
• Couple of FlexPicker videos
http://www.youtube.com/watch?v=8G59zTXVHHU
http://www.youtube.com/watch?v=KC70eDs1D2Y
• Robotics for Extreme Environments
https://www.bloomberg.com/news/features/2017-02-16/one-job-the-robots-can-
have-cleaning-nuclear-waste
https://www.youtube.com/watch?v=OLvAQFz5wh8&t=171s
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55. Summary
The aim of this lecture is to understand the brief
introductions to robotics, actuators and sensors,
and manipulators:
• Introduction to Robotics
– History of robotics
– Application of robotics
• Actuators and sensors
• Manipulators
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Editor's Notes
Generalised coordinates: has minimum number of parameters involved ,,with much less parameters
How many constrains the placement of each joint will be introduce?
With 3 orientation parameters and one position vector, we can describe an end effector
Later we will use rotation matrix to transfer the frames
We call m0 because it’s independent, before was m
>> if we have an end effector in a plane (x,y), how many parameter do we need? 2 for position and one for orientation
In space, maximum DOF we can have is 6
Three revolute joints and this robot moving in plane!
This vector shows configuration of the manipulator
>> This joint space is very important for motion planning
So (x,y, α ) represents fully position and orientation of end effector
SO>>> robot is reduced to the point θ in configuration space and its end effector is reduced to a point (x,y,alpha) in operational space
