Robot Intelligence
Kevin Warwick
Robot Intelligence Characteristics
There are many different animals/insects:• Each has its own intelligence which is appropriate for that creature
e.g. humans or spiders.
• Each has its own range of sensors and actuators.
• Each has its own usual environment – its intelligence works well in
that environment.
• In other environments a creature may well not be able to survive or
prosper due to its intelligence and/or physical capabilities.
• A creature’s intelligence may well not fit at all with another
creature’s physical or mental requirements e.g. spiders playing
tennis or humans flying around caves using inbuilt echo location.
If a robot welder is stupid because it cannot make a cup of tea then so
too is a human stupid because they do not have an ultra-violet
sense.
Task Characteristics
What sort of Job does the robot do?
Inhospitable or Remote Environments:• Dangerous Environments (Chemical or Nuclear) e.g.
Bomb Disposal/Mine Clearance/Military.
• Environments too costly to send a human e.g. Undersea.
• Environments that would take too long to send a human
e.g. Space Exploration
• Environments that are physically impossible to place a
human e.g. Microscopic Environments
Tasks with high fatigue factors and demanding duty cycles
e.g. spot welding cars
Tasks that are unpleasant for people to perform e.g.
hoovering, cleaning, washing up.
Robot Hardware
What makes a robot
Any robot is made from a collection of various hardware components:-
• Locomotion – how the robot moves within the environment. E.g.
Wheels or Legs.
• Sensing – how the robot obtains information about itself and the
current state of the environment. E.g. Camera or Ultra-Sonic Range
Finder.
• Reasoning – how the robot utilises the information obtained from its
sensors to form decisions and actions. E.g. Reactive Controller or
Computer running AI program.
• Communication – how the robot communicates to a human or
machine operator and vice versa. E.g. Remote Control, Text
Interface or Video Link.
Environment and Task Driven
Constraints
Different Locomotion Strategies must be chosen
according to the task the robot has to perform
and the particular environment the task must be
performed in.
• How fast must the robot be able to move?
• Is the terrain rough or is it smooth like a floor?
• Is the environment unstructured or is it well
known and mapped?
Different Categories of Robot
Terrestrial – robots that move on the ground.
•
Mostly wheeled but also with tracks or legs.
•
More exotic designs include climbing, rolling and slithering robots
e.g. Robot Snakes.
Aquatic – robots that operate in water.
•
Most are neutrally buoyant and use water jets or propellers to
move.
Airborne – robots that fly.
•
Typically helicopters or fixed wing aircraft.
•
Unusual types include dirigibles (air balloons) and controlled
parachutes.
Space – robots that operate in microgravity.
•
Independently propelled robots “free flyers” e.g. Satellites
Types of Control
• Teleoperation – the robot is effectively remote
•
•
controlled with images from a camera mounted
on the robot being relayed back to the operator.
e.g. Underwater ROVs, Bomb disposal robots.
Semi-Autonomous – some decisions are made
automatically by the robot but the overall
behaviour is dictated remotely, such as
interesting targets to explore. e.g. Mars Rover.
Autonomous – all decisions are made by the
robot itself. e.g. Dwarf Robot.
Locomotion
(noun) Power of motion from place to place
For a robot to be able to interact with its environment it
must be able to:• Move within the environment in some manner
• Sense the environment it moves through
Kinematics:• The study of motion ignoring the forces that actually
generate that motion.
• Given some control inputs, how will a robot move?
(FORWARD KINEMATICS)
• Given some desired motion, which control inputs
should be chosen in order to obtain the desired
motion? (INVERSE KINEMATICS)
Statics and Static Stability
• Forces and moments propagate through a
robot’s structure
• Static Stability – defines a set of gaits that allow
a robot to remain “standing” without any control
wheels/legs.
Dynamics and Dynamic Stability
• How forces generate accelerations that produce
motion
• Dynamic stability – having to dynamically control
gait in order to ensure a robot does not fall over.
e.g. a single legged hopping robot.
Robot Motion
The motion of a robot will depend on the
mechanism through which the motion is
generated and supported
• Wheeled
• Legged
• Aquatic
• Flying
• Rocket Propelled
Let us consider, as an example, a description of
these tasks for wheeled robots
Wheeled Mobile Robots
• Wheels utilise friction
•
and ground contact to
enable motion
Lets consider the case
of an ideal wheel
pictured on the left.
The Ideal Wheel
Consider an Ideal Wheel
• Wheel rotates about the x-axis.
• Motion is solely in the y-direction.
• Measurement of wheel motion (odometry) from
e.g. a wheel encoder is perfectly accurate.
- A distance of 2.π.r in the y-direction is covered
for every rotation of the wheel.
Of course things aren’t quite that easy!
An actual wheel is considerably more
complicated than the ideal:• May be lateral slip if there is insufficient
traction
• Rough terrain and bumps, compression
and cohesion between the wheel and
ground surfaces often leads to a loss in
accuracy
• Some of the resultant motion will be in the
z direction
• Consequently, Odometry will be
inaccurate:• Driven wheels are more prone to error due
to the forces acting on the wheel
• One technique – for measurement - is to
use an additional non-driven, non-load
bearing, light wheel to more accurately
recover the motion of the robot – in terms
of both distance covered and in direction if
the light wheel has a castor. This can be
used for as a good approximate for low
velocity motion.
The Instantaneous Centre of
Curvature [ICC]
The Instantaneous Centre of
Curvature [ICC]
• Consider the case where several wheels are in
•
•
•
contact with the surface – see previous slide.
If all wheels in contact with the surface are to
roll – then the axes of each wheel must intersect
through a single centre of rotation – the ICC
(case a).
If no consistent ICC exists then the wheels
cannot roll (case b).
Not only must the ICC exist but each wheel’s
velocity must be consistent with a rigid rotation
about the ICC. E.g. If a set of three wheels were
equidistant from the ICC they would all have to
move at the same velocity.
Pose of a Robot and Frames of
Reference
• Vehicle on a plane has three degrees of
freedom
– two in translation (x, y)
• Based on a fixed frame of reference, a {W} or
World frame
– one in orientation 
•  = 0 is defined to point along the Wx direction
• positive rotations are counter-clockwise
– triplet (x, y, ) is defined as the pose of the
robot
Types of Robot Motion
• Holonomic Robots – can move in any
direction instantaneously. This is clearly
impossible as any real robot will have mass.
• Omni-Directional Robots – can in practice
move in any direction but takes time as the
robot has mass.
– Such robots are, in general, treated as being
Holonomic.
– E.g. Differential Drive with a castor wheel – dwarf
robots.
• Non-Holonomic Robots – this type of robot is
limited in the way it can move e.g. Car Parking.
– Normally limited by dynamic or kinematic restraints –
e.g. limited turning ability
Pose of an ideal “holonomic”
differential drive robot.
Pose of an ideal “holonomic”
differential drive robot.
• Consider the differential drive robot shown
in the previous Slide. This is an ideal
differential drive robot (with supporting
castor wheel ignored for the purpose of
simplicity)
• Inter-wheel spacing is D.
• Orientation of the robot is θ w.r.t. {W}.
• Position of the robot is (x,y) w.r.t. {W}.
• Where will the ICC be located?
Where is the ICC?
• The ICC will be located at some point along the axis of
the wheels.
– If Vleft=Vright
• Robot will move in a straight line forward/backwards – no change in
•
orientation i.e. ω=0.
The ICC is effectively at ∞ therefore the radius of curvature is also
∞ (i.e. a straight line!).
– If Vleft=-Vright
• The robot will turn on the spot – no translation purely change in
•
orientation.
The ICC is in the centre of the wheels and the radius of curvature is
0 (i.e. it rotates!).
– If │Vleft│≠│Vright│
• The robot will both turn and move (i.e. both translation and
rotation).
Where is the ICC?
• We can start by
writing some
equations using the
relationship between
Angular and Linear
Velocity.
Where is the ICC?
• So for each wheel on the robot
• [1] V  (R  D 2)
• [2] V  (R  D 2)
• Assuming we know VLeft and VRight (i.e. we
Left
Right
can control the speed of the wheels!)
• We can then solve the simultaneous
equations for ω and R.
Solving for R:
• From [1]  
• So:
VLeft
RD 2

and from [2]
VLeft
RD 2
VRight
RD 2

VLeft . D 2  VRight . D 2  VRight .R  VLeft .R
D
(VLeft  VRight )  R.(VRight  VLeft )
2
R
RD 2
VLeft ( R  D 2)  VRight (R  D 2)
VLeft .R  VLeft . D 2  VRight .R  VRight . D 2
• Therefore:
VRight
D(VLeft  VRight )
2(VRight  VLeft )
Solving for ω:
• From [1]
VLeft

VLeft

D 2
VRight

D 2 R
from [2]

VLeft
D 2


D
D 2 R
VRight

.D  VRight  VLeft
VLeft  .D  VRight
• Therefore:-
VRight
(VRight  VLeft )
D
Robot Intelligence
• Intellectual abilities/performance need to be
•
•
•
•
compatible with actuators/sensors and must
take account of mechanical reality.
Can operate on equations of motion etc (normal
route)
Can operate on learned behavioural route
(highly non-linear/human approach)
Can operate on taught approach (Asimo) –
programmed
Can operate under remote control