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Introduction to Computer Vision and Robotics
Robotic Sensors
Mohamad Javad AeinWS 2014-2015
Modeling Sensing
Actuation
Motion Planning
AIControl
Kinematics
Dynamic
Modeling
Kinematics
Control
Sensing
ActuationDynamic
Modeling
KinematicsToday!
Control
Sensing
ActuationDynamic
What is a sensor?
TransducerInput energy Output energy
SensorInput energy Electrical energy
What is a sensor?
TransducerInput energy Output energy
ActuatorElectrical Output energy
Why do we need sensors?
Why do we need sensors?
Uncertainty in actuator
Uncertainty in Environment
Why do we need sensors?
Why do we need sensors?
Sensor: detects events or changes in quantities
Types of sensors
Proprioception(PC)
Types of sensors
Proprioception(PC)
Motor speed
heading
Joint torque
Battery status
Types of sensors
Proprioception(PC)
Exteroception (EC)
Motor speed
heading
Joint torque
Battery status
Types of sensors
Proprioception(PC)
Exteroception (EC)
Motor speed
heading
Joint torque
Battery status
Distance to objects
Ext. Force/torque
Light intensity
Tactile sensor
Types of sensorsThermistor
Types of sensors
Passive
Thermistor
Types of sensors
Passive
Thermistor
Ultrasonic sensor
Types of sensors
Passive
Active
Thermistor
Ultrasonic sensor
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
Range and Span
Minimum and Maximum value
Range
Span
Difference of Max and Min values
e.g : Themperature range -40 to 70
e.g : span 110 degrees
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
Minimum detectable change in input
Resolution
e.g: Themperature range 0.1 degree
e.g: 0.1 % of span
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
Difference between output and true value
Accuracy
e.g: Themperature accuracy 0.5 degree
e.g: 1 % of span
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
AccuracyResolution vs
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
Precision
Repeatability of measurement
e.g: Themperature precision 0.1 degree
e.g: 0.2 % of span
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
AccuracyPrecision vs
Not precise: Bad sensor!
Not accurate: calibration!
Range and Span
Sensor characteristics
Precision
Accuracy
Resolution
Dead zone
AccuracyPrecision vs
Not precise: Bad sensor!
Not accurate: calibration!
Range and Span
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception Exteroception
Position/Velocity
Heading
Wheel speed
Position/Velocity
Heading
Obstacles
Proprioception Exteroception
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Motor/Axis sensor
Classes of sensors
Motor/Axis sensor Potentiometer
Classes of sensors
Motor/Axis sensor Potentiometer
Absolute position!
CheapLow performance
Classes of sensors
Motor/Axis sensor Resolver
Classes of sensors
Motor/Axis sensor Incremental encoder
Classes of sensors
amplitude
ω=αt
direction
00=001=110=211=3
Example: 1000 pulse/turn
α=360rsupdeg
1000=0.36deg
Motor/Axis sensor Incremental encoder
Classes of sensors
amplitude
ω=αt
direction
00=001=110=211=3
Example: 1000 pulse/turn
α=360rsupdeg
1000=0.36deg
Motor/Axis sensor Incremental encoder
Speed
No absolute position!
Classes of sensors
Motor/Axis sensor Absolute encoder
Classes of sensors
Gray code
Motor/Axis sensor Absolute encoder
Normal binary
Classes of sensors
Motor/Axis sensor
Incremental encoder
Potentiometer
Resolver
Inductive encoder(Incoder)
NEW!
Absolute encoder
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Heading sensor
inclinometer
compass
Classes of sensors
Heading sensors compass
Earth magnetic field
noisy
Sensitive to roll and pitch
Together with accelerometer
Mechanical
Hall effect
Magneto resistive
Mechanical
Hall effect
Magneto resistive
Classes of sensors
inclinometerHeading sensors
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Positioning
Classes of sensors
GPS
Global positioning system
Electromagnetic wave (speed of light)Position and velocity
expensive
Only outdoors
Next: Indoor Positioning System (IPS)
Positioning
Classes of sensors
Ultrasound
Mechanical wave (speed of sound)Position and velocity
Local
Positioning
Classes of sensors
Retroreflective beaconPositioning
Inertial navigation system (INS)
Inertial measurement unit (IMU)
Gyroscope
Accelerometer
Classes of sensors
Gyroscope Angular rate sensor
Mechanical
Precession
Classes of sensors
Gyroscope Angular rate sensor
Mechanical
Measuring Angular Velocity
Classes of sensors
Gyroscope Angular rate sensor
Optical Gyroscope
Sagnac effect Ring laserFiber optic
Classes of sensors
Gyroscope Angular rate sensor
Vibrating Gyroscope
Classes of sensors
Accelerometer Acceleration sensor
Mass-Spring system
Inertial navigation system (INS)
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Range/Proximity
Classes of sensors
Bumper sensorRange/Proximity
Classes of sensors
InfraredRange/Proximity
Classes of sensors
Laser range finder
Measure distance from observer to target
Range/Proximity
Classes of sensors
Ultrasonic range finder
SONAR: sound navigation and ranging
Range/Proximity
Classes of sensors
Range/Proximity
magnetic range finder
Camera
Inductive
Hall effect
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Tactile
Classes of sensors
Tactile sensors Pressure array
Tactel (tactile element)
Capacitive sensor Piezoelectric
Position/Velocity
Heading
Wheel speed
Proprioception
Position/Velocity
Heading
Obstacles
Exteroception
Joint Position
Joint Velocity
Joint Torque
Ext. Force/Torque
Grasp (Fingertips)
Obstacles
Proprioception
Exteroception
Force/torque
Classes of sensors
Force/Torque Torque sensor
Classes of sensors
Force/Torque 6 DOF F/T
Overview
What is a sensor
Why do we need sensors?
Types of sensors
Sensor characteristics
Classes of sensors
Actuators
� Motors
� Hydraulic/Pneumatic Actuators
� Artificial Muscles
� Inflatable Robot/Actuators
� Omnidirectional Wheels
Actuators
� Direct current (DC) considered, since battery
driven systems
Motors
� Direct current (DC) considered, since battery
driven systems
� Motor design:
± Standard DC
± Stepper Motors
± Servo Motors
Motors
� Direct current (DC) considered, since battery
driven systems
� Motor design:
± Standard DC
± Stepper Motors
± Servo Motors
� Adjustment of speed and direction of motion
Motors
DC Motor t Principle
DC Motor t Principle
� Torque produced by motor:
torque constant of motor, current in armature,
generated by the voltage applied to the motor
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
Wm K
mi
Km i
Va
DC Motor t Principle
� Torque produced by motor:
torque constant of motor, current in armature,
generated by the voltage applied to the motor
� Output power:
applied (required) torque, angular velocity of axis
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
Wa
Wm K
mi
Km i
Va
Po W
aZ
Z
DC Motor t Principle
� Torque produced by motor:
torque constant of motor, current in armature,
generated by the voltage applied to the motor
� Output power:
applied (required) torque, angular velocity of axis
� Input power:
applied voltage, current in armature
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
Wa
Wm K
mi
Km i
Va
Po W
aZ
Z
Pi V
ai
Va
i
DC Motor t Principle
� Torque produced by motor:
torque constant of motor, current in armature,
generated by the voltage applied to the motor
� Output power:
applied (required) torque, angular velocity of axis
� Input power:
applied voltage, current in armature
� Efficiency: (not constant for all speeds)
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
Wa
Wm K
mi
Km i
Va
Po W
aZ
Z
Pi V
ai
Va
i
K P0
Pi
WaZ
Vai
DC Motor
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
� Possibility to change the direction
of motion
DC Motor t Pulse Width Modulation (PWM)
� So far motor either runs or not
� Control of speed also necessary
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
DC Motor t Servo Motor
� DC motor with encapsulated
gearbox and electronics for PW
control of desired (angular)
position
� ~ +-120o around center position
DC Motors t In General
Remember:
� No (externally available) sensor attached to motor
� Wheel encoders have to be attached additionally
Criteria for motor selection:
� Task (servo/step/normal motor)
� Provides enough torque and speed
� Weight
� Size
� Efficiency
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
DC Motors t In General
Remember:
� No (externally available) sensor attached to motor
� Wheel encoders have to be attached additionally
Criteria for motor selection:
� Task (servo/step/normal motor)
� Provides enough torque and speed
� Weight
� Size
� Efficiency
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
K
Other Actuators
� Hydraulic/Pneumatic Actuators
� Artificial Muscles
� Inflatable Robot/Actuators
� Omnidirectional Wheels
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
� Single- and double-acting cylinders
Single-acting Double-acting
Hydraulic/Pneumatic Actuators
� Single-acting cylinders exert force either on
extension or retraction
� They require an outside force to complete the
second motion
� Double-acting cylinders generate force during
both extension and retraction
Hydraulic/Pneumatic Actuators
Hydraulic/Pneumatic Actuators
� Also hydraulic rotation actuators
http://www.youtube.com/watch?v=U4KpMiXOUAI
� Can be used with air or fluid
Artificial Muscles
Artificial Muscles
� Humanoid with fluid muscles
www.youtube.com/watch?v=pgKBWkY3Qks
Inflatable Robot
http://www.hizook.com/blog/2011/11/21/inflatable-robots-otherlab-walking-robot-named-ant-roach-and-complete-arm-plus-hand
Inflatable Robot
http://www.youtube.com/watch?v=BUtBd4sVrzA
� Pneumatic hand
� Wheel with additional small discs around the
circumference
� Normal forward movement
� Slide laterally with great ease
Omnidirectional Wheels
Omnidirectional Wheels
� Robot with omnidirectional wheels
http://youtu.be/XmEuu9X6s1E
Omnidirectional Wheels
� Fork lifter with omnidirectional wheels
http://youtu.be/CjcyHicm3NA
� Principle of DC motors
� Other actuators:
� Hydraulic/Pneumatic Actuators
� Artificial Muscles
� Inflatable Robot/Actuators
� Omnidirectional Wheels
� ...
Actuators t Summary
