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Sensors for Humanoid Robot
Daniel Baptista1
Filipe M. T. Silva1
Vítor M. F. Santos2
1
Department of Electronics and Telecommunications
2
Department of Mechanical Engineering
University of Aveiro, PORTUGAL
Centre for Mechanical Technology and Automation  TEMA
Institute of Electronics Engineering and Telematics  IEETA
 http://www.mec.ua.pt/robotics
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Overview
 Introduction
 Sensors for humanoid
 Feet Sensors
• Strain gauges
> New Solutions
» Load cell
» The linear variable differential transformer (LVDT)
» Capacitive sensors
» The pressure linear potentiometer
» Multi-Axis Force/Torque Sensor
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Accelerometers
Gyroscope
Electronic Magnetic Compasses
CCD Camera
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Introduction
 Complete humanoid model
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22 degrees of freedom
Weight - 5 kg
Height - 60 cm
Max. width - 25 cm
Foot print - 20  8 (cm2)
 Actuation
 Servomotors with transmission belts
 Sensors
 A CCD Camera
 Servos’ position (through its internal
potentiometers)
 Sensitive feet to applied forces
 Accelerometers/Inclinometers
 Gyroscopes
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Envisaged sensorial capabilities
Vision unit (on
the head)
Gyroscopes for angular velocity
GYROSTAR
ENJ03JA from
MURATA
Potentiometer for
position feedback
(HITEC Motor)
Accelerometers for
accelerations and inclinations
ADXL202E from
ANALOG DEVICE
Motor electric current
Sensitive feet
Strain gauges on a slightly
compliant material
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors
 The strain gauges sensors esteem the Humanoid’s body
balance
 There are 4 strain gauges sensors on each foot. They
are used to…
 measure ground reaction forces
 calculate the location of the Center of Pressure (CoP)
Adjustable screw
Strain Gauge
Flexible beam
Foot base
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors
 The first version of strain gauges amplifier
 No temperature compensation
 Unbalanced Wheatstone bridge
Power regulator
PIC
Reset button
Power plug
Piggy-back
board 1
CAN bus
PWM plugs
Servo fuse
RS232
plug
Fuse
status LED
Piggy-back
board 2
Connector
to sensor
Unit CAN
Address
Connector
to sensor
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors
 The second version of strain gauges Amplifier
 High consumption of current
 Bad contact in connectors the white board
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors
 The third version of strain gauges amplifier
 The mechanical screw adjust in the feet introduces perturbations
 The potentiometer in the bridge causes problems
PCB Design
 But, we are not satisfied!
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 1
 Load Cell
 The load cell used piezoresistors sensors in
Wheatstone bridge
 The force sensor operates on the
principle that the resistance of
silicon implanted in the
piezoresistors will increase when
the resistors flex under an applied
force.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 2
 The linear variable differential transformer (LVDT)
 The transformer has three solenoidal coils
placed end-to-end around a tube. The
centre coil is the primary, and the two outer
coils are secondaries.
 A cylindrical ferromagnetic core, attached
to the object whose position is to be
measured, slides along the axis of the tube.
As the core moves, these mutual
inductances change, causing the voltages
induced in the secondaries to change.
 The coils are connected in reverse series,
so that the output voltage is the difference
between the two secondary voltages.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 3
 Capacitive sensors
 Capacitive sensors measure the distance between two plates
via their capacitive effect
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 4
 The pressure linear potentiometer
 Implementation in Sony’s SDR-4X and suspected in
QRIO
 There are 4 force sensors in the
foot sole. The sensors are
specially designed diaphragm type
sensor. The measurable range is
0~5 kg and the resolution is 10g.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 5
 The Multi-Axis Force/Torque Sensor system
measures all six components of force and torque
 Strain gauge sensor is attached
to each measurement beam and
each beam measures only one
component of translational force.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Feet sensors – New solution 5
 Honda’s ASIMO utilizes six-axis force sensors in
each foot of the robot.
 These sensors measure forces and moments in all
three directions as seen at the ankle.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Accelerometer/Inclinometer
 The Accelerometer/Inclinometer used are
ADXL202E (Analog Devices).
 The ADXL202E will measure accelerations with a fullscale range of ±2 g.
 The ADXL202E can measure both dynamic acceleration
(e.g., vibration) and static acceleration (e.g., gravity).
When the accelerometer is
oriented so both its X and Y
axes are parallel to the
earth’s surface it can be
used as a two axis tilt sensor
with a roll and a pitch axis.
Pitch  ASIN ( Ax / 1g )
Roll ASIN ( Ay / 1g )
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Accelerometer/Inclinometer
 Circuit of conditioning signal for Accelerometer
/Inclinometer
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Accelerometer/Inclinometer
 Gravity acceleration measurement
 Static acceleration (gravity)
 Dynamic acceleration
(gravity + dynamic moving)
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Gyroscope
 Piezoelectric Vibrating Gyroscopes
 The gyroscopes is an angular velocity sensor that
uses the phenomenon of Coriolis force, which is
generated when a rotational angular velocity is
applied to the vibrator.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Gyroscope
 Piezoelectric Vibrating Gyroscopes (GYROSTARr)
(muRata)
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Electronic Magnetic Compasses
 Electronic Compasses
 Two-axis magnetic compasses measure the horizontal vector
components of the earth's magnetic field using two sensor
elements in the horizontal plane but orthogonal to each
other.
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
CCD Camera
 Unibrain Fire-i Digital Board Camera
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
CCD Camera
 OpenCv the image processing
 Color Filter
 Template match
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Sensors for Humanoid Robot
End
Thank you
Daniel Baptista1
Filipe M. T. Silva1
Vítor M. F. Santos2
UNIVERSITY OF AVEIRO, PORTUGAL
Centre for Mechanical Technology and Automation
Institute of Electronics Engineering and Telematics
Power Management
 Low Dropout Linear Regulator UCC283-5 3A (Texas
Instrument)
PCB Design