Download Fig 3. The SILO4 leg configuration

Southern Taiwan University
Mechanical Engineering Department
Presentation
SILO4 Walking Robot
Course: Robotic
Teacher: Wu. Min- Kuang
Student: Phan. Quy- Phai
Student number: M961Y211
Taiwan, January 2008
Out line
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Introduction.
Main characteristic .
Robot configuration.
Body structure.
Leg configuration.
Food design.
Some insights parts developed .
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+ System Configuration.+ Computing system.
+ Sensors and sensor system.+ Control algorithms.
Summary.
References.
Introduction
During the last three decades, walking –machine technology has been exciting
field of investigation for robotic, and many improvements have been
developed since then first computer-controller prototypes of the early 1970s.
Since then, a large number of walking robots has been developed all over the
word.
One of the walking robots is SILO4 walking robot. The SILO4 walking robot is
a medium-sized quadruped mechanism built for basic research and
development as well as for educational purposes. The SILO4 is a compact,
modular, robust machine cable of negotiating irregular terrain,
surmounting obstacles up to 250 mm tall and
carrying about 15kg in payload at
a maximum velocity of about 1.5 m/min,
depending on the gait it is using.
The SILO4 has proven very efficient in research
on motion generation, terrain adaptation, stability
analysis, e.t.c. And it is expected to be the same in
subjects such as artificial intelligence, perception
integration, teleoperation and so on.
This robot can work in an outdoor environment
under non extreme conditions.
Fig . SILO4 is walking on bad way.
Main characteristic.
• Four legs
• Small size and low weight for easy
handing.
• Mechanical robustness.
• Slenderness, so as to avoid motor
position that give big leg volumes.
• Compactness, with all motors and
electrical cables conveniently
housed.
• Agility in changing trajectories for
good omnidirectionality
• Control provided by a true real-time
multitasking operating system
supporting network communication
Fig 1. SILO4 robot
Robot configuration
• The SILO4’s legs are placed around the body in a
circular configuration.
• In astatically stable, the configuration is
distributed symmetrically about longitudinal and
transversal body axes are distributed symmetrical.
• The place along the sides of legs is parallel to the
longitudinal.
Body structure
• The body of the robot is similar to a
parallelepiped measuring about 310 x
310 x 300 mm.
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it contains all of the drivers and
electronic card.
• It is made of aluminum, body’s weight
is about 18 kg.
• The upper part of body installs
auxiliary equipment and exteroceptive
sensors.
• The four side walls also can be used for
the same above purposes.
Fig 2. Numeration of the parts in SILO4 Walking
Leg configuration
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The legs of the robot are based on an
insect-type configuration.
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The leg parts are mainly manufactured in
aluminum, and some specific parts are
made of aluminum 7075T6.
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The second and third joints’ axes lie
parallel to each other and perpendicular to
the axis of the fist joint.
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The first link is about 60 mm long, and the
second and third links are about 240mm.
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Each joint is actuated by a dc servomotor,
the motor are embedded in the leg structure.
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The motor are provided with planetary gear.
Fig 3. The SILO4 leg configuration
Leg configuration (continue)
Fig 4. (a) Spiroid
gear. (b) A spiroid
gear mounted
in the second and
third joints of the
legs
• The output shaft of a planetary drives the first joint.
• The second and third joints have an additional reducer
based on a skew - axis spiroid mechanical.
• Spiroid gear consist of a tapered pinion, which
resembles a worm, and a face gear with teeth curved
in a lengthwise direction.
This is table summarizes the main characteristics of
the leg joints
Food design
• The normal SILO4
foot consists of a
passive universal joint.
• A three –axis
piezoelectric force
sensor placed in the
third link above
passive joints.
• A simpler articulated
foot without a force
sensor and half-sphere
foot with a passive
joint. [see Fig 4(b) and
4(c), respectively ]
Fig 5. SILO4 foot configurations
This is summarizes the main features of the
SIL04 walking robot.
System Configuration
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The overall SILO4 system
admits two different
configuration.
+ The first configuration
consists of : a unique
computer on board the robot,
a dc power supply provides
power to computer and robot
motors, a screen and
keyboard.
+ The second configuration
consists of: two computer
( the controller runs on the
onboard computer), a
batteries, radios.
Fig 6. SILO4 system configurations
Computing system
• The control system, is a distribute
hierarchical system compose of a PCbased computer, a data-acquisition
board, and four three-axis control board
based on the LM 629 microcontroller,
interconnected through an industry
standard architecture (ISA) bus.
• The LM629 microcontroller include
digital proportional-integral-derivative
(PID).
• Every controller has a dc motor joint
driver based.
• Additional component could be added
depending on the sensor used in the
system
Fig 7. SILO4 hardware architecture.
Sensors and sensor system
• The robot possess internal sensors, and it uses an
encoder on each joint as a position sensors.
• The robot can include different sensors depending
on the foot type:
+if the robot has articulate feet with force sensors
then the sensor system will possess a three-axis
force sensor and two potentiometers per foot.
+ if the robot is articulate with no force sensors
then the sensor system will incorporate an on/off
switch on each foot sole for ground detection.
• No absolute sensors have been installed to fix the
origin of the encoder.
Fig 8 . The force Sensor
and Potentiometers
Control algorithms
• Task of robot are distributed in a software architecture by layers. These
layers can be divided:
+ hardware interface: this layer contain the software drives.
+ axis control: this layer performs the control of individual robot
joint.
+ leg layer control: this layer is in charge of coordinating all three
joints in a leg to perform coordinated motion .
+leg kinematics: this layer contain the direct and inverse kinematics
function of a leg.
+trajectory control: this mode is in charge of coordinating the
simultaneous motion of four legs.
+stability mode: determines whether a given foot position
configuration is stable.
+Gait generator: general the sequence of leg lifting and foot
placement to move the robot in a stable manner.
+graphic and user interfaces: contain the functions for ploting on the
computer screen .
Summary
Indeed, there are currently three SILO4 robots in use testbeds as the
Industrial Automation Institute .
Otherwise The SILO4 has proven very reliable and suitable for its
main purpose, and it has already been used as a testbed for many
tasks. The SILO4 was demonstrate at the Second and Third
International Conferences on Climbing and Walking Robot and has
been offered as a common platform for the above mentioned
purposes. To overcome the marketing and maintainability
shortcomings plaguing the SILO4 commercial predecessors and to
facilitate the use of this legged machine as a real common platform
demonstrate.
Therefore, we can see clearly that: this robot is really became a
common testbed for experiments and discussion in areas such as
artificial intelligence, perception, motion generation, terrain
adaptation, and stability analysis. This is the new developmental
step at the walking robot area.
Reference
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Thanks for your attention!