Southern Taiwan UniversityMechanical Engineering Department

SILO4 Walking RobotSILO4 Walking Robot Course: Robotic Teacher: Wu. Min- Kuang

Student: Phan. Quy- Phai Student number: M961Y211

Taiwan, January 2008

PresentationPresentation

Out lineOut line• Introduction.• Main characteristic .• Robot configuration.• Body structure.• Leg configuration.• Food design.• Some insights parts developed .

+ System Configuration.+ Computing system. + Sensors and sensor system.+ Control algorithms.• Summary.• References.

IntroductionIntroduction During the last three decades, walking –machine technology has been exciting fiel

d 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 configurationRobot 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 structureBody structure

• The body of the robot is similar to a parallelepiped measuring about 310 x 310 x 300 mm.

• 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 configurationLeg configuration• The legs of the robot are based on an insec

t-type configuration.

• The leg parts are mainly manufactured in aluminum, and some specific parts are made of aluminum 7075T6.

• The second and third joints’ axes lie parallel to each other and perpendicular to the axis of the fist joint.

• The first link is about 60 mm long, and the second and third links are about 240mm.

• Each joint is actuated by a dc servomotor, the motor are embedded in the leg structure.

• The motor are provided with planetary gear. Fig 3. The SILO4 leg configuration

Leg configuration Leg configuration (continue)(continue)

• 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 resemb

les a worm, and a face gear with teeth curved in a lengthwise direction.

Fig 4. (a) Spiroid gear. (b) A spiroid

gear mounted

in the second and third joints of the l

egs

This is table summarizes the main characteristics of the leg joints

Food designFood 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 ConfigurationSystem Configuration • The overall SILO4 system a

dmits 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 systemComputing system

• The control system, is a distribute hierarchical system compose of a PC-based 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 systemSensors 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 algorithmsControl 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 join

t. + leg layer control: this layer is in charge of coordinating all three jo

ints in a leg to perform coordinated motion . +leg kinematics: this layer contain the direct and inverse kinematics f

unction of a leg. +trajectory control: this mode is in charge of coordinating the simul

taneous motion of four legs. +stability mode: determines whether a given foot position configurat

ion is stable. +Gait generator: general the sequence of leg lifting and foot placeme

nt to move the robot in a stable manner. +graphic and user interfaces: contain the functions for ploting on the

computer screen .

SummarySummary 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 m

ain 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.

ReferenceReference • [1] K. Berns, The Walking Machine Catalogue. Available: • http://www.fzi.de/ipt/WMC/walking_machines_katalog/walking_ • machines_katalog.html • [2] S.M. Song and K.J. Waldron, Machines That Walk: The Adaptive Suspension Ve

hicle. Cambridge, MA: MIT Press, 1989. • IEEE Robotics & Automation Magazine 31 • [3] J.E. Bares and W.L. Whittaker, “Configuration of autonomous walkers • for extreme terrain,” Int. J. Robot. Res., vol. 12, no. 6, pp. 535–559, • 1993. • [4] J.E Bares and D.S. Wettergreen, “Dante II: Technical description, results • and lesson learned,” Int. J. Robot. Res., vol. 18, no. 7, pp. 621–649, • 1999. • [5] P. Gonzalez de Santos, M.A. Armada, and M.A. Jimenez, “Ship building with R

OWER,” IEEE Robot. Automat. Mag., vol. 7, pp. 35–43, • Apr. 2000. • [6] C.M. Angle and R.A. Brooks, “Small planetary rovers,” in Proc. • IEEE/RSJ Int. Workshop Intelligent Robots and Systems, Ikabara, Japan, • 1990, pp. 383–388. • [7] M. Fujita, “AIBO: Toward the era of digital creatures,” Int. J. Robot. • Res., vol. 20, no. 10, pp. 781–794, 2001. • [8] H. Kitano, M. Fujita, S. Zrehen, and K. Kageyama, “Sony legged robot.

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