11/12/01

A Hobby Robotics Recipe

Keisuke UTO @utotch

How To Make Multi-Robot Formation Control System

Motivation

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•  Denso.Inc Company Group(Car Equipment Company In Japan) holds a idea contest “Muran”(means Eggs of dreams) every other year

•  Employee can submit ideas which they want to be come true and if the ideas are adopted, they can get some money to make them.

•  I subscribed a idea of next page

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You can line up Radio Controlled Cars by only drawing a curve!

Line up to a ‘S’ shape

We finished line up!

Roger!!

Robots line up to be a shape of you input

Multi-Robot Formation Control by stroke input

If you input a stroke,

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How do I realize this idea?? I thought a implementation of next page.

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Rough Design of a implementation

WiFi

ZigBee

USB Camera

iPad

Swarm Robots

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But, a budget of making this system was limited. Can I make this system by a limited budget ?? It’s difficult to make robots which can move free directions. (It’s difficult to move free directions by normal 4 wheels cars) I surveyed that how to make this system by using market products.

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Ideas of moving free directions system

Mechanum wheel

Airtrex Omni Directional Drive Honda U3-X

NISSAN Pivo2 Omni-Wheel

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Can I get moving free directions system in market product??

WowWee.Inc ROVIO ($350)

http://www.wowwee.com/en/products/tech/telepresence/rovio/rovio

Which has a camera, and can be controlled by WiFi It’s too expensive if I buy it a lot.

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Since a budget is limited, I gave up to make my system using market products. Then I decided to make them by myself. I didn’t predict many hard troubles of making robot by myself…

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Hardware design of meeting my budget

http://www.tosadenshi.co.jp/blog/18cm.html

18cm Omni-Wheel Kit Reasonable Version 14,500JPY

Tosa Electric.Inc(in Japan)

4 Wheel urethane omni-wheel kit 53,000JPY

Appendix

I adapted this system which is most reasonable.

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Robot Implementation LEGO Blocks

XBee Wireless Module

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Robot Implementation(detail)

Motor IC x 4 (Toshiba TA7291P)

Micro Computer (Arduino FIO)

Omni-Wheel

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I introduce some parts and technologies of making my system

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Arduino FIO

・2500 JPY ・Xbee can be attached directly ・Analogue Input (x8) ・Digital I/O (x14) ・Enable PWM Output (x6)

Summary

Microcontroller ATmega328P Operating Voltage 3.3V Input Voltage 3.35 -12 V Input Voltage for Charge 3.7 - 7 V Digital I/O Pins 14 (of which 6 provide PWM output) Analog Input Pins 8 DC Current per I/O Pin 40 mA Flash Memory 32 KB (of which 2 KB used by bootloader) SRAM 2 KB EEPROM 1 KB Clock Speed 8 MHz

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ZigBee

http://www.switch-science.com/products/detail.php?product_id=96

One of specs of wireless communication in short distance

In Japan, 2.4GHz (250Kbps) band can be used.

Xbee Wireless Module(2500JPY) We can use Xbee as a pseudo serial port

Point-to-Point

Point-to-Multi-Point

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How To Make Swarm Robots (by myself)

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How to make Robots

A My Colleague said> You should make printed circuit boards I said> I don’t have skills of doing that.

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Make!

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And still more Make!

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And still more more Make!!

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Done!!

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Overview of my system

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How do I implement computer vision system?? I implement them totally by myself .

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But…, There were many difficult problem to detect multiple 2D markers which were placed a far distance from a camera…

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Problems of image recognition Image Capture Resolution:640x480

・Inside pattern of markers are broken and lost information in 640x480 capture resolution. (This is not improved very much if I use large size of markers) ・Normal printed markers on a paper shine by light.

Problem

Impossible!

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Problems of image recognition

・made black parts of markers with not paper but cloth ・changed capture resolution to 960x720 ・tune camera’s exposure setting ・tune camera position & direction ・Redesign marker pattern with Error Correction Code

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Marker Detection Binarize

Edge tracing Corner Detection

Dilation & Erosion

Template Matching

Labeling

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Homography Calcuration

Calibrating by 4-point algorithm previously

Convert initial view to top view and control robots positions to be a desired shape

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Design of Error Correction Code Reed-Solomon Code Ex) CD, QR Code

I gave up to adopt this because of implementing cost

Hamming Code

I adopted this because implementation is simple

・1bit error can be corrected

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Implementation of iPad Event Handling

WiFi

Web Server (Jetty)

Matlab

Xbee Service

Send touch events by Ajax

Image Recognition

Robots Control

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Implementation of Feedback Control PID Control

P(Proportional gain) I(Integral gain) D(Derivative gain)

Time

Difference

Time

Difference

Control input value in proportion to a difference

Eliminate a offset by integrating differences

Offset

Time

Difference

Improve response sensitivity by derivative of difference

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… Then I can all the way to make my system. I wanted to implement collision avoidance system but I didn’t have time…

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Final System Design

WiFi

ZigBee Wireless communication

USB Camera (Detect Robots Positions)

Stroke Input on iPad Swarm Robots (with Omni-Wheels)

PC 2D Code

(with Error Correction)

11/12/01 http://d.hatena.ne.jp/Cherenkov/20101115/p1

A Scene of Idea Contest Exhibition

Picture by @Cherenkov Thanks!

Controlling a swarm of robots by drawing on your iPad

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You can watch a movie on YouTube

http://www.youtube.com/watch?v=SzXFGeB6Hxs

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Thanks!

Keisuke UTO @utotch