MakingGoogle Cardboard &

Laser CutterEiichiro Iwata

2016年 12月 15日

PFxセミナー

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Self Introduction• Name

• Eiichiro Iwata (@eiichiroi)

• Profile• M.E in Computer Science – Saitama University 2008 - 2010

• ICPC World Finals 2009• Preferred Infrastructure, Inc. 2010 - 2016/10

• Developed Search Engine “Sedue”• Developed Analysis Platform for BigData “Sedue for BigData”

• Retrieva, Inc. 2016/11 - present• Developing Q&A search solution ”Answer Finder”

• Fobby• Brewing coffee (mame club)• Playing games (Spaltoon, Catan, Syogi, …)• Making (electronic) devices (Today’s topic)

Table of Contents• Making• Google Cardboard

• Laser Cutter

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What’s Google Cardboard? (1/4)

4https://vr.google.com/intl/en_us/cardboard/

What’s Google Cardboard? (2/4)• Google VR• “Virtual reality for everyone”• = SmartPhone + Headset(Cardboard/Daydream)

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Google Cardboard Daydream 3rd partyhttps://vr.google.com/intl/en_us/cardboard/https://vr.google.com/daydream/

What’s Google Cardboard? (3/4)

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Headset Price SupportedPhone

Memo Date

GoogleCardboard(3rd party)

cardboard $10〜 20 >= Android 4.1Low-cost for trial.Hold it by hands. 2014/06

Daydream fabric $79 PixelMoto Z

High-end and Comfortable.With wireless controller.

2016/11

What’s Google Cardboard? (3/4)• Apps• Cardboard (Official demo apps)

• Google Earth (you can fly around in Google Earth)• YouTube VR (watch videos with VR-mode or 360-degree video)• …

• Cardboard Camera• you can take 3D photo, enjoy it with Cardboard App

• etc

• SDK• for Andriod / iOS / Unity / Unreal Engine

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Headset’s specification is public.

8https://vr.google.com/intl/en_us/cardboard/get-cardboard/

Made it by hands.

9print out sheets and cut it on cardboards by cutter knife

Made it by hands and hands.

10Bought lenses at \100 shop

Completion!(but focus distance is not fit…)

Fold them

Impressions for Google Cardboard• fun and interesting• focus distance of lenses is very important• precisions to cut cardboards by hands is less…• I want to cut cardboards with high precision.• Let’s make laser cutter and cut cardboard by it.

• Supplement:• It is distributed at Google I/O 2014 (2014/06)• I Maked at 2014/07.• Now, we can buy kits easily. it is recommended.

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What’s Laser Cutter?• Machine tools that use a laser to cut materials

• CNC (Computer Numerical Control) is popular

• Materials• papers• wood board• acrylic board• …• (〜 3mm)

• Note:• Need more power(powerful laser cutter) if the material is

thick or hard. It also have focus distance problem.

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CAD/CAM(AutoCAD, Illustrator, …)

Laser Cutter

Drawing(DXF, SVG, CDR format)

GCode

convert

create & save

load & execute

3-ways to use laser cutter• Rent at shops (Recommended)• Need only data files and materials• FabCafe Tokyo (at Shibuya)• DMM.make AKIBA

• Buy Laser Cutter Kit & Make it• laserbot (makeblock)• Mr. Beam (Kickstarter project)• Smart Laser Kit Mini (SmartDIY)

• Design & Make myself (Not recommended)• Refer open source blueprint (Smart Laser Kit Mini)

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easy

hard

Laser Cutter(1.6W)

CO2 Laser Cutter(60W)Powerful!

https://akiba.dmm-make.com/about/machinesDetail/32http://www.makeblock.com/laserBot-robot-kit

Smart Laser Kit Mini (Official demo)

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• See following url• https://vimeo.com/135843224

Components

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Laser ModuleX-Drivng Module

Y-Drivng Module Y-Drivng ModuleController

Principles of Laser Cutter• X-Axis move (Y-Axis move)• Power source is torque of stepper motor• Timing belt convert from torque to linear momentum• Carriage move along the axis• Limit switch is origin(0). It is also called home position

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CarriageStepper Motor

with pulley Idler

Timing Belt

Limit switch

Axis

Principles of Laser Cutter• Laser Diode• emit light and focus specific wavelength by lenses

• its power depend on wavelength and current• elements determine wavelength(fixed)• drived by constant-current circuit

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short & strong long & weaklaser cutter(445nm, 2W)

DVD-R/RW drives(780nm, 400mW)

Principles of Laser Cutter• Laser Diode• its power depend on wavelength and current

• elements determine wavelength(fixed)• drived by constant-current circuit

• more current, more power!

• note:• Need heat sink & fan• Need glasses to save eyes• CO2 laser is different from laser diode

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http://cms.diodenring.de/electronic/microcontroller/111-blue-laser-diodes

(Electrical) Architecture

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GRBLGRBL Controller

Arduino Uno

Laser Module XY-Driving Module

software

hardware

USB(Serial)

PC

communicate

Host Microcomputer

Driver Circuit

Laser Diode

CNC Shield

X-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

X-Driving Module• X-Driving Module• Arduino CNC Shield

• Stepper motor with driver chip(pololu drv8825)• X-Limit switch(to detect origin)

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Y-Driving Module• Y-Driving Module are almost equal to two X-Driving

modules• Two motors move in the same way• direction of rotation is reversed because of attaching

direction

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(Electrical) Architecture

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GRBLGRBL Controller

Arduino Uno

Laser Module XY-Driving Module

software

hardware

USB(Serial)

PC

communicate

Host Micro Controller

Driver Circuit

Laser Diode

CNC Shield

X-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

GRBL / GRBL Controller• GRBL• embedded CNC controller run on Arduino• open source• Receive commands(GCode) via USB(Serial port)• Control arduino and its I/O (laser and stepper motors)

• GRBL Controller• software(communicate with GRBL) run on PC• open source• Load and Send commands(GCode) via USB(Serial port)

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GRBL’s parameters calc from parts• stepper motors spec• ratation degree: 1.8 [degree/step]• number of steps per 1 ratation: 200 [step/ratation]

• pulley spec• number of teeth: 20 [teeth/ratation]• pitch: 2 [mm/teeth]• -> 2 * 20 = 40 [mm/rotation]

• number of steps per 1mm (with 1/32 step mode)• 200 / (1/32) / 40 = 160 [step/mm]• Minimum moving unit

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GCode• Numerical Control Programming Language

• used for CNC (laser cutter, 3D printer, milling machine…)• GRBL accepts GCode

• Command types• Config

• Area(max X, max Y)• Min moving unit, max speed, max acceleration

• Move• Straight• Arc• Spline• …

• Other control• Laser/Fan switches

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GCode Examples(Header begin)G90 (Set absolute distance mode.)G21 (Use millimeters for length units.)F100.000000 (Set feed rate.)(Header end)

M08 (Set coolant on.)G1 X0.000000 Y0.000002 (Move linearly to the point)M03 (Set spindle on.)G1 X1.790347 Y0.829030G1 X1.252361 Y1.058336G1 X3.183819 Y2.989780… 26

Configuration in header

(Electrical) Architecture

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GRBLGRBL Controller

Arduino Uno

Laser Module XY-Driving Module

software

hardware

USB(Serial)

PC

communicate

Host Micro Controller

Driver Circuit

Laser Diode

CNC Shield

X-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Testing as Pen Plotter• Use pen instead of Laser Module• Test XY-Driving module & GRBL• Test data is desert tile of Catan (board game)

• various designs for 3D printers, laser cutters, milling machines are shared in thingiverse.com

• DXF format

• Wrote DXF2GCode converter• GRBL don’t support spline curves

• spline curve can be approximated by lines• Load DXF & output approximated shapes

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example of b-spline curve

Testing as Pen Plotter: Result

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DXF Format (ideal)

There are many wasteful moves(paths)!(Note: pen is always on the paper)

Result (real)

GCode Path Optimizer• To find best GCode path is equal to solve a traveling

salesman problem(TSP)• must visit all shapes

• implement greedy algorithm• select nearest shape from current shape• approximate solution• complexity is O(V2): V is number of shapes

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GCode Path Optimizer: Result

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before afterGood enough!

(Electrical) Architecture

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GRBLGRBL Controller

Arduino Uno

Laser Module XY-Driving Module

software

hardware

USB(Serial)

PC

communicate

Host Micro Controller

Driver Circuit

Laser Diode

CNC Shield

X-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Y-MotorDriver

Stepper Motor

Laser Module• Made from scratch• because this module is not public at that time

• Main parts• Laser diode (〜 2W)• Constant-current circuit

• Constant-current circuit• LM317

• can generate constant-current• Darlington transistor

• need to drive high current from microcomputer• two transistor are combined to large one

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write circuit diagram by hands.darlington

Testing as Laser Cutter: paper• materials• paper(0.087mm, white)

• feed rate 600 [mm/min]: good• feed rate 800 [mm/min]: almost cut• feed rate 1000 [mm/min]: don’t cut well

• drawing paper(0.4mm, black)• feed rate 100 [mm/min]: slightly burned• feed rate 150 [mm/min]: good• feed rate 300 [mm/min]: good for engraved mark

• thick and color of material is important• best feed rate is different

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Testing as Laser Cutter: cardboard

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feed rate is too slow, slightly burned

feed rate is good,but it’s not cut completely

multiple trials

In more thick materials, it is important to repeat.focus is off…?

Other problems in making• it is difficult to find various parts myself• Aluminum frame size, screw/nuts size, high power diode

• short laser driver circuit & broke laser diode• diode is very sensitive• retried with new parts…

• broke balsa plates because I rotate Y-Axis motors in reverse directions• need to add emergency stop button…

• many parameters per materials• feed rate, height of laser(focus distance), …

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Parts shops• Monotaro• aluminum frames• bearing

• eBay (Ali Express)• Laser Diode

• Home improvement center (ex. DOIT, Tokyu Hands)• Screw & Nuts• Wooden plates (balsa plates)

• Akizuki Denshi / Sengoku Denshi at AKIHABARA• Electric parts (board, connectors, wire, transistors …)

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EC site

Conclusion• Making Google Cardboard• Let’s buy kits and fun!

• Making Laser Cutter• Fun & Interesting• Several problems happen in real world• I have not created google cardboard by laser cutter yet• Not recommended. Rent it at shops!

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