Introduction: POLYRO (oPen SOurce FriendLY RObot)
This is an instructable on building a relatively low-cost wheeled robot platform for developing ROS applications. Think of ROS as an operating system for your robot (providing hardware abstraction, device drivers, libraries, visualizers, message-passing, package management, and more). THIS ROBOT IS NOT PLUG AND PLAY. ROS runs on Ubuntu, so you should feel comfortable working with Linux.
POLYRO, short for oPen sOurce friendLY RObot (yes I know, it's a bit of a stretch), is based off of the TurtleBot platform (from the good folks at Willow Garage) and inspired a great deal by Pi Robot (developed by Patrick Goebel). I designed this platform with Human-Robot Interaction (HRI) in mind. This is the first of many future iterations, so check for updates to the design. Please keep an open mind when following this tutorial. Many of the parts and tools can be substituted (or purchased for less) and there are many improvements to be made. As always, when working with power tools use the proper safety gear.
Step 1: Suggested Tools and Parts
- Removable Double-Sided Tape
- Screw Driver Set
- Needle-nose Pliers
- Jig Saw (or maybe a Scroll Saw)
- Saw Horses
- Drill Press (Dremel Work Station)
- Dremel Sanding/Grinding Kit
- Soldering Iron
- Glue Gun
- Large Format Printer (Kinkos)
- Metal Ruler
- Safety Goggles
- Work Gloves
- Dust Mask
1 x $150 to $300
iRobot Create® Programmable Robot
Item Number: 4400
1 x $129.99 – www.irobot.com
Kinect for Xbox 360 with AC Adapter (Refurbished)
1 x $119.99 – www.Gamestop.com
Wide 2" Gusseted Plastic Angle Bracket (pack of 8)
4 x $1.59 - www.budgetrobotics.com
Risers, Set of Four 1" Steel)
4 x $1.69 - www.budgetrobotics.com
Gusseted Plastic Angle Bracket (pack of 8)
2 x $1.59 – www.budgetrobotics.com
White Expanded PVC 24" x 48" .120" Thick
Item #: 42485
1 x $12.85 – www.usplastic.com
White Expanded PVC 24" x 48" .240" Thick
Item #: 42488
1 x $27.86 – www.usplastic.com
Gray Expanded PVC 24" x 48" .120" Thick
Item #: 42501
1 x $16.50 – www.usplastic.com
250 Grams of ShapeLock
1 x $14.95 – www.shapelock.com
Bioloid Frame F3
Item #: M-300-B-BPF-F3
3 x $1.49 – www.trossenrobotics.com
Bioloid Frame F2
Item #: M-300-B-BPF-F2
1 x $1.49 – www.trossenrobotics.com
Dynamixel AX-12A Robot Actuator
Item #: FRS-B-AX-12A
11 x $44.90 – www.trossenrobotics.com
Robotis USB2Dynamixel Adapter
Item #: FRS-B-USB2D
1 x $49.90 – www.trossenrobotics.com
Item #: FRS-B-SMPS2DYNA
1 x $4.90 – www.trossenrobotics.com
Bioloid Bolt & Nut Set
Item #: M-300-B-BPF-BNS
1 x $23.40 – www.trossenrobotics.com
Bioloid 6-Port Cable Hub
Item #: FRS-B-6-PT-C-H
1 x $4.95 – www.trossenrobotics.com
3 pin Bioloid Servo/Sensor Cables (Set of 25)
Item #: FRS-B-CBL
1 x $34.90 – www.trossenrobotics.com
Logitech QuickCam E 3560 Refurbished
2 x $10.99 – www.microcenter.com
On Stage Foam Ball-Type Mic Windscreen (Blue)
2 x $4.95 – www.amazon.com
Wall Mount Bracket Dock Stand for Kinect
1 x $9.99 – www.meritline.com
USB to PDA 9-pin Serial Adapter
1 x $29.99 – www.mircocenter.com
6” Novak Heat Shrink Tubing Assortment 24 pcs
1 x $3.74 – www.amazon.com
High-Tech Rosin Core Silver-Bearing Solder (1.5 Oz.)
1 x $5.79 – www.radioshack.com
25-Position Male Solder D-Sub Connector
1 x $2.29 – www.radioshack.com
1 x $5.00 – www.schmartboard.com
USB 2.0 4 Port Hub – (Black)
2 x $2.99 – www.microcenter.com
0.33μF and 0.1μF capacitors
2 x each
Voltage regulator 12V 1A
2 x each
22 AWG wire (red and black)
Machine Round Head w/Nut (4-40 x 3/8)
USB extension cable
Velcro tape (optional)
White model paint (optional)
Step 2: Preparations
The parts which are cut from the sheets of expanded PVC were first designed using Adobe Illustrator. I have provided the original files for both reference and editing. Those files were then printed to scale using a wide format b/w printer at Kinkos. Using tons of removable double-sided tape, I outlined the parts on the reverse side of each printed sheet of paper. The sheets of paper were then placed carefully on the sheets of expanded PVC.
Parts 1 PDF: White Expanded PVC 24" x 48" .240" Thick
Parts 2 PDF: White Expanded PVC 24" x 48" .120" Thick
Parts 3 PDF: Gray Expanded PVC 24" x 48" .120" Thick
Step 3: Cutting the PVC Sheets
*It is important to take the proper safety precautions when working with power tools. Please use the proper protective gear when cutting, sanding, drilling, etc.
Once you have mounted the sheets of paper to the sheets of PVC, clamp them to the saw horses. When starting a cut or cutting tight corners, I find that drilling holes first (using the dremel) is very helpful for producing cleaner results. Always cut the small shapes from inside of the larger ones before cutting the larger shapes.
After cutting all of the parts from the PVC sheets, use different sanding drum bits from the Dremel Sanding/Grinding Kit to refine each part. Clamping a metal ruler to a part helps immensely when shaping straight edges using the Dremel. Next drill holes using the Dremel Work Station, guided by the paper still taped to each PVC part. Finally, peel off the paper and voilà, you have finished parts.
Step 4: Fabricating the Eyelids
The eyelids were made using Shapelock, a tough, machinable, paintable plastic, which becomes pliable at 150F. It is suggested not to overheat Shapelock. Just boil water and pour it into a bowl that you do not intend to use again (for eating from). Next, place the Shapelock material into the water until it becomes transparent. After that, remove the Shapelock using tongs and squeeze the excess water. Before it cools off, mold the Shapelock to the shape of the eyelids. This can be done with a plastic ball (slightly larger than the webcam). I drew the shape of the eyelids on the plastic ball with permanent maker as a guide. Once you have two eyelids which you are comfortable with, sand them with the dremel.
You will also need an additional T-shaped part to connect and move the eyelids. This too can be fabricated using Shapelock. Please refer to the pictures below for dimensions. Sand the part down using the Dremel and make sure that it can rotate freely through the holes in the bridge of the nose.
Step 5: Assembly
*Note: Before assembling be sure to test and position each servo to 0 using RoboPlus Manager. It is also important to assign separate ID's to each servo.I will continue to update this tutorial over time while I work on Polyro v2.
The original design files have been attached in both Illustrator and PDF formats; this is to help guide your assembly and allows for you to make changes to the original design. I also tried to group specific parts together within the three PDF's (arm parts, head parts, etc.). It should be easy to assemble POLYRO using the Illustrator file, PDF's and photos of the finished robot.
The Gusseted Plastic Angle Brackets were chosen to simply the assembly process and add stability to the robot. When assembling, start from the bottom and work your way up. Drill a hole in the *Polyro Base (see image above) large enough for the iRobot Serial Cable to pass through before attaching it to the Create. Mount the Kinect Bracket Dock Stand before adding the metal risers to the Kinect Mount Base (see image above).
I used #4 x 5/8" metal screws for the arms and shoulder brackets (see image above). Bolts from the Bioloid Bolt & Nut Set also work great when assembling the arm.
*When preparing to mount the USB cameras to the AX-12 servos, you can disgard the clamp-like base, but be sure keep the black circular part that snaps into the bottom of the camera. This small circular piece will be screwed onto the modified Bioloid Servo Bracket (shaped into a circle using the Dremel). Once that is done, it is easy to snap the USB cameras onto the servos.
Step 6: Wiring
Powering the Kinect and AX-12 servos was fairly easy using the Create's Cargo Bay Connector. I simply attached two 12V regulators from the 10/21 and 11/25 pins (see page 10 of the iRobot Create Owner's Guide). The process of creating the 12V regulator can be found here:
Instead of using the Create serial cable or RooStick (as in the tutorial), I simply ran it straight from the Cargo Bay Connector. For powering the AX-12 Servos, I simply repeated the process, only splicing a Dynamixel 3-pin cable (please reference the photo below). Remember to cover the solder joints with heat shrink to avoid any shorting. Once this is complete, the Kinect and AX-12 servos will be powered from the Create battery. I would like to eventually charge the netbook from the iRobot Create Home Base (like in this project ) or replace the netbook with something that can be run from the Create's battery (such as the Roboard).
Step 7: Software
Video of TurtleBot can be seen here:
- Dynamixel Servos: http://www.ros.org/wiki/robotis
- Stereo Vision using USB cameras: http://www.ros.org/wiki/uvc_camera
Instead of installing TurtleBot, you can also search the available software on ROS.org and install each driver manually.
Step 8: Afterthoughts
I am working on a website and will eventually create a dedicate ROS page for the POLYRO project. If anyone is interested in working with me to develop applications for POLYRO, please feel free to contact me. In the second prototype, I will add additional degrees of freedom to the neck, arms and head. I will also try to make improvements to the original design. I look forward to seeing your modifications to POLYRO and I appreciate any input that you may have.
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