This Instructable details how to build a low cost 4 servo Arduino Uno controlled bipedal robot that is framed with inexpensive 3D printed “I Braces”; that can hold a standard servo and interconnect with additional braces to form various modular structures.
My goal in this project was to:
A. Show my 3yr old daughter that you can make anything you put your mind to!
B. Not break the bank (wife mandated)
C. Only run on 4 servos (to start with)
D. Stand >= 10” tall
E. Leave room for upgrades/reworks without scrapping parts
F. Give live commands to the biped
G. Communicate wirelessly (I have lots of extra Android phones laying around)
I'm happy to say I was able to accomplish all the above with project MegaPed!
See MegaPed in action:
I arranged the uploaded pictures in order with captions so that you can easily follow along with the basic build. I also added a written walk-through below. Remember, you can deviate in almost all areas with this build; I hope others can better my setup and create unique derivatives that they in turn share back with the community!
General Installation Walkthrough:
1. Procure all parts and pieces in the below “MegaPed Build-out Breakdown:” section
2. Build frame from braces (make it your own and go custom if you like!)
Bridge (connects legs together)
3. Physically install servos into “I Braces” for both hips and ankles
4. Connect ankles to legs
5. Connect legs to bridge
6. “Harness” servos with a power rail and ground rail (see images)
7. Install simple 12V rocker toggle (see wiring PDF)
8. Run servo control wires up through center of bridge
9. Mount Arduino Protection Plate on center of bridge
10. Install Arduino Uno into Protection Plate and lock it in
11. Connect servo control wires to digital pins (see wiring PDF)
12. Mount Bluetooth modem on bridge (I used a free 3D printed holder design)
13. Install Arduino IDE
14. Connect Uno to PC’s USB port
15. Download and open my Arduino sketch (MegaPedSketch.ino)
16. Upload the sketch to your Uno (check your baud rate; also you can’t have the Bluetooth modem installed at this point and communicate via USB!)
17. Disconnect the Uno from your PC after successful sketch upload
18. Wire up Bluetooth modem to Uno under the bridge (see wiring PDF)
19. Pop on the Arduino Protection Box top
20. Mount up the AA holder and connect it to your toggle
21. Zip tie a 9 volt battery under the bridge for direct connection to the Arduino
22. Revel in delight as you watch your creation attempt its 1st step!!!
MegaPed Build-out Breakdown:
If you play with Arduino regularly you may already have everything sans the 3D printed parts which can be ordered online using my source files within my Instructable if you don’t have access to a 3D printer.
Qty Total $’s Description with Amazon.com links
1 $18.00 Arduino Uno
4 $34.00 Common Sense servo: CSRC-311 (2 hips and 2 ankles)
19 $8.00 (ABS) Servo “I Braces” (No 3D printer? Upload my file to http://Shapeways.com )
1 $2.00 (ABS) Arduino Protection Box (another of my Instructables for free download)
4 $3.00 AA batteries (for servo power)
1 $3.00 Quad AA holder
1 $2.00 9 volt battery (for Arduino Uno)
1 $2.00 12 volt toggle switch
10 $5.00 Breadboard wire kit (you’ll have plenty left over for other projects)
100 $4.00 Mini Zip-Ties
10 $4.00 Standard sized Zip-Ties
1 $4.00 Velcro (small/medium strip) (optional)
Grand Total (USB tether only): ~$89.00
1 $39.00 Bluetooth modem with breakout (BlueSMiRF Silver)
1 $0.00 Bluetooth serial command app for your Android device
(sorry iOS users not sure what app you can use..)
Grand Total Including Bluetooth Control: ~$128.00
I hope you get some utilization out of MegaPed! If there is any interest I will share future mods to MegaPed. I plan to scale MegaPed challenging my modular "I Brace" design with additional servos for smoother weight transfer due to additional degrees of freedom as well as better harnessing of weight lower into the frame (lower center "g"). I want to keep this all open source so we can help usher more useful and unique usages for consumer bots! As rapid prototyping at home becomes more and more possible with 3D printers and DIY CNC machines, projects like this take on more meaning and can only better equip the tinkerer in all of us.
If you do attempt a build please keep in touch and Make On Ya'll! (I can say that, I live in Texas...)