This year, we took NodeBots Day to a new level, securing a larger venue and adding new robots – SoccerBots and Drones! Despite the exciting new technology additions, the event remained entirely free to the public thanks to volunteers and sponsorships from the community (757 Makerspace and Old Dominion University) and forward-thinking companies like Langa, 80|20 Consulting, Grow, Sparkfun, and my employer, Emerging Technology Advisors.
While this growth is exciting, increased attendance (and repeat attendees) presented us with new challenges in planning our 2016 event:
- How do we keep repeat attendees interested, while maintaining a beginner-friendly event?
- How do we include newer technology without overwhelming our volunteer staff and attendees?
- How do we ensure that everyone gets something from the event when there are over 100 people?
The first, and probably riskiest, change was an update to the existing robot kit. We’ve been very successful over the years using a variation of the open-source Sumobot-Jr wood-cut kit for NodeBots Day and other classes and workshops, but the required hardware has also steadily increased in price. During my last year working for Emerging Technology Advisors, I tested several pre-packaged robotics products for our client events and education initiatives. Robotics kits like the ServoCity Runt Rover and the MakeBlock mBot are relatively inexpensive and can be assembled with much less effort than our existing open-source kit. For future NodeBots Day robot kits, I wanted this assembly simplification, but without sacrificing the creative modifications we had seen with our classic wood-cut chassis. I also wanted to be able to share our design changes back to the NodeBots community that had provided us with our original kit design.
When I compared parts and pricing, the largest hardware expense in our current robot kit was the continuous-rotation servos. A single servo was costing us around $13 whereas a set of hobby motors and rubber wheels would cost around $7 from our hardware sponsor, Sparkfun. A revised design would keep the look and function of the classic sumobot chassis, but would allow for side-mounted (and inexpensive) hobby motors and rubber wheels like the mBot. I also wanted to continue to support our current microcontroller, the Arduino Uno, but without adding any additional wiring complexity to control the motors. I started the task of creating the “motorized” chassis like many of my other new engineering projects: I reached out to the NodeBots community to see if this design already existed. Markus Leutwyler’s open-source sumobot had motor fittings that were very close to what we needed for the side pieces of our chassis. Then I visited our local makerspace for computer-aided drafting assistance to combine this design with our wood cutting plans from the previous summer. Several laser-cuts, adjustments, tweaks, motor-fittings, and test drives later, we had a sumobot chassis that would run with mBot motors and Runt Rover rubber wheels.
Once the chassis was finalized, the volunteer team collaborated for some additional changes to decrease the overall kit cost further and reduce the difficulty of assembly. We added a clone of the popular Adafruit motor/servo shield to eliminate the breadboard, lead wires, and H bridge for motor control. Instead of the 4 AA battery pack in the rear of the robot, a single 9-V battery improved the balance (and cost) to power the motors. The final design of the Norfolk.js “motorized” sumobot reduced our event budget by at least 20% per kit.