The Making of Sphero - Peacekeeper Edition
02 Apr 2013
Last month, we launched a 3-foot tall version of Sphero – the Peacekeeper Edition. Our announcement coincided with April Fools’ Day, featuring an Indiegogo page where fans could pledge as much as $10,000 to purchase their own 150-pound Sphero. Almost everyone thought the Peacekeeper was a joke – but the joke was that it’s real. Every shot in the video (see below) was actually filmed by us, including the lions. As it turns out, robotic balls are great for cats of all sizes. But the question remains. How did we manage to make a functioning Sphero over 2500x the size of the original? Here’s how.
It all starts with the shell. Unexpected as it seems, one of the hardest things about making a robot ball is finding a shell that is rigid and round. We knew that unless we could find a shell that would work, the entire idea would never become a reality. About six months ago, we found a company in California that makes plastic domes for museum displays, submersible vehicles, point of sale displays and the like. As it turns out, if you buy two domes you have a shell. We bought 6 halves and began to experiment.
Once we had the shells we had to solve two problems; stabilizing the flexibility of the shell, and securing the two halves. The flexibility issue was solved by getting a thicker shell and coating it with a popular truck-bed liner (rugged, we know). To join the two halves, we used simple hinges found at our local hardware store. Joining the halves with hinges also helped with rigidity and durability for the lions.
The internal mechanism is literally just a scaled up Sphero. We made the robot’s frame from aluminum joinery. The bottom of the mechanism needed to be heavy (just like with your Sphero), so we used two marine grade batteries. To put things in perspective, the motors could easily power an electric wheelchair.
Instead of a smartphone, we hooked up a RC controller with a secondary kill switch to make sure that if things got crazy we could stop the giant ball from rolling into traffic – or worse. The controller is coupled to a Sphero circuit board. Just like the real Sphero, the circuit board provides the drive mechanism with a sense of orientation and commands the motors to stabilize the robot. It also allows for complete programmability. While we could have used Bluetooth, the Peacekeeper moves so fast that it gets out of range rather quickly. As a result, we left it with transmit functions for the RC controller for the time being.
Charging is not by induction. That would be a huge power draw, and could take days. Right now, the user needs to disassemble the Peacekeeper’s shell and simply plug in the charger built into the ball. It takes a bit of work and you need help to lift off the shell, but the batteries last for a long time. Enough for everything from rolling over a fruit stand to playing with lions.
In retrospect, the design is overkill. The motors could power an 8-foot diameter ball and the batteries are incredibly expensive. But for the first prototype and functioning robot, it was all worth it.
As our Indiegogo campaign comes to a close, we actually have one Peacekeeper customer (who happens to be our board member). We’re going to make him a refined version of the Peacekeeper that won't weigh as much, and won’t be covered in mud. We’ll post the delivery here when it is finished – stay tuned. Rumor has it, Feld’s coworkers do not want the ball in their office. They fear the Peacekeeper may not be suitable for a peaceful work environment.
For safety, for peace, for fun – Peacekeeper by Orbotix.
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