Self-balancing Unicycle Using Arduino And Sparkfun IMU


Here’s proof that you can build cool stuff with simple tools. This self-balancing unicycle uses an Arduino and a five degree of freedom IMU from Sparkfun to keep the rider upright. Well, it’ll keep you upright as long as you have good side-to-side balance. But that’s true of any unicycle, right?

The Raptor was built by [Nick Thatcker] who is no stranger to self-balancing transportation. A few years back he built a Segway clone and the same type of geared motor used in that project also went into this one. I connects to the wheel with a chain, allowing him to keep the motor hidden in the saddle. He gets between 90 and 120 minutes of used on one charge with a top speed of 10 MPH. The motor could move you along faster but he has limited this in firmware to ensure it has enough power to ‘catch up’ if you lean too far forward.

Don’t miss the demo after the break. If you like this unicycle there are several others worth looking at.

21 thoughts on “Self-balancing Unicycle Using Arduino And Sparkfun IMU

        1. Sounds like a problem for a power transmission!

          With the right kind of planetary gearing mayhem I’m sure you could figure a way to seamlessly change the relative torque direction on the tire?

          1. If that is the case, why then does every self balance system consist of electric motors and controls?

            This is not to say that it would be impossible to build a self balance system utilizing an internal combustion engine. The complexity of doing so is not a smidgeon harder, it’s a magnitude harder.

            1. You have to insure that the materials you utilize in the transmission are such that they can handle the forces that would be applied when the gears are instantly reversed.

            2. These reversal forces are on the order of thousands per second if not greater which could cause the gears to vibrate into pieces.

            Take industrial robots as a case in point. Not one of them as far as I know, have an Internal Combustion Engine powering an axis. It is not likely that you could find one. The servo motors employed on these devices are more efficient at performing the task than an I.C.E. would be, this is in addition to the servo motors more compact space and ability to reverse direction without the need of a transmission.

      1. As much as I enjoy the gratifying rumble of a few hundred horses runnin the same direction, electric motors and drives are starting (i know, shut up) to produce IMPRESSIVE performances, by any standard ( except the sound, which is kinda cool too, just not as). As battery technology improves, electric motors can reach their full potential.

        1. The likes of Tesla Motors are pushing battery tech to the limits. The viability of electric cars hinges on it! You’ll find that once Tesla has perfected it, the Chinese will copy it and make it even cheaper/more accessible.

  1. imo it seems like it should be designed to ride more like a motorcycle… use gyros & self balancing to maintain a maximum forward/backward lean angle, but give it a throttle & brake so you don’t only have to lean forward to make it accelerate like a segway…

    1. I agree with you.

      The Segway and clones for the most part require the rider to stand in order to operate and because of this the rider can still react fast enough to stop the machine, and if we consider the fact that the CEO died after driving a test model off a cliff, the rider does not not always have enough time to react.

      With a uni-cycle, the rider, even on a self balance machine, must balance left to right in order to steer and keep from falling over. There is not enough time to lean back should one find oneself in a situation where stopping must be now; whereas a break and throttle would give one the ability to react as necessary.

      To provide the necessary disclaimer, I’ve never ridden a Uni-cycle, so my line of thought may be flawed.

  2. This is seriously cool. I just visualize myself driving past these Segway-riders, watching their face of amazement and how they realize that their expensive toys are now all ‘last-year’s’ toys.

    Guys, I’m off to the garage. Got work to do :-)

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