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Students designing an omnidirectional sphere-wheeled electric motorcycle


September 14, 2012

A group of students from the Charles W Davidson College Of Engineering at San Jose State University are working on an omnidirectional, self-balancing SDS electric motorcycle

A group of students from the Charles W Davidson College Of Engineering at San Jose State University are working on an omnidirectional, self-balancing SDS electric motorcycle

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Thanks to gyros, accelerometers and sophisticated control mechanisms, remaining upright on a two-wheeled vehicle is no longer quite the balancing act it might once have been, even when at a standstill. Visions of future mobility like Honda's U3-X take such ideas in whole new directions, quite literally, by including multi-directional capabilities, and concepts such as Supple go even further still by ditching wheels altogether in favor of balls. It's this freedom of movement that inspired a group of students from the Charles W Davidson College Of Engineering at San Jose State University to begin work on the ambitious Spherical Drive System (SDS) electric motorcycle.

The SDS concept vehicle is described as a self-balancing electric motorcycle that rides on spheres. Rather than using the kind of mechanical gyros that help keep the Gyrobike or the C-1 from Lit Motors in an upright position, the SDS creation uses data from MEMS gyroscopic sensor technology and an onboard accelerometer to electronically control balance.

"The motorcycle operates on a friction based drive system that directly drives the surface of the sphere with custom manufactured omniwheels, attached to Animatics motors," explained team leader Max Ratner. "The method for balancing the motorcycle is similar to a Segway in that it uses accelerometers and gyros for detecting the pitch angle and correcting for any displacement from vertical. The user will control the motorcycle just like any modern motorcycle with a throttle, leaning, and handlebars. Additionally, there will be a set of joysticks that will allow for additional maneuvers such as forward/reverse/side-to-side motions/spinning the vehicle."

The electric bike's three-motor drive system that gives the vehicle its potential to move in any direction is modeled after a system known as an inverted pendulum, and features omniwheels made from zinc-coated 4130 steel and Animatics Smart motors powered by Lithium Iron Magnesium Phosphate batteries with a built-in battery management system. The rather shiny frame is fashioned from 304 stainless tubing, and there's suspension front and rear in the shape of Fox racing shocks.

The vehicle's computer-controlled operation (much of which is undertaken using an ARM architecture microcontroller) should help keep bike and rider safe, but if the vehicle were to leave the ground for any reason, the spheres will remain contained within the swingarms. Ratner told us that the "spheres are essentially carbon fiber and fiberglass shells, coated with a durable industrial rubber for traction."

The SDS motorcycle is still very much a work in progress and, now that original team members have graduated, only Ratner, Henry Li and Andrew Parmar remain on the project full time. The initial aim is to get the vehicle stable and in control at speeds up to about 10 mph (16 km/h) but the designers say that, in theory at least, it could zoom up to 60 mph (96.5 km/h).

There is still quite a bit to do before then, however. Ratner confirmed that "the vehicle is about 85 percent assembled in terms of hardware and about 20 percent done in terms of software and electrical. We have about 90 percent of our parts."

Work on the control system is currently being undertaken by three new recruits from San Jose State University (Lynn Comiskey, Evan Ly and Jessica Chen) as part of their own class project.

"The challenges posed by the control system include an attempt to balance an inherently unstable system, interfacing with multiple drive motors, and combining potentially noisy sensor readings such as those from an accelerometer into something usable and reliable," Ratner told us. "The control system has been proved out on our test rigs but there is quite a bit of stuff to change in the code to make it applicable to the final bike. This testing will likely happen around the end of 2012."

Backing from companies and organizations like Animatics, Wolfe Engineering, Atmel and IEEE has helped toward meeting project costs, and the team is presently on the lookout for sponsors to help mold and manufacture the fairings that will hide much of the exposed workings and help enhance the vehicle's already striking appearance.

Source: SDS (and you can follow project progress via the SDS Facebook page) via The Kneeslider

About the Author
Paul Ridden While Paul is loath to reveal his age, he will admit to cutting his IT teeth on a TRS-80 (although he won't say which version). An obsessive fascination with computer technology blossomed from hobby into career before the desire for sunnier climes saw him wave a fond farewell to his native Blighty in favor of Bordeaux, France. He's now a dedicated newshound pursuing the latest bleeding edge tech for Gizmag. All articles by Paul Ridden

cornering and banking have to be emulated electronically. sometimes the wheel isn't too bad after all. what problem did this solve?


Looks like something that should have been in iRobot.

Two Replies

Why even have two balls? Why not just a single ball...er...like a unicycle? What happens when the ball sucks up a piece of road debris and jams inside the drive mechanism?


Why don't we apply electro osmotic pressure like earth worms do to the spherical wheels

Udhaya Kumar

What happens when it gets wet? Its friction based and slippery balls are not desirable for friction driven systems. How will you take a bend? In essence one of the joys of biking is the lean to turn. on balls that are trying to keep you upright you will then transfer the inertia to your head as you try taking a nice fast bend while sitting upright. To make this thing anything better than a curiosity would mean absolute control of driving the ball without using a frictive system.


Heavy, expensive, and no traction in the rain. If i was the professor I would have tried to keep it from ever seeing the light of day even if I did give the students good grades.


I bet those ball-tires would be useful in warehouses where there's not always a clear path to move around. Put a couple on a platform and use it to carry loads around piles of stuff in storage. I've worked in a warehouse before and something like that would have been a whole lot easier to work with than a standard pallet jack.

Forward Thinker

Absolutely awesome. It could do nothing but putt around in the lab & it would still be cool!

Think of this little mod...turn that whole passager carriage 90 degrees, drop it a few inches & roll between the spheres instead of parallel. Make it so!

Very appealing design, hats off to ya

Gregg Velosi

Forward Thinker, my thoughts exactly. this would be great for use on a forklift.

Denis Klanac

The spheres themselves could be the armatures in spherical induction motors. That's an avenue worth exploring.

This idea has possibilities beyond a mere electric motorcycle. The balancing controls could have a number of other applications in industry and in other kinds of consumer products. Parallel parking a spherical-wheel car would be simple, and as mentioned a spherical-wheel pallet jack would be more maneuverable.

The questions are: would the advantages outweigh the added cost, and can the cost be brought down to something reasonable?

William Lanteigne

Caught my attention. But I'm also voting for the "hover board". C'mon... It's the future already... Just saying. Also need somebody to assist in the developing of a revolutionary helmet. Email me @ philipd113@gmail for more detailed info if interested or can assist. Thanks.

GuaGe Duncannon

Quote: "Heavy, expensive, and no traction in the rain. If i was the professor I would have tried to keep it from ever seeing the light of day even if I did give the students good grades." -Pikeman

Reduction in weight is eminent. This is a prototype designed to demonstrate the concept and tech. Pricing depends on many things. Most times the result is a far LESS expensive solution than the prototype. If they want to market it as a product, they will make it a fair deal. Traction in the rain may seem like a design fault, but you're forgetting that this design isn't a real-world design. Its sole purpose is to demonstrate the concept/tech. Motors that are capable of spinning at a much higher rpm, can and will offer a better basis for real-world applications.

And simply because you think something is not going to work, doesn't give you the right to cap people's ideas. I can think hundreds of implementations for the current model and you're lacking the capacity to think of one. Heck, you even have the audacity to say "If i was the professor I would have tried to keep it from ever seeing the light of day even if I did give the students good grades", the very moment where this design got such a good response. I can't help but wonder how many brilliant ideas where forever lost because of your inability to recognise them.


impressive technology, even if the bike is flawed. One thought occurs to me - could this be developed into an ultra mobile wheelchair using a single ball device?


It looks cool but I am not sure it is safe to drive, especially to take corners at high speed. The physic of motorcycle wheel and leaning may not be achievable with the balls.

James Ng

Those are some big balls. I want video of this bike.

Larry Hoffman

Kudos are in order. Yes to the nay sayers, using friction OUTSIDE the ball poses problems. It was my first reaction as i have seen many sprocket less custom bikes use friction transfer to the tires' surface. Yes when wet or hitting an oily surface one looses all hopes of secure friction and will throw the thing off balance. In lieu of having the drives outside the ball.....what if they were INSIDE?

Mike DuBois

Does anyone else think this looks like the Flintstones car?


Jeff Michelson

Ok, a bike with balls for wheels....C'mon! It's 2012, where is my hoverboard??

Michael Schramm

Awesome skeleton. Keep it naked. The body shells drags down the designs purity at present, in my very own opinion. That the frame is beautiful speaks of its good design.

Jeremy Starseed

To get any decent amount of traction out in the real world of various kinds of pavement, the surface of the spheres will need to have a fairly aggressive tread design coupled with enough squish to it to develop a good footprint. Spheres are used in bearings for a reason; the small amount of contact area means very little resistance (friction) to movement. Braking is what really concerns me in all this. Just how is all of the stored (kinetic) energy of the machine going to be dissipated or maybe recovered at the same rate that decent friction brakes do today? 75% of a motorcycle's braking power is in the front wheel due to weight transfer. Yeah, I think that I'll just stand back here on the sidelines and watch for a while before I hop onto one.


Expanded Viewpoint

Looking forward to seeing one of these in the Isle of Man TT.


An interesting theoretical exercise, and well executed for what it is. Perhaps I'm being short-sighted, though, but I can't see any realistic application in the case of 'real world' motorcycling.

The biggest problem I see in the vehicle's dynamics, other than effective braking as noted by other posters, is the excessive lean angle required to go around a corner. The CoG acts through the contact patch with the road. Given its radius, the effective width of the tyre when compared to the cross-section of normal tyres is huge. Thus for even a relatively slow rate of turn, the bike will have to lean over dramatically more than a normal bike. I'd be surprised if it could ever achieve much more than walking pace turns.


Also after going through the pics, questions arise of aerodynamics and drag on this vehicle. Now how how about a simpler tech that goes into a skate board?? Or perhaps a tow hitch or a wheel borrow for instance. Still impressive, makes me want to watch I robot. Better yet, just skip the bike and make the car, lower ground clearance will make up for any drag the spheres produce.

GuaGe Duncannon

Funny how many comments could all be replaced with a simple "get a horse!"

For all the instant critics on here, how many of you have ever or will ever invent or create anything?

The capacity here to develop a more versatile vehicle to replace wheelchairs is immense- and that's just one channel for this concept to flow in.

How many people looked at the Wright's Flyer and said.... "Absolutely! Supersonic within 50 years! We can do this!" ....obviously,not many- if any.

How far have we gone in the 65 years since the Bell X-1?

How far will we get if we just keep looking at the momentary surface and saying "Bah,humbug" to every new potential breakthrough into new realms of discovery?

It reminds me of the senator who wanted to close the Patent Office as a waste of taxpayer's money because, "We already have the gas light,the telegraph and the steam locomotive- what else of importance could there be left to discover?"

When you see sci-fi like "I,Robot" do you expect such tech to just pop-out, ready to go?

New streams of consciousness must get flowing if they are ever to turn into rivers- many of the former waters are drying up and/or going stagnant.


i hope our grandchildren will be using this idea on cars or motorcycles.

all ideas are welcome. in a nutshell, its ideas like this one that accelerate our progress.

automotive concerns

I just saw the future of Robot mobility today. Great work!

Mike Giles

I guess they must have thought this option off already. Putting up basic right hand rule of motor, making the cup as a solenoid, the spheres as armature with spring mounted bushes, the sphere may be rotated in any direction.

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