While on a college tour around California, I saw college students riding up a hill on these strange wheels. They would move their legs forward and backward, as if they were walking, but they would magically move sideways. After I saw them jump off and put the wheels in their backpack to enter a building, I decided I had to get some. 

There are two types of these "magical" wheels; Freeline Skates and Orbit Wheels. There are a few main differences between them. The Freeline Skates have two small sized skateboard wheels below the foot platform. This eliminates two degrees of freedom, yaw and pitch, which makes them easier to handle for beginners. The flat top foot platform makes Freeline Skates top choice among skaters, because they enable for more complicated tricks. Because Freeline Skates use skateboard wheels, they can be easily swapped; however they are more likely to get caught in a cracks on a sidewalk. On the other hand, the Orbit Wheels have a large hub-less wheel with foot holders on an inside flat edge. The bigger wheels lend for easier travel over cracks, but they also have more degrees of freedom. The choice of which to buy ultimately comes down to the preferences of the customer. 

I chose to learn on the Orbit Wheels, because I had recently learned how to ride a unicycle and I liked the idea of having many degrees of freedom to control to remain balanced. After about six hours of dedicated practice over a two-week-long period, I was able to wiggle my way across rooms. I soon found their limitations and starting thinking about how I could improve them. First of all, the Orbit Wheels have a narrow and pointed wheel causing the wheels to dig into soft grass. I wanted to improve on their design by making a thicker and faster wheel. I decided I would build my version of a new Orbit Wheel while at my first semester of MIT.

Upon arriving to MIT, I stumbled around and found the MIT Electronics Research Society. MITERS is a student run shop where tinkerers of all kinds gather and build cool things. Electric vehicles were one of MITERS's many fads at the time. That's where the Electric Orbit Wheels were born, my first real project at MITERS. 

For the Epilog Challenge:

What would I do with a Epilog Zing 16 Laser? Well... I would definitely tinker and experiment with it. Maybe try to make 3 -dimensional shapes with acrylic or make book covers out of wood. I'd raster funny images on peanut, butter, and jelly sandwiches, or even on cakes! I would certainly not limit it to a prototyping tool. 


Submitted by MITERS for the Instructables Sponsorship Program

Step 1: Concept and Design Specifications

The concept of how orbit wheels work is kind of hard to wrap your head around. This poster has a fantastic diagram explaining the physics behind how the Electric Orbit Wheels provide sideways motion. A good image to keep in mind is if the Electric Orbit Wheels were coated in a paint, their trails would be similar to sine waves or snake paths. The two waves are offset in the direction of travel, because your feet are slightly separated. 

When it comes to mechanical things, the Electric Orbit Wheels feature a water jetted frame and a custom hub-less wheel. The wheel is driven by a water jetted ring gear embedded inside a urethane tire. The 80 shore (the same durability/hardness as skateboard wheels) urethane was poured around stacked aluminum rims in a 3D printed mold. Because of the two independent wheels, the Electric Orbit Wheels have an infinite turning radius. 

Since the vehicle is so small, the battery pack is spread out around the vehicle to maximize the range. The pack is composed of A123 28650 Systems LiFePo4 Battery Cells and arranged in a 5S2P configuration for a total of 18V and 4.4Ah. "5S" corresponds to five cells in series and "2P" corresponds to two groups of cells in parallel. This results to about 35 Watt hours of energy stored in the battery pack and a 1.5 mile/ 2.4 km range. 

The Electric Orbit Wheels use a HobbyKing Brushless Car ESC (Electronic Speed Controller) rated at 60A peak and also includes reverse. This controller is more robust than most controllers used in RC Airplanes, because it is meant for use on the ground. The HobbyKing ratings are usually overestimated, thus making the controller the limiting factor of the Electric Orbit Wheels. 

The motor controller controls a Turnigy Aerodrive SK3 - 4250-350kv Brushless Outrunner. The motor can draw 1007 Watts peak. Again, that is a HobbyKing rating so it is probably much less than 1000 Watts. The motor and motor controller are controlled by a RC HobbyKing GT-2 2.4Ghz 2Ch Tx & Rx throttle. The top no load speed is around 10 mph (16 km/h). 

Bill of Materials:

Here's a Google doc spreadsheet containing the materials, cost, and website urls:

What about skipping the gearing and going Direct drive, setting your magnets into your wheel, and coils underneath, this would increase your efficiency dramatically, and make it quieter to run. (Much harder to build, lots of coils to wind) :)
<p>proficnc,</p><p>do you have any suggestions or designs to go from for a hub-less electric drive?</p>
proficnc: <br>So, I actually did that :3. I haven't compiled an instructable post for it yet; I'm actually dabbling in selling it to interested companies. <br><br>b3nzom3da: <br>ThinGap makes really cool ring motors. And if you put a hub wheel around the ring, I like to call them hub-less hub wheels :). They don't have as much documentation, but you can reverse engineer a lot from looking at the pictures on their website. <br><br>I also read through Charles Guan's thorough post on how to make a hub wheel (which also contains fantastic links to other resources).<br><br>Hope that's a good start. Here's a sneak peak...
<p>That was my original idea, but I decided to build it with direct drive first as a prototype. </p>
<p>Hi,</p><p>i see on hobbyking power, voltage, current specs for the motor, but do you have any idea of the torque they deliver.</p><p>It is probably not so interesting to talk about torque on a propeller, but for an idea to electrify for instance a Brompton folding bike, i would begin calculting from a torque of 15 Nm on the wheel, with most e-bikes having 250W motors, i can't imagine these tiny motors delivering this kind of torque needed on a bike, even with a gear ratio of 10 you are using.</p>
<p>hola junto con saludarte quisiera saber si puedes compartir conmigo los archivos de tu invento </p>
Very cool.
<p>Hi,</p><p>This is an awesome build! Are orbit wheels anything wearing like heelys?</p><p>Is this possible to make orbit wheels out of wood for those of us who can't afford/don't have access to metal working tools? A machine shop would probably charge me a lot of money to have them cut out (given that I would be asking for a small order). I would probably put those batteries in a backpack to keep them safe and more crash resistant. I would also probably use flat, rectangular packs so they stack up nicely. :D</p><p>I also have quite a bit of experience with RC car and I am wondering why brushless sensor less motors would not work? From my experience on RC cars, they seem to work fine, but there is a bit of stuttering when the motor is revving up. Changing the gearing to a lower gear ratio is oftentimes the solution. Furthermore, if you don't want to go faster than 10 mph, why not change the gearing so that you can maximize torque and reduce heat issues. Or is there a risk to stripping gears with a smaller pitch from your experience?</p><p>One last note. It seems that the esc that you are using would be prone to overheating. I am suspicious that the esc and motor would overheat with extended use....</p>
<p>Thanks :)</p><p>I haven't ever worn heelys, but I imagine orbit wheels a quite different. </p><p>Absolutely! Feel free to make use of the materials you have access to. You might need to make some modifications for the rim though. I'm not sure how well the urethane would stick to the wood, and the ring gear should be made of a harder material (metal/plastic). You could definitely use wood for the structural frame.</p><p>I used a Car ESC sensor-less motor controller. It requires the electric orbit wheel to be spinning before activating the motor, but that's solved by orbit wheeling in a snake-like motion. </p><p>Yes, I'm also surprised the controller doesn't overheat. I haven't ridden the electric orbit wheel continuously on a full battery life cycle (just short five minute bursts), so overheating hasn't been a problem. </p>
<p>Can you provide a full list of materials that consists of everything I will need, the one you provided doesn&rsquo;t included things like the steel rods or the Dean plugs, and should we send in the dxf files for the acrylic and frame? And if there are files for the aluminum housing for the motor controller could you please add that too, so we can send that in to the water jetting company. Also, i knew you drew the diagram for the battery packs, but could you maybe elaborate more on how to connect the electronic components to the batteries and such? Also you said you used a lathe, and if we don&rsquo;t have a lathe, is that ok? Can we use another device to create these, perhaps a Dremel or do are they really not that important, so i don&rsquo;t have to bother. I know I am asking for a lot, but answers to these questions would really help me, and I would really appreciate it. Thank you.</p>
<p>The acrylic frame was just a prototype, so no, don't have those cut out. (I don't think I uploaded the .dxf files for the acrylic prototype anyway). As for the motor controller housing, I machined it all on the mill. You could probably make something work with wood. Or you could put all the electronics (including the battery pack) in a backpack to avoid cramming all the wires around the motor controller in a tiny box and all the batteries around the frame. There's a lot of improvements/modifications that could make the construction of the wheel easier with the specific materials and tools available to you. My design worked for me, but it might not necessarily work for everyone; feel free to change it! :)</p><p><strong>Wiring:</strong></p><p>The main things to worry about are connecting the two halves of the battery pack (if you decide to go this route), powering the motor controller, joining the balance connectors, and making an adapter for charging. See the attached diagram. Then the rest is just cramming in all the wires. </p><p>Yes, it's absolutely possible to make these without a lathe. Use a hack saw to cut the steel rods and then file them to make sure they're all about the same length. I wouldn't recommend using a Dremel; you could use a drill press to drill the center hole. The steel rods are important (they hold the two halves of the wheel together). The precision of the center hole in the steel rods is not important (it may cause some problems with bearing spacing, but you can use this to your advantage and tighten the rods down such that there isn't any slack between the wheel and bearings). </p><p>Be creative with it! :)</p>
<p>Also what kind of charger do we need to buy for this?</p>
<p>Most RC Hobby Battery Chargers will work. I used this one:</p><p><a href="http://www.hobbyking.com/hobbyking/store/__5548__imax_b6_charger_discharger_1_6_cells_genuine_.html" rel="nofollow">http://www.hobbyking.com/hobbyking/store/__5548__i...</a></p>
what would it take to wire a backpack full of batteries to this?
<p>about 2 wires and a switch. just make sure that empty batteries are not connected to full batteries to prevent a surge, and you're good. in a backpack you could comfortably fit 5s6p besides your books, so 3x as much. however it would weigh a lot too.</p>
<p>I actually did make an additional 5S4P battery pack to increase my range for the 10 km Midnight Sun Run up in Fairbanks, Alaska. I had Orbit Wheeled the race previously in 2012, and thought it would be fun to return with the electric version. </p>
<p>Nice!!</p><p>what do you estimate was your total range with this pack?</p><p>how much does it weigh?</p>
<p>Ideally the exterior pack would have been twice the range of pack on the wheel resulting in a total 4.5 mile range. It weighs about 3.4 pounds.</p><p>Unfortunately, I didn't get to use it in the race because I had accidentally messed up the communications between the receiver and transmitter with some last minute soldering.</p>
<p>That's too bad...</p><p>3.4 pounds seems as it would still be quite manageable in a backpack, so that's good. Do you have any plans to further develop this idea? you might even get good results if you were to kickstart production! </p>
<p>Yes, I have a few improvements I'd like to incorporate in a future prototype. </p>
We need 10 of the batteries, right?
<p>Yes, you will still need 10. I'd recommend getting a few extra in case soldering doesn't go as well as planned. It is possible to damage the cells with too much heat, and you want to make sure they are all 3.5 V. </p>
I tried to find the batteries you listed above but I couldn't find them I could only find the A123 26650 and the 18650 but could fin the one you specified above as A123 28650. And I couldn't compare them because I don't know what the 28650 is like. Which one should I use?
<p>Yes, you can use the green A123 26650 cells. They are actually a better cell compared to the white A123 28650 cells I used. Meaning, they can hold 0.6 A/h more (with a 5S2P pack) and supply 17.5 V to the controller (which you could modify to make the motor spin faster). Here's the nominal voltage and capacity for both cells:</p><p>A123 <strong>28650</strong>: (white cardboard cover)</p><p>Nominal Voltage: 3.3 V</p><p>Nominal Capacity: 2.2 A/h</p><p>A123 <strong>26650</strong>: <a href="http://www.a123systems.com/lithium-ion-cells-26650-cylindrical-cell.htm" rel="nofollow">http://www.a123systems.com/lithium-ion-cells-26650...</a></p><p>Nominal Voltage: 3.5 V</p><p>Nominal Capacity: 2.5 A/h</p>
<p>how much did this cost you and if possible could you put up a material list</p>
<p>I bought enough materials to make two Electric Orbit Wheels and additional components in case a motor or controller burnt out. It ended up costing around $300 (not including shipping) with the additional materials. However, it would only cost about $215 to make a single wheel. Here's a Google doc spreadsheet containing the Bill of Materials:</p><p><a href="https://docs.google.com/spreadsheet/ccc?key=0ArkLjZiIqp-ZdEx5R2trMnhNc0dickFwcUhySk5PZkE&usp=sharing" rel="nofollow">https://docs.google.com/spreadsheet/ccc?key=0ArkLj...</a></p>
Wow. Awesome build. <br> <br>What are your thoughts about taking the battery capacity one step further and setting up a &quot;charge&quot; circuit that engages while you coast, essentially using the DC motors as a generator to charge the batteries during coast, same principle as diesel electric locomotives work? Obviously, it would be a little bulkier, but also extend your range alot farther.
<p>That's a great idea. It's the same principle behind regenerative braking. You wouldn't want to engage this feature while coasting, because, due to conservation of energy, it will decrease your kinetic energy. Thus, it's great if you want to stop or slow down. Then you're storing the energy rather than wasting it as heat with brake pads. </p>
<p>maybe he meant breaking- like dancing?</p>
<p>&quot;5S&quot; corresponds to five cells in series and &quot;2S&quot; corresponds in two groups of cells in parallel&quot; </p><p>Don't you mean 2P?</p><p>also, neat idea!!</p>
Excellent work. I'm glad to see MITERS continues to produce great projects. I wonder if the clear polycarbonate snowboard I built is still hanging from the ceiling...
Congrats, your project is awesome!
congrats on winning the contest!!!
post a videos of you riding it that would be cool <br>
so you have first prise for two contests lucky you, entered just in time and won both first prise
I think you mean braking (when slowing down) and not breaking. :) <br>Anyway, neat 'ible, these look very fun to ride!
oh my. after reading through this i realize how seriously average dumb i am. wow! what an amazing project.
Righteous. Very very good build.
This is an insane build. I'm so glad there are people like this out there, with the skills to pull this off!!
Awesome. You know, I imagine it's probably a good thing the motor doesn't start from a complete stop. I imagine it's probably easier to retain your balance if the motor engages while you're already in motion.
<strong>ESC</strong> stands for Electronic <em><strong>Speed</strong></em> Controller; at least, it does in the context of RC brushless motor speed controllers.
Thanks for the catch.
didn't it cost you more to make them then to buy them?
It did cost more to make them, but building things is fun. :)
Those yellow crocs doe ლ(ಠ益ಠლ)
I love you MIT. Now streamline the build, make it out of off the shelf components, and start selling kits.
it looks so awesome and amazing i wish to make one ლ(ಠ益ಠლ) but unfortunately i dont have the ability to do so ):
Hey Jaguar, we found this project awesome and we've featured you on our new tech/hack/mod blog site: http://modthat.com/ (direct link here: http://modthat.com/diy-electric-orbit-wheels/ ) keep up the great work!
edit: links that work: <a href="http://modthat.com/diy-electric-orbit-wheels/" rel="nofollow">http://modthat.com/diy-electric-orbit-wheels/</a>

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