DIY Sphere Robot




This is a spherical robot design that I am working on. I intend to use this to create a replica of BB-8 (lots more work to do!). It is about 18" in diameter and very intuitive to control. I have spent about $400 for everything in this instructable. The internal structure and drive system is made from primarily Actobotics parts available through Servo City.

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Step 1: Assemble the Drive System

The next few steps will describe how to assemble the drive system. The drive system uses entirely Actobotics parts (listed later). This motor and gear ratio results in a nice balance of power and speed in the final robot.

Step 2: Prepare the Motors and Connections.

Before mounting the motors, I soldered on a motor backing that allows me to easily connect a male 20 JST connector. I find this useful for using motors in other projects later and making robot modifications and maintenance much easier. I will connect my motor to the ESC (electronic speed control) later using an XT60 connector (many other connectors would work fine), so I soldered the male JST connector to a male XT60 connector.

Pay attention to positive and negative! The Actobotics motors have a white dot on the positive terminal but they can also be wired the opposite way. For this robot, make positive and negative the same for each motor.

You could solder wires directly to the motor and ESC, but connectors really make everything easier for the future.

2x - (JST20M) 20 awg Male JST Connector

2x - (605120) Gearmotor Board D (for 32mm Planetary Gearmotors)

2x - Male XT60 connectors

Step 3: Assemble the Drive System (2X)

The following steps will describe how to make one of the wheel assemblies. You must make 2 of these wheel assemblies. Each is identical.

Parts for ONE wheel assembly

(638284) 612 RPM Heavy Duty Precision Planetary Gearmotor

3x - (535198) .250 inch ID x .500 inch OD Flanged Ball Bearing (Stainless Steel) (These come in 2 packs, you need 3 for each wheel assembly, 6 total)

At least 64x - (632106) .250 in L x 6-32 Zinc-Plated Alloy Steel Socket Head Cap Screws

(585442) 3.00 inch Aluminum Channel

3x - (545360) 90 Degree Quad Hub Mount C

(633104) 1/4 inch Shafting & Tubing Spacers (12 pk)

(634064) 1/4 inch x 1.50 inch D-Shaft

(595630) Drive Wheel Adaptor A

(615242) 16 Tooth, 32 Pitch, 1/4 inch Bore Pinion Gear

(615206) 80T, 32P, 1/2 inch Bore Aluminum Gear

(545548) 1/4 inch Bore Set Screw Hub (0.770 inch)

(6432K12) 1/4 inch Collar

(634078) 1/4 inch x 3.00 inch D-Shaft

(595624) 4.90 inch Robot Wheel (Blue)

(625106) 1/4 inch to 6mm Set Screw Shaft Coupler

Step 4: Mount Gear

Place bore set screw hub into aluminum gear (gear flange side down). Screw the drive wheel adaptor into the gear and hub as pictured using 4 zinc plated screws.

Step 5: Check the Wheel Orientation

The wheels are not symmetrical but can be mounted 2 ways. One side has ridges and a more shallow taper. I put my wheels on with the ridges facing outwards.

Step 6: Mount Wheel

Place the mounted gear into the wheel, then the other part of the wheel adapter into the wheel, and then screw everything together firmly.

Step 7: Attach Motor Mount to Motor

Attach planetary motor mount B to motor. Be sure the mount is oriented such that the screws sink into the mount when tightened.

Step 8: Attached Drive Shaft

Mount the 1.5" long D-shaft onto the motor using the coupling. Be sure the coupling is as far down onto the motor as possible and the D-shaft is pushed in as far as possible (this will result in the correct length later). Obviously be sure to tighten the couplings such that the hex screws screw onto the flat side of the D-shaft. Make sure the hex screws are tight, mine have comes loose. Use locktite if necessary.

Step 9: Mount Motor

Screw the motor onto a 3" piece of aluminum channel as pictured. I used longer screws (1/2") but this is not necessary.

Step 10: Attach Bearing and Joint

Place bearing into the upper hole of the motor assembly with the flange on the outside of the channel. Place the joint against the bearing as pictured and screw onto the channel with 4 screws. This sandwiches the bearing between the channel and the joint holding it in place.

When attaching the joint, screw each screw in loosely first, then tighten each slowly and evenly so the joint is flush with the channel.

Step 11: Attache 2 Joints

Screw in two quad hub mounts with 8 screws as pictured. When attaching these joints, screw each screw in loosely first, then tighten each slowly and evenly. It's much easier to put the screws in this way.

Step 12: Place Bearings in Joints

Slide 2 bearings into place with flange facing outward.

Step 13:

Attach 1/4 in collar to the 3" D shaft leaving exactly a quarter inch sticking out. Add 2 spacers. Slide the shaft through the bearings mounted above the motor.

Step 14: Pinion Gear

Add one spacer to each shaft. Attach pinion gear. Make sure everything is pushed together tightly on the shaft but not tight enough to create friction.

Step 15: Wheel Mounting

Put the wheel assembly on the top shaft. make sure the set screws screw into the flat side of the D shafts

Step 16: Attach to Main Body

Attach whole assembly to end of a 9" piece of channel

Step 17: Set Up Power Distribution

I use a Turnigy 2200mAh 3S 20C Lipo Pack with XT60 connector. I soldered a female XT60 to some standard RC connectors to be attached to the ESCs later. Looks a little sloppy but it works. PAY ATTENTION to positive and negative obviously. You can easily ruin your ESCs or battery by creating a short circuit or connecting things backwards.

Step 18: Attach ESCs

I used a HobbyWing QUICRUN 1060 Brushed ESC (1/10) (one for each motor). Red and black wires connect to positive and negative of battery. Yellow is motor positive, blue motor negative. The signal wires will go to the drive computer later. These come with a switch. I keep the ESC off until everything is hooked up properly. Jumppers should be set to LIPO and F/R. Instructions that come with the ESCs explain how to do this. I stuck my ESCs to the robot with double sided tape (included with ESC) right above the motors.

I used a jig saw to cut a small hole in the channel to fit my XT60 connectors through when attaching the motors.,

Step 19: Reciever, Mixer, and Capacitor

My receiver is a Neewer® Fs-r9b 2.4g 8ch Receiver Rx-9x8c For Turnigy 9x Fs-th9b 9ch Transmitter. Obviously get a receiver compatible with your transmitter. To make all of the controls super easy, I use an IMX-1 invertible RC tank mixer drive computer. Information and user guide HERE. Be sure to do the recommended calibration. I put the drive input in channel 3, steering input in channel 1, and invert in channel 5 (this comes in handy but is not required). This set up allows for intuitive control of the whole robot on the right stick of the transmitter. Channels may vary between RC systems.

Plug the ESC signal wires into the front of the IMX-1 mixer. The white wires (signal) should be facing the inside of the board.

Also pictured is a Novak 5626 Glitch Buster Capacitor. This can plug into any channel and prevent radio glitchs caused by high amp motors being near the receiver. I was having a few glitches here and there. This capacitor makes everything smooth and glitch free.

Step 20: Center Piece

The center of the robot is a 3" piece of aluminum channel attached with (545532) Channel Connector Plate A and four screws. I cut a small corner of the channel out with a jig saw to make room for wires coming out of the battery.

Step 21: Attaching Ballast

The bottom piece of 6" channel is also connected with (545532) Channel Connector Plate A and four screws.

Step 22: The Ballast

I made my ballast using lead wheel weights for balancing car wheels. These conveniently have double sided tape already on them. I used about 1.5-2 lbs of weight to fill up a piece of 6" aluminum channel. Be sure to leave space in the middle for the battery to sit. Be sure to not add too much weight to the sides or bottom or it will hit the sphere after final assembly. I also attached craft foam (like egg carton foam) to the bottom using zip ties. This is optional but helps eliminate wobble from the robot.

Step 23: Careful!

I used 2x - 18 in. Clear Acrylic Globes - with 8 in. Neckless Opening - American 3202-18020-017. These are quit fragile. I used a dremel and cut off wheel most successfully to cut mine but still melted a bit of plastic. These will shatter so be careful.

Step 24: Prep Sphere, Cut Circle, Glue Tabs

You will need 2x - 18 in. Clear Acrylic Globes - with 8 in. Neckless Opening - American 3202-18020-017. Use the opening of one sphere as a stencil to cut a circle out of the other sphere (8"). I used a dremel sanding tool to score the inside of the opening so epoxy will stick better. Cut 8 rectangles out of 1/16" thick balsa wood (can use box cutter/knife). The rectangles are 1" x 1-3/4" each. Using 5 min epoxy, glue the rectangles to the inside of the sphere as shown. the placement of the wood "tabs" allow for the robot to slide in and out of the sphere. I beveled the edges of the tabs so later the wheels can ruin over them more easily.

Step 25: You're Done!

The robot is now complete. See my video for a demo. Be careful taking it in and out of the sphere so you don't break the wooden tabs. I close the "door" of the sphere using duct tape at the moment but I'm working on a latching mechanism.



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    25 Discussions


    3 years ago

    Here is a video of the head mechanism so far


    Tip 1 year ago

    Excellent project and great instructable ! I just wanted to add one little tip that, you didn't have to use a mixer as an extra part as your remote (Turnigy 9X) already allows mixing on the remote settings.

    I am thinking of building a smaller version but seeing yours made me realize it gets better as it gets bigger :P


    3 years ago

    Congratulations, nice work. I'm already working on designing my own sphere robot. And I have one question for you. You have used gears to join the motor with the wheel, instead of putting the motor directly to the wheel axis. I was thinking to do the same, but you can find the same motor that you have used with different RPM, you use 612RPM, too fast to put it directly on the axis, but the same model of moto come with gears for 16RMP, 24,etc.What's your reason to use gears instead of using a lower RPM motor? I can see that lowering the center of gravity is one advantage, but is there anything more than I'm missing?


    3 years ago

    Great instructables project! I've started building it :D I think you left off the planetary motor mount B from your gear list though (part 555174).

    Are you going to post plans on how you built the rest of it that is shown in the video? That would be awesome.


    3 years ago

    i love it as soon as my holidays start i am gonaa get to work on this


    I am a struggling graduate student with little time and money! Don't give up, just go slow. I've been working on this for months. Sometime I don't touch it for a few weeks, then I use a Saturday or something. Save my money in between haha. you can do it!


    3 years ago

    I'm building a full size bb8 my self. I have most of the parts but I can't find the plastic sphere. Where did you get yours?

    1 reply

    Reply 3 years ago

    I got mine here:

    Recently I found ones that are actually 20" like the real BB-8 here:

    Bobby Dean

    3 years ago

    A small idea is to charge your batteries using the wireless charging plates technology that phones are using, that way you don't wreck the wooden tabs as often. I think that you did an amazing job with the build though. Good luck and have fun

    2 replies
    jfnahabedianBobby Dean

    Reply 3 years ago

    Thank you! I've been trying to figure out how to accomplish induction charging for 3s LIPO batteries but I havn't found an easy solution for the type of battery I am using. Do you know of an induction charging system for charging LIPOs?

    Bobby Deanjfnahabedian

    Reply 3 years ago

    Just an idea but what if you put the necessary charging supplies into the ball with it that way the charger connects and gives the power to the input lead. If you do it like this then you don't have to worry as much about the battery due to the fact that all of the electronics are already connected inside the ball. Just an idea though


    Reply 3 years ago

    Hello, the descriptions of how the electronics work are described in the steps.


    3 years ago

    An idea for your robots head...a post rising up from the arm like, the counterweight does. Add some powerful neo-magnets to the end and make it hug close to the surface. The head would use 3 captured ball bearings to ride the outer surface and with a few more magnets should always stay on top.
    You'll probably need to increase the counterweight with this method.

    Cool build and good luck.

    2 replies