Hidden R2-D2 Controller

July, 2017

I’ve very much enjoyed my finished R2-D2 over the past 9 months and have had many opportunities to bring her to events to the delight of many children (young and old).  One reoccurring conversation I have with the younger audience:

Kid:  How is R2-D2 moving?
Me:  She drives hersel…
Kid: (interrupting, noticing the huge RC controller in my hand) Oh!  You’re controlling it.
 Posing for pics

As much as I love my Frsky Taranis X9D controller, it is quite large and hard to conceal and it does tend to ruin the illusion for my younger audience.  The Taranis gives me many advantages over a more traditional game controller that most R2 builders use since I can control up to 16 channels and get one controller in the body (channels 1 – 8) and one controller in the head (channels 9 – 16) with no wires in between.  I know other R2 Builders who are masters as hiding their controller behind their backs or inside empty backpacks or other tricks.  My issue is that I like to accompany my R2-D2 in costume as an X-Wing pilot and I have no way to hide or easily conceal the RC controller.

I got this idea that I could take my Taranis controller and re-package it so it would be easier to conceal under my X-Wing pilot costume.  I really did not want to risk breaking my controller in the process, so I bit the bullet and bought a second controller to tear apart.  That way, if anything should go wrong, I have a backup.

I started by opening the case and extracting all the circuit boards and battery.  The Taranis is built quite modularly and most of the peripheral switches have JST connectors to the main board, so extraction was not that challenging.

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Now that I had the case removed, I could get an idea of how big the new box would be.  I also got my first look at how the controls worked so I could do a bit of reverse-engineering to figure out what wires controlled each function.

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I cut off all the peripherals and carefully labeled each of the wires.  Any unused wires were either cut short or tucked away.  I carefully examined the joystick controllers and concluded that they were fundamentally just 2 potentiometers on a fancy platform that tracked the X and Y axis of the joy stick.  They were rather big and I was struggling to determine how I could package these to conceal in my hand.  Then it occurred to me that someone else has already done this in a very ergonomic package – a Wii Nunchuck controller!

I confiscated a pair of Nunchuck controllers that were collecting dust from the Wii in the basement and cracked them open to see if they were usable.  A special tri-wing screwdriver required to open this and other Nintendo products, which I already had on hand because of an earlier project performing some mods to my Wii (which is a story for another blog post…).  Long story-short, I ended up performing some major surgery on the Nunchucks to bypass all the on-board circuitry (gyro, accelerometer and I2C chips) and just get me access to the pair of pots and the 2 buttons.  Solarbotics Nunchucky breakout adapter gave me an easy way to break out the 4 pins of the Nunchuck.  However, to do everything I needed, I needed 2 additional wires (3V, GND, X Pot, Y Pot, C Btn, Z Btn) since I was not using the onboard I2C capabilities.  So, I fed 2 long wires into the Nunchuck through a small drilled hole in the bottom of the handle, and taped them along the Nunchuck cord to keep them from tangling.  After much trial-and-error, I got the nunchucks to perform all the functions needed to control R2-D2:

Right Hand Nunchuck:

  • Joystick controls movement (R2’s 2 wheel motors)
  • C button controls the holo-lens light
  • Z button controls the voice (random playback of different R2 noises)

Left Hand Nunchuck:

  • Joystick controls movement of the holo-lens
  • Rocker switch (replaced C/Z buttons) controls the head spin.

Next, the project box for the circuit boards and battery.  I wanted it as small as possible so it could be strapped to my back on a harness and expose ports for the Nunchuck controllers to connect.  After MUCH searching, I came across the Hammond 1554H2GY project box which closely met my needs, but was too tall.  (BTW, Newark aka Element 14 is my favorite place to shop for project boxes online – they have a great website for searching through lots of options).

A project box that was overly tall meant that it would look extra bulky when I strap it to my back.  Unfortunately, I could not find any alternatives.  So, I took the box to the bandsaw and cut the box in a way that I could keep the bottom and the top part with the screw threads and the lip for the lid, but remove about 3/4″ of middle space that was unneeded.

 

I sanded the cut edges, and used CA glue to bond it back together.  I used a bunch of clamps to hold it into place while drying.  The end result was the perfect size for my needs.

I then when to work modifying the project box to provide the holes needed to expose all the peripherals.

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I drilled a hole in the top for the antenna, cut a hole for the power switch on the left, Cut slits to fit the Nunchucky boards on the side and holes to feed the connectors for the extra two wires for each Nunchuck.  I also cut a square out of the bottom to expose the barrel plug adapter for recharging the battery.  After testing, i realized I needed to expose an LED so I knew if the unit was on.  The main functions of the unit can still be controlled with the 6 buttons on the main display board by opening the case, but I really should not need to access them often (if ever).

The moment of truth – I paired the Frsky X8R receivers with the newly packaged Taranis X9D controler and it worked!  I just needed to do some minor trimming on the joysticks to get them exactly center and I was good to go.  Frankly, I was a bit surprised it worked on the first try!

I bought a padded shoulder harness (meant to be used for sled pulling by athletes) and some hook-and-loop straps to keep it secure on my back under my costume.  I used rivets to attach the straps to keep anything from sliding around.  I intentionally mounted the box on the outside of the harness to hopefully give it some breathing room while I’m wearing it.  The padding on the harness seems unnecessary since the box is not very heavy, but I may feel differently after wearing it for a few hours.

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For fun, I tried to put my costume on over top to see how it would look and feel.  There is a hardly-noticeable rectangular bump on my lower back, under my costume (under the bib and above the straps), but I don’t think any kid would associate that with an RC controller.  It’s surprisingly comfortable.

20170704_192059 For my comfort and convenience, I bought some wristbands and use those to manage the wires inside my sleeve.  It also lets me release the controllers and free my hands so I can do other things if needed.  I could even tuck the Nunchuck inside my sleeves if I needed to hide them.

I think this will be a much better way to control my R2-D2 and still stay in costume.  I am a bit concerned about the circuitry overheating and the fact I do sweat when wearing the heavy costume.  Hopefully, the project box has enough ventilation, but not too much to let any water in.  I’ll have to get creative with the kit if I decide to add more features to R2 that requires additional remote controls, but I’ll cross that bridge if/when I get there.

 

July 9 Update:

I attended a con this weekend and brought my R2 with my new controller.  Overall, it was a great success, but I still have some work to do:

Good Points:

  • People were generally baffled about how R2 was being controlled.  When asked, I just said, “there’s a guy inside”.  When they noticed the Nunchucks, I playfully denied that they were controlling R2 and just said that they were purely coincidental.
  • The unit on my back did not overheat or have any adverse issues.  While I did sweat in costume, the unit was not impacted at all.  (whew!)

Bad Points:

  • The C&K rocker switched I used for controlling his head spin is a piece of garbage!  The plastic rocker plate popped off 6 times, and I had to stop using it.  Very frustrated.  I think I’m going to revert back to just using the C/Z buttons on the Nunchuck instead of using a rocker.  I’ll just have to be careful not to press them both at once.
  • After using rivets to secure the hook & loop straps to the harness, it hung a bit lower than when I tested it which made it more difficult to put on my costume.  Also, the harness is a pain to get on because it uses side buckles which I had difficulty reaching while wearing it.  Finally, the harness started sliding off my shoulder under my costume during the con – it needed a strap in between the shoulder blades to keep them centered on my shoulders.  I’ve found a new harness with a front buckle that will allow me to keep it higher on my back.  This new harness has less padding, and I think will work better.
  • Because my main goal was stealth, I attempted to hold the Nunchucks in my hand in a way that they were not easily seen.  Unfortunately, this made it a challenge to use my thumb on the joystick.  So, I had to adjust my grip to make them a bit more visible.  Most of the time, I walked with my hands to my side or behind my back.  There was an awkward moment during the con when someone asked to shake my hand because I had to drop the controller and it dangled down as I was shaking.  It would be great if the Nunchucks were self retracting up into my sleeve.  I’ll have to think hard on how make this better.
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7 Comments

  1. ” It would be great if the Nunchucks were self retracting up into my sleeve. I’ll have to think hard on how make this better.”

    How about a badge reel or two to pull it back up your sleeve?

  2. For not pressing the C and Z buttons together, maybe you could fabricate little seesaw cover for them.

    For the retraction, maybe tether them to something on your back, so that they are pulled in as you raise your arm and drop down when they’re by your sides – like how a sleeve is naturally pulled away from your hand as you move.

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