Hand Motion Controlled R/C Car




About: I am an electrical engineer. I graduated from U of Waterloo. I used to work for Adafruit Industries as an EE. Now I work for Sony PlayStation as a EE.
This is a must-do hack for any cheap R/C car, it uses the tilt sensing switches I made so you can control a car just by tilting the controller like a wiimote.

There are many possibilities with this hack, for example, you can turn the controller into a base-less joystick, or put it on a helmet and control it with your head.

this will also work for R/C tanks (or other two motor drive stuff) except the switches needs to be placed diagonally

Another possibility to explore is making a mini segway, if you can get the tilt switch sensitive enough and the controller mounted onto the car (the car must be wheelie-ready). This might not work so good.

Below is two pictures of the car I'm working with (the front end spins, not steer, but it is not a problem with some practice)

You will need:
  • r/c car
  • tilt sensing switches (see step 2)
  • hot glue gun
  • soldering iron
  • wires
  • some pvc pipe (see step 4)
  • collection of hand tools

Demo Video:

Step 1: Making the Tilt Sensing Switch

I made another instructable before, just for this switch
Click Here To See It

But I had to adjust the switch by drilling more holes into it until i got it just right.

The second picture shows how it works.

Step 2: Opening and Testing the Controller

First you need to figure out how the controller works.

Open it up, save and map out each screw
If your antenna wire is moving around, hot glue it down.

You need to use a multimeter to test what connects to where, have fun at it. What I found in my controller was 4 metal flaps, all connected together, which presses against 4 jumper wires underneath them. The 4 flaps are connected to the negative terminal of the battery, this makes it really easy to hack.

You might also have one with buttons instead of sticks, I have no idea how those work so you need to figure it out.

If you are unlucky, and each flap or button are not connected to all the other buttons, then you might need to use 4 tilt sensing switches, except make them SPST.


Step 3: Adding Some Wires

Now you know what needs to be connected to what, solder some wires to those places. (colours of the wires doesn't matter)

Now try and control the car by touching the wire ends together, if it doesn't work, figure out why, it could be a simple bad solder joint.

Drill some small holes so the wires can get out, put the wires though them, take care making sure that the wires won't be bothering any of the mechanical parts inside the controller (such as the stick or the metal flap, or stopping the casing from shutting completely).

Close the case, test it again by connecting the wires and by using the sticks, it's better to have both of control methods working.

If you want to make the controller one big base-less joystick, cut a large dowel (or pipe), and attach it to the top or bottom of the case before you close the case. Make sure everything fits.

Below are three examples of what I soldered

Step 4: Mounting the Switches

If you are lazy, just attach the switches to a block of wood.

What I did made it completely adjustable, you need:

*3/4" pvc pipe
*3/4" pvc pipe cap
*1/2" pvc pipe
*some tape

Put the tilt switch that will control the forward/reverse on to the face of the 3/4" pvc pipe cap.
Cut a segment of 3/4" pipe, and drill 2 holes for the antenna to go through, and in my case, one of them might need to be bigger.
Cut a small stub (1-1/2" to 2" long) of 1/2" pipe, attach the steering tilt switch on the side of the pipe
Put lots of tape on the 1/2" pipe stub, and insert it into the 3/4" pipe, it should fit snuggly
Put the 3/4" cap with the tilt switch on the other end of the 3/4" pipe
Put the entire assembly onto the controller

This way lets you adjust the switches every way possible

Look at the diagram and pictures if you get confused

Step 5: Hooking Up the Switch

You might have noticed I put spade connectors onto the switches, you can do this too, but you don't really need to.

Wiring is simple enough, loop the wire around the screws and then tighten them.

If you have one wire from the negative battery terminal like me, put a switch on it, I would but I didn't have any switches handy.

Step 6: Testing, Calibrating, Finishing

Now if everything was done right, it should work, so test it, and if using it feels awkward, then rotate the switches until everything feels balanced when you are driving.

You are done.

Step 7: Mini Segway Idea

This is just an concept

If you have a car like mine then you can try making a more sensitive tilt switch and mount the controller right on the car mount it in a way that the switch is neutral when the car is almost balanced on its rear wheels
If the car leans forward, the the switch will make the car move forward, making it lean back
if the car leans back, the switch will make the car move in reverse, making it lean forward.
If everthing is balanced, theoretically the car will remain in place and balanced on its rear wheels
If the front is slightly heavier, then the car will start to move forward slowly while trying to stay balanced
If the rear is slightly heavier, then the car will start to move backwards slowly while trying to stay balanced

This will only work if the car doesn't over react and the switch works fast enough.



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    62 Discussions


    8 years ago on Step 2

    I think hacking the rc with the buttons is much more easy....you just have to find two of its four wires which are actually connected to the rc and then soldier wires to them...!!!


    8 years ago on Introduction

    Although i am not sure how the mercury motion senser works(probably because i have never seen on)i think you can make it by taking the wires of the circuit you want to complete with it and sticking them at close distance on one side of of a thin tube...do the same on the other side as well.so when the tube is tilted to one side it will engulf one pair of wires and complete the circuit...i am going to make the one with the ball bearings and i will post an instructables as soon as i find ball bearings and make the sensor....!!!


    Reply 8 years ago on Introduction

    well mercury doesnt conduct electricity because it is liquid....it conducts because it is metal...the only metal that is liquid at room temperature.....and only polar liquids or solutions having ionic compounds as the solute can conduct electricity....!!!!


    Reply 10 years ago on Introduction

    grammar fail, now you are stating that not even a single liquid conducts electricity :P


    8 years ago on Introduction

    by the way you can make the sensor your self....and instead of using a metal ball or mercury you can use a solution of water and lots and lots of salt.....that will work....by the way this idea struck my mind while reading the comment and i havent tried it yet but i will try to post an instructable as soon as i make it.

    1 reply

    Reply 8 years ago on Introduction

    but the sensor would be quiet big it wont be really very easy to make a very small one although it can be made with smaller tools and lots of patience.


    Reply 8 years ago on Introduction

    you can easily control it via pc with the help of a 4 relay phidget...well they are a bit hard to find but if you do there is going to be just a little soledering and a little programming.you just solder two wire each to the +ive and -ive sides of each button and attach the wires to the relays in the phidget then you do the programming for it(which i cant do properly,actually i dont have a phidget,yet)and you are done.

    TropicalRCProf I.tiki

    Reply 8 years ago on Introduction

    I have just managed to do this with the Heng Long RC Tanks . They are the 1:16 scale tanks so I'm not sure if this is the size that you mean. If it is let me know as I can help you with this!


    9 years ago on Introduction

    Your concept can bedone by somehow adding this instructable's circuitry into your rc. I dunno how to do it, though

    astro boy

    9 years ago on Introduction

     GRRR my stupid car has 2 tiny solder tabs and so i had to take the buten of to use them and the solder wont eaven stick! >:0

    astro boyBowenj

    Reply 9 years ago on Introduction

     you might if it will let you touch that kinda info via the usb make a custom plug or it could send it to a mac or pc and then the mac or  pc would control via serial port