Sunday, September 22, 2013

Remote Controlled EV3 Lego Excavator 42006

Remote Controlled Excavator

I got the LEGO Excavator a few months ago but the controls on it were way too difficult for my kids to use.  Heck I had a hard time remembering what combination the three switches had to be in to make it open/close the claw or raise/lower the arm.  I found some videos on youtube where people used a lot of power functions gear to make their excavators remote controllable.  The way they did it was cool but I don't own tons of power functions parts so I decided to make mine remote controllable by combining it with my EV3.

The hardest part was figuring out how to control six movements with only four motors. I built a motor multiplexer that uses two motors to control four movements.  This is used to control the claw, arm, rotating the platform,etc.   I used the other two motors to control the tracks.

It is a big hit with my kids :)


  • LDD Instructions - I didn't include instructions for the arm/boom since they are the exact same as the standard 42006.  When you build it turn the mux so that it is engaging the gear at the top.
  • EV3 Software - There is a program called RunFirst that you need to run one time when you first build the excavator.  This program creates a text file that is used to remember where the multiplexer is located.  This way if you turn the EV3 off and turn it back on, we know which gear is currently engaged by the mux.

Tuesday, September 10, 2013

Lego Technic Two Input, Four Output Motor Multiplexers

Motor Multiplexers

I bought the Lego Excavator 42006 a few months ago (for the kids of course) along with the power functions add-on so you could motorize moving the boom up & down along with opening and closing the claw.  The controls are pretty bad though, there are three switches that you have to toggle in just the right combination to get the movement that you want.  It takes me several tries to find the combo I'm looking for, for my 4-year old it is really frustrating.

I also got an EV3 kit recently so I've been working on combining the two so that I end up with a remote-controlled excavator.  I figure that will be much more enjoyable for the kiddos.  The challenge is the EV3 brick only supports 4 motors but I need to be able to control six movements on the excavator.

  • Opening and closing the claw
  • Moving the boom up and down
  • Moving the boom in  and out
  • Rotating the entire platform clockwise and counter clockwise
  • Moving the left track forward and backwards
  • Moving the right track forward and backwards
I need to run both tracks at once in order to move forwards, backwards and steer so that leaves me two motors to control the claw, boom up/down, boom in/out and platform rotation.  I started working on a hardware based motor multiplexer that would let me control four functions from two motors.  

It took me a few iterations to get something compact enough to fit in the excavator.  The turntable mux at the beginning of this video is the one I'm using for the Excavator.  The other two work, they were just too bulky.  The two at the end are a little different in that they will let you enable two outputs at once unlike the turntable mux which only enables one output at a time. Someone else may find them useful though so I included them in the video.

I'm still working on the Excavator but it shouldn't be much longer now that I have the mux figured out.

Build Instructions

Here are the LDD (LEGO Digital Designer) files: