Closing the Loop on Hobby Servos with MRL

kwatters's picture

This is really a page to talk about how to measure the actual angle that a servo has reached, rather than the last position the servo was told to move to.  The aim is to be able to allow the servos to automatically configure their actual max/min angles.  In addition, it should allow for quicker response to the stop() method.

The stop() method stops the sweeper that is currently running for the servo.  However, this only tells it to stop the sweeper, the servo will continue to move to the last position it was told to go to.

TopCodes Service


TopCodes service allows to recognize a special code. You can print these codes using the attached topcodes.pdf.

The service gives back the following information :

  • Number of the code recognized
  • Coordinates of the center of the code (x,y)
  • Diameter of the code (which can be used to find distance)
  • Angular rotation of the code



New Service For Robot

beetlejuice's picture
Hello GroG,
All good ?
It's done, Eclipse is well installed, and all is ok, i can compile MRL without problem.
can you explain me the next step to create my own service please.
And i've also an other question . I'm trying to make to activate the leds of my robot mouth move while it's speaking.

dc-dc power supply used on Azul

harland's picture

I decided this weekend to make a pc board for the DC-DC voltage regulator circuit. I have not used the pc board machine for a couple of years. It can only do single sided or 2 sided boards. I designed the circuit and board in “Eagle Software”. That software puts out a file, Gerber format, that the machine takes in and cuts. Decided to go with Kevin’s advice and put 4 LM338’s on it. So it should be able to handle 20 amps. Trying to brush Azul’s hair I had the 2 channel DC-DC circuit (now in Azul) drop down to 3.3 volts and fail.

Working with springs

killbox's picture

After having a fatal "twist" of my wrist I decided to try to incorporate springs into the return tendons. 

The twist of the wrist breaking six tendons and folding the forearm near a print flaw I saw that the wrist though realistic was too realistic for the unstrechable line we are using. Now I haven't fixed this yet but I did make it so your fingers may be less floppy and an easier time trying to tension the tendons in the hand.

Now my springs that I bought are a little weak, but this mistake turned into a great find.

Using OpenSCAD to edit STL files

kwatters's picture

Here's a simple example of how to use OpenSCAD to edit a pre-existing STL file.  This is useful if you want to add or subtract areas to the existing file.  

OpenSCAD is an open source CAD program that allows users to programmatically build up models using basic geometries.  The below example is based off of the part 

Download OpenSCAD from   (It's free)

Download the STL file that you want to edit. For this example I used

a new robot homemade in cardboard

ambroise's picture

hello everybody

i find a new robot

very eeasy for star to build a robot in cardboard


Blender Inmoov python pyserial parallax propeller

Gareth's picture



Just a taster for an up coming walkthrough integrating Serial devices with Blender.

Serial Service - now has 1 click Virtual UART

GroG's picture

WOOHOO I sent a file through a virtual serial cable !

In this quick demo I do the following