Let's Make Robots!

MarkusB's blog

Pulse oximeter Mk II

I just started to build a second version of a pulse oximeter. If you don't know what a pulse oximeter is, here is a simple but detailed description what a pulse oximeter is and how it works.


Today I found this in a local Carrefour store in Qingdao for 70 RMB. It has two RGB LED's which illuminate the ears and a couple of buttons. When certain buttons are pressed, it plays some songs or speaks some text (in Chinese).

I will probably hack it and build an emotional/chat robot out of it. In a first step I will take it apart and see what's inside (if my daughter let me...)

Interactive Stochastic Learning Automaton - cleaned up code

I have cleaned up the interactive Stochastic Learning Automaton code I once wrote and attached it in this short blog. Just send '0' or '1' via serial monitor, if a chosen action was favorable or unfavorable and see how the automaton learns to chose the right action over time.

T-800 reloaded

A funny afternoon in the office, some robot talk, and one of my Chinese artwork girls with some photoshop fu came up with this (it's me!)

That said, I really want to build a life-sized humanoid robot...And it will kill us all!

Simple 4 pixel camera sensor

In the following I describe a simple 4 pixel camera sensor, which can be versatilely used in robotics.

The sensor consists in general of four pin photo diodes with a relatively large photo sensitive area, arranged in a square, and an according collimator lens. Every photo diode can be thought of a quadrant of a two dimensional graph. We can use the sensor to measure the intensity of light, detect motions, track a light source in two dimensions or do basic 2-D optical flow calculations.

COSMA's brain

Attached you find the Rev. 0 schematic of COSMA's brain (Eagle). This board connects directly to a FTDI  board. As I need MOSI, MISO and SCK also for the micro SD card, I added solder jumpers, so those pins are not connected to the SD card/voltage level shifter while burning the bootloader on the chip.

The board mainly contains:

- ATMEGA2560

COSMA - Update 2

For the first protoype of COSMA I decided to build stackable proto shields for the Arduino Mega. Later I will layout a single PCB, including all.

Proto shield one

Proto shield two

My daughter

My daughter Mia is 2 years old. Every evening she is sitting next to me and helping me building a robot.

COSMA - Update 1

In the meantime I named the robot astronaut Cosma, a maiden name, ancient Greek for Cosmos. Below you'll find a more specific design study. I think I will 3-D print the main body and the head. I've furthermore tested a FSR (force sensing resistor) as a kind of pain receptor and the ArduEye.

We could be the third sending a humanoid robot to Space

After Robonaut 2 and the ongoing KIBO project, we could be the third to send a humanoid robot to Space. See my attached AT-A-GLANCE project description.


HMOD-1 Update 2

HMOD-1 Update 1

Some further work done...

Changed geared motors of the Makeblock platform (from 6 V, gear ratio 1:75 to 12 V, gear ratio 1:184):


CNC machined nylon deck:


Platform with nylon deck, Arduino Mega, motor controller and Li-Po battery:

HMOD-1 Update 1

I am working since a while on a new humanoid to continue my AI experiments. So far I have finished a conceptual 3-D-drawing, based on the parts I want to use. The 2WD base is from Makeblock, the upper body the Johnny 5 torso from Lynxmotion. I have cancled the base rotate turntable and changed the original 1 DOF head with ultrasonic sensor to a 2 DOF head with compound eye.

Math machine learning

Whenever I observe my daughter, I find that she likes to collect things. The more, the better. Usually as much as she can carry. As she can not count, how can she distinguish, what are more things and what are less things?

My daughter with objects in both hands

Simple trial-and-error algorithm - yet

I am experimenting these days with trial-and-error algorithms.

Revised algorithm of choice

In the last two days I have reworked the algorithm of choice completely. The code is now much shorter and a great number of actions can be easily added.  I have listed the code sketch below.

Concept of a learning robot based on VSLA

My next robot will be based on a variable structure stochastic learning automaton (VSLA) , which is similar to the approach David L. Heiserman describes in his book How to Build Your Own Self-Programming Robot. As I am using quite a lot of mathematical notations and equations I have attached the first chapter as a pdf for better readability. I'll add more chapters later.

Update 22/09/2012: Chapter 2 attached

Pulse oximeter - Update 02/09/12

I am currently in the engineering phase to build a pulse oximeter. I mainly make use of the following references:

Homemade compound eye

The compound eye from DAGU, designed by Oddbot, is cool and cheap. But I needed a round board to imitate the human eye, so I made one by myself. The IR LED's and photo transistors are the same as in the original design. As I had no PN 100 transistor, I used a BD 139 (the 4 IR LED's draw approx. 100 mA @ 5 V).

Front view of the perf board

6 DOF robot hand finished

I finished the 6 DOF robot hand for my project Te no atama today. Here are some pictures. The thumb has two degrees of freedom. The primarily function of the hand is to display hand gestures. A 2 DOF wrist will be added. All servos have a metal gear and are digital.


Sneak preview of my new project. Just some pics...

More soon...

Second static test firing of DoubleSShot rocket motor failed big (again)

Second static test firing of DoubleSShot rocket motor failed big (again). CATO of the rocket motor.


Just a sneak preview: Elektro. Robot entry is following soon...

Rubik's cube solving robot

This blog is dedicated to build a Rubik's cube solving robot. I'll not give you any guarantee to even update this blog or finish it. I just want to share and discuss some ideas.

The first thing I did was to buy 3 Rubik's cubes at taobao.com (a kind of Chinese Ebay), each around 10 RMB.  I bought 3 pieces, because I wanted to avoid one or two samples are getting damaged during my experiments and evaluations and I needed then to find exactly the same kind of probes for my experiments again, which can be quite annoying.

1000USD for 10000 likes

A very easy rule: For every 10000 likes our partner Sugar Shot to Space receives on facebook, I will donate 1000USD for the eXSShot mission to space:http://www.googlelunarxprize.org/lunar/teams/selene/blog/1000usd-for-10000-likes


First static test firing with hexaphenox propellant, using an empty C6 motor casing. Combustion chamber pressure was way too high which led to the explosion of the motor. Hexaphenox is a rocket fuel I have developed:)

Lunar Rover

Hi all,

Just want to share some videos of a moon rover study I am doing for the Google Lunar X Prize. No time now to submit a robot project entry, the rover is quite complex, maybe later. I'll add videos here as they come along. Thanks for watching.