Posted in D L Williams, Education, NXT Robotics

Radiation-Sensing NXT Robot

I built this NXT robot and equipped it with a dream-gear wireless game controller from and a radiation sensor from This video shows it detecting the radiation coming from an old piece of Fiestaware that used uranium as a pigment. This was prepared for the Austin Science Festival 2010, but I also use it to teach object-oriented programming to my spring physical chemistry class at Sam Houston State University.

YouTube Video

I made this robot for the Austin Science Festival in October 2010.  Even though there were dozens of NXT robots, this one was the only one with a wireless game controller.

My principles for making NXT robots are:

  • The robot should be as simple as as possible.  Problems increase as (bells)^2 + (whistles)^3.
  • The robot must be necessary to overcome a human weakness.  In other words, robots are more patient, more precise, more vigilant, more robust (sometimes), and smaller than humans. 
  • The robot should log its data whenever possible.  This captures the other advantage that the robot has over humans – better numerical memory.

With these principles in mind, I decided to create the Radiation-Sensing Robot.  It was wireless because remote sensing of radiation protects the human controller.  It was simple since the radiation monitor was used in audible click mode.  It did not log its data because this would have made the robot too complex for its intended purpose.   


The software block from worked fine.  One important tip!  The wireless controller needs to be in ANALOG mode for the signal to be understood by the NXT software block.  This prevented us from getting the simple tank software program from to work for about 1.5 days.  If we had pushed the analog button (as mentioned in the fine print of the programming documentation), we would have had the simple tank routine working in about 30 minutes.  Live and learn…

I do not have building instructions for my version of the tank.  I have been building with legos for about 40 years, and I just made it up.  If there is interest, I can take some closeup photos allowing you to figure it out.


Dr. Darren L. Williams (@pchem4all) is an Associate Professor of Physical Chemistry at Sam Houston State University. When he is not blending solvents, he is tinkering with contact angle measurements, FTIR microspectroscopy, etc. . He welcomes your comments and questions by phone (936-294-1529) and by email (williams “at”

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