DualGrip-NXT Rover

Sometimes I build robots that attempt to solve real world challenges.  Other times, robots are built based on random ideas. This robot is a case of solving a LEGO challenge – specifically, with their Technic tracks/treads #575518.  At no fault of theirs, these plastic tracks are slippery on many surfaces.  Great for carpets, flat areas, dirt (if you dare) – and great for turning as well.  However, when you try to climb with them, they are as slick as ice.

If you Google them, you will find some great ideas on making these treads more ‘sticky’.  Some have used 1/2 Technic pins (which fit nicely into the supplied holes), others have used elastics wrapped around them – all great ideas that work fine.  I attacked the challenge from a different angle.  The result is DG – or Dual Grip (yes, the name is somewhat plain).  DG went through numerous revisions as I worked out kinks related to weight, stability, traction, sensors, flex etc.  At the bottom I have included some pictures on previous versions of DG – some changes significant, others subtle.

The idea was to have a treaded robot that could navigate varying terrain, turn quickly and of course, climb.  Based on my experience with my other robots using the same tracks (eg UNV and DynaTrax), I found that they were not very good when it came to inclines.  I figured that the LEGO rubber wheels have great traction on most surfaces, so why not slap a set of them along with the treads.  However, this posed another challenge.  I did not want both wheel systems in contact with the ground at all times as this would make turning tougher and be redundant.



Wall Follower was one of those “proof-of-concepts” robots.  The intent was to build something small and compact that was fast and versatile.  Wall Follower can navigate around a room, on a table, in a maze, whatever. It is built from one of the basic robot platforms in the Mindstorms Contructopedia. Motion is done by 2 motors, each of which can steer by removing power to one. The main sensor is the DIRPD sensor (grey) mounted on the front. Through programming, the sensor can detect 3 distance ranges, near, far and too-close. The NQC program has a few main tasks. They are:
1) To follow the wall and avoid obstacles without hitting anything using the DIRPD sensor.
2) If it gets stuck, a routine will get it out of the situation
3) If it reaches an area where there is no wall and a drop-off is present. Detect an avoid.



PicoCam was built as a proof of concept.  Its purpose was simple, navigate an area using typical avoidance routines while capturing live wireless video/audio and transmitting it to a receiver. The was never really completed because I had other ideas brewing…  The pictures shown here are of the final version, with working navigation, but I did not bother going the last step to get the live video to display (even though it will work).


You would think I have a template for “room-navigating” robots… TrackerBot evolved from the recent PicoCam robot I created.  After I had finished PicoCam, I decided I wanted to try something with tracks.  TrackerBot and PicoCam share similar intelligence, with TrackerBot having some slight improvements.  The general idea is that it will navigate a room using a variety of sensory input for obstacle avoidance.  There are 3 Cybermaster touch sensors, 1 DIRP light sensor and 1 line following standard Lego light sensor.

The DIRP light sensor (seen here at the top), does most of the work.  It is set-up as a light sensor and detects left, center and right objects. It does a pretty good job of making sure TrackerBot does not hit things.  The Cybermaster touch sensors are used to detect objects that are low, at the back or out of the line of sight of the DIRPD sensor. They are wired such that all 3 sensors can be placed on one port (more on this after).

TrackerBot is also equipped with a pinhole wireless colour camera.  It can broadcast live colour video with sound to the receiver and show its progress on TV.  It is more of a proof of concept than any real function.  Read on for more details…



Big Wheel (BW) was an experiment at building a robot that uses the HailFire Driod (StarWars) large wheels. It’s job is simple; build an autonomous robot that can navigate any area while avoiding obstacles by not hitting them in the first place. To do this, BW uses a DIRPD sensor to “see” left, right and center. This allows BW avoide obstacles from 3 views before actually hitting them.



One of my early projects was to build a fire extinguishing robot. I did this using the parts I had at the time. It was based on a walker platform and used a pneumatic circut to “blow” the fire out when detected. It worked reasonably well with the provided light sensor. Recently, I discovered the PIR (Passive Infrared Sensor) from TechnoStuff. This sensor was built to detect infrared heat and seemed to be a good fit for my next project. I mounted it to my new FireBot in tandem with a standard light sensor. Together, they would do the job of detecting a flame.

A candle was used as the “fire” in this project. The PIR sensor was mounted alongside with the standard Lego Light Sensor. For more details on this sensor, visit my Reviews section.


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