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.



Sept. 06:

Pete @ Techno-Stuff has just sent me another new sensor from Techno-Stuff. This time it’s a Accelleration / Tilt sensor. Instead of going into great detail on how it works, I will quote from his site:

The Accel Sensor lets your robot measure it’s acceleration. The sensor can also be used to measure tilt. This is a two channel device that lets you measure acceleration or tilt along two perpendicular axis. Acceleration is a change in speed. When you push the gas pedal of a car, and the car speeds up, this is acceleration. The Dual Acceleration/Tilt Sensor (Accel) measures acceleration by it’s effect on a small mass. The sensing mass is also affected by gravity. Because of this, the sensor can be used to measure gravity. Gravity is constant, and points straight down. Since the Accel sensor can measure gravity, you can use it as a tilt sensor. The sensor is most sensitive to tilt when it is mounted so the sensing channels are perpendicular to gravity. (the electrical connector is horizontal) When mounted this way, the light sensor value will be 50, indicating zero acceleration. The value will increase or decrease depending on the direction of tilt.

So, to put the sensor to the test, I thought what better way to do this than to use my NXT kit.



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