When we work as Robot Design judges, we every so often see construction where the color sensor is not centered between the wheel and/or the gyro sensor is stuck somewhere at the side of the bot.
If we then ask, why the bot is build like that we often get “Because it cannot be done differently!” as an answer. For scoring in robot design this is close to the worst-case answer. 🙂 A better answer would be “Because it works this way.” Well, that is certainly correct.
Nevertheless, it is worthwhile to invest in a robust, compact construction. We call our proposal “EV3 minimal core“. It covers what we consider to be the three most important requirements. Anything else around the core still has to be developed by you.
Gyro sensor inside
The gyro sensor indeed sends the same values, regardless where you place it on your bot. However, if you put it deep into the “core” of the bot, you significantly save space. Moreover, because the cables stay inside you reduce the risk of cable loops getting tangled with models.
Color senor for line following
For the color sensor the situation is different. If its not centered between the wheels, while the software assumes symmetries, is may happen that e.g. linie following is not running smooth. Even more important are two additional aspects: The distance between the sensor and the mat should be 1 to 1,5 LEGO units. Moreover, the sensor needs to be positioned significantly in front of the wheels, if you want to follow a line.
Third motor for tools
Independent of the sensors, newbie teams usually face the challenge how to attach the third motor in a way that is stable while allowing to drive tools in an easy way.
Workable for school team too
Finally, we considered that many school teams only have the parts of a single LEGO MINDSTORMS Education Core Set (45544). We used this as a constraint when developing the “EV3 minimal core“. The construction is made to be used with the standard wheels/tires and the caster wheel found in the core set.
The construction for you to rebuild
Simply download Minimaler Kern.pdf, build the core, and then your own robot around it
Last Update: May 25, 2018
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