Common Problems for National Robotics Competition 2011 (NRC 2011) Regular Category Upper Secondary – Robot Recycler

by trainer on July 12, 2011

Common Problems for National Robotics Competition 2011 (NRC 2011) Regular Category Upper Secondary – Robot Recycler

This will be a compilation of common problems faced by upper secondary school students competing in the NRC 2011 regular category upper secondary while doing the robot recycler using Lego NXT. Edited from various questions and responses from the Malaysia Lego Education forum in Facebook to make it easier to understand.



Problem No.1

Some competitors do not have the colour sensor. So we have a question asked by Baem Blaine regarding the placement of the cubes due to a limitation of its robot having no colour sensor, as such could only identify red and blue. The question is (rephrased a bit):

Can i sort the cubes into eight different groups? (i.e. red, blue, big cube, small cube, big red cube, small red cube, big blue cube and small blue cube ).

Solution to Problem No.1

  • Yes, anyway you like it to be.
  • Although two random cubes will still be drawn out by the judges which is announced after the first quarantine time.
  • It is still better to use the colour sensor to anticipate all conditions.

Answers by Azli Syahrin and Boltz Kcj



Problem No.2

How to programme the colour sensor. This is a relatively new sensors, so most schools are still not used to it.

Solution to Problem No.2

  • Download the sample solution at
  • From there you can download the sensor block (make sure you r using NXT 2.0 and above).
  • Highly recommended for the robot recycler category robot will be “Senior Skill 4″ which contains sample design, program, even video on how it works.
  • You can use this as your guideline of understanding how to program it.

Answers by MohamadLutfi Shakur and Azli Syahrin



Problem No.3

Many teams are scoring zero or negative marks as of now in the Robot Recycler category for NRC 2011 Regular Category Upper Secondary.

Solution to Problem No.3

  • Get inspired from the sample solution from the robot recycler.
  • Don’t copy completely but use it as a guide to solve based on the design of your robot recycler.
  • Avoid last minute preparation.
  • Try to understand the flow of the competition.
  • The ultrasonic sensor cannot be too near to any object, must have a gap of at least 5cm.

Answers by Azli Syahrin and Tengku Hazrul



Problem No.4

This is asked by Yong Xuan regarding some technicalities in the rules which is useful for all. For the robot recycler, can the cubes be sroted even when it touched the black line and almost in the bin.

Solution to Problem No.4

  • To avoid controversy, it is better to ensure that the cube cannot touch the black line, else it will not be counted as correct.

Answers by Tiong Hock Tee


Hope this post helps all students participating in the NRC 2011 Regular Category for Upper Secondary – Robot Recycler using Lego Mindstorm NXT.

[DisclaimerAll answers/suggestions given here are based on opinions and should not be taken to overrule the Rules and Regulations of NRC 2011 (if there are clashes). So you will still need to read up the rules on your own to avoid disqualification. SDJ Robotics will not be liable for any disqualification due to recommendations in this post. Good luck.]


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