Common Problems for National Robotics Competition 2011 (NRC 2011) Regular Category Lower Secondary – Stair Climber

by trainer on July 11, 2011

Common Problems for National Robotics Competition 2011 (NRC 2011) Regular Category Lower Secondary – Stair Climber

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


Problem No.1

Receptacle. This question is raised wonderfully by Mohaann which could also affect the designs of other schools which are similar to it. The receptacle is built up to a height of 1/2 of the ping pong ball. However there are two extra “large walls” outside of the receptacle to ensure that the ping pong ball does not fall out. Will this design be disqualified?

Solution to Problem No.1

  • Yes, the design will be disqualified as it prevents the ping pong ball from falling out.
  • This violates the free movement of the ping pong ball in the sense that it is prevented from falling off and also invariably increased the height of the receptacle.
  • The ping pong ball is required to rest freely without any intervention. So definitely will be disqualified.

Answers by Adam Ihsan and SDJ Robotics


Problem No.2

Definition of “moving freely” for the ping pong ball.

Solution to Problem No.2

  • Ping pong ball is not set in a fixed position.
  • And it must be able to fall out.

Answers by Tty Lim and SDJ Robotics


Problem No.3

Use of pieces for the ping pong ball receptacle which is not from 9797, 9695 or 9648. Wong Hong Wen gave a brilliant suggestion of using the ‘heavy brick’ to attach it at two opposite end of the basket which will auto-balance when climbing the stairs, solving the receptacle issue.

Solution to Problem No.3

  • This is not possible as pieces must come from 9797 or 9695 or 9648.

Answers by Azli Syahrin


Problem No.4

When descending the stairs, especially the last step, does the robot need to just touch the last step or ensure that the entire robot body touches the final base (lowest base step)? Also asked wonderfully by Zaihaslinda Ismail.

Solution to Problem No.4

  • For both ascending (going up) and descending (coming down) the stairs, the complete body of the robot must be within the base area before marks are counted.

Answers by Salehuddin Arjunaidy


Problem No.5

This is a question raised by Mohammad Farid which might be useful to newbies. For the stair climber category, will the stairs be attached to the wall or not? (Additional question regarding the pingpong ball)

Solution to Problem No.5

  • The stairs will not be attached to the wall.
  • The ball used for this category will be a standard ping pong ball which will be the standard 40mm diameter ping pong ball.

Answers by Azli Syahrin, Zaihaslinda Ismail and SDJ Robotics


Problem No.6

What is the best battery for the stair climber. Something raised by Dayall Zetarian but probably in the minds of many.

Solution for Problem No.6

There are few suggestions, among them:

  • Use AA batteries due to the light weight as compared to the Lego’s own rechargeable battery.
  • Among AA batteries, Panasonic Evolta seemed to give rather good power output although it is expensive.
  • At least use a battery which has 2000mAh. This can be checked from the battery’s body.
  • But for long-run, considering that batteries are used in every training, it is better to buy the new LEGO batteries for Rm440 from Sasbadi. Very stable battery output.

Answers by Boltz Kcj, SDJ Robotics, Isabelle Wong, Foong Chung Seng and Azli Syahrin.

Hope it helps all students participating in the NRC 2011 Regular Category for Lower Secondary – Stair Climber Robot 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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