NJRC Training Lesson 2

Lesson 2 Use of third motor to build a gribber with two claws.
Dated 25th March 2008



Students assembled a NXT bot with claws

































One Group completed the assembly



This student proudly presented his completed assembly

NJRC Lesson 1

The National Junior Robotics Competition (NJRC) is an exciting and unique event organized annually by the Singapore Science Centre and the Agency for Science Technology and Research (A*STAR), and is sponsored by the Ministry of Education and Singapore Totalisator Board. This all-round competition promotes strategy building, teamwork and creativity amongst the student-participants.

Teams
The NJRC is open to the following categories:
A: Primary 3 to Primary 6

Teams, of not more than 5 students each, will work together in order to fulfill the mission of the competition

The primary task for the teams will be to build a robot to take on the challenge during the NJRC event. Using the LEGO® MINDSTORMS® kit, students have to construct the robot and program their creation to overcome a specially designed and challenging course called 'the playing field'.

Side Events/ Open Categories
Every year, there will be side events such as SUMO and Sprint race as well as an open category where students can use any material on the specific theme. It will occurr on the Grand Finals.

Dates to be remembered
Challenge Announcement:
28 June 2008

Presentation Week:
25 August - 29 August 2008
29 August 2007 (Presentation Finals)

Challenge Week:
2 September - 5 September 2008

6 September 2008 (Grand Finals)

Use of a third motor to make a claw



Learning Journey on use of NXT Claw
First Attempt


Second Attempt


Third Attempt


Contemplation on how to procced



Exchange of ideas



Mini Competition


Outdo one another we learned more



We quarrelled and we agreed



We need to learn
- how to organize ourselves and distribute our tasks within the team.
- how to write journals using Microsoft Powerpoint
- how to use digital camera to take pictures and edit pictures.
- how to record video clips using movie camers.
- how to do research on topics to be announced by NJRC committee.
- how to make presentation to class
Only the best teams would be selected by teacher to represent the school.

NXT Basic Lesson 6

Lesson 6 dated 4th March 2008
Revision of Basic Concepts

Gears and Gear Ratio
Gears are used for two basic purposes:

1) increase or decrease rotation speed
2) increase or decrease power or "torque"

Torque is inversely proportional to speed.

You can calculate the "gear ratio" by using the number of teeth of the "drive gear" divided by the number of teeth of the "driven gear.

To increase speed and reduce torque use a large drive gear coupled to a smaller driven gear. In this example we use a 40 tooth drive gear to turn smaller gears to get the illustrated gear ratios.

So the 8 tooth gear will turn 5 complete rotations for the every rotation of the 40 tooth gear. The motor has been geared up.

To reduce speed and increase torque use a small Lego gear turning a larger gear. For the 40 tooth gear in this example the gear ratio is 8/40, or 1/5. This gear ratio can also be written as 40:8 or 5:1.

So for every five rotations of the 8 tooth gear, the 40 tooth gear will have turned only once. The motor has been geared down.



Gears Video











First student to pass the test






Video Clip



Frequently asked questions on NXT-G Program on Line tracing

What are the reasons why our NXT robost not able to trace the black line ?

Reasons were (85% very careless) as follows:

- Setting of Light Sensor too far from the black line
- Setting of port of light sensor did not match with NXT-G Program
- Setting of light sensor value for bright is wrong. Normally should be adjusted 0.5 point downward.
- Setting of power setting of either B or C motor be reduced from 75% to 50% or below.
- Using split and loop block was in wrong sequence.
NXT-G for the Line Follower Program




How NXT zig-zag their path on the black line ?







Video Clip


Test Result for the class

Photo Sharing - Video Sharing - Photo Printing - Photo Books

1. Assemble a NXT robot with minimum number of parts to move around with a light sensor and an ultrasonic sensor.


2. Write a NXT-G program to trace a black line and stopped an object based on robot created from 1.


3. Make your robot to drive forward for 5 rotations at 50% power

How long did it take to go 5 rotations
………. secs
What about 10% power ……… secs

70% power ? ………...secs

Only one team headed by Preston Ngou and Jerry Koh completed the project in time.
Rest of the teams were rather slow in their construction and programming.
Nonetheless they need to put in extra effort. They were playful nonetheless very smart and need time to mould them.