Using a Test Bed to Learn about the NXT

We do robot demonstrations to share our passion of robotics with others.  For a recent demo we created a couple of “test beds” to demonstrate some of what you can do with an NXT.

Sometimes it is difficult to easily see how a robot is using its sensors and to tell what all is happening when it is driving around on the floor.  For our demonstrations, we do have robots that drive around on the floor, but the test bed demo helps people see the parts and how they work much better.

One of our testbeds

One of our test beds is pictured at left.  We had an NXT, a motor, a light sensor, and ultrasonic sensor all mounted to a base plate.  We wrote a program that would turn on the motor when the light sensor saw dark.  While the motor was on, if the ultrasonic sensor detected something close (within 4 inches) it would turn the motor off.  We explained that the motor would turn off and on based upon what the sensors detected.  The kids had fun moving the slip of paper with different colors on it and sticking their hand in front of the ultrasonic sensor to see turn the motor on and off.  We also had programmed the sensor readings to be displayed on the NXT’s display.

This is a great learning tool for FLL teams too.  I wish we would have done this before we started using sensors for FLL.  It was very interesting for us to see how the readings fluctuated.  Experimenting in this manner helps you realize what kinds of readings the sensors produce.  Move the light sensor up and down to see how distance from the surface affects the reading.  Place a shield over the light sensor and see how that affects the readings.  This will help you understand the capabilities of the sensors and what is required to get a good reading.

A second testbed

We created another test bed for demonstration purposes (at right). This one features a menu on the display that allows the user to press arrow buttons to increase or decrease the power level of the motor.  The wheels attached to the motors spin faster as the power level is increased.  This also shows that a menu can be created to prompt input from a user.

From this kind of display, people new to robotics can quickly see the sensors and motors and gain an understanding of what is happening.  FLL teams can use a test bed set up to test the capabilities of the various sensors.  This better understanding encourages and enables people to do more with the NXT.  Give it a try!

Posted in NXT, test bed, Tutorial

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