NXT Basic Lesson 5

Lesson 5 Basic NXT Lessons dated 19th Feb 2008
Use of Sound Sensor and Touch Sensor




The Sound Sensor makes your robot hear!
The Sound Sensor can detect both decibels [dB] and adjusted decibel [dBA]. A decibel is a measurement of sound pressure.
dBA: in detecting adjusted decibels, the sensitivity of the sensor is adapted to the sensitivity of the human ear. In other words, these are the sounds that your ears are able to hear.
dB: in detecting standard [unadjusted] decibels, all sounds are measured with equal sensitivity. Thus, these sounds may include some that are too high or too low for the human ear to hear.

The Sound Sensor can measure sound pressure levels up to 90 dB � about the level of a lawnmower. Sound pressure levels are extremely complicated, so the Sound Sensor readings on the MINDSTORMS NXT are displayed in percent [%]. The lower the percent the quieter the soundFor example:

• 4-5% is like a silent living room
• 5-10% would be someone talking some distance away
• 10-30% is normal conversation close to the sensor or music played at a normal level
• 30-100% are people shouting or music being played at a high volume

The most efficient way to do this is to use a sound switch. The only difficult part is to figure out what sound level (on a scale of 1-100) your threshold decibel level is. This can be done easily by running the program while your NXT is plugged into the computer and checking the current sound reading in the room, seen in the "feedback box" shown below. In this example, the motors run while the sound is above a certain reading and stop when the sound is below that value.





The Touch Sensor gives your robot a sense of touch. The Touch Sensor detects when it is being pressed by something and when it is released again.

Suggestions for use
You can use the touch Sensor to make your robot pick up things: a robotic arm equipped with a Touch Sensor lets the robot know whether or not there is something in its arm to grab. Or you can use a Touch Sensor to make your robot act on a command. For example, by pressing the Touch Sensor you can make your robot walk, talk, close a door, or turn on your TV.

Students in class


































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