Lego Mindstorms NXT Part 3: Sensors

Lego Mindstorms NXT 1.0 base kit includes:

• 3 identical servo motors that have built-in reduction gear assemblies with internal optical rotary encoders that sense their rotations within one degree of accuracy.
• The touch sensor detects whether it is currently pressed, has been bumped, or released. The orange Enter button and the gray right and left NXT buttons can be programmed to serve as touch sensors. In the NXT-G programming software, a value of 0 is given out when it is not pressed, and a value of 1 is given out if it is pressed down.
• The light sensor detects the light level in one direction, and also includes a LED for illuminating an object. The light sensor can sense reflected light values (using the built-in red LED), or ambient light. In the NXT-G programming software the sensor senses light on a scale of 0 to 100, 100 being very bright and 0 being dark. If calibrated, the sensor can also be used as a distance sensor.
• The sound sensor measures volume level on a scale of 0 to 100, 100 being very loud, 0 being completely silent.
• The ultrasonic sensor can measure the distance from the sensor to something that it is facing, and detect movement. It can show the distance in both centimeters and inches. The maximum distance it can measure is 233 cm with a precision of 3 centimeters. The ultrasonic sensor works by sending out ultrasonic sound waves that bounce off an object ahead of it and then back. It senses the time it took for that to happen. This sensor is only accurate at detecting flat surfaces.

In the Lego Mindstorms NXT 2.0 base kit, it includes: 2 Touch sensors, one Color sensor (detects several different colors), and an Ultrasonic sensor.

These parts are not included in the Lego Mindstorms NXT base kit and may be bought separately:

• Third-party companies also manufacture sensors such as the compass, gyroscope, infrared tracker, RFID reader and accelerometer sensors sold by Lego.
• The temperature sensor can measure temperature in Celsius or Fahrenheit.

The sensors come assembled and programmed. In the software (see Lego Mindstorms NXT Part2: Programming ), you can decide what to do with the information that comes from the sensors (for example you can program the robot move forward until it touches something). Lego also sells an adapter to the Vernier sensor product line. Vernier produces data collection devices and related software for use in education.