Dual IR Proximity Detector
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Limited stock.      DIRPD-T    Dual IR Proximity Detector    $39.00                      

This sensor has been tested with NXT using the Lego NXT conversion cable (W770323).

Proximity Detector lets you know when you are getting near a wall or large object.

Building a robot that moves around is easy.  Making one that does not self-destruct is more difficult.  Lego sells a mechanical switch that can be used to detect when your robot hits a wall.  Unforturnatly, when you hit the wall, it is sometimes too late.  Fast moving robots usually can not stop in time to prevent the robot from breaking apart.  The Proximity Detector provides warning BEFORE you hit the wall.  This gives your robot time to reverse, or turn away from the wall.  The detector trigger point is adjustable from 12 to 18 cm.  (5-7 inches), which gives most robots enough time to stop or turn.

NOTE:  This product uses the same Infra-red technology that the RCX uses to communicate with your PC.  When the IR Proximity Detector is in operation, it may interfere with communication between the RCX and PC.

Proximity detector for Mindstorms

Dual IR proximity sensor        

Infrared sensor on Lego robot       Simple Robot.

This simple robot will avoid collisions with walls and beverage cans.  When the  DIRPD detects an object, it turns off the motor on the opposite wheel.  When the edge is no longer seen, the motor is turned back on.  Look at this example program after you read the programming section below.


You program the detector just like the Lego light sensor.  Use the Light Sensor block in the Mindstorms program environment to cause program branches.  The DIRPD returns four different values depending on what it sees.  In the example below, Motor A will run when the DIRPD sees an object on the left.  Motor C will run when it sees an object on the right.  Both motors run when it sees an object straight ahead.  If you put lights on the motor outputs, this program is useful for testing the range of the IRPD.

Wall avoiding program in RIS 1.0

If you are programming in NQC, here is an example provided by Miles "Xerces".   Thanks Miles!