Make Your Own Sensors - LEGO MINDSTORMS Robots Manual

11

Make Your Own Sensors

In this chapter:
• Mounting
• Passive Sensors
• Powered Sensors
• Touch Multiplexer
• Other Neat Ideas
• What About Actuators?
• Online Resources
If you're not afraid of a soldering iron, you can create your own robot sensors. Although you can buy the ''official" sensors from the LEGO online store or LEGO DACTA (see the Appendix A,
Finding Parts and Programming Environments), there's not a very wide selection. Furthermore, they are expensive—$10US for the touch sensor, $20US for a light sensor, $15US for the rotation
sensor, and $25US for the temperature sensor. Building your own sensors is a great way to expand your robot's capabilities without spending a lot of money.
This chapter describes different ways of fitting sensors into LEGO bricks, provides discussions of various types of sensors you can build, and considers some innovative possibilities for putting
multiple sensors on one RCX input.
Mounting
The first thing you should think about is how you are going to attach your new sensors to the LEGO world. There are two goals to consider here:
1. The sensor, ideally, should be a LEGO brick itself so you can easily attach it to your robots. The sensors that come with RIS exhibit this property: the touch sensors and the light sensor are
simply specialized bricks.
2. The sensor needs to connect electrically to the RCX. Somehow the electrical connections from the sensor circuit will need to mate with the RCX's input connections.
There are four basic approaches—cut wire, copper tubing, machine screws, and a conductor plate—which are described in the following sections.
Cut Wire
The simplest approach to attaching a new sensor is to cut one of the wire bricks that comes with RIS. Figure 11-1 shows half of one of these wire bricks.
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