From Robotics: Appin Knowledge Solutions

3.4 SENSOR DESIGN

Without sensors, a robot is just a machine. Robots need sensors to deduce what is happening in their world and to be able to react to changing situations. This section introduces a variety of robotic sensors and explains their electrical use and practical application. The sensor applications presented here are not meant to be exhaustive, but merely to suggest some of the possibilities.

Sensors as Transducers

The basic function of an electronic sensor is to measure some feature of the world, such as light, sound, or pressure and convert that measurement into an electrical signal, usually a voltage or current. Typical sensors respond to stimuli by changing their resistance (photocells), changing their current flow (phototransistors), or changing their voltage output (the Sharp IR sensor). The electrical output of a given sensor can easily be converted into other electrical representations.

Analog and Digital Sensors

There are two basic types of sensors: analog and digital. The two are quite different in function, in application, and in how they are used with the RoboBoard. An analog sensor produces a continuously varying output value over its range of measurement. For example, a particular photocell might have a resistance of 1k ohm in bright light and a resistance of 300k ohm in complete darkness. Any value between these two is possible depending on the particular light level present. Digital sensors, on the other hand, have only two states, often called on and off. Perhaps the simplest example of...

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Products & Services
Level Sensors
Level sensors are used to detect liquid or powder levels, or interfaces between liquids. There are two basic level-measurement types: continuous and point or multi-point.
Light Sensor Chips
Light sensor chips convert light into electrical signals which are then conditioned to produce a desired electrical output. They are sometimes called light-to-frequency chips, light-to-voltage chips, or ambient light sensors.
Optical Triangulation Position Sensors
Optical triangulation position sensors use reflected waves to pinpoint position and displacement. The source of these waves may be a light emitting diode (LED), infrared (IR) light, or laser.
Magnetic Field Sensors
Magnetic field sensors measure magnetic field strength, direction, and/or magnetic flux. They are used for scientific measurement, navigation, and industrial applications.
Ultrasonic Linear Position Sensors and Switches
Ultrasonic linear position sensors and switches use ultrasonic waves in combination with light and frequency readings for position and displacement sensing.

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