Sensors

A sensor is a device that detects, or senses, the surrounding environment. In terms of robotics, and specifically FIRST, sensors enable the robot to better understand what is around it and how to react. The types of sensors used in FIRST are electrical, meaning that they send signals to the Robot Controller that is then converted into some value for use by the program. There are two main classes of sensors, analog and digital. An analog sensor, such as a potentiometer, will have a value in the range of 0 to 1023 (10 bits). A digital sensor, such as a limit switch, is much more limited, only having off and on states, represented by 0 and 1.

Sensors are important aspects of programming, allowing truly complex robots that can react intelligently to dynamic situations. The use of advanced sensors is often necessary to develop an effective autonomous mode, though many other uses are possible. Sensors can count the number of rotations of a particular wheel and then the program can adjust speed based on this information; sensors can determine whether some apendage is fully extended, and then shut off power to a motor; sensors can allow the robot to avoid objects that the robot operator might not see.

Each year the list of sensors included with the kit of parts varies, but here are examples of sensors that were included in prior kits of parts.

• IR sensor
• Banner sensor
• Gyroscope
• Current sensor
• Pressure sensor
• Accelerometer
• A vision system such as CMUcam2.
• Encoder

See electronics rules for the current year’s game for information on where and which sensors may be bought, and the price limit on them.