Using sensors

[artdutra04]

Here are a few brief summaries of some common types of sensors used in FRC applications:


Limit switch: can be used for simple control of manipulators, to prevent them from driving past the mechanical limits of the system. Digital signal.

Light sensor: can be used to follow lines, detect colors, and be used to create an optical encoder to sense rotation by pointing it at a disc with alternating white and black stripes. Analog signal.

IR range sensor: used to measure distance. Analog signal.

Ultrasonic sensor: used to measure distance. Needs interrupts to work correctly.

Hall effect sensor: detects ferrous materials, such as the teeth on a steel gear or sprocket. Can be used to sense gear teeth passing by, to work as an encoder. May need interrupts.

Encoder: generic term for sensor that measures rotation; with a known wheel size can be used to gauge how far robot has driven/spun. Generally needs interrupts to work correctly.

Quadrature Encoder: Basically it's a "dual encoder" that can sense rotation as well as which direction it is rotating in.

Accelerometer: measures acceleration. Can be used to find abrupt changes in speed, or for inertial navigation.

Gyro: measures change in angle. Can be used in place of potentiometer if space to mount one is not available. Can also be used to sense how far a robot has turned.

Potentiometer: Variable resistor used to detect rotation over a limited range, commonly about 270^o. Can be used on arms, to know exactly where the arm is. Analog signal.