• Updated on: Aug 02, 2013

## Measuring rotation of a wheel or other shaft using encoders

Encoders are devices for measuring the rotation of a spinning shaft. Encoders are typically used to measure the distance a wheel has turned which can be translated into the distance the robot has traveled. The distance traveled over a measured period of time represents the speed of the robot, and is another common use for encoders. Encoders can also directly measure the rate of rotation by determining the time between pulses. This article covers the use of quadrature encoders (defined below) For non-quadrature incremental encoders, see the article on counters. For absolute encoders the appropriate article will depend on the input type (most commonly analog, I2C or SPI).

• Updated on: Aug 02, 2013

## Using Counters

Counter objects are extremely flexible elements that can count input from either a digital input signal or an analog trigger.

• Updated on: Jul 31, 2013

The NI 9201 Analog to Digital module has a number of features not available on simpler controllers. It will automatically sample the analog channels in a round robin fashion, providing a combined sample rate of 500 ks/s (500,000 samples / second). These channels can be optionally oversampled and averaged to provide the value that is used by the program. There are raw integer and floating point voltage outputs available in addition to the averaged values. The diagram below outlines this process.

• Updated on: Jul 30, 2013

## Measuring robot distance to a surface using Ultrasonic sensors

Ultrasonic sensors are a common way to find the distance from a robot to the nearest surface

• Updated on: Jul 30, 2013

## Determine robot orientation with a compass

A compass uses the earth’s magnetic field to determine the heading of the robot.

• Updated on: Jul 30, 2013

## Accelerometers - measuring acceleration and tilt

Accelerometers measure acceleration in one or more axis. One typical usage is to measure robot acceleration. Another common usage is to measure robot tilt, in this case it measures the acceleration due to gravity.

• Updated on: Jul 30, 2013

## WPILib Sensor Overview

The WPI Robotics Library supports the sensors that are supplied in the FRC kit of parts, as well as many commonly used sensors available to FIRST teams through industrial and hobby robotics suppliers.

• Updated on: Jul 30, 2013

## Choosing a Base Class

The base class is the framework that the robot code is constructed on top of. WPILib offers two different base classes, as well as a third option which is not technically a separate base class.

• Updated on: Jul 23, 2013

## Your Second Program and beyond

By now you've learned how to code and deploy your first Java program. This article highlights additional resources as you look to add features and move beyond the basics presented so far.

• Updated on: Jul 23, 2013

## Your Second Program and beyond

By now you've learned how to code and deploy your first C++ program. This article highlights additional resources as you look to add features and move beyond the basics presented so far.