.. glossary::
accelerometer
A common sensor used to measure acceleration in one or more axis.
auto
The first phase of each match is called Autonomous (auto) and consists of the robot's running pre-programmed instructions.
back-EMF
In electric motors, the force generated by the interaction of spinning magnets in a coil of wire which opposes spinning motion.
boolean
A form of data with only two possible values (true or false), intended to represent the two truth values of logic and Boolean algebra.
call stack
A specially-organized region of memory which helps the program keep track of what function it is in. As each function calls another, the call point is recorded and added to the top of the structure, forming a "stack" of references. Additionally, local variables will also be stored in this stack. See `call stack <https://en.wikipedia.org/wiki/Call_stack>`__ on Wikipedia for more info.
central limit theorem
A core concept in probability which states that when many independent variables are added up, the result tends to look like a "normal" (or Gaussian) distribution, regardless of whether the independent variables themselves are normally distributed. See `Central Limit Theorem <https://en.wikipedia.org/wiki/Central_limit_theorem>`__ on Wikipedia for more info.
Classical Mechanics
The branch of physics which studies and describes the motion of relatively large, relatively slow objects. See `Classical Mechanics <https://en.wikipedia.org/wiki/Classical_mechanics>`__ on Wikipedia for more info.
COTS
Commercial off the shelf, a standard (i.e. not custom order) part commonly available from a vendor to all teams for purchase.
composition
A formal software term for building (or "composing") software entities out of smaller component entities. See `object composition <https://en.wikipedia.org/wiki/Object_composition>`__ on Wikipedia for more info.
CRTP
Continuously Recurring Template Pattern - A software idiom in which a class `X`` derives from a class template instantiation using `X`` itself as a template argument. See `CRTP <https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern>`__ on Wikipedia for more info.
C++
One of the three officially supported programming languages.
declarative programming
A style of software which focuses on describing *what* a program should do, rather than *how* it gets done. See `declarative programming <https://en.wikipedia.org/wiki/Declarative_programming>`__ on Wikipedia for more info.
dependency injection
A software design pattern where each class receives all objects it depends upon. Sometimes these are passed through the constructor, but not always. See `dependency injection <https://en.wikipedia.org/wiki/Dependency_injection>`__ on Wikipedia for more info.
deprecated
Software that has been replaced and will no longer receive new features. Deprecated software will be maintained for at least 1 year, but may be removed after that. For example, if a method is deprecated prior to the 2022 season, it will be usable in the 2022 season, but may be removed prior to the 2023 season. Teams are encouraged to not use deprecated methods in new code. WPILib always deprecates features at least one year prior to removing them from the codebase.
design pattern
A particular, intentionally-chosen style of organizing code. A design pattern intentionally excludes using certain features of a programming language to constrain developers into solutions that are well-suited to a particular problem-space. See `design pattern. <https://en.wikipedia.org/wiki/Design_pattern>`__ on Wikipedia for more info.
DHCP
Dynamic Host Configuration Protocol, the protocol that allows a central device to assign unique IP addresses to all other devices.
DLL
An acronym which stands for "Dynamic-Link Library", a shared library or resource used for programs or files within the Microsoft Windows operating system. See `Dynamic-link library <https://en.wikipedia.org/wiki/Dynamic-link_library/>` for more information.
encapsulation
A software design pattern which uses a class to hide the implementation details of other classes. See `encapsulation <https://en.wikipedia.org/wiki/Encapsulation_(computer_programming)>`__ on Wikipedia for more info.
entry
In :term:`NetworkTables`, a combined :term:`publisher` and :term:`subscriber`. The subscriber is always active, but the publisher is not created until a publish operation is performed (e.g. a value is "set", aka published, on the entry). This may be more convenient than maintaining a separate publisher and subscriber.
enumeration
A list of all elements of a set, typically used to refer to a set of pre-defined values.
event-driven programming
A style of programming where certain parts of code generate "events" as a result of some input (sensors, user interaction, etc). Then, other parts of code listen for and respond to "handle" these events. See `event-based <https://en.wikipedia.org/wiki/Event-driven_programming>`__ on Wikipedia for more info.
floating point
A method for approximating real numbers in computer-based arithmetic, using a fixed precision integer scaled by an integer exponent. Typically computer systems support both "single" precision (32-bit storage) and "double" precision (64-bit storage) floating point values, as defined by IEEE 754.
FMS
Field Management System, the electronics core responsible for sensing and controlling the FIRST Robotics Competition field.
FPGA
Field-programmable gate array - a specialized integrated circuit consisting of many digital logic elements, which can be configured to act in different patterns. This allows its behavior to be changed after manufacturing. In the context of FRC, National Instruments provides a specific configuration for the RIO's FPGA which allows it to process the electrical inputs and outputs at a very high rate. See `FPGA <https://en.wikipedia.org/wiki/Field-programmable_gate_array>`__ on Wikipedia for more info.
GradleRIO
The mechanism that powers the deployment of robot code to the roboRIO.
gyroscope
A device that measures rate of rotation. It can add up the rotation measurements to determine :term:`heading` of the robot. (“gyro”, for short)
heading
The direction the robot is pointed, usually expressed as an angle in degrees.
imperative programming
A style of programming that focuses on *what* the code should be doing, step by step, every loop. See `imperative programming <https://en.wikipedia.org/wiki/Imperative_programming>`__ on Wikipedia for more info.
IMU
Inertial Measurement Unit, a sensor that combines both an :term:`accelerometer` and a :term:`gyroscope` into a single sensor.
Java
One of the three officially supported programming languages.
JSON
JavaScript Object Notation. A standardized way of organizing data into named values. The organized data can be easily :term:`serialized`. While the original usage was in Javascript, it can be used and interested by most modern programming languages. See `JSON <https://en.wikipedia.org/wiki/JSON>`__ on Wikipedia for more info.
KOP
Kit of Parts, the collection of items listed on the Kickoff Kit checklists, distributed to the team via FIRST Choice, or paid for completely (except shipping) with a Product Donation Voucher (PDV).
KOP chassis
The KOP contains a drive base (chassis) distributed to every team (that did not opt out) as part of the :term:`KOP`. For the 2023 season, the KOP chassis is the `AM14U5 <https://www.andymark.com/products/am14u5-6-wheel-drop-center-robot-drive-base-first-kit-of-parts-chassis>`__.
LabVIEW
One of the three officially supported programming languages.
NetworkTables
A publish-subscribe messaging system to communicate data between programs.
mass
the amount of matter in a physical object. Objects with more mass will resist changes in motion more than objects with less mass. See `mass <https://en.wikipedia.org/wiki/Mass>`_ on Wikipedia for more info.
moment of inertia
The property of an object that describes both how much mass it has, and how that mass is distributed relative to a certain axis of rotation. Objects with higher moments of inertia resist changes in rotational motion more than objects with lower moments of inertia. Increasing the moment of inertia is accomplished by adding more mass, or moving the mass further away from the axis of rotation. See `moment of inertia <https://en.wikipedia.org/wiki/Moment_of_inertia>`_ on Wikipedia for more info.
mutable
An object that can be modified after it is created.
NetComm
A software daemon running on the NI roboRIO controller to maintain communications with the Driver Station, :term:`FPGA`, and user program.
permanent-magnet DC motor
The classification of all legal motors for the FIRST robotics competition. This type of motor takes direct current as input, and uses it to create a magnetic field. In turn, this magnetic field interacts with a physical magnet to create a force that turns the output shaft. Electrical ("brushless") or mechanical ("brushed") means are used to ensure the electrically-generated magnetic field always points in a direction that creates forces when it interacts with the physical magnet, even as the motor's shaft rotates. See `permanent-magnet motor <https://en.wikipedia.org/wiki/Brushed_DC_electric_motor#Permanent-magnet_motors>`__ on Wikipedia for more info.
persistent
In :term:`NetworkTables`, a :term:`topic` that is saved to a file by the server and restored at startup.
property
In :term:`NetworkTables`, named information (metadata) about a :term:`topic` stored and updated separately from the topic's data. A topic may have any number of properties. A property's value can be any data type that can be represented in JSON.
publisher
In :term:`NetworkTables`, an object that defines a :term:`topic` and creates and sends timestamped data values.
pose
The collection of position and rotation information that describes how a rigid body is oriented in space, relative to some fixed reference point.
PWM
An acronym which stands for "Pulse Width Modulation", a method for motor controllers, sensors, and other components to transmit or receive their operational status. For motor controllers, PWM is often used to affect the power output to the motor or connected actuator. See :ref:`PWM` for more information.
RAII
Resource Acquisition Is Initialization; a language behavior (in C++, but not in Java) where holding a resource is tied to object lifetime.
retro-reflection
The property of reflecting incoming light back at the same angle it came in at, rather than an incident angle (like a mirror), absorbing it, or scattering it. Most FRC vision processing targets are retro-reflective. See `retroreflector <https://en.wikipedia.org/wiki/Retroreflector>`_ on Wikipedia for more information.
recursive composition
A type of :term:`composition` in which the composite object may contain components of the same type as itself. For example, a command group may contain one or more command groups. See `recursive composition <https://en.wikipedia.org/wiki/Object_composition#Recursive_composition>`__ on Wikipedia for more info. See also :term:`recursive composition`.
retained
In :term:`NetworkTables`, a :term:`topic` that is kept alive by the server even after all publishers stop publishing.
serialized
The property of a data organization scheme that allows the description of the data to be sent in order, byte by byte, over some communication channel. Reading or writing a file on disk is done in this serial fashion (IE, the data is read or written byte by byte, not all at once). Sending data over a SPI or I2C bus is also done byte by byte, again requiring the data can be serialized.
simulation
A way for teams to test their code without having an actual robot available.
software library
A collection of code that can be imported into and used by other software. See `software library <https://en.wikipedia.org/wiki/Library_(computing)>`__ on Wikipedia for more info.
solenoid valve
A airflow-controlling valve which is actuated by a small electromagnet. Strictly speaking, the *solenoid* is the coil of wire which forms the electromagnet, and the *valve* is the mechanism which actually redirects airflow. However, the set of solenoid and valve together is often simply called "a solenoid". See `solenoid valve <https://en.wikipedia.org/wiki/Solenoid_valve>`__. on Wikipedia for more info.
state machine
A programming construct that divides a problem into many discrete, well-defined, mutually-exclusive "states", then defines how the problem is solved by moving between different states. See `state machine <https://en.wikipedia.org/wiki/Finite-state_machine>`__ on Wikipedia for more more info.
subscriber
In :term:`NetworkTables`, an object that receives timestamped data value updates to one or more :term:`topic`\s.
telemetry
The process of recording and sending real-time data about the performance of your robot to a real-time readout or log file. For the linguists among us, the word's roots are "tele" (remote) and "metry" (measurement). See `telemetry <https://en.wikipedia.org/wiki/Telemetry>`__ on Wikipedia for more info.
teleop
The second phase of each match is called the Teleoperated Period (teleop) and consists of drivers controlling their robots.
topic
In :term:`NetworkTables`, a named data channel.
torque
A force applied at a distance from some axis of rotation
trajectory
A trajectory is a smooth curve, with velocities and accelerations at each point along the curve, connecting two endpoints on the field.
transitory
In :term:`NetworkTables`, a :term:`topic` that will disappear after the last :term:`publisher` stops publishing.
user program
In the context of the roboRIO control system, the primary FRC runtime program that handles all communication and robot operations.
watchdog
A timer mechanism often built into embedded devices or software to monitor the runtime status of a program and reset it if crashes or errors occur. The watchdog will reset the main program if the timer itself is not reset, an activity which occurs during normal operations of the program.