# Glossary 1. Reference - The target position we would like to be at. This is often used interchangably with other terms such as set point or target. 2. Gain - A value we multiply by another value. In a PID controller Kp, Ki, and Kd are "gains" 3. Feedback - a process where given a measurement and a desired state we calculate the best input to reach the state. A synonym for closed-loop control 4. Feedforward - a process where given just a desired state we calculate the best input to reach the state. A synonym for open-loop control 5. PID control - A type of feedback control with three main components. A proportional, an integral, and a derivative. 6. Integral - the sum of a signal over time 7. Derivative - the rate of change of a singal 8. Full State Feedback - a feedback control method that is basically just a bunch of proportional controllers strapped together. 9. State - where our system currently is, usually a combination of position / velocity. 10. RoadRunner - A library for *FIRST* Tech Challenge that incorperates a ton of really powerful control techniques. It has built in localization (using drive encoders or dead wheels), trajectory generation, and trajectory following algorithms 11. Path - a set of points that makes up where our robot should be in space. Usually traversed through by the robots current position. 12. Trajectory - a set of position and velocity points, usually indexed by the given time. 13. State machine - a way to code your robots that emulates asynchronous behavior but without the side effects. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://www.ctrlaltftc.com/continued-learning/glossary.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.