# Robotics Glossary: Plain-Language Definitions

> Plain-language definitions of robotics and electronics terms, from ADC and PWM to odometry and URDF.

Canonical: https://roboticsengineering.in/free-library/robotics-glossary/ | Published: 2026-11-04 | Updated: 2026-11-04

**Plain-language definitions of the robotics and electronics terms this site uses.** Short on purpose. Follow the links for the full explanation.

## Electronics

- **ADC (analogue to digital converter):** turns a voltage into a number a microcontroller can read.
- **Brownout:** a supply dip low enough to reset or upset a microcontroller. See the [ESP32 brownout fix](https://roboticsengineering.in/fix/esp32-brownout-detector-was-triggered/).
- **Decoupling capacitor:** a small capacitor near a chip’s supply pins that smooths short current spikes.
- **GPIO:** general purpose input/output, a pin you can set as an input or an output.
- **I2C:** a two-wire bus for talking to sensors and displays. See [I2C device not found](https://roboticsengineering.in/fix/i2c-device-not-found-arduino-esp32/).
- **Level shifter:** a circuit that converts signals between voltages such as 3.3 V and 5 V.
- **Logic level:** the voltage a chip treats as high or low.
- **PWM (pulse width modulation):** switching a signal on and off quickly; the share of time it is on is the duty cycle.
- **Pull-up resistor:** a resistor that holds a line high until something pulls it low.
- **SPI:** a fast bus using separate clock, data in, data out and select lines.
- **UART:** asynchronous serial, the link used by the Arduino Serial Monitor.

## Power

- **Buck converter:** a switching regulator that steps a voltage down efficiently.
- **C-rating:** the maker’s claimed discharge rate of a battery as a multiple of its capacity. Treat it as a claim, not a guarantee.
- **LDO:** low dropout linear regulator; simple but it wastes the voltage difference as heat.
- **Voltage sag:** the drop in battery voltage when a load draws current.
- **Wh (watt-hour):** energy; volts times amp-hours.

## Motion and mechanics

- **Backlash:** play between meshing gears that causes lost motion.
- **BLDC motor:** brushless DC motor, driven by an electronic controller.
- **Degrees of freedom (DOF):** the number of independent motions a mechanism has.
- **Encoder:** a sensor that reports rotation as counts.
- **End effector:** the tool at the end of a robot arm, such as a gripper.
- **Gear ratio:** input speed divided by output speed; it trades speed for torque.
- **H-bridge:** a circuit that lets a controller drive a motor in both directions.
- **Stall torque:** the torque a motor produces when held from turning, usually at its highest current.
- **Stepper motor:** a motor that moves in fixed steps.
- **Torque:** turning force, force times distance.

## Control and navigation

- **Dead reckoning:** estimating position from motion alone, so error grows over time.
- **Forward kinematics:** joint angles to end effector position.
- **Inverse kinematics (IK):** end effector position to joint angles. Try the [robot arm playground](https://roboticsengineering.in/robot-arm-playground/).
- **Odometry:** position estimated from wheel motion.
- **PID controller:** a controller that combines proportional, integral and derivative terms of the error.
- **Setpoint:** the target value a controller tries to reach.
- **Singularity:** an arm pose where it loses the ability to move in some direction.
- **SLAM:** building a map while estimating position inside it.

## Software and industry

- **Cobot:** a collaborative robot designed to work near people under a safety assessment. See the [cobot buying guide](https://roboticsengineering.in/cobot-buying-guide-india/).
- **PLC:** programmable logic controller, an industrial computer for machines and cells.
- **ROS 2:** an open robotics software framework. See the [robots hub](https://roboticsengineering.in/robots/).
- **URDF:** a file format that describes a robot’s links and joints. Check one in the [URDF viewer](https://roboticsengineering.in/urdf-viewer/).
- **Teach pendant:** the handheld unit used to jog and program an industrial robot.

Missing a term? Use the [contact page](https://roboticsengineering.in/contact/). More background is in the [Learn hub](https://roboticsengineering.in/learn/).

Last reviewed: November 2026. Free to copy and adapt for your own project, with credit. Written, checked and maintained by [Jignesh Panchal](https://www.linkedin.com/in/jignesh-s-panchal/) of [Jaadu Digital](https://jaadudigital.com/). See the [editorial standard](https://roboticsengineering.in/editorial-standard/).