Robotics Glossary: 80+ Terms Explained Simply

Use this page as a quick reference. Each entry is one or two sentences, written for a student building their first robots rather than for a control-theory exam. Terms are grouped alphabetically.

A – C

• Actuator — a device that converts energy into physical motion, such as a motor, servo or solenoid.
• ADC (Analog-to-Digital Converter) — a circuit that turns a continuous voltage into a number a microcontroller can read.
• AGV (Automated Guided Vehicle) — a mobile robot that transports materials, often following markers or a planned route in a warehouse.
• AI (Artificial Intelligence) — algorithms that perform tasks associated with human intelligence, such as perception, learning and decision-making.
• Algorithm — a finite sequence of steps for solving a problem.
• Analog signal — a signal that varies continuously, as opposed to a digital HIGH/LOW signal.
• AprilTag — a square visual marker used by cameras to estimate position and orientation accurately.
• Autonomous — able to operate without continuous human control.
• Axis — one direction of motion or rotation in a coordinate system.
• Back-EMF — the voltage a spinning motor generates in opposition to its supply; useful for estimating speed.
• Baud rate — the number of signal changes per second in serial communication, commonly 9600 or 115200.
• BOM (Bill of Materials) — a list of every part in a build, with quantity, cost and supplier.
• Brownout — a voltage drop severe enough to reset or destabilise a microcontroller.
• Brushless motor — a motor without brushes, driven electronically; common in drones and high-performance robots.
• Buck converter — a switching regulator that steps voltage down efficiently.
• CAD (Computer-Aided Design) — software for creating 2D drawings and 3D models of mechanical parts.
• Calibration — adjusting a sensor or system against a known reference so its readings are accurate.
• Caster — an unpowered wheel that supports the chassis and allows it to turn freely.
• Chassis — the structural frame that holds a robot's components.
• Closed-loop control — control that uses feedback to compare the actual state with the desired state.
• Computer vision — extracting information from images or video, such as objects, edges or motion.
• Controller — the computing unit that reads sensors and commands actuators.
• CPR (Counts Per Revolution) — the number of encoder counts produced in one full rotation.

D – F

• DC motor — a motor driven by direct current; simple and common, but needs gearing and feedback for precise control.
• Dead reckoning — estimating position by integrating motion measurements without external references.
• Degrees of freedom (DOF) — the number of independent motions a robot or mechanism can perform.
• Differential drive — a drive system with two independently controlled wheels; steering comes from wheel speed difference.
• Digital signal — a signal interpreted as discrete states, usually HIGH or LOW.
• Duty cycle — the fraction of a PWM period during which the signal is high, controlling average power.
• Encoder — a sensor that measures rotation or linear position.
• End effector — the tool at the end of a robotic arm, such as a gripper, welder or camera.
• ESC (Electronic Speed Controller) — a driver that controls brushless motor speed.
• Embedded system — a computer dedicated to a specific function inside a larger device.
• Endstop — a switch that detects when a mechanism reaches the end of its travel.
• Failsafe — a designed safe behaviour when communication, power or a sensor fails.
• Feedback — information about the actual output used to correct future control actions.
• Fiducial marker — a known visual pattern used for localisation by a camera.
• Firmware — software permanently stored on a microcontroller or embedded device.
• Forward kinematics — calculating the position of an arm's end effector from its joint angles.

G – I

• G-code — a language of instructions used by CNC machines and many 3D printers.
• Gear ratio — the relationship between input and output speed and torque in a gear train.
• Gimbal — a pivoted support that allows an object to rotate about one or more axes.
• GPIO — general-purpose input/output pins on a microcontroller or single-board computer.
• Ground — the common reference point in an electrical circuit; all grounds in a system must be connected.
• Ground truth — the known, accurate reference value used to evaluate a sensor or algorithm.
• Hall effect sensor — a sensor that detects magnetic fields, often used for position or speed sensing.
• Haptics — technology that provides force, vibration or motion feedback to a user.
• H-bridge — an electronic circuit that can reverse the polarity applied to a motor, enabling forward and reverse motion.
• Hexapod — a six-legged robot; also a six-axis motion platform.
• Holonomic — able to move in any direction without first rotating.
• Humanoid — a robot with a human-like body structure, often with a head, torso and two arms.
• I2C — a two-wire bus (SDA and SCL) used to connect sensors and peripherals to a controller.
• IMU (Inertial Measurement Unit) — a sensor package that measures acceleration and angular velocity, often with a magnetometer.
• Inertia — a body's resistance to changes in its motion.
• Inverse kinematics — calculating the joint angles required to place an end effector at a desired position and orientation.
• IR sensor — an infrared sensor used for line detection, proximity or remote control.

J – L

• Jerk — the rate of change of acceleration; high jerk makes motion harsh and can damage mechanisms.
• Jitter — small, unwanted variation in timing or position.
• Kalman filter — an algorithm that estimates a system's state by combining noisy measurements and a model.
• Kinematics — the study of motion without considering the forces that cause it.
• Latency — the delay between an input and the corresponding output.
• LiDAR — a sensor that measures distance using laser light, producing accurate maps and obstacle data.
• Linear actuator — an actuator that produces straight-line motion rather than rotation.
• Loop rate — how many times per second a control loop runs.

M – O

• MCU (Microcontroller Unit) — a compact integrated circuit with a processor, memory and input/output peripherals.
• Mechatronics — the integrated engineering of mechanical, electrical, control and software systems.
• MEMS — micro-electromechanical systems; tiny sensors and actuators built on silicon, common in IMUs.
• Motor driver — an electronic circuit that supplies the current and voltage a motor needs, controlled by logic signals.
• Motor stall — the condition where a motor is powered but cannot rotate, drawing high current and generating heat.
• Multiplexer — a circuit that selects one of several input signals to route to a single output.
• Navigation — determining where a robot is and how to reach a destination safely.
• NEMA 17 — a common stepper motor mounting standard with a 1.7-inch faceplate.
• Neural network — a machine-learning model made of connected layers of simple computational units.
• Noise — unwanted variation in a signal that can hide the information you need.
• Odometry — estimating distance travelled and heading from wheel or motor measurements.
• Open-loop control — control that issues commands without checking the actual result.
• Optical encoder — an encoder that uses light and a patterned disc to measure rotation.
• Overcurrent — current exceeding a component's safe limit, often caused by a stall or short circuit.

P – R

• Payload — the mass a robot can carry in addition to its own structure.
• PCB (Printed Circuit Board) — a board that mechanically supports and electrically connects electronic components.
• PID controller — a feedback controller that combines proportional, integral and derivative terms to reduce error.
• PLC (Programmable Logic Controller) — a rugged industrial controller used for automation and machinery.
• Pneumatics — actuation using compressed air, common in industrial grippers and automation.
• Polarity — the direction of voltage across a component; reversing it reverses a DC motor.
• Potentiometer — a variable resistor used as a voltage divider, often for tuning or position sensing.
• PWM (Pulse-Width Modulation) — rapidly switching a signal on and off to control average power, used for motor speed and LED brightness.
• Quadcopter — a drone with four rotors.
• Quadrature encoder — an encoder with two channels 90 degrees out of phase, allowing direction detection.
• RC (Radio Control) — remote control of a vehicle or robot using radio signals.
• Real-time — a system that guarantees a response within a defined deadline.
• Regenerative braking — recovering energy by using a motor as a generator during braking.
• Relay — an electrically operated switch used to control higher-power loads.
• Resolution — the smallest change a sensor or actuator can detect or produce.
• ROS (Robot Operating System) — a middleware framework and toolset for building robot software; despite the name, it is not an operating system.
• RPM (Revolutions Per Minute) — a measure of rotational speed.

S – U

• Sample rate — how many measurements a system takes per second.
• Schmitt trigger — a circuit that cleans a noisy signal into a sharp digital transition.
• Sensor fusion — combining data from multiple sensors to produce a better estimate than any one sensor alone.
• Serial communication — sending data one bit at a time over a wire, commonly using UART.
• Servo — a motor with built-in feedback and control, usually for precise angular position.
• Servo horn — the arm or wheel attached to a servo's output shaft.
• SLAM (Simultaneous Localisation and Mapping) — building a map while tracking the robot's position within it.
• Slew rate — the maximum rate at which a signal or actuator output can change.
• Solenoid — an electromagnetic actuator that produces linear motion when energised.
• Stall current — the current a motor draws when it is powered but not turning.
• Stepper motor — a motor that moves in fixed angular steps, useful for precise open-loop positioning.
• Subsumption architecture — a robot control design made of layered behaviours, each able to override lower layers.
• Swarm robotics — coordinating many simple robots to achieve a collective task.
• Telemetry — data transmitted from a robot to a remote station for monitoring.
• Teleoperation — direct human control of a robot from a distance.
• Thermal throttling — reducing performance to prevent overheating.
• Through-hole — a component mounting style where leads pass through a board and are soldered.
• Torque — rotational force; the twisting strength a motor can deliver.
• Trajectory — a path through space with timing information, not just a geometric route.
• Transistor — a semiconductor switch or amplifier used to control current electronically.
• UART — a common asynchronous serial protocol using transmit and receive lines.
• Ultrasonic sensor — a sensor that measures distance by timing sound pulses reflected from an object.
• Underactuated — having fewer actuators than degrees of freedom, so not every motion can be controlled independently.

V – Z

• Voltage regulator — a circuit that maintains a stable output voltage despite changes in input or load.
• Waypoint — a target position a robot navigates toward.
• Wheel slip — loss of traction causing measured rotation to differ from actual travel.
• Worm gear — a gear arrangement with high reduction and self-locking behaviour.
• Yaw — rotation about the vertical axis, often called heading.
• Yaw rate — how fast a robot is rotating about its vertical axis, measured by a gyroscope.
• Z-axis — the vertical axis in a 3D coordinate system.
• Zigbee — a low-power wireless mesh protocol used in some sensors and home automation.

Missing a term? Ask in the community and we will add it. If you are new to the field, read What Is Robotics? next, then follow the beginner roadmap.

Frequently asked questions