Robot Glossary

Plain-English definitions of the terms used across the guide, from sensors and chips to software and buying jargon.

# A B C D E F G H I K L M N O P Q R S T U V W X Z

0–9

18650 #
A standard cylindrical lithium-ion battery cell, 18 mm by 65 mm. Many robot kits use removable 18650 cells. Compute & electronics

A

Ackermann steering #
Car-style steering where the front wheels turn. Used on robot cars such as Donkey Car. Motion & mechanics
Actuator #
Anything that makes a robot move, such as a motor, servo, hydraulic cylinder or artificial muscle. Motion & mechanics
API #
Application Programming Interface. The set of commands a program can send to a robot or service. Software & AI
Arduino #
A popular family of beginner-friendly microcontroller boards and the simple programming environment that goes with them. Compute & electronics
AUV #
Autonomous Underwater Vehicle. An underwater robot that follows a mission on its own, without a tether. Robot types

B

Ballbot #
A robot that balances on top of a single ball, which lets it move in any direction. Robot types
Barometer #
An air-pressure sensor, used by drones to estimate altitude. Sensors & perception
Biomimetic (bio-inspired) #
Inspired by animals, as in robot fish, snakes and flapping-wing fliers. Robot types
Biped #
A two-legged walking robot. Robot types
Blockly / Scratch (Block-based coding) #
Visual, drag-and-drop programming languages made of blocks, used to teach coding on education robots. Software & AI
Bluetooth #
Short-range wireless used by many toy and companion robots to connect to a phone app. Compute & electronics
BOM #
Bill of Materials. The list of parts, and their total cost, needed to build a DIY robot. Buying & programs
Brushless motor (BLDC) #
An electric motor with no brushes, controlled electronically. Brushless motors are efficient and powerful for their weight, and power drones and the joints of modern legged robots. Motion & mechanics

C

C++ #
A fast, compiled programming language used for real-time robot control and much of ROS. Software & AI
CAN bus (CAN, CAN-FD) #
A robust wired network originally from cars, widely used to connect the motor controllers in robot joints. Compute & electronics
Cliff sensor #
A downward-facing sensor that detects drop-offs such as stairs or table edges so a robot does not fall. Sensors & perception
CM4 / CM5 #
Raspberry Pi Compute Module 4 and 5. A full Raspberry Pi shrunk onto a board that plugs into a product's own carrier board, common in commercial robot kits. Compute & electronics
Cobot #
Collaborative robot. An arm designed to work safely next to people, with force sensing and speed limits. Robot types
Companion robot #
A robot built mainly for social interaction and emotional connection rather than useful work. Robot types
Cycloidal / harmonic drive (strain wave gear) #
Compact high-ratio gearboxes used in robot joints. Harmonic drives are precise and common in arms, and cycloidal drives are tough and often 3D-printed in hobby builds. Motion & mechanics

D

Depth camera (RGB-D camera) #
A camera that reports how far away each pixel is, not just its color. Common types are stereo cameras, structured-light cameras and time-of-flight cameras. Examples include Intel RealSense, Orbbec and Luxonis OAK-D. Sensors & perception
Differential drive (skid steer) #
Steering by driving two wheels (or tracks) at different speeds, like a tank. The most common layout for small rovers. Motion & mechanics
Discontinued #
No longer made or sold new by the manufacturer. Used or leftover units may still be available. Buying & programs
Docker #
Software that packages programs with their dependencies into containers, often used to run ROS on robots and computers. Software & AI
DOF #
Degrees of Freedom. The number of independent ways a robot can move, which usually equals the number of motorized joints. A typical robot arm has 6 DOF, and a humanoid 20 to 40 or more. Motion & mechanics
Domain randomization #
Varying masses, friction, delays and other physics in simulation during training so a learned policy works on the imperfect real robot. Software & AI
Dynamixel #
ROBOTIS's line of smart servos, a standard in research and education robots. Motion & mechanics

E

EDU version #
A higher-priced tier of a robot, often named "EDU", that unlocks the SDK and developer access. Several consumer robots can only be programmed in their EDU version. Buying & programs
Encoder #
A sensor on a motor or joint that reports its exact position or speed. Encoders let a robot know where its limbs and wheels actually are, which is essential for smooth, closed-loop control. Sensors & perception
ESP32 #
A cheap microcontroller from Espressif with built-in Wi-Fi and Bluetooth. It runs many small robots, toys and motor controllers. Compute & electronics

F

FCC #
The US Federal Communications Commission, which must approve wireless devices, including drones and robots, before they can be sold in the US. Buying & programs
Firmware #
The low-level software built into a device, such as a motor controller or the robot's base. Software & AI
Flight controller #
The small computer on a drone that reads its sensors and adjusts motor speeds hundreds of times per second to keep it stable. Compute & electronics
FOC #
Field-Oriented Control. A method for driving brushless motors smoothly and precisely, used in robot joints and gimbals. Motion & mechanics
Force/torque sensor (F/T sensor) #
A sensor that measures pushing and twisting forces, often at a robot arm's wrist or in each joint. It lets robots handle objects gently and stop safely when they bump into people. Sensors & perception
FPV #
First-Person View. A live video feed from the robot's own camera, used to drive or fly it as if on board. Sensors & perception

G

Gazebo #
A long-standing open-source robot simulator closely tied to ROS. Software & AI
Gimbal #
A motorized mount that keeps a camera steady or lets it pan and tilt. Motion & mechanics
GPIO #
General-Purpose Input/Output pins on a board, used to connect buttons, LEDs, sensors and other simple hardware. Compute & electronics
GPS #
Satellite positioning that works outdoors with a few meters of accuracy. It does not work indoors or underwater. Sensors & perception
GPU #
Graphics Processing Unit. A processor built for massively parallel math, now the standard hardware for running and training neural networks. Compute & electronics
Gray market #
Buying a product through unofficial channels, often importing it from another country. Prices may be higher, and warranty and support are limited. Buying & programs
Gripper (End effector) #
The "hand" at the end of a robot arm, from simple two-finger clamps to dexterous multi-finger hands. Motion & mechanics

H

Hexapod #
A six-legged walking robot. With three feet always down it is naturally stable, which makes it a favorite hobby build. Robot types
Hobby servo (PWM servo) #
A cheap servo controlled by a PWM signal, with no feedback to the main computer. Common in toy and kit robots. Motion & mechanics
Humanoid #
A robot with a human-like body, usually two legs, two arms and a head. Robot types
Hydraulic actuator #
An actuator driven by pressurized fluid. Very powerful for its size, and used in the original Boston Dynamics Atlas and BigDog, but heavy, noisy and complex. Motion & mechanics

I

I2C #
A two-wire bus for connecting small sensors and chips to a microcontroller or computer. Compute & electronics
Imitation learning (Learning from demonstration) #
Teaching a robot by demonstration. A person controls the robot (often with a leader arm or VR) while data is recorded, and a policy learns to copy the behavior. Software & AI
Import duties (duties, tariffs) #
Taxes charged when goods cross a border. Robots shipped from overseas can add significant duties and fees on top of the listed price. Buying & programs
IMU #
Inertial Measurement Unit. A chip with accelerometers and gyroscopes (and often a magnetometer) that reports how a robot is tilting, turning and accelerating. Every balancing or walking robot depends on one. Sensors & perception
Inverse kinematics (IK) #
Working backwards from a desired hand or foot position to the joint angles that achieve it. Software & AI
Inverted pendulum #
A body balanced on a small base, like a Segway or a two-wheeled robot. Staying upright requires constant active control. Motion & mechanics
Isaac Sim / Isaac Lab (Isaac Gym) #
NVIDIA's robot simulator and its reinforcement-learning framework, which trains thousands of simulated robots in parallel on a GPU. Software & AI

K

Kickstarter / Indiegogo (crowdfunding) #
Crowdfunding sites where backers pre-pay for products that are not yet made. Robot campaigns often ship late, and some never ship at all. Buying & programs
Kinematics #
The math relating a robot's joint angles to the position of its feet, hands or tools. Software & AI

L

Leader-follower #
A teleoperation setup where a person moves a small "leader" arm and a "follower" robot arm copies it. Used to collect imitation-learning data. Software & AI
LeRobot #
Hugging Face's open-source Python library and community for low-cost robot learning, with datasets, pretrained policies and cheap reference hardware such as the SO-101 arm. Software & AI
Lidar (LiDAR, laser scanner) #
A sensor that measures distance by timing reflected laser pulses. A spinning 2D lidar produces a slice of the room for mapping and obstacle avoidance, and a 3D lidar produces a full point cloud. It is the main reason a robot can build an accurate floor map. Sensors & perception
LIPM #
Linear Inverted Pendulum Model. A simplified model of a walking robot used with ZMP and other walking controllers. Motion & mechanics
LiPo #
Lithium polymer battery. Light and powerful, so it is used in most drones and robots, but it must be charged and stored carefully to avoid fire risk. Compute & electronics
LLM #
Large Language Model, such as ChatGPT, Claude or Llama. Robots use LLMs for conversation and for planning tasks from spoken instructions. Software & AI

M

Magnetometer #
A sensor that measures magnetic fields and acts as a digital compass for heading. Sensors & perception
Mecanum wheel #
A wheel with angled rollers around its rim that lets a four-wheeled robot slide sideways. Works best on hard floors. Motion & mechanics
Microcontroller (MCU) #
A tiny single-chip computer that runs one program directly, with no operating system. Microcontrollers handle real-time jobs like reading sensors and driving motors. Compute & electronics
Mobile manipulator #
A robot that combines a mobile base with one or more arms, so it can both move around and handle objects. Robot types
MPC #
Model Predictive Control. A control method that repeatedly plans a short sequence of future actions using a model of the robot, used in many dynamic legged robots. Motion & mechanics
MSRP #
Manufacturer's Suggested Retail Price, the official list price. Buying & programs
MuJoCo #
A fast, free physics simulator (now open source from Google DeepMind) widely used for robot learning. The MuJoCo Menagerie provides ready-made models of many commercial robots. Software & AI

N

NPU (TPU, AI accelerator) #
Neural Processing Unit. A small AI accelerator built into many modern chips (including Rockchip and Qualcomm) for running neural networks efficiently. Compute & electronics
NUC #
Intel's line of palm-sized PCs (Next Unit of Computing), used as on-board computers in research robots. Compute & electronics
NVIDIA Jetson (Jetson) #
NVIDIA's family of small AI computers with a built-in GPU (Nano, Xavier, Orin Nano, Orin NX, AGX Orin). They run vision models and neural-network policies on the robot itself. Compute & electronics

O

Odometry #
Estimating how far and in which direction a robot has moved, from wheel encoders, leg motion or cameras. Software & AI
Omni wheel (holonomic drive) #
A wheel with small rollers around its rim so it can also roll sideways, used in three-wheeled "holonomic" robots that can move in any direction. Motion & mechanics
ONNX #
An open file format for trained neural networks, used to move a policy from a training framework onto a robot. Software & AI
Open source (open-source) #
Software or hardware whose code and designs are published for anyone to use and modify, under licenses such as MIT, Apache-2.0 or CERN-OHL. Software & AI
OpenCV #
The most widely used open-source computer vision library. Software & AI
Optical flow #
Estimating motion by tracking how the image from a downward camera shifts. Small drones use it to hover in place indoors without GPS. Sensors & perception
Orin #
NVIDIA's current generation of Jetson modules (Orin Nano, Orin NX, AGX Orin), rated from about 20 to over 200 TOPS of AI performance. Compute & electronics
Ornithopter #
A flying machine that flies by flapping its wings like a bird or insect. Robot types
OTA (Over-the-air) #
Over-The-Air updates, meaning new firmware or features delivered wirelessly. Compute & electronics

P

Payload #
The weight a robot or arm can carry, including any tool attached to it. Motion & mechanics
Policy #
In robot learning, the trained neural network that maps sensor readings to motor commands. Software & AI
PPO #
Proximal Policy Optimization. The most common reinforcement-learning algorithm for training robot locomotion. Software & AI
Pre-order #
Paying for a product before it ships. On this site, robots that have not shipped to any customer yet are listed as "Announced only". Buying & programs
Push recovery #
A walking robot's ability to stay upright after being shoved, a key test of real dynamic balance. Motion & mechanics
PWM #
Pulse-Width Modulation. A way to control a motor or hobby servo by rapidly switching power on and off. Hobby servos read their target angle from a PWM signal. Compute & electronics
PX4 / ArduPilot (PX4, ArduPilot) #
The two main open-source autopilot software stacks for drones, rovers, boats and submarines. Software & AI
Python #
The most common programming language for robot scripting, AI and research tools. Software & AI

Q

Quadruped #
A four-legged walking robot, often called a robot dog. Robot types
Qualcomm Snapdragon (Snapdragon) #
Qualcomm's phone-class processors, also used in drones and some robots for their efficient CPU, GPU and AI hardware. Compute & electronics
Quasi-direct drive (QDD, direct drive) #
A joint design using a strong brushless motor with a low gear ratio. It stays fast and "back-drivable", so legs can absorb impacts, which is why most modern robot dogs and humanoids use it. Motion & mechanics

R

Raspberry Pi #
A family of small, inexpensive Linux computers popular in hobby robots. Models include the Pi 4, Pi 5, Zero and the Compute Modules (CM4, CM5), which are the same computer on a small plug-in board. Compute & electronics
Reach #
How far a robot arm can extend from its base. Motion & mechanics
Reinforcement learning (RL) #
A machine-learning method where a policy learns by trial and error, usually in simulation, guided by rewards. Most modern walking robots learn to balance this way. Software & AI
Repeatability #
How precisely a robot arm returns to the same point again and again, usually a fraction of a millimeter on industrial arms. Motion & mechanics
Reseller #
A third-party store that sells a manufacturer's robots. Prices and delivery times can differ a lot from the maker's own store. Buying & programs
RGB-D #
An image that combines normal color (RGB) with depth (D) for every pixel, produced by a depth camera. Sensors & perception
Rockchip #
A Chinese maker of ARM processors (such as the RK3566 and RK3588) found in many single-board computers and robots. Several include an NPU for AI. Compute & electronics
ROS #
Robot Operating System. Despite the name, it is not an operating system but a widely used open-source framework of tools and libraries for robot software. Most research robots support it. Software & AI
ROS 2 (ROS2) #
The current generation of ROS, redesigned for reliability and real products. ROS 1 reached end of life in 2025. ROS 2 runs best on Ubuntu Linux. Software & AI
ROV #
Remotely Operated Vehicle. An underwater robot driven by a person through a tether. Robot types
RP2040 #
The Raspberry Pi Foundation's own microcontroller chip, used in the Raspberry Pi Pico and many hobby boards. Compute & electronics
RTK #
Real-Time Kinematic. A correction technique that improves GPS accuracy to about a centimeter using a nearby base station. Sensors & perception

S

SDK #
Software Development Kit. The official libraries and documentation for controlling a robot from code. A "full SDK" gives low-level control, while a limited one only offers high-level commands. Software & AI
Servo #
A motor packaged with gears, a position sensor and a controller so it can be told to move to a specific angle. Motion & mechanics
Sim-to-real (sim2real) #
Training a robot's behavior in simulation and then running it on the real robot. Randomizing the simulation helps the policy survive real-world differences. Software & AI
Single-board computer (SBC) #
A complete computer on one circuit board, such as a Raspberry Pi or Jetson developer kit. Compute & electronics
SLAM #
Simultaneous Localization and Mapping. The technique a robot uses to build a map of an unknown space while tracking its own position in it, usually with lidar or cameras. Software & AI
Smart servo (Serial bus servo) #
A servo on a shared data bus that reports its position, load and temperature back to the computer. Dynamixel (ROBOTIS) and Feetech STS are the best-known brands. Motion & mechanics
Sonar #
Sound-based ranging and imaging, used mainly underwater where light and radio travel poorly. Sensors & perception
STEM #
Science, Technology, Engineering and Math. Used to describe educational robots and kits. Buying & programs
Stereo camera #
Two cameras mounted side by side that estimate depth the way human eyes do, by comparing the two views. Sensors & perception
STM32 #
A large family of ARM microcontrollers from STMicroelectronics, widely used for motor control and flight controllers. Compute & electronics
Structured light #
A depth-sensing method that projects a known pattern of infrared dots or lines and measures how the pattern deforms on surfaces. Sensors & perception
Subscription #
A recurring fee some companion robots charge for cloud features such as voice assistants or AI conversation. Buying & programs

T

Teensy #
A small, fast microcontroller board by PJRC that works with Arduino code. Popular for projects that need more speed than a typical Arduino. Compute & electronics
Teleoperation (Teleop) #
Controlling a robot remotely in real time, with a gamepad, VR headset or a matching leader arm. Software & AI
Tether #
A cable connecting an underwater robot to the surface, carrying power, video and commands, since radio barely travels through water. Motion & mechanics
Thermal camera #
A camera that sees heat (infrared radiation) instead of visible light. Used on inspection robots to spot hot equipment or people in the dark. Sensors & perception
ToF #
Time of Flight. A sensor that measures distance by timing how long emitted light takes to bounce back. Single-point ToF sensors measure one distance, and ToF cameras measure a whole depth image. Sensors & perception
TOPS #
Trillions of Operations Per Second. A rough measure of AI chip speed. Useful for comparing chips within one vendor, less so across vendors. Compute & electronics

U

UART #
A simple serial connection between two chips, often used between a robot's main computer and its motor controller. Compute & electronics
Ultrasonic sensor #
A sensor that measures distance with sound pulses above human hearing. Cheap and common on hobby robots, but less precise than lidar. Sensors & perception
URDF #
Unified Robot Description Format. A file describing a robot's links, joints and shapes, used by ROS and simulators. MJCF is the MuJoCo equivalent. Software & AI
USV #
Uncrewed Surface Vessel. An autonomous or remotely operated boat. Robot types
UWB #
Ultra-Wideband. A short-range radio technology that measures distance between devices precisely, used for indoor positioning and "follow me" features. Sensors & perception

V

VLA #
Vision-Language-Action model. A large AI model that takes camera images and a text instruction and outputs robot actions. Software & AI

W

Webots #
An open-source robot simulator popular in education. Software & AI
WebRTC #
A web standard for low-latency video and data streaming, used by some robots to stream their cameras to a browser or laptop. Software & AI
Wheel-legged #
A robot with wheels at the end of its legs, combining fast, efficient rolling with the ability to step, jump or balance. Motion & mechanics
Whole-body control #
Coordinating all of a robot's joints at once, legs, torso and arms, to balance while moving and manipulating. Motion & mechanics
Wi-Fi #
Wireless networking. Many programmable robots stream video and take commands over Wi-Fi so a laptop can act as the brain. Compute & electronics

X

x86 #
The Intel and AMD processor architecture used in ordinary PCs. Some larger robots carry a small x86 PC such as an Intel NUC. Compute & electronics

Z

ZMP #
Zero Moment Point. A classic walking-control method that plans foot placement so the robot's center of pressure stays inside its feet. Stable on flat floors but weak against pushes. Motion & mechanics