Robot Glossary

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

Built-in autonomy (Autonomy) #

What a robot does on its own with the software it ships with. This guide uses four levels. None / scripted robots move only when controlled or play preset motions. Reactive robots respond to their surroundings, for example by avoiding obstacles or following a person. Robots that navigate go to places on their own, such as mapped rooms or their charging dock. Task-level robots carry out multi-step jobs like inspections or deliveries. Walking, hovering and balancing alone do not count, and neither does anything the owner has to program. Software & AI

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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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

MAVLink #

A lightweight messaging protocol for drones, boats and underwater vehicles, used by PX4 and ArduPilot. Software & AI

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. The MuJoCo Guide covers what it can do, where it runs and its limits. Software & AI

N

Nav2 #

The standard ROS 2 navigation stack, which plans paths and drives a robot to a goal while avoiding obstacles. Software & AI

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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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. Robot Vision and Depth Sensors compares it with other sensors, with example robots. 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