Glossary

Technical terms, abbreviations, and acronyms used across the HUMA portal. Each entry links to where the term appears in context.

B

BLDC — Brushless DC Motor

A synchronous electric motor driven by DC power through an electronic commutator rather than mechanical brushes. BLDCs dominate humanoid robotics because they offer high torque-to-weight ratios, long lifetimes (no brush wear), and precise speed control. Nearly every actuator in the HUMA parts catalog — CubeMars, T-Motor, Maxon, EYOU — is built around a BLDC stator/rotor pair, typically using NdFeB permanent magnets.

Used in: Parts database (actuator listings), kit BOMs, component comparison tables.

BOM — Bill of Materials

A complete, structured list of every component required to build a product, including part numbers, quantities, suppliers, and unit costs. In humanoid robotics, the BOM is the single most important document for cost estimation, supply chain planning, and manufacturing. HUMA's kit builder generates a live BOM that passes electrical, mechanical, and communication compatibility checks.

Used in: Kit builder, kit templates (Kit 00 through Kit 03), supply chain pages.

C

CAGR — Compound Annual Growth Rate

The annualised rate of return that smooths year-over-year growth into a single percentage. Used extensively in market sizing: if the humanoid robotics market is valued at $2.8 billion in 2024 and projected at $38 billion by 2035, the CAGR is roughly 27%. CAGR understates volatility but is the standard metric for investor decks and industry reports.

Used in: Market analysis page, company profiles (funding context).

CAN / EtherCAT / RS-485 — Communication Protocols for Actuator Control

CAN (Controller Area Network) is a robust, low-latency bus protocol originally designed for automotive use, now the most common protocol for QDD actuators (CubeMars, T-Motor). EtherCAT (Ethernet for Control Automation Technology) is a high-speed deterministic protocol favoured by Harmonic Drive, Maxon, and industrial actuators — it requires an EtherCAT master and offers microsecond-level synchronisation. RS-485 is a differential serial standard used by Unitree and some budget actuators. Mixing protocols in a single build requires bus bridges or separate controllers.

Used in: Parts database (protocol field on every part), kit builder compatibility checks, component comparison.

D

DOF — Degrees of Freedom

The number of independent axes of motion in a mechanical system. Each actuated joint in a humanoid robot typically represents one DOF. A basic bipedal humanoid (Kit 00) has 18 DOF; a research-grade platform (Kit 03) has 32 DOF. More DOF enables more dexterous manipulation and more human-like movement, but increases BOM cost, control complexity, and power draw linearly.

Used in: Kit builder (target DOF), kit templates, company comparison table, research pages.

F

FSA — Fourier Smart Actuator

A family of integrated actuator modules designed by Fourier Intelligence (Shanghai) for their GR-series humanoid robots. FSAs combine a BLDC motor, harmonic or planetary reducer, driver electronics, and an absolute encoder in a single sealed unit. They represent the vertically integrated approach to actuator design — as opposed to assembling motor + gearbox + encoder from separate vendors.

Used in: Company profiles (Fourier Intelligence), actuator comparison.

M

MJCF — MuJoCo XML Format

The native scene description format for MuJoCo (Multi-Joint dynamics with Contact), DeepMind's physics simulator. MJCF files define robot morphology, joint limits, actuator properties, collision geometry, and contact parameters in XML. MuJoCo is the dominant simulator for reinforcement learning-based locomotion and manipulation research. Most sim-to-real transfer pipelines for humanoids start with an MJCF model.

Used in: Software/AI pages, research section, sim-to-real references.

N

NdFeB — Neodymium Iron Boron (Nd2Fe14B)

The strongest class of permanent magnets commercially available, made from an alloy of neodymium, iron, and boron. NdFeB magnets are the core of every high-performance BLDC motor used in humanoid robotics. China controls approximately 90% of global NdFeB production and nearly all rare-earth refining, making magnet supply a critical geopolitical chokepoint for the humanoid industry.

Used in: China risk analysis, supply chain pages, actuator deep-dives.

O

OEM — Original Equipment Manufacturer

A company that manufactures components or complete products that are then branded and sold by another company. In the humanoid robotics supply chain, OEM relationships are layered: a motor OEM (e.g., T-Motor) sells to an actuator integrator, who sells to a humanoid OEM (e.g., Figure AI), who sells to an end-user. Understanding OEM tiers is critical for supply chain mapping and margin analysis.

Used in: Supply chain pages, company profiles, business model analysis.

P

P% / M% / C% — Neumann Self-Replication Scoring (Part Count / Mass / Cost)

A framework inspired by von Neumann's self-replicating machine theory, applied to humanoid robots: what percentage of its own parts (P%), mass (M%), and cost (C%) could a humanoid robot manufacture? A robot that can 3D-print its own frame scores high on P% and M% but low on C% (since actuators and compute dominate cost). These metrics measure progress toward autonomous manufacturing and are tracked for each HUMA kit.

Used in: Self-replication analysis page, kit builder advanced metrics.

Q

QDD — Quasi-Direct Drive

An actuator design philosophy that uses a low gear ratio (typically 6:1 to 10:1) between the motor and the joint, preserving the motor's backdrivability and enabling force-sensitive, compliant motion. QDD actuators (CubeMars AK-series, T-Motor RMD-series) are popular in legged robots because they allow the robot to absorb impacts without damaging gears. The trade-off is lower peak torque compared to high-ratio harmonic drives.

Used in: Parts database, actuator comparison, kit builder, company profiles.

R

RaaS — Robotics as a Service

A business model where customers lease robots and pay per hour, per task, or per month rather than purchasing outright. RaaS lowers the barrier to adoption (no capex), creates recurring revenue for the provider, and allows fleet management, remote updates, and performance-based pricing. Major humanoid companies (Figure, Apptronik, 1X) are pursuing RaaS for warehouse, logistics, and manufacturing deployment.

Used in: Market analysis, company profiles (business model section), case studies.

S

SLA — Service Level Agreement

A contract between a service provider and a customer that defines expected uptime, response times, maintenance schedules, and penalties for non-compliance. In humanoid RaaS deployments, SLAs specify robot uptime guarantees (e.g., 95% operational availability), mean time to repair, and spare parts delivery windows. SLA terms directly drive aftermarket parts inventory and maintenance network design.

Used in: Case studies, business model pages, aftermarket/maintenance analysis.

T

TRL — Technology Readiness Level

A 1-to-9 scale originally developed by NASA to assess the maturity of a technology. TRL 1 is basic principles observed; TRL 9 is proven in operational environment. In humanoid robotics, most bipedal locomotion is at TRL 5-6 (validated in relevant environment), whole-body manipulation is TRL 3-4, and autonomous multi-task operation in unstructured environments is TRL 2-3. HUMA tracks TRL for key capabilities across companies.

Used in: Company profiles, research section, technology comparison.

U

URDF — Unified Robot Description Format

An XML format for describing robot models in ROS (Robot Operating System). URDF files specify link geometry, joint types and limits, inertial properties, and visual/collision meshes. While less expressive than MJCF (no closed kinematic chains, limited actuator modelling), URDF is the de facto standard for ROS-based control stacks and is required for MoveIt motion planning, Gazebo simulation, and RViz visualisation.

Used in: Software/AI pages, research section, ROS integration guides.

V

VLA — Vision-Language-Action Model

A foundation model that takes visual input (camera frames) and language instructions (natural language commands) and outputs motor actions (joint torques or end-effector trajectories). VLAs like Google RT-2, Physical Intelligence pi0.5, and NVIDIA GR00T N1.5 represent the frontier of humanoid robot intelligence — enabling robots to generalise across tasks without per-task programming. Running VLAs on-robot requires significant compute (Jetson AGX Orin class or above).

Used in: Software/AI pages, compute requirements in parts database, kit builder (compute tier selection).
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