Reference
Humanoid Robotics Glossary
Clear, source-backed definitions of humanoid robotics, embodied AI, robot learning, training data, control, and simulation terms.
A
Hardware & control
Actuator
An actuator is a robot’s power mechanism that converts electrical, hydraulic, pneumatic or other supplied energy into controlled mechanical force, torque or motion. In a humanoid, actuators drive joints, often through transmissions; they are distinct from the joints and sensors, and their arrangement need not correspond one-to-one with the robot’s degrees of freedom.
Hardware & control
Autonomy
Robot autonomy is the ability to perform an intended task from the robot’s current state and sensor information without human intervention during that task. Autonomy is contextual and can differ by function, environment and operating phase; it is not a single permanent capability level for the whole robot.
B
Hardware & control
Bimanual manipulation
Bimanual manipulation is the use of two hands or robot manipulators to carry out one manipulation task with spatial, temporal, or force coordination between them. The two sides may play symmetric roles, such as lifting a large object together, or asymmetric roles, such as one hand holding an object while the other operates a tool.
Hardware & control
Biped robot
A biped robot is a legged mobile robot that travels using two legs. Biped describes the locomotion structure, not the robot’s overall resemblance to a person: a biped can lack arms or a head, while a robot described as humanoid may use wheels instead of two-legged locomotion.
C
Hardware & control
Centre of mass
The centre of mass is the mass-weighted average position of a body or multibody system. For a humanoid, the whole-robot centre of mass changes as its joints move or its payload changes, and its position and acceleration are central variables in balance, locomotion and whole-body control.
Hardware & control
Centre of pressure
The centre of pressure is the point on a support surface at which the resultant of a distributed contact pressure or ground-reaction force can be represented as acting. In legged robotics it summarises how load is applied through one foot or across coplanar contacts and is commonly estimated from a measured contact wrench.
Hardware & control
Control frequency
Control frequency is the rate, usually expressed in hertz, at which a robot control loop reads state, updates its controller or policy, and issues commands. A robot can contain several nested loops at different rates, so policy frequency, actuator-control frequency, sensor sampling rate, and dataset frame rate should not be assumed to be identical.
Hardware & control
Control latency
Control latency is the elapsed time between a relevant event or observation and the physical effect of the resulting robot command. It can include sensor exposure and transport, preprocessing, policy inference, network transfer, controller scheduling, actuator response, and communication back to a human operator. The measured boundary must be stated because each component has a different latency.
Hardware & control
Coordinate frame
A coordinate frame is a defined origin and set of oriented axes used to express positions, orientations, motions, forces, or other spatial quantities. A value has no complete geometric meaning until its frame and convention are known. Transformations relate measurements expressed in frames such as world, robot base, camera, end effector, object, or sensor.
D
Hardware & control
Degree of freedom
A degree of freedom (DoF) is one independent parameter needed to specify a robot’s configuration; equivalently, a robot’s DoF is the dimension of its configuration space. It describes possible motion, not the number of motors. Joint constraints, closed kinematic chains and environmental contacts can make joint count, actuator count and controllable motion differ.
Hardware & control
Dexterous manipulation
Dexterous manipulation is the controlled, skillful reconfiguration of an object through coordinated motion and contact, often using multiple fingers. It can involve changing an object's pose within a hand, regrasping, sliding, rolling, finger gaiting, or making precise contact with the environment. The term describes capability, not a fixed minimum number of fingers or joints.
E
F
Hardware & control
Feedback control
Feedback control is a closed-loop control method that measures a system’s current output or state, compares it with a target and adjusts the command using the resulting error. In robotics, feedback can correct joint, end-effector, balance or force errors as new sensor measurements arrive.
Hardware & control
Floating base
A floating-base model represents a robot’s root body with six unconstrained spatial degrees of freedom—three for translation and three for rotation—instead of fixing it to the world. Those base coordinates are not directly actuated; a legged robot changes them through joint motion and external contact forces.
Hardware & control
Force closure
Force closure is a property of a set of contacts whose admissible forces can collectively generate a wrench opposing any external disturbance wrench under the chosen contact model. It describes directional force and moment capability without, by itself, accounting for finite actuator strength, object damage or uncertainty in the contacts.
Hardware & control
Force–torque sensing
Force–torque sensing is the measurement of forces and rotational moments transmitted through a robot interface, commonly with a six-axis sensor reporting three force components and three torque components. The combined quantity is a wrench expressed at a specified origin and in a specified coordinate frame. It measures the resultant load at the sensor, not a spatial pressure map across every contact.
Hardware & control
Friction cone
A friction cone is the set of contact-force vectors allowed by a Coulomb friction model: the normal force is nonnegative and the tangential force magnitude cannot exceed the friction coefficient times that normal force. It represents a force constraint at a contact, not a physical cone or a guarantee that the robot will not slip.
G
Hardware & control
Gait
A gait is a recurring pattern of leg motion and contact phases used for legged locomotion. For a biped, it describes how left and right stance, swing, double-support and any flight phases repeat over a cycle; gait is narrower than locomotion, which also includes starts, stops, turns, transitions and recovery.
Hardware & control
Gripper
A gripper is a robot end effector designed to seize and hold an object. It may use fingers, jaws, suction, magnetism, adhesion, or another grasping mechanism. A gripper can open and close with one command or expose several independently controlled joints, but it is not synonymous with every end effector or with a complete robot hand.
H
I
Hardware & control
Impedance control
Impedance control regulates the dynamic relationship between a robot’s motion error and the force or torque it exerts, usually by giving the robot virtual stiffness, damping and sometimes inertia. It lets an end effector or limb yield predictably during contact instead of trying to hold an exact position regardless of interaction forces.
Hardware & control
Inverse kinematics
Inverse kinematics (IK) finds robot configurations that satisfy a desired position, orientation or other geometric constraints. It reverses the question asked by forward kinematics: instead of computing where a hand or foot is from the joint values, it searches for joint values that place it at a target. A target can have multiple solutions or no feasible solution.
K
L
Hardware & control
Loco-manipulation
Loco-manipulation is the integrated performance of locomotion and object manipulation, in which a robot moves its own body while reaching, carrying, pushing, pulling, or otherwise controlling something in the environment. In humanoids and other legged robots, the task couples contact planning, balance, whole-body motion, and manipulation rather than treating walking and arm control as independent stages.
Hardware & control
Locomotion
Robot locomotion is the process by which a robot transports its body from one place to another through physical interaction with its environment. Robots may walk, roll, crawl, hop, fly, or swim. For a humanoid, locomotion usually means coordinated legged movement such as walking, turning, stepping, climbing, or recovering balance.
M
Hardware & control
Manipulability
Manipulability describes how readily a robot can produce task-space velocities in different directions at a particular configuration, given a specified bound on joint velocities. It is often represented by a Jacobian-derived ellipsoid or scalar measure; it is not a general score for grasp quality, payload capacity or task success.
Hardware & control
Mobile manipulation
Mobile manipulation is the coordinated use of locomotion and manipulation by a robot that combines a mobile base or body with one or more arms or other manipulators. Mobility expands the robot's reachable workspace, while the manipulator grasps, pushes, operates tools or makes contact; the base and arm may move separately or at the same time.
Hardware & control
Model predictive control
Model predictive control is a feedback-control method that uses a dynamics model to optimise a sequence of future actions, applies the first action or short part of that sequence, and replans from an updated state estimate. In receding-horizon MPC, the planning window moves forward at each update.
O
P
R
Hardware & control
Robot
A robot is a programmed, actuated mechanism with some degree of autonomy that performs locomotion, manipulation or positioning. The term includes the mechanism and its control system, but it does not imply a human-like body, machine learning, general intelligence or fully independent operation.
Hardware & control
Robot dynamics
Robot dynamics describes the relationship between forces and torques acting on a robot and the motion they produce, accounting for mass, inertia, gravity, velocity-dependent effects and external contact. Forward dynamics predicts acceleration from applied forces; inverse dynamics computes forces or torques for a specified motion.
Hardware & control
Robot embodiment
A robot embodiment is the particular body and sensorimotor interface through which a robot perceives and acts. It includes morphology and kinematics, actuators, end effectors, sensors, physical limits, and the observation and action conventions exposed to a controller or learned policy. Two robots can perform the same task while having different embodiments.
Hardware & control
Robot Jacobian
A robot Jacobian is a configuration-dependent matrix that maps joint velocities to a specified task velocity, such as the linear and angular velocity of an end effector. It describes instantaneous motion, rather than the end effector's finite displacement or the forces needed to accelerate the robot.
Hardware & control
Robot kinematics
Robot kinematics describes the geometric relationship between a robot’s joint configuration and the position, orientation and velocity of its links or end-effector, without modelling the forces that cause the motion. Forward kinematics computes pose from joint values; inverse kinematics searches for joint values that achieve a requested pose.
Hardware & control
Robot manipulation
Robot manipulation is a robot's controlled physical interaction with objects or its environment to change or maintain their state. It includes grasping, carrying, pushing, pulling, inserting, wiping, folding, tool use, and other tasks performed through selective contact. Manipulation can use a gripper, hand, tool, arm, or another part of the robot.
S
Hardware & control
SLAM
Simultaneous localisation and mapping
SLAM is the joint estimation of a moving robot or sensor rig's pose and a map of its environment from sensor observations. It addresses the coupled problem of needing a map to localise while needing pose estimates to build that map.
Hardware & control
State estimation
State estimation is the process of inferring variables that are not known exactly—such as a robot’s base pose, velocity, contact state or sensor bias—from noisy measurements, control inputs and a model of how the system evolves. An estimator should provide both an estimate and, where possible, a representation of its uncertainty.
Hardware & control
Support polygon
The support polygon is the convex hull of a robot’s contact areas on a declared support surface. For a biped on level ground it is formed by the loaded parts of one or both feet; it changes when contacts are added, removed or reduced to an edge or toe.
T
Hardware & control
Tactile sensing
Tactile sensing is the detection and measurement of physical contact properties at a robot's surface or contact interface. Depending on the sensor, it can report pressure or force distribution, contact location, shear, vibration, slip, texture, temperature, or deformation. Tactile data complements vision by measuring interactions that may be hidden at the point of contact.
Hardware & control
Torque control
Torque control is a control mode in which desired joint torques, or equivalent linear forces, are the command variables sent to a robot’s low-level actuators. Unlike position control, it does not directly command where each joint should be. Motion and contact instead emerge from the applied efforts, robot dynamics, feedback, constraints and any higher-level controller.