Humanoid robot

A humanoid robot is a robotic system designed to resemble the human body in form and, in some cases, behaviour. Most humanoid robots include a torso, a head, two arms and two legs, although some models replicate only parts of the anatomy. When the exterior is shaped to closely imitate human appearance, the robot is referred to as an android. Humanoid robots serve a wide range of functions, from research into biomechanics and cognition to applications in medicine, industry and entertainment.

Historical Background

The idea of a human-shaped artificial being appears across multiple ancient cultures. Early conceptualisations were largely mythological or philosophical, while later centuries produced working mechanical prototypes. These developments laid the groundwork for modern robotics.
In Ancient Greece, myths describe the god Hephaestus creating animated humanoids. In the Iliad, he fashions golden female attendants with human-like voices. Another story attributes to him the creation of Talos, a bronze automaton built to guard Crete.
In China, the Liezi, a 3rd-century BCE Taoist text, recounts how the engineer Yan Shi presented King Mu of Zhou with a lifesize humanoid automaton made of wood and leather. This early robot was said to walk, sing and move its limbs.
In the Middle East, the 13th-century Muslim engineer Ismail al-Jazari designed several ingenious automata, including a waitress that dispensed drinks from an internal reservoir and a device that replenished a hand-washing basin automatically.
In Italy, Leonardo da Vinci developed detailed sketches in the 15th century for a mechanical knight clad in armour. Operated by pulleys and cables, it could sit, stand and move its arms.
In Japan, between the 17th and 19th centuries, craftsmen created karakuri puppets—precursors to humanoid robots—used in theatre, homes and religious festivals. These included butai karakuri for stage plays, zashiki karakuri used domestically to perform small tasks and dashi karakuri that reenacted traditional tales during festivals.
In France, Jacques de Vaucanson built the human-sized Vaucanson Flute Player in the 18th century. Constructed of wood and driven by bellows, pipes and weighted mechanisms, it could play melodies on a flute by imitating human breathing and finger movement.
In South Korea, research at KAIST led to the creation of HUBO, the country’s first humanoid robot, and the later establishment of the K-Humanoid Alliance in 2025 to support collaboration in robotics research and development.

Applications of Humanoid Robots

Humanoid robots now serve as research platforms, assistive technologies and tools for public demonstration. Their design enables them to use equipment and environments intended for human operators.
In scientific research, humanoids help investigate human movement, balance and learning. Studies of biomechanics and cognition inform the development of robotic motion and, in turn, provide insights into human physiology.
In medicine and biotechnology, humanoid robots facilitate the development of advanced prostheses and orthotic devices. They support rehabilitation programmes, exemplified by robots such as WABIAN-2, which assists patients with lower-limb recovery. Their ability to simulate human posture and gait makes them excellent test subjects for exploring personalised healthcare technologies or acting as robotic care assistants.
In industry and service roles, humanoids can assist with tasks that require manipulation of tools and machinery designed for human workers. This includes roles such as reception, basic manufacturing operations and laboratory assistance. Full autonomy remains difficult to achieve due to the complexity of real-world environments.
In entertainment, humanoid robots have been central to storytelling and performance for centuries. Modern examples include animatronic figures in theme parks and the development of “stuntronics”, which are highly dynamic humanoid robots acting as stunt doubles. Humanoids also feature in media exploring future applications of robotics, such as the documentary Plug & Pray.
In technology demonstration, many advanced humanoids, including Honda’s ASIMO, are designed to showcase breakthroughs in bipedal locomotion, manipulation and coordination. Although domestic humanoids exist, they typically excel only at specialised tasks and lack the autonomy required for full household integration.
Humanoid robots are also proposed for space exploration, where human-like dexterity would be useful in hazardous or remote environments without the need for return journeys.

Sensors

Sensors provide the interface between the robot and its physical environment. Humanoid robots employ two broad classes of sensors: proprioceptive and exteroceptive.
Proprioceptive sensors provide internal measurements, including joint position, limb orientation and motion. These mirror human systems such as the inner ear’s semicircular canals. Technologies include accelerometers for detecting acceleration, tilt sensors for inclination, force sensors embedded in hands and feet, and position or speed sensors integrated into joints.
Exteroceptive sensors capture information about the external environment. Tactile sensors supply data about texture, force and torque; for instance, the Shadow Hand places arrays of tactels beneath synthetic skin to detect contact. Vision sensors—usually CCD cameras—enable object detection and tracking. Sound sensors, such as microphones, allow the robot to perceive speech and ambient noise.

Actuators

Actuators function as the robot’s muscles. These motor-driven mechanisms generate movement and are integrated into joints throughout the body. The design aims to replicate human biomechanics as closely as possible, balancing strength, precision, and flexibility. Different robots employ electric motors, hydraulic systems or advanced artificial muscles depending on the required performance.

Technological Significance

Humanoid robots provide a bridge between engineering and the life sciences. They serve as platforms for testing locomotion theories, developing assistive technologies and advancing autonomous systems. Their anthropomorphic form allows them to interact with tools, environments and interfaces originally created for humans, giving them the potential to operate in domains where traditional robots are less effective. As research progresses, humanoid robots continue to offer insights into human capabilities while supporting the development of intelligent, adaptive machinery for future applications.