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Honda's ASIMO, an example of a humanoid robot

A humanoid robot is a robot with its overall appearance based on that of the human body, allowing interaction with made-for-human tools or environments. In general humanoid robots have a torso with a head, two arms and two legs, although some forms of humanoid robots may model only part of the body, for example, from the waist up. Some humanoid robots may also have a 'face', with 'eyes' and 'mouth'. Androids are humanoid robots built to aesthetically resemble a human.


File:TOPIO 3.0.jpg

TOSY's TOPIO, a humanoid robot, can play ping pong.[1]

A humanoid robot is an autonomous robot because it can adapt to changes in its environment or itself and continue to reach its goal. This is the main difference between humanoid and other kinds of robots. In this context, some of the capacities of a humanoid robot may include, among others:

  • self-maintenance (like recharging itself)
  • autonomous learning (learn or gain new capabilities without outside assistance, adjust strategies based on the surroundings and adapt to new situations)
  • avoiding harmful situations to people, property, and itself
  • safe interacting with human beings and the environment

Like other mechanical robots, humanoid refer to the following basic components too: Sensing, Actuating and Planning and Control. Since they try to simulate the human structure and behaviour and they are autonomous systems, most of the times humanoid robots are more complex than other kinds of robots.

This complexity affects all robotic scales (mechanical, spatial, time, power density, system and computational complexity), but it is more noticeable on power density and system complexity scales. In the first place, most current humanoids aren’t strong enough even to jump and this happens because the power/weight ratio is not as good as in the human body. The dynamically balancing Anybots Dexter can jump, but poorly so far. On the other hand, there are very good algorithms for the several areas of humanoid construction, but it's very difficult to merge all of them into one efficient system (the system complexity is very high). Nowadays, these are the main difficulties that humanoid robots development has to deal with.

Humanoid robots are created to imitate some of the same physical and mental tasks that humans undergo daily. Scientists and specialists from many different fields including engineering, cognitive science, and linguistics combine their efforts to create a robot as human-like as possible. Their creators' goal for the robot is that one day it will be able to both understand human intelligence, reason and act like humans. If humanoids are able to do so, they could eventually work in cohesion with humans to create a more productive and higher quality future. Another important benefit of developing androids is to understand the human body's biological and mental processes, from the seemingly simple act of walking to the concepts of consciousness and spirituality. Right now they are used for welding. In the future they can greatly assist humans by welding and mining for coal.

There are currently two ways to model a humanoid robot. The first one models the robot like a set of rigid links, which are connected with joints. This kind of structure is similar to the one that can be found in industrial robots. Although this approach is used for most of the humanoid robots, a new one is emerging in some research works that use the knowledge acquired on biomechanics. In this one, the humanoid robot's bottom line is a resemblance of the human skeleton.


File:Nao robot.jpg

Nao (robot) is a robot created for companionship. It also competes in the RoboCup soccer championship

File:Enon robot.jpg

Enon was created to be a personal assistant. It is self-guiding and has limited speech recognition and synthesis. It can also carry things.

Humanoid robots are used as a research tool in several scientific areas.

Researchers need to understand the human body structure and behaviour (biomechanics) to build and study humanoid robots. On the other side, the attempt to simulate the human body leads to a better understanding of it.

Human cognition is a field of study which is focused on how humans learn from sensory information in order to acquire perceptual and motor skills. This knowledge is used to develop computational models of human behaviour and it has been improving over time.

It has been suggested that very advanced robotics will facilitate the enhancement of ordinary humans. See transhumanism.

Although the initial aim of humanoid research was to build better orthosis and prosthesis for human beings, knowledge has been transferred between both disciplines. A few examples are: powered leg prosthesis for neuromuscularly impaired, ankle-foot orthosis, biological realistic leg prosthesis and forearm prosthesis.

Besides the research, humanoid robots are being developed to perform human tasks like personal assistance, where they should be able to assist the sick and elderly, and dirty or dangerous jobs. Regular jobs like being a receptionist or a worker of an automotive manufacturing line are also suitable for humanoids. In essence, since they can use tools and operate equipment and vehicles designed for the human form, humanoids could theoretically perform any task a human being can, so long as they have the proper software. However, the complexity of doing so is deceptively great.

They are becoming increasingly popular for providing entertainment too. For example, Ursula, a female robot, sings, dances, and speaks to her audiences at Universal Studios. Several Disney attractions employ the use of animatrons, robots that look, move, and speak much like human beings, in some of their theme park shows. These animatrons look so realistic that it can be hard to decipher from a distance whether or not they are actually human. Although they have a realistic look, they have no cognition or physical autonomy.

Humanoid robots, especially with artificial intelligence algorithms, could be useful for future dangerous and/or distant space exploration missions, without having the need to turn back around again and return to Earth once the mission is completed. =)


A sensor is a device that measures some attribute of the world. Being one of the three primitives of robotics (besides planning and control), sensing plays an important role in robotic paradigms.

Sensors can be classified according to the physical process with which they work or according to the type of measurement information that they give as output. In this case, the second approach was used.

Proprioceptive Sensors

Proprioceptive sensors sense the position, the orientation and the speed of the humanoid's body and joints.

In human beings inner ears are used to maintain balance and orientation. Humanoid robots use accelerometers to measure the acceleration, from which velocity can be calculated by integration; tilt sensors to measure inclination; force sensors placed in robot's hands and feet to measure contact force with environment; position sensors, that indicate the actual position of the robot (from which the velocity can be calculated by derivation) or even speed sensors.

Exteroceptive Sensors

Exteroceptive sensors give the robot information about the surrounding environment allowing the robot to interact with the world. The exteroceptive sensors are classified according to their functionality.

Proximity sensors are used to measure the relative distance (range) between the sensor and objects in the environment. They perform the same task that vision and tactile senses do in human beings. There are other kinds of proximity measurements, like laser ranging, the usage of stereo cameras, or the projection of a coloured line, grid or pattern of dots to observe how the pattern is distorted by the environment. To sense proximity, humanoid robots can use sonars and infrared sensors, or tactile sensors like bump sensors, whiskers (or feelers), capacitive and piezoresistive sensors.

File:Shadow Hand Bulb large Alpha.png

An artificial hand holding a lightbulb

Arrays of tactels can be used to provide data on what has been touched. The Shadow Hand uses an array of 34 tactels arranged beneath its polyurethane skin on each finger tip.[2] Tactile sensors also provide information about forces and torques transferred between the robot and other objects.

Vision refers to processing data from any modality which uses the electromagnetic spectrum to produce an image. In humanoid robots it is used to recognize objects and determine their properties. Vision sensors work most similarly to the eyes of human beings. Most humanoid robots use CCD cameras as vision sensors.

Sound sensors allow humanoid robots to hear speech and environmental sounds, and perform as the ears of the human being. Microphones are usually used for this task.


Actuators are the motors responsible for motion in the robot.

Humanoid robots are constructed in such a way that they mimic the human body, so they use actuators that perform like muscles and joints, though with a different structure. To achieve the same effect as human motion, humanoid robots use mainly rotary actuators. They can be either electric, pneumatic, hydraulic, piezoelectric or ultrasonic.

Hydraulic and electric actuators have a very rigid behaviour and can only be made to act in a compliant manner through the use of relatively complex feedback control strategies . While electric coreless motor actuators are better suited for high speed and low load applications, hydraulic ones operate well at low speed and high load applications.

Piezoelectric actuators generate a small movement with a high force capability when voltage is applied. They can be used for ultra-precise positioning and for generating and handling high forces or pressures in static or dynamic situations.

Ultrasonic actuators are designed to produce movements in a micrometer order at ultrasonic frequencies (over 20 kHz). They are useful for controlling vibration, positioning applications and quick switching.

Pneumatic actuators operate on the basis of gas compressibility. As they are inflated, they expand along the axis, and as they deflate, they contract. If one end is fixed, the other will move in a linear trajectory. These actuators are intended for low speed and low/medium load applications. Between pneumatic actuators there are: cylinders, bellows, pneumatic engines, pneumatic stepper motors and pneumatic artificial muscles.

Planning and Control

In planning and control the essential difference between humanoids and other kinds of robots (like industrial ones) is that the movement of the robot has to be human-like, using legged locomotion, especially biped gait. The ideal planning for humanoid movements during normal walking should result in minimum energy consumption, like it happens in the human body. For this reason, studies on dynamics and control of these kinds of structures become more and more important.

To maintain dynamic balance during the walk, a robot needs information about contact force and its current and desired motion. The solution to this problem relies on a major concept, the Zero Moment Point (ZMP).

Another characteristic about humanoid robots is that they move, gather information (using sensors) on the "real world" and interact with it, they don’t stay still like factory manipulators and other robots that work in highly structured environments. Planning and Control have to focus about self-collision detection, path planning and obstacle avoidance to allow humanoids to move in complex environments.

There are features in the human body that can’t be found in humanoids yet. They include structures with variable flexibility, which provide safety (to the robot itself and to the people), and redundancy of movements, i.e., more degrees of freedom and therefore wide task availability. Although these characteristics are desirable to humanoid robots, they will bring more complexity and new problems to planning and control.

Timeline of developments

Year Development
c. 250 BC The Lie Zi described an automaton.[3]
c. 50 AD Hero of Alexandria described a machine to automatically pour wine for party guests.[4]
1206 Al-Jazari described a humanoid "robot band" that applied a cam-lever mechanism which, according to Charles B. Fowler, performed "more than fifty facial and body actions during each musical selection."[5] Al-Jazari also created hand washing automata with automatic humanoid servants and maids performing tasks such as refilling a basin after it is flushed, or offering soap and towels to users washing their hands.[6] His elephant clock also featured an automatic humanoid mahout striking a cymbal after every hour or half-hour.[7] His programmable "castle clock" also featured five robotic musicians who automatically play music when moved by levers operated by a hidden camshaft attached to a water wheel.[8]
1495 Leonardo da Vinci designs a humanoid automaton that looks like an armored knight, known as Leonardo's robot. [1]
1738 Jacques de Vaucanson builds The Flute Player, a life-size figure of a shepherd that could play twelve songs on the flute and The Tambourine Player that played a flute and a drum or tambourine. [2]
1774 Pierre Jacquet-Droz and his son Henri-Louis created the Draughtsman, the Musicienne and the Writer, a figure of a boy that could write messages up to 40 characters long. [3]
1921 Czech writer Karel Čapek introduced the word "Robot" in his play R.U.R. (Rossum's Universal Robots). The word "Robot" comes from the word "robota", meaning, in Czech, "forced labour, drudgery". [4]
1969 D.E. Whitney publishes his article Resolved motion rate control of manipulators and human prosthesis.
1970 Miomir Vukobratović has proposed Zero Moment Point a theoretical model to explain biped locomotion. [5]
1972 Miomir Vukobratović and his associates at Mihajlo Pupin Institute build the first active anthropomorphic exoskeleton.
1973 In Waseda University, in Tokyo, Wabot-1 is built. It was able to communicate with a person in Japanese and to measure distances and directions to the objects using external receptors, artificial ears and eyes, and an artificial mouth. [6]
1980 Marc Raibert established the MIT Leg Lab, which is dedicated to studying legged locomotion and building dynamic legged robots. [7]
1983 Using MB Associates arms, "Greenman" was developed by Space and Naval Warfare Systems Center, San Diego. It had an exoskeletal master controller with kinematic equivalency and spatial correspondence of the torso, arms, and head. Its vision system consisted of two 525-line video cameras each having a 35 degree field of view and video camera eyepiece monitors mounted in an aviator's helmet. [8]
1984 At Waseda University, the Wabot-2 is created, a musician humanoid robot able to communicate with a person, read a normal musical score with his eyes and play tunes of average difficulty on an electronic organ. [9]
1985 Developed by Hitachi Ltd, WHL-11 is a biped robot capable of static walking on a flat surface at 13 seconds per step and it can also turn. [10]
1985 WASUBOT is another musician robot from Waseda University. It performed a concerto with the NHK Symphony Orchestra at the opening ceremony of the International Science and Technology Exposition.
1986 Honda developed seven biped robots which were designated E0 (Experimental Model 0) through E6. E0 was in 1986, E1 - E3 were done between 1987 and 1991, and E4 - E6 were done between 1991 and 1993. [11]
1989 Manny was a full scale anthropomorphic robot with 42 degrees of freedom developed at Battelle's Pacific Northwest Laboratories in Richand, Washington, for the US Army's Dugway Proving Ground in Utah. It could not walk on its own but it could crawl, and had an artificial respiratory system to simulate breathing and sweating.[12]
1990 Tad McGeer showed that a biped mechanical structure with knees could walk passively down sloping surface. [13]
1993 Honda developed P1 (Prototype Model 1) through P3, an evolution from E series, with upper limbs. Developed until 1997.[14]
1995 Hadaly was developed in Waseda University, to study human-robot communication and has three subsystems: a head-eye subsystem, a voice control system for listening and speaking in Japanese, and a motion control subsystem to use the arms to point toward campus destinations.
1995 Wabian is a human-size biped walking robot from Waseda University.
1996 Saika, a light-weight, human-size and low-cost humanoid robot, was developed at Tokyo University. Saika has a two-DOF neck, dual five-DOF upper arms, a torso and a head. Several types of hands and forearms are under development also. Developed until 1998. [15]
1997 Hadaly-2, developed at Waseda University, is a humanoid robot which realizes interactive communication with humans. It communicates not only informationally, but also physically.
2000 Honda creates its 11th bipedal humanoid robot, ASIMO. [16]
2001 Sony unveils small humanoid entertainment robots, dubbed Sony Dream Robot (SDR). Renamed Qrio in 2003.
2001 Fujitsu realized its first commercial humanoid robot named HOAP-1. Then its successors HOAP-2 and HOAP-3 have been announced in 2003 and 2005, respectively. HOAP is designed for a broad range of applications for R&D of robot technologies.
2003 JOHNNIE, an autonomous biped walking robot built at the Technical University of Munich. The main objective was to realize an anthropomorphic walking machine with a human-like, dynamically stable gait [17]
2003 Actroid, a robot with realistic silicone "skin" developed by Osaka University in conjunction with Kokoro Company Ltd. [18]
2004 Persia, Iran's first humanoid robot was developed using realistic simulation by researchers of Isfahan University of Technology in conjunction with ISTT. [19]
2004 KHR-1, a programmable bipedal humanoid robot introduced in June 2004 by a Japanese company Kondo Kagaku.
2005 The PKD Android, a conversational humanoid robot made in the likeness of science fiction novelist Philip K Dick, was developed as a collaboration between Hanson Robotics, the Fedex Institute of Technology, and the University of Memphis.[20]
2005 Wakamaru, a Japanese domestic robot made by Mitsubishi Heavy Industries, primarily intended to provide companionship to elderly and disabled people. [21]
2007 TOPIO, a ping pong playing robot developed by TOSY Robotics JSC. [22]
2008 KT-X, the first international humanoid robot developed as a collaboration between the 5 time consecutive RoboCup champions, Team Osaka, and KumoTek Robotics. [23]
2009 HRP-4C, a Japanese domestic robot made by National Institute of Advanced Industrial Science and Technology shows human characteristics in addition to bipedal walking.
2009 Turkey, Turkey's first dynamically walking humanoid robot, SURALP, is developed by Sabanci University in conjunction with Tubitak. [24]

See also


  1. REDIRECT Template:Multicol
  • Actroid
  • AIBO
  • Android
  • Choromet
  • Cog
  • GuRoo
  • Gynoid
  • HOAP
  • HRP-4C
  • iCub
  • KHR-1
  • KT-X
  • Nao (robot)
  • Kismet
  1. REDIRECT Template:Multicol-break
  • MechRC Shadowstalker
  • PINO
  • Plen
  • QRIO
  • REEM
  • RoboCup
  • Robonaut
  • Robonova-1
  • RoboSapien
  • Shadow Hand
  • Toyota Partner Robot
  • Uncanny valley
  1. REDIRECT Template:Multicol-end


  1. includeonly>"Nano technology | Computer | Robot | TOSY TOPIO - Table Tennis Playing Robot", DigInfo News. Retrieved on 2007-12-05.
  2. Shadow Robot Company: The Hand Technical Specification. URL accessed on 2009-04-09.
  3. Joseph Needham (1986), Science and Civilization in China: Volume 2, p. 53, England: Cambridge University Press
  4. Hero of Alexandria; Bennet Woodcroft (trans.) (1851). Temple Doors opened by Fire on an Altar. Pneumatics of Hero of Alexandria. London: Taylor Walton and Maberly (online edition from University of Rochester, Rochester, NY). Retrieved on 2008-04-23.
  5. Fowler, Charles B. (October 1967), "The Museum of Music: A History of Mechanical Instruments", Music Educators Journal 54 (2): 45-9
  6. Rosheim, Mark E. (1994), Robot Evolution: The Development of Anthrobotics, Wiley-IEEE, pp. 9–10, ISBN 0471026220 
  7. The Machines of Al-Jazari and Taqi Al-Din, Foundation for Science Technology and Civilization
  8. Ancient Discoveries, Episode 11: Ancient Robots, History Channel,, retrieved on 2008-09-06 


  • Asada, H. and Slotine, J.-J. E. (1986). Robot Analysis and Control. Wiley. ISBN 0-471-83029-1.
  • Arkin, Ronald C. (1998). Behavior-Based Robotics. MIT Press. ISBN 0-262-01165-4.
  • Brady, M., Hollerbach, J.M., Johnson, T., Lozano-Perez, T. and Mason, M. (1982), Robot Motion: Planning and Control. MIT Press. ISBN 0-262-02182-X.
  • Horn, Berthold, K. P. (1986). Robot Vision. MIT Press. ISBN 0-262-08159-8.
  • Craig, J. J. (1986). Introduction to Robotics: Mechanics and Control. Addison Wesley. ISBN 0-201-09528-9.
  • Everett, H. R. (1995). Sensors for Mobile Robots: Theory and Application. AK Peters. ISBN 1-56881-048-2.
  • Kortenkamp, D., Bonasso, R., Murphy, R. (1998). Artificial Intelligence and Mobile Robots. MIT Press. ISBN 0-262-61137-6.
  • Poole, D., Mackworth, A. and Goebel, R. (1998), Computational Intelligence: A Logical Approach. Oxford University Press. ISBN 0-19-510270-3.
  • Russell, R. A. (1990). Robot Tactile Sensing. Prentice Hall. ISBN 0-13-781592-1.
  • Russell, S. J. & Norvig, P. (1995). Artificial Intelligence: A Modern Approach. Prentice-Hall. Prentice Hall. ISBN 0-13-790395-2.

Further reading

External links