Milestone-Proposal:Honda's P2, First Bipedal Robot, 1996
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Docket #:2025-14
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To the proposer’s knowledge, is this achievement subject to litigation? No
Is the achievement you are proposing more than 25 years old? Yes
Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes
Did the achievement provide a meaningful benefit for humanity? Yes
Was it of at least regional importance? Yes
Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes
Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes
Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes
Year or range of years in which the achievement occurred:
1996
Title of the proposed milestone:
Honda's P2, First Bipedal Robot, 1996
Plaque citation summarizing the achievement and its significance; if personal name(s) are included, such name(s) must follow the achievement itself in the citation wording: Text absolutely limited by plaque dimensions to 70 words; 60 is preferable for aesthetic reasons.
In 1996, Honda’s P2 became the world’s first autonomous bipedal humanoid robot capable of stable walking and stair climbing. Incorporating real-time posture control, dynamic balance, gait generation, and multi-joint coordination, P2 marked a breakthrough in legged robotics. Its innovative integration of mechatronics and control algorithms had a profound impact on subsequent humanoid robot development, shaping research directions and setting benchmarks in mobility, autonomy, and human-robot interaction.
200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.
Honda’s P2 humanoid robot, introduced in 1996, represents a historic milestone in robotics history. As the first self-contained, autonomous humanoid robot capable of stable, dynamic bipedal walking, P2 demonstrated real-world feasibility of human-like locomotion. It introduced advanced dynamic balance control, real-time feedback systems, and highly articulated motion planning—setting a technical benchmark that would serve as the foundation for future generations of humanoid robots.
At a time when most global robotics research was focused on quadrupeds or wheeled robots with limited autonomy, P2 stood out for its fully integrated architecture and human-scale physicality. Its development marked a major shift in robotics—from machines optimized for industrial tasks to intelligent, mobile agents designed for social and assistive roles. The robot not only surpassed existing alternatives, such as Boston Dynamics' quadrupeds or Sony’s entertainment-oriented QRIO, but also achieved a level of stability and adaptability that remained unmatched for years.
Scientifically, P2 contributed to robotics, biomechanics, and AI by addressing the complex problem of dynamically stable bipedal locomotion. Socially, it reshaped public perception of robots and accelerated the development of applications in healthcare, rehabilitation, education, and personal assistance. Its technological and conceptual breakthroughs paved the way for the ASIMO series and inspired international research in humanoid robotics, setting a trajectory that continues to shape the industry today.
IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.
IEEE Robotics & Automation Society
In what IEEE section(s) does it reside?
IEEE Tokyo Section
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
Unit: IEEE Tokyo Section
Senior Officer Name: Toshiro Hiramoto
IEEE Organizational Unit(s) arranging the dedication ceremony:
Unit: IEEE Tokyo Section
Senior Officer Name: Toshiro Hiramoto
IEEE section(s) monitoring the plaque(s):
IEEE Section: IEEE Tokyo Section
IEEE Section Chair name: Toshiro Hiramoto
Milestone proposer(s):
Proposer name: Chiaki Ishikawa
Proposer email: Proposer's email masked to public
Proposer name: Tadaaki Hasegawa
Proposer email: Proposer's email masked to public
Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.
Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):
Honda Collection Hall, Mobility Resort Motegi, 120-1, Hiyama, Motegi-cho, Haga-gun, Tochigi, 320-3533, Japan.
GPS Coordinate: 36.5268157,140.2266043,17
Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.
Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The plaque will be desplayed on Honda Collection Hall.
Are the original buildings extant?
No.
Details of the plaque mounting:
It is placed on Honda Collection Hall where many displays related to Honda products are placed.
How is the site protected/secured, and in what ways is it accessible to the public?
Visitors can come to the Honda Collection Hall without security check.
Who is the present owner of the site(s)?
What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include detailed support at the end of this section preceded by "Justification for Inclusion of Name(s)". (see section 6 of Milestone Guidelines)
Historical Significance
Overview of Honda P2
A demonstration video of the Honda Humanoid Robot P2, developed by Honda in 1996, is available following "P2model.flv" file. It showcases P2's advanced bipedal locomotion and human-like movements.
The Honda P2 (Prototype 2), unveiled in December 1996, was the world's first self-regulating, two-legged humanoid robot capable of autonomous walking. As a groundbreaking development in the field of robotics, it embodied years of research into dynamic walking and human-robot interaction. The P2 represented a significant evolution from earlier prototypes, featuring a more compact and human-like design as well as an onboard power source and computing system (see Figure 1).
Height and Weight
//疑似人間ならTallかな
The P2 stood approximately 182 centimeters (6 feet) tall, giving it a human-like stature that enabled research into more natural interactions with people and environments.
The robot weighed about 210 kilograms (463 pounds), with the bulk of the weight consisting of actuators, control systems, and the onboard power supply.
Walking Speed and Degrees of Freedom
P2 was capable of walking at approximately 1.2 kilometers per hour (0.75 miles per hour), a notable achievement for bipedal locomotion at the time.
The P2 featured 30 degrees of freedom, allowing for smooth, flexible movements across its limbs, torso, and neck. This enabled more human-like postures and motion sequences.
Power Source and Autonomy
Unlike earlier tethered models, P2 carried its own power supply, marking a major step toward mobile, autonomous humanoid robots. It could operate without an external control or power cable.
Control System
P2 was equipped with an onboard computer capable of processing sensor input and calculating stable bipedal walking in real-time. This innovation allowed the robot to autonomously maintain balance while walking and performing basic tasks.
Significance
P2 was the direct predecessor to the later and more famous ASIMO robot. As the first prototype to achieve autonomous, dynamic walking with a human-scale body, it laid the technological foundation for modern humanoid robotics.
Figure 1: Honda's P2 humanoid robot walking autonomously. This image demonstrates the robot in motion, supported by its self-contained power and control systems. The dynamic walking posture reflects the real-time balance and coordination achieved by P2 in 1996.
Technological Breakthroughs in Bipedal Locomotion
Honda’s P2 robot, introduced in 1996, marked a historic breakthrough in the field of humanoid robotics. As one of the world’s first practical bipedal robots, P2 demonstrated stable and autonomous walking—something that had long eluded researchers due to the complexity of dynamic balance control. Compared to its predecessor P1, P2 featured significant advancements in motion control, sensor integration, and real-time responsiveness, enabling more human-like gait and posture. These innovations laid the technical foundation for future humanoid robots, including Honda’s ASIMO.
Scientific Contributions to Human-Machine Understanding
Beyond engineering, P2 also contributed significantly to scientific fields such as biomechanics, human-robot interaction, and computational control. The robot’s design necessitated interdisciplinary insights—combining mechanical engineering, control theory, sensor fusion, and biological inspiration. As researchers worked to approximate human-like movement, they deepened their understanding of human balance, locomotion dynamics, and adaptive control systems. These contributions had downstream effects on fields such as prosthetics, rehabilitation engineering, and assistive technologies.
Societal Impact and Public Engagement
P2’s public demonstrations were pivotal in changing perceptions of robotics. By showing that humanoid robots could perform lifelike movements and function in familiar environments, P2 sparked global interest and inspired a new generation of roboticists. It was not merely a research project—it was a statement that robots could one day serve practical and social roles beyond factory automation. Through media coverage and public exhibitions, Honda successfully positioned P2 as a symbol of technological progress and social benefit.
Technical Achievements of P2
Real-Time Dynamic Balance Control
One of P2’s most remarkable technical achievements was its ability to perform dynamically stable walking in real time. Unlike static robots that relied on fixed postures or support mechanisms, P2 utilized feedback loops from onboard sensors to adjust its joint movements instantaneously. This allowed it to shift its center of gravity and adapt to varying surfaces—enabling human-like walking over flat, inclined, and uneven terrain.
This accomplishment represented a major leap forward from earlier robotics, which often depended on external computation or guide rails. P2’s onboard processing enabled it to operate untethered, autonomously assessing and responding to its environment.
Sensor Integration and Control Algorithms
P2 employed an advanced array of sensors—including gyroscopes, accelerometers, and joint encoders—that worked in concert to determine posture, velocity, and impact forces. These sensors fed into a custom control system that calculated optimal joint torques and trajectories in real time. The robot’s motion was smooth, responsive, and stable—far beyond what had been seen in any humanoid system before.
The algorithms developed for P2 served as the basis for future humanoid control architectures, and their principles continue to influence robotics education and design standards today.
Power Autonomy and Full-Body Integration
P2 was one of the first full-sized bipedal robots to operate without a tethered power supply or external processor. It carried its own batteries and computing hardware, representing a significant achievement in energy management, component miniaturization, and thermal regulation.
Moreover, P2’s physical structure—joint placements, limb lengths, and mass distribution—was engineered to resemble human biomechanics, further supporting balance and coordination. This physical realism allowed P2 to serve as a testbed for biomechanical modeling and future assistive robotics.
Long-Term Influence and Legacy
Foundation for ASIMO and Successor Systems
P2 served as the direct forerunner of ASIMO, one of the world’s most recognized humanoid robots. Many of ASIMO’s capabilities—such as smoother walking, running, and stair climbing—were made possible through the foundational work conducted on P2. The knowledge gained from P2's design, testing, and public demonstration cycles translated directly into more sophisticated iterations of Honda’s humanoid robot line.
Catalyzing Global Research and Development
P2’s unveiling was a wake-up call for the global robotics community. It showed that humanoid robotics was no longer theoretical—it was possible, and happening. This motivated universities, private companies, and government institutions around the world to accelerate their humanoid research programs.
Additionally, P2’s success helped validate humanoid robotics as a viable field of study and industry investment. Numerous robotics curricula began incorporating dynamic balance control, human-inspired locomotion, and sensor-driven adaptability—areas where P2 had already demonstrated real-world success.
Influence on Non-Industrial Robotics Applications
P2 also had an indirect but profound influence on robotics applications in healthcare, rehabilitation, and home assistance. The control methods and mobility strategies developed for P2 informed the development of powered exoskeletons, prosthetics, and assistive walking devices. By proving that stable bipedal movement was achievable by machines, P2 helped unlock a new wave of human-assistive technologies that are still evolving today.
What obstacles (technical, political, geographic) needed to be overcome?
Development Challenges and Solutions
Overcoming Technological Limitations of the Late 20th Century
When Honda began its humanoid robot project in the late 1970s, the technological landscape was vastly different from today. Computational power, sensor precision, and actuator performance were all limited. One of the greatest challenges in bipedal locomotion was ensuring real-time balance and motion control with the hardware available at the time. Falling or instability during walking was a common issue.
To solve these challenges, Honda developed a proprietary dynamic balance control system using gyroscopes, accelerometers, and force sensors to monitor the robot’s posture. With sophisticated software and custom-built actuators, P2 was able to adjust its movements in real time to maintain stability—even on uneven terrain. These technologies greatly exceeded the state-of-the-art capabilities of the era.
During the late 20th century, robotics and AI were becoming strategic domains in global technological competition, particularly amid the Cold War backdrop. Japan, while rising as a technological power, had to carefully position its innovations to avoid associations with military applications. Honda’s choice to emphasize peaceful, civilian uses of robotics—such as education, healthcare, and daily assistance—allowed it to avoid controversy while promoting constructive applications of high technology.
Furthermore, as a private company, Honda had to develop its robotic technologies without direct government mandates or defense funding. This independence allowed greater flexibility in research focus and long-term vision, centered around social contribution rather than strategic advantage.
Bridging Geographic and Industrial Gaps
At the outset of its development, Japan lagged behind the U.S. and Europe in some aspects of robotics research. Many leading institutions and companies were located in the West, and access to knowledge was limited. Honda overcame this by actively engaging in international collaboration, sending engineers abroad, and absorbing global best practices in mechatronics, AI, and control systems.
By fostering a culture of interdisciplinary research and investing heavily in its own facilities and human capital, Honda transformed its relative geographic disadvantage into a source of originality and innovation. P2 became not just a Japanese success, but a globally recognized benchmark.
What features set this work apart from similar achievements?
Comparison with Contemporary Robotic Approaches
At the time of its unveiling in 1996, Honda’s P2 stood apart from other robotic systems being developed worldwide. A number of approaches existed—most notably quadruped robots, wheeled robots, and other bipedal platforms—but P2 offered a combination of human-like form, autonomous control, and practical mobility that was unprecedented. The following comparisons illustrate how P2 surpassed its contemporaries:
Comparison with Quadruped Robots
Quadruped robots, such as early prototypes developed by Boston Dynamics, were primarily engineered for stability and mobility on rugged terrain. Their four-legged structure gave them superior balance and load distribution, making them well-suited for traversing uneven ground or climbing over obstacles. However, these robots typically required external control systems and were often tethered to off-board power supplies. Their mechanical design, while robust, lacked the compact integration necessary for real-world deployment in human environments.
In contrast, Honda’s P2 was a fully autonomous, self-contained humanoid robot that operated untethered. Its bipedal form was not only a technical challenge but a strategic decision aimed at integrating robots into daily human life. By mimicking human gait and posture, P2 could navigate stairs, doorways, and other architectural features common in homes, offices, and public infrastructure—tasks that quadrupeds of the time could not perform effectively. While quadruped robots had advantages in outdoor scenarios, P2’s anthropomorphic design made it better suited for collaborative and assistive roles in human-centric environments.
Comparison with Wheeled Robots
Wheeled robots have long been favored in industrial and academic settings for their simplicity, speed, and energy efficiency. These robots are well-suited for controlled environments with flat surfaces, such as factories and laboratories. However, their limitations become apparent when faced with real-world conditions—stairs, curbs, uneven floors, and cluttered spaces often hinder their mobility.
P2’s bipedal locomotion allowed it to overcome many of these limitations. Unlike wheeled robots, P2 could step over obstacles, adjust its posture to maintain balance on sloped surfaces, and traverse complex terrain that mimics everyday human environments. This capacity significantly broadened its range of potential applications. Furthermore, the ability to walk upright enabled P2 to interact with tools, furniture, and human users in a way that wheeled robots could not. While wheeled systems were efficient, P2 demonstrated a level of flexibility and environmental adaptability that positioned it as a major technological leap forward.
Comparison with Other Bipedal Robots
During the late 1990s and early 2000s, several other bipedal humanoid robots emerged, including Sony’s QRIO. These robots often prioritized user interaction, compact design, and entertainment value. QRIO, for example, focused on expressive motion, communication, and personality-driven behavior. However, these designs typically sacrificed physical mobility and robustness for size and accessibility, limiting their effectiveness in tasks requiring substantial locomotion or load-bearing capability.
In contrast, Honda’s P2 was conceived as a full-sized humanoid robot with an emphasis on real-world utility. Its large frame, sophisticated control systems, and powerful actuators enabled it to perform stable, dynamic walking across a variety of surfaces. Unlike smaller bipedal robots, P2 demonstrated not just anthropomorphism but functional parity with human movement. This made it a foundational model for future service robots, as it bridged the gap between robotic novelty and practical application. Its emphasis on stability, autonomy, and scalability made it far more advanced than its peers at the time.
Conclusion
Honda’s P2 surpassed other robotic approaches of its time by delivering a holistic integration of human-like motion, autonomous control, and real-world applicability. Unlike quadruped, wheeled, or entertainment-focused robots, P2 demonstrated the potential for humanoid robots to operate independently in environments designed for people. Its success laid the groundwork for future humanoid systems and shifted global expectations of what robotics could achieve in society.
Why was the achievement successful and impactful?
Why the achievement was successful and impactful?
Honda’s P2, unveiled in 1996, was a groundbreaking achievement in robotics, marking the first autonomous, full-scale bipedal humanoid robot capable of dynamic walking. This milestone demonstrated the feasibility of human-like locomotion in machines, setting a new standard in robotics.
The success of P2 can be attributed to several key factors
Innovative Engineering: P2 was equipped with advanced technologies, including a 138V 6Ah Nickel-Zinc battery, four Micro SPARC II microprocessors, and a wireless Ethernet modem. These components enabled real-time control of its movements and interactions with the environment .
Human-Like Mobility
Unlike previous robots that used springs or wheels, P2 achieved stable walking by analyzing human biomechanics. It could navigate uneven surfaces and stairs, maintaining balance even when subjected to external forces .
Advanced Control Systems
P2 utilized a sophisticated control system, including a six-axis force sensor on each ankle and wrist, and two cameras for vision processing. This system allowed for precise movement and adaptability in various environments .
Impact on Robotics and Society
P2's development shifted the focus of robotics from industrial applications to human-centric designs. It inspired subsequent advancements in humanoid robots, including Honda's ASIMO, and influenced research in fields like biomechanics and artificial intelligence .
In summary, Honda's P2 was not just a technical achievement; it was a catalyst that propelled the field of humanoid robotics forward, demonstrating the potential for robots to interact with and assist humans in meaningful ways.
Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.
Bibliography
[1] Kazuo Hirai, Masato Hirose, Yuji Haikawa, Toru Takenaka: “The Development of Honda Humanoid Robot”, Proceedings of 1998 IEEE International Conference on Robotics & Automation, Leuven Belgium, May 1998.
[2] JRM staff writer: JRM’s 25 Years Anniversary of Publication Reviews “Autonomous Walking Humanoid that Astonished the World – Honda’s ASIMO”, JOURNAL OPEN ACCESS, 2014 Volume 26 Issue 1 Pages 15-17, DOI https://doi.org/10.20965/jrm.2014.p0015
Media:Fujipress_JRM-26-1-3.pdf
[3] Masato Hirose and Kenichi Ogawa: “Honda humanoid robots development”, Philosophical Transactions of The Royal Society, A 2007, 365, 11-19, doi:10,1098/rsta.2006.1917
[4] S. V. Viraktamath, Rashmi N Raikat: "Humanoid Robot: A Review", Irnternational Journal for Research in Applied Science & Engineering Technology (IJRASET), Vol. 9, Issue: VIII, August 2021
ISSN: 2321-9653;
Media:Humanoid_Robot_A_Review.pdf
[Remarks] There is a description of Honda's P2 on 2885 page.
[5] Sangbae Kim, Patrick M. Wensing: “Design of Dynamic Legged Robots”, Foundations and Trends in Robotics, Vol. 5, No. 2, pp. 117–190, (2014)
DOI: 10.1561/2300000044
[Remarks] There is a description of Honda's P2 on pages 18 to 19.
[6] A demonstration of the Honda Humanoid Robot P2 can be viewed on [YouTube - Honda P2 by H-Tune]
https://www.youtube.com/watch?v=d2BUO4HEhvM
[Remarks] If you are unable to play this YouTube video, please try searching for "Honda Human Robot P2" by "H-Tune".
Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to ieee-history@ieee.org. Please see the Milestone Program Guidelines for more information.
Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to ieee-history@ieee.org with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).
Please recommend reviewers by emailing their names and email addresses to ieee-history@ieee.org. Please include the docket number and brief title of your proposal in the subject line of all emails.
