Zen and the Art of Aibo Engineering

When Sony's robot dog, Aibo, was first launched in 1999, it was hailed as revolutionary and the first of its kind, promising to usher in a new industry of intelligent mobile machines for the home. But its success was far from certain. Legged robots were still in their infancy, and the idea of making an interactive walking robot for the consumer market was extraordinarily ambitious. Beyond the technical challenges, Sony also had to solve a problem that entertainment robots still struggle with: how to make Aibo compelling and engaging rather than simply novel.

Sony's team made that happen. And since Aibo's debut, the company has sold more than 170,000 of the cute little quadrupeds-a huge number considering their price of several thousand dollars each. From the start, Aibo could express a range of simulated emotions and learn through its interactions with users. Aibo was an impressive robot 25 years ago, and it's still impressive today.

Far from Sony headquarters in Tokyo, the town of Kta, in Aichi Prefecture, is home to the Sony factory that has manufactured and repaired Aibos since 2018. Kta has also become the center of fandom for Aibo, since the Hummingbird Cafe opened in the Kta Town Hall in 2021. The first official Aibo cafe in Japan, it hosts Aibo-themed events, and Aibo owners from across the country gather there to let their Aibos loose in a play area and to exchange Aibo name cards.

One patron of the Hummingbird Cafe is veteran Sony engineer Hideki Noma. In 1999, before Aibo was Aibo, Noma went to see his boss, Tadashi Otsuki. Otsuki had recently returned to Sony after a stint at the Japanese entertainment company Namco, and had been put in charge of a secretive new project to create an entertainment robot. But progress had stalled. There was a prototype robotic pet running around the lab, but Otsuki took a dim view of its hyperactive behavior and decided it wasn't a product that anyone would want to buy. He envisioned something more lifelike. During their meeting, he gave Noma a surprising piece of advice: Go to Ryan-ji, a famed Buddhist temple in Kyoto. Otsuki was telling Noma that to develop the right kind of robot for Sony, it needed Zen.

Aibo's Mission: Make History

When the Aibo project started in 1994, personal entertainment robots seemed like a natural fit for Sony. Sony was a global leader in consumer electronics. And in the 1990s, Japan had more than half of the world's industrial robots, dominating an industry led by manufacturers like Fanuc and Yaskawa Electric. Robots for the home were also being explored. In 1996, Honda showed off its P2 humanoid robot, a prototype of the groundbreaking ASIMO, which would be unveiled in 2000. Electrolux, based in the United Kingdom, introduced a prototype of its Trilobite robotic vacuum cleaner in 1997, and at iRobot in Boston, Joe Jones was working on what would become the Roomba. It seemed as though the consumer robot was getting closer to reality. Being the first to market was the perfect opportunity for an ambitious global company like Sony.

Aibo was the idea of Sony engineer Toshitada Doi (on left), pictured in 1999 with an Aibo ERS-111. Hideki Noma (on right) holds an Aibo ERS-1000.Raphael Gaillarde/Gamma-Rapho/Getty Images; Right; Timothy Hornyak

Sony's new robot project was the brainchild of engineer Toshitada Doi, co-inventor of the CD. Doi was inspired by the speed and agility of MIT roboticist Rodney Brooks's Genghis, a six-legged insectile robot that was created to demonstrate basic autonomous walking functions. Doi, however, had a vision for an "entertainment robot with no clear role or job." It was 1994 when his team of about 10 people began full-scale research and development on such a robot.

Hideki Noma joined Sony in 1995. Even then, he had a lifelong love of robots, including participating in robotics contests and researching humanoids in college. I was assigned to the Sony robot research team's entertainment robot department," says Noma. It had just been established and had few people. Nobody knew Sony was working on robots, and it was a secret even within the company. I wasn't even told what I would be doing."

Noma's new colleagues in Sony's robot skunk works had recently gone to Tokyo's Akihabara electronics district and brought back boxes of circuit boards and servos. Their first creation was a six-legged walker with antenna-like sensors but more compact than Brooks's Genghis, at roughly 22 centimeters long. It was clunky and nowhere near cute; if anything, it resembled a cockroach. When they added the camera and other sensors, it was so heavy it couldn't stand," says Noma. They realized it was going to be necessary to make everything at Sony-motors, gears, and all-or it would not work. That's when I joined the team as the person in charge of mechatronic design."

Noma, who is now a senior manager in Sony's new business development division, remembers that Doi's catchphrase was make history." Just as he had done with the compact disc, he wanted us to create a robot that was not only the first of its kind, but also one that would have a big impact on the world," Noma recalls. He always gently encouraged us with positive feedback."

We also grappled with the question of what an entertainment robot' could be. It had to be something that would surprise and delight people. We didn't have a fixed idea, and we didn't set out to create a robot dog."

The team did look to living creatures for inspiration, studying dog and cat locomotion. Their next prototype lost two of the six legs and gained a head, tail, and more sophisticated AI abilities that created the illusion of canine characteristics.

A mid-1998 version of the robot, nicknamed Mutant, ran on Sony's Aperios OS, the operating system the company developed to control consumer devices. The robot had 16 degrees of freedom, a million-instructions-per-second (MIPS) 64-bit reduced-instruction-set computer (RISC) processor, and 8 megabytes of DRAM, expandable with a PC card. It could walk on uneven surfaces and use its camera to recognize motion and color-unusual abilities for robots of the time. It could dance, shake its head, wag its tail, sit, lie down, bark, and it could even follow a colored ball around. In fact, it was a little bundle of energy.

Looks-wise, the bot had a sleek new coat" designed by Doi's friend Hajime Sorayama, an industrial designer and illustrator known for his silvery gynoids, including the cover art for an Aerosmith album. Sorayama gave the robot a shiny, bulbous exterior that made it undeniably cute. Noma, now the team's product planner and software engineer, felt they were getting closer to the goal. But when he presented the prototype to Otsuki in 1999, Otsuki was unimpressed. That's when Noma was dispatched to Ryan-ji to figure out how to make the robot seem not just cute but somehow alive.

Seeking Zen for Aibo at the Rock Garden

Established in 1450, Ryan-ji is a Rinzai Zen sanctuary known for its meticulously raked rock garden featuring five distinctive groups of stones. The stones invite observers to quietly contemplate the space, and perhaps even the universe, and that's what Noma did. He realized what Doi wanted Aibo to convey: a sense of tranquility. The same concept had been incorporated into the design of what was arguably Japan's first humanoid robot, a large, smiling automaton named Gakutensoku that was unveiled in 1928.

The rock garden at the Ryan-ji Zen temple features carefully composed groupings of stones with unknown meaning. Bjorn Christian Torrissen/Wikipedia

Roboticist Masahiro Mori, originator of the Uncanny Valley concept for android design, had written about the relationship between Buddhism and robots back in 1974, stating, I believe robots have the Buddha-nature within them-that is, the potential for attaining Buddhahood." Essentially, he believed that even nonliving things were imbued with spirituality, a concept linked to animism in Japan. If machines can be thought of as embodying tranquility and spirituality, they can be easier to relate to, like living things.

When you make a robot, you want to show what it can do. But if it's always performing, you'll get bored and won't want to live with it," says Noma. Just as cats and dogs need quiet time and rest, so do robots." Noma modified the robot's behaviors so that it would sometimes slow down and sleep. This reinforced the illusion that it was not only alive but had a will of its own. Otsuki then gave the little robot dog the green light.

The cybernetic canine was named Aibo for Artificial Intelligence roBOt" and aib, which means partner" in Japanese.

In a press release, Sony billed the machine as an autonomous robot that acts both in response to external stimuli and according to its own judgment. AIBO' can express various emotions, grow through learning, and communicate with human beings to bring an entirely new form of entertainment into the home." But it was a lot more than that. Its 18 degrees of freedom allowed for complex motions, and it had a color charge-coupled device (CCD) camera and sensors for touch, acceleration, angular velocity, and range finding. Aibo had the hardware and smarts to back up Sony's claim that it could behave like a living creature." The fact that it couldn't do anything practical became irrelevant.

The debut Aibo ERS-110 was priced at 250,000 yen (US $2,500, or a little over $4,700 today). A motion editor kit, which allowed users to generate original Aibo motions via their PC, sold for 50,000 yen ($450). Despite the eye-watering price tag, the first batch of 3,000 robots sold out in 20 minutes.

Noma wasn't surprised by the instant success. We aimed to realize a society in which people and robots can coexist, not just robots working for humans but both enjoying a relationship of trust," Noma says. Based on that, an entertainment robot with a sense of self could communicate with people, grow, and learn."

Hideko Mori plays fetch with her Aibo ERS-7 in 2015, after it was returned to her from an Aibo hospital. Aibos are popular with seniors in Japan, offering interactivity and companionship without requiring the level of care of a real dog.Toshifumi Kitamura/AFP/Getty Images

Aibo as a Cultural Phenomenon

Aibo was the first consumer robot of its kind, and over the next four years, Sony released multiple versions of its popular pup across two more generations. Some customer responses were unexpected: as a pet and companion, Aibo was helping empty-nest couples rekindle their relationship, improving the lives of children with autism, and having a positive effect on users' emotional states, according to a 2004 paper by AI specialist Masahiro Fujita, who collaborated with Doi on the early version of Aibo.

Aibo broke new ground as a social partner. While it wasn't a replacement for a real pet, it introduced a completely new category of companion robots designed to live with humans," says Minoru Asada, professor of adaptive machine systems at Osaka University's graduate school of engineering. It helped foster emotional connections with a machine, influencing how people viewed robots-not just as tools but as entities capable of forming social bonds. This shift in perception opened the door to broader discussions about human-robot interaction, companionship, and even emotional engagement with artificial beings."

Building a Custom Robot

• To create Aibo, Noma and colleagues had to start from scratch-there were no standard CPUs, cameras, or operating systems for consumer robots. They had to create their own, and the result was the Sony Open-R architecture, an unusual approach to robotics that enabled the building of custom machines.
• Announced in 1998, a year before Aibo's release, Open-R allowed users to swap out modular hardware components, such as legs or wheels, to adapt a robot for different purposes. High-speed serial buses transmitted data embedded in each module, such as function and position, to the robot's CPU, which would select the appropriate control signal for the new module. This meant the machine could still use the same motion-control software with the new components. The software relied on plug-and-play prerecorded memory cards, so that the behavior of an Open-R robot could instantly change, say, from being a friendly pet to a challenging opponent in a game. A swap of memory cards could also give the robot image- or sound-recognition abilities.
• Users could change the modular hardware and software components," says Noma. The idea was having the ability to add a remote-control function or swap legs for wheels if you wanted."
• Other improvements included different colors, touch sensors, LED faces, emotional expressions, and many more software options. There was even an Aibo that looked like a lion cub. The various models culminated in the sleek ERS-7, released in three versions from 2003 to 2005.
• Based on Scratch, the visual programming system in the latest versions of Aibo is easy to use and lets owners with limited programming experience create their own complex programs to modify how their robot behaves.
• The Aibo ERS-1000, unveiled in January 2018, has 22 degrees of freedom, a 64-bit quad-core CPU, and two OLED eyes. It's more puppylike and smarter than previous models, capable of recognizing 100 faces and responding to 50 voice commands. It can even be potty trained" and fed" with virtual food through an app.
  -T.H.

Aibo also played a crucial role in the evolution of autonomous robotics, particularly in competitions like RoboCup, notes Asada, who cofounded the robot soccer competition in the 1990s. Whereas custom-built robots were prone to hardware failures, Aibo was consistently reliable and programmable, and so it allowed competitors to focus on advancing software and AI. It became a key tool for testing algorithms in real-world environments.

By the early 2000s, however, Sony was in trouble. Leading the smartphone revolution, Apple and Samsung were steadily chipping away at Sony's position as a consumer-electronics and digital-content powerhouse. When Howard Stringer was appointed Sony's first non-Japanese CEO in 2005, he implemented a painful restructuring program to make the company more competitive. In 2006, he shut down the robot entertainment division, and Aibo was put to sleep.

What Sony's executives may not have appreciated was the loyalty and fervor of Aibo buyers. In a petition to keep Aibo alive, one person wrote that the robot was an irreplaceable family member." Aibo owners were naming their robots, referring to them with the word ko (which usually denotes children), taking photos with them, going on trips with them, dressing them up, decorating them with ribbons, and even taking them out on dates" with other Aibos.

For Noma, who has four Aibos at home, this passion was easy to understand.

Hideki Noma [right] poses with his son Yuto and wife Tomoko along with their Aibo friends. At right is an ERS-110 named Robbie (inspired by Isaac Asimov's I, Robot"), at the center is a plush Aibo named Choco, and on the left is an ERS-1000 named Murphy (inspired by the film Interstellar).Hideki Noma

Some owners treat Aibo as a pet, and some treat it as a family member," he says. They celebrate its continued health and growth, observe the traditional Shichi-Go-San celebration [for children aged 3, 5, and 7] and dress their Aibos in kimonos....This idea of robots as friends or family is particular to Japan and can be seen in anime like Astro Boy and Doraemon. It's natural to see robots as friends we consult with and sometimes argue with."

The Return of Aibo

With the passion of Aibo fans undiminished and the continued evolution of sensors, actuators, connectivity, and AI, Sony decided to resurrect Aibo after 12 years. Noma and other engineers returned to the team to work on the new version, the Aibo ERS-1000, which was unveiled in January 2018.

Fans of all ages were thrilled. Priced at 198,000 yen ($1,760), not including the mandatory 90,000-yen, three-year cloud subscription service, the first batch sold out in 30 minutes, and 11,111 units sold in the first three months. Since then, Sony has released additional versions with new design features, and the company has also opened up Aibo to some degree of programming, giving users access to visual programming tools and an application programming interface (API).

A quarter century after Aibo was launched, Noma is finally moving on to another job at Sony. He looks back on his 17 years developing the robot with awe. Even though we imagined a society of humans and robots coexisting, we never dreamed Aibo could be treated as a family member to the degree that it is," he says. We saw this both in the earlier versions of Aibo and the latest generation. I'm deeply grateful and moved by this. My wish is that this relationship will continue for a long time."