From a sold-out toy in 1999 Tokyo to a four-legged inspector in mines, ruins and care homes, the story of the mechanical pet is arguably the story of robotics itself.
On the morning of 1 June 1999, three thousand silver robot dogs went on sale in Tokyo. They were the size of a Jack Russell, cost the rough equivalent of two and a half thousand US dollars, and could not, in any meaningful sense, fetch, bark on command, or be cuddled in any comfortable way. They sold out in twenty minutes. A further two thousand units went to America a few days later, and were gone in four. The buyers were, mostly, not children.1 Many of them queued at Sony stores in business suits.
This was not because Sony had managed to engineer the perfect pet. It was because the AIBO, short for Artificial Intelligence Robot, was the first time a recognisably modern robot had been offered for the home, and to a generation raised on R2-D2 and the Tamagotchi, the novelty alone was enough. A few weeks later, The New Yorker ran a cartoon by Jack Ziegler showing an AIBO cocking its leg against a fire hydrant and dispensing nuts and bolts.1 The mechanical pet had arrived.
Twenty-seven years later, the robot dog has had several more lives. It has died, been mourned at a Buddhist temple, been reincarnated, gone to work in a Canadian copper mine, walked into the ruins of Chernobyl, climbed an embankment beside the M5, and, perhaps most consequentially, been sat on the lap of an elderly woman in Cornwall who has not had a visitor in three weeks. None of which, in the late 1990s, anyone could have reasonably predicted.
A Mutant.. Dog?
The AIBO came out of Sony's Computer Science Laboratory, which had quietly opened in 1990, and the Digital Creature Lab that grew out of it under the engineer Toshitada Doi. Doi liked the idea of building a machine that was useful precisely because it was useless. From 1994 he worked with the artificial intelligence researcher Masahiro Fujita on a series of prototypes, most of them six-legged and insect-like. One of them, named MUTANT, could track a ball, shake hands and sleep.2 By the time the project reached production, the AIBO had four legs, eighteen joints, and the silhouette of a beagle.
What set the AIBO apart was not the engineering, which was extraordinary for the time, but its temperament. It could see with a small camera, hear in stereo, and through interaction with its owner gradually develop something like a personality, moving from a wobbly mechanical infancy to a steadier adulthood. People named them, scolded them, and praised them. In an episode of Frasier from 2001, Frasier Crane gives his father an AIBO ERS-210 to keep him company while he is away. Eddie the terrier is unimpressed.1
Between 1999 and 2006, Sony sold around 170,000 AIBOs across five generations.3 The little robot became the standard platform for the Four-Legged League of the RoboCup, where universities across the world programmed teams of AIBOs to play autonomous football against one another, an event that ran from 1999 to 2008 and quietly trained a generation of robotics researchers.1 Then, in January 2006, with Sony struggling financially, the company pulled the plug. Production ended. The Tokyo repair clinic closed in 2014.
This is where the story becomes affecting. In Japan, where AIBOs had been treated as members of the family, owners began holding Buddhist funerals for their broken pets. At the four-hundred-and-fifty-year-old Kofuku-ji temple in Chiba prefecture, the head priest Bungen Oi conducts memorial services for AIBOs that can no longer be repaired, their components harvested afterwards for the resurrection of others.4 "All things have a bit of soul," Oi told The Japan Times in 2018.4 By that point, more than eight hundred AIBOs had received last rites.5
While Sony was selling its first AIBOs in 1999, a small Massachusetts spin-out called Boston Dynamics was helping to refine the way the robot walked. Marc Raibert, an MIT and Carnegie Mellon professor who had founded the company in 1992, had spent the better part of two decades pioneering the field of legged locomotion at his Leg Laboratory. He had built the first self-balancing hopping robots; his lab had shown that robotic running was possible.6 Sony was Boston Dynamics' first major commercial client. The company also helped develop the control system for Sony's later humanoid robot QRIO.7 The AIBO and the company that would later build Spot are, in other words, siblings.
In 2003 came a contract from DARPA, the United States defence research agency, to develop a four-legged robot capable of following soldiers across terrain too rough for wheeled vehicles. The result was BigDog, a noisy, mule-sized quadruped that could climb thirty-five-degree slopes carrying 150 kilograms of equipment.8 The military funding kept coming, through Cheetah (which set a land speed record for legged robots at 28 mph in 2012), AlphaDog, WildCat and LittleDog. None entered front-line service. BigDog was eventually shelved as too loud for the battlefield. But by then, Boston Dynamics had become the world's foremost laboratory of legged motion, and its YouTube videos of robots being kicked, recovering, and bounding through snow had quietly altered the public's sense of what was possible.9
The commercial breakthrough came almost two decades after BigDog. After a series of ownership changes (Google in 2013, SoftBank in 2017, Hyundai in 2020), Boston Dynamics released its first commercial product in 2019: Spot, a sleek yellow quadruped about the size of a labrador, fully electric, with a ninety-minute battery, a top speed of three miles an hour, and the ability to carry up to fourteen kilograms of sensors or tools.10 The first Spots leased to customers that year cost roughly $75,000 a piece.11
Sony, sensing the moment, revived the AIBO in November 2017 and shipped its new ERS-1000 model from January 2018: white, cloud-connected, with mechanical eyelashes and facial recognition, manufactured in the town of Kota in Aichi prefecture. The town now has an AIBO-themed café.3 The mechanical dog had a second life.
The origin story of the robot dog
The first AIBO was not really a pet, and it was not really a toy. It was a proof of concept. Sony had bet that consumers would pay several thousand dollars for a machine whose only function was to be charming, and consumers had. The two precedents that mattered most, the Tamagotchi (1996) and the Furby (1998), were lifeless by comparison. The AIBO could see and hear and walk and learn. The people who bought it loved it.
For the engineering community, the AIBO was a research platform as much as a product. The RoboCup Four-Legged League, which ran on the back of Sony-supplied AIBOs from 1999 to 2008, was for many graduate students their first exposure to the kind of dynamic control problems Marc Raibert had been pioneering at MIT a decade earlier.1 In 2006, the AIBO was inducted into the Robot Hall of Fame at Carnegie Mellon.1 Many of the engineers who passed through those university teams later went on to build the next generation of quadrupeds at Boston Dynamics, Unitree, ANYbotics and others.
For Japan, the AIBO mattered for reasons that have only become clearer with time. Japan in 1999 was already staring at a demographic cliff. Birth rates were falling, the population was ageing rapidly, and the country was, and remains, the world's leading market for consumer robotics. The AIBO was not merely a clever toy. It was a quiet prototype of the kind of machine that might one day be useful in a country with too few young workers to care for its elderly.
Boston Dynamics' contribution was different, and slower to arrive. BigDog was not a commercial product. But the steady drip of viral videos through the late 2000s and 2010s changed perceptions, drew investment, and, crucially, drew the engineers. By the time Spot went on sale in 2019, there was a clear sense in the robotics industry that quadrupeds had a serious future, and that the field belonged, at least for the moment, to a small Massachusetts company that had spent two decades quietly making robots fall over and stand up again.
But its just a pet right?
For the first time, the robot dog has a serious portfolio of useful work.
The most striking is in mining. Beneath the Canadian Shield in Ontario, Glencore's Kidd Creek mine descends 9,600 feet below sea level, the deepest base metal mine on earth. Inspecting the working face of such a mine immediately after blasting is hazardous: there are unexploded charges, residual carbon monoxide and other gases, and unstable rock. For several years now, Glencore has used Spot, mounted with gas sensors and lidar, to enter such areas while ventilation is still under way, sending back data and images while human inspectors wait at a safe distance.12 In northern Sweden, the LKAB Kiruna iron mine, with its six hundred kilometres of underground tunnels, runs a similar system. Operators in a nearby city, sometimes miles away, control Spot from a console; the robot navigates newly blasted galleries, releases a paired drone when it reaches places it cannot walk, and at the end of the shift returns to a custom metal doghouse to recharge.13
Then there are the ruins. In October 2020, researchers from the University of Bristol took Spot to Chernobyl and walked it through the New Safe Confinement structure built over the destroyed Unit 4 reactor.14 In 2022, decommissioning crews at the Fukushima Daiichi plant in Japan began using Spot to enter parts of the reactor buildings that had not been opened since the 2011 tsunami, measuring radiation, taking debris samples and mapping spaces that the older wheeled robots could not negotiate because of what Boston Dynamics' head of nuclear programs calls the dirty laundry problem: if a hamper of clothes has been thrown across the floor, a tracked robot is finished, but a legged robot can pick its way through.15
Offshore, BP has sent Spot some two hundred miles into the Gulf of Mexico to its Mad Dog rig, for routine inspections of equipment that would otherwise require a helicopter and a small team of human inspectors.16 Closer to home, in February 2024, National Highways began trialling Spot on the embankment of the M5 motorway in Somerset, between junctions 20 and 21, where defects had been identified beside the St Georges railway bridge. The robot, operated remotely by the contractor BAM Ritchies and equipped with a Leica lidar tracker, scanned slopes too steep, too obscured by vegetation, or too dangerous for traditional inspectors.17 Live trials have continued across the South West road network since.18
In August 2025, Nottinghamshire Police became the first British force to begin testing a robot dog for armed-response work. The £24,000 unit, designed by a twenty-two-year-old engineer named Nathan Wallace and funded by the Office of the Chief Scientific Adviser, is fitted with thermal cameras, three-dimensional scanning, an AI weapon detector, and a loudspeaker that allows officers to speak to a suspect remotely. It is, the force has been careful to say, not a replacement for police dogs or armed officers, but a reconnaissance tool. The intention is to roll it out, if the trial succeeds, by 2026, primarily for hostage and chemical-hazard scenarios.19
The cases that may matter most, however, are quieter. They are the robot pets being used to keep older people company.
“Loneliness is as harmful as obesity or smoking fifteen cigarettes a day.”
Holt-Lunstad et al., cited by Loneliness Awareness Week
The British numbers are sobering. Around 3.9 million adults in Great Britain now report feeling lonely often or always, a figure that has been rising steadily, and 58 per cent of UK adults say they experience loneliness at least some of the time.20 Age UK forecasts that by 2034, 1.2 million people aged 65 and over in England will be chronically lonely.21 Chronic loneliness in later life is linked to depression, cognitive decline, stroke and dementia. It is, by most reckonings, one of the largest public-health problems Britain faces.
Robot pets have stepped, modestly, into the gap. The Japanese seal-shaped robot PARO, developed by the National Institute of Advanced Industrial Science and Technology and approved as a neurological therapeutic device by the US Food and Drug Administration, has for two decades been used in care homes to calm patients with dementia, increase social interaction, and reduce the need for psychotropic medication. A scoping review of socially assistive robots in dementia care found PARO in seventeen of the twenty-three relevant studies.22 In the United States, an offshoot of the Hasbro toy company called Ageless Innovation produces the Joy for All companion cat and dog, battery-operated and far cheaper than PARO at around £100 a unit, now distributed by charities and state programmes from New York to Florida.23
The British research effort has been led, intriguingly, from the south-west of England. At the University of Plymouth's Centre for Health Technology, the researcher Hannah Bradwell has run a randomised controlled trial of Joy for All pets in eight care homes in Cornwall. The intervention group showed statistically significant reductions in depression, delusions, anxiety, elation and apathy compared with controls, alongside qualitative reports of reduced agitation among residents with moderate-to-severe dementia.24 Crucially, the team found no novelty effect: the benefits persisted across months. They have also, separately, published guidance on how care homes should disinfect their robotic pets, because by 2020 enough of them were in circulation that microbial contamination had become a real concern.25
The point is not that a robot pet substitutes for a real animal or a real visitor. The peer-reviewed literature is meticulous on this score: these devices sit somewhere between music therapy and a soft toy. They cannot replace family. But for a person with advanced dementia, soothed by something that purrs and turns its head, the difference between a real cat and a battery-powered one is often, in practice, not the point.
This is the quiet revolution that has crept up while no one was particularly watching. The lineage that began with AIBO in 1999, ran through MIT's Leg Lab, exploded out of DARPA contracts and culminated in Spot has, three decades on, produced a robot that is genuinely useful: not as a battlefield mule, not as a household servant, but as an inspector for places too dangerous for people, and as a companion for people who would otherwise have only the television for company. Other applications exist, including military and policing ones with which the industry is uneasy. Boston Dynamics and five other quadruped makers, including Unitree, signed an open letter in October 2022 pledging not to weaponise their robots, citing the makeshift efforts of bad actors to do so.26 Howjythty hb the pledge will hold in a world of potental lower-cost clones is another question, but the intent is on the record.
And the unsettled question
The economics are about to make all of this very interesting indeed.
In 1999, an AIBO cost $2,500. A Spot today costs around $75,000. But the Chinese quadruped maker Unitree now sells its Go2 Air model, a capable LiDAR-equipped robot dog, for $1,600, and the Pro variant, with AI voice integration, for $2,800.11 Within ten years it is entirely plausible that a dependable, semi-autonomous robot companion will sit on a shelf at John Lewis for under a thousand pounds. Within twenty, the price curve suggests it may cost less per year than a real dog.
Imagine, then, a near-future scenario in which a robot dog is prescribed by the NHS. Not by the dozen for care homes, but one per resident. One per lonely widower in a Birmingham flat. One in the bedroom of a child on the autism spectrum, helping them practise reading aloud. One pacing the perimeter of a remote Cumbrian farmhouse, watching an elderly relative who has refused to go into care. One in a mountain-rescue truck in the Lake District, waiting its turn underground. One alongside the inspector at the next big offshore wind farm. None of these is fantasy. Each is a real prototype, somewhere, already running.
The optimistic case for the robot pet is that it will turn out to be the most useful piece of consumer robotics anyone ever sold. It is the right size, the right shape, the right metaphor. Humans have collaborated with dogs for at least fifteen thousand years; we know, instinctively, what to do with a four-legged creature that follows us, watches us, fetches for us, guards us. A mechanical dog is a category we already understand how to use. That is no small advantage.
The harder question is whether companionship without reciprocity is companionship at all. A dog that does not need to be walked, fed, or grieved over is not really a dog. A friend who cannot judge us is not really a friend. And so the open question, at the end of three decades of remarkable engineering, is whether the robot pet will turn out to cultivate the human capacity for connection or to substitute for it. Whether it will draw lonely people back into the world, or hold them, more comfortably, inside the shrinking circle of their own room. Whether the funerals at Kofuku-ji are a charming oddity, or the first sign of something deeper that is coming.
Bungen Oi, the priest who conducts those rites, gave one possible answer when asked why he would do such a thing for a plastic robot. "The owner's heart," he said, "is going inside the robot's heart, like a transfer."5 Whether that is a quiet gift or a quiet loss is the bit we have not yet worked out.
For the moment, though, the robot dog is good at the boring parts of its job. It walks underground when humans cannot. It checks the gauges on a North Sea rig. It scans the M5 embankment without closing a lane. It calms a frightened patient. The mechanical pet has, finally, grown up - a long way from the Tamagotchi.
Sources
1. AIBO. Wikipedia. https://en.wikipedia.org/wiki/AIBO
2. The Complete History of Sony's Robot Dog Aibo. Virtual Paws. https://virtual-paws.com/history-of-aibo/
3. Zen and the Art of Aibo Engineering. IEEE Spectrum, 2024. https://spectrum.ieee.org/aibo
4. In Japan, Old Robot Dogs Get A Buddhist Send-Off. NPR, 2018. https://www.npr.org/sections/thetwo-way/2018/05/01/607295346/in-japan-old-robot-dogs-get-a-buddhist-send-off
5. Japanese Buddhist Temple Holds Funerals for Defunct Robot Dogs. Buddhistdoor Global, 2018. https://www.buddhistdoor.net/news/japanese-buddhist-temple-holds-funerals-for-defunct-robot-dogs/
6. Marc Raibert. Wikipedia. https://en.wikipedia.org/wiki/Marc_Raibert
7. The Robots Running This Way. MIT Technology Review, 2014. https://www.technologyreview.com/2014/06/03/172697/the-robots-running-this-way/
8. BigDog. Robots Guide / IEEE Spectrum. https://robotsguide.com/robots/bigdog
9. Boston Dynamics. Wikipedia. https://en.wikipedia.org/wiki/Boston_Dynamics
10. Spot. Robots Guide / IEEE Spectrum. https://robotsguide.com/robots/spot
11. How Much Does a Robot Dog Cost? Pricing Guide. RobotSourced, 2026. https://robotsourced.com/pricing/robot-dogs
12. Spot is the golden retriever of mine data. Metal Tech News, 2021. https://www.metaltechnews.com/story/2021/04/28/mining-tech/spot-is-the-golden-retriever-of-mine-data/540.html
13. LKAB and Luleå University of Technology. Boston Dynamics case study. https://bostondynamics.com/case-studies/lkab-and-lulea-university-of-technology/
14. Spot the Robot Dog Seen at Chernobyl Nuclear Power Plant. Interesting Engineering, 2020. https://interestingengineering.com/spot-the-robot-dog-seen-at-chernobyl-nuclear-power-plant
15. Spot in Fukushima Daiichi. Boston Dynamics case study, 2025. https://bostondynamics.com/case-studies/spot-in-fukushima-daiichi/
16. A Retrospective on Uses of Boston Dynamics' Spot Robot. Boston Dynamics, 2026. https://bostondynamics.com/blog/retrospective-on-boston-dynamics-spot-robot-uses/
17. National Highways trials four-legged robot for inspection of geotechnical assets. Ground Engineering, 2024. https://www.geplus.co.uk/news/national-highways-trials-four-legged-robot-for-inspection-of-geotechnical-assets-15-02-2024/
18. Robot dog 'Spot' to survey M5 motorway and other major West Country roads. ITV News, 2024. https://www.itv.com/news/westcountry/2024-02-16/robot-dog-spot-to-survey-m5-and-other-major-roads
19. Officers testing 'revolutionary' robot dog. Nottinghamshire Police, August 2025. https://www.nottinghamshire.police.uk/news/nottinghamshire/news/news/2025/august/officers-testing-revolutionary-robot-dog/
20. Tackling Adult Loneliness 2025: ONS and CSJ figures cited. Government Events, 2025. https://www.governmentevents.co.uk/event/tackling-adult-loneliness/
21. 'You are not alone in feeling lonely.' Age UK, December 2024. https://www.ageuk.org.uk/latest-press/articles/age-uks-new-report-shows-you-are-not-alone-in-feeling-lonely/
22. The effect of PARO robotic seals for hospitalized patients with dementia. ScienceDirect, 2020. https://www.sciencedirect.com/science/article/abs/pii/S0197457220303244
23. Robotic Pets Bring Joy to Owners. Fairfax County Family Services, 2023. https://www.fairfaxcounty.gov/familyservices/older-adults/golden-gazette/2023-08-robotic-pets-bring-joy-to-owners
24. Implementing Affordable Socially Assistive Pet Robots in Care Homes Before and During the COVID-19 Pandemic: stratified cluster RCT, University of Plymouth. JMIR Aging, 2022. https://aging.jmir.org/2022/3/e38864/
25. Don't forget to clean robotic support pets, study says (Bradwell et al., University of Plymouth). ScienceDaily, 2020. https://www.sciencedaily.com/releases/2020/08/200826140907.htm
26. General Purpose Robots Should Not Be Weaponized. Boston Dynamics open letter, October 2022. https://bostondynamics.com/news/general-purpose-robots-should-not-be-weaponized/
Further reading
On AIBO and the dawn of consumer robotics
• Zen and the Art of Aibo Engineering — https://spectrum.ieee.org/aibo (IEEE Spectrum's 25th-anniversary retrospective with original Sony engineer Hideki Noma — the definitive long read.)
• Aibo (1999). Robots Guide / IEEE Spectrum — https://robotsguide.com/robots/aibo (Excellent technical and historical reference page.)
On Boston Dynamics and the legged-robot lineage
• The Robots Running This Way — https://www.technologyreview.com/2014/06/03/172697/the-robots-running-this-way/ (MIT Technology Review's profile of Marc Raibert and the Leg Lab's path to BigDog and Spot.)
• Interview: Marc Raibert of Boston Dynamics — https://www.theengineer.co.uk/content/interviews/interview-marc-raibert-of-boston-dynamics (The Engineer interview, useful for the BigDog and DARPA story in Raibert's own words.)
• BigDog, the Rough-Terrain Quadruped Robot (Raibert et al.) — https://www.cs.swarthmore.edu/~meeden/DevelopmentalRobotics/bigdog.pdf (The original IFAC paper. Technical, but lucid.)
On Spot at work — industrial, hazardous and rescue applications
• Spot at Kidd Creek (Metal Tech News) — https://www.metaltechnews.com/story/2021/04/28/mining-tech/spot-is-the-golden-retriever-of-mine-data/540.html (Highly readable piece on the world's deepest base-metal mine and its four-legged inspector.)
• Spot in Fukushima Daiichi (Boston Dynamics case study) — https://bostondynamics.com/case-studies/spot-in-fukushima-daiichi/ (The dirty-laundry problem, explained.)
• LKAB and Luleå University of Technology — https://bostondynamics.com/case-studies/lkab-and-lulea-university-of-technology/ (Spot in the world's largest underground iron mine, six hundred kilometres of tunnels.)
• National Highways trials a 'Spot' of innovation — https://www.geplus.co.uk/news/national-highways-trials-four-legged-robot-for-inspection-of-geotechnical-assets-15-02-2024/ (Ground Engineering's account of the M5 trial.)
On robot pets, dementia care and loneliness
• Implementing Affordable Socially Assistive Pet Robots in Care Homes (Bradwell et al., JMIR Aging 2022) — https://aging.jmir.org/2022/3/e38864/ (The University of Plymouth's Cornwall trial. Essential reading on the British evidence base.)
• Impacts of Low-cost Robotic Pets for Older Adults and People With Dementia (scoping review, PMC) — https://pmc.ncbi.nlm.nih.gov/articles/PMC8082946/ (A clear-eyed survey of what the evidence does and does not show.)
• Age UK: You are not alone in feeling lonely (December 2024) — https://www.ageuk.org.uk/latest-press/articles/age-uks-new-report-shows-you-are-not-alone-in-feeling-lonely/ (Britain's most recent loneliness-in-later-life report. Sobering but practical.)
On the ethics and the future of the robot dog
• General Purpose Robots Should Not Be Weaponized (Boston Dynamics et al., 2022) — https://bostondynamics.com/news/general-purpose-robots-should-not-be-weaponized/ (The original open letter.)
• See Spot save lives: fear, humanitarianism, and war in the development of robot quadrupeds (Roberts, 2021) — https://pmc.ncbi.nlm.nih.gov/articles/PMC8611997/ (A scholarly look at how the military and humanitarian framings of Spot have evolved together.)
• In Japan, Old Robot Dogs Get a Buddhist Send-Off (NPR, 2018) — https://www.npr.org/sections/thetwo-way/2018/05/01/607295346/in-japan-old-robot-dogs-get-a-buddhist-send-off (The Kofuku-ji story. Strange, moving, short.)
