CHAPTER 05/1966–1980

The Winter After the First Boom

A time when expectations fell short, and the seeds that kept growing meanwhile (1966–1980)

Research money and hopes shrank, and people say an arrived. But open the sources and you find that winter arrived differently in each country, and meanwhile many seeds of today's AI were growing in Japan too.

011965–1985 · The winter weather map

Did winter come everywhere at once?

Did come in the same years in the United States, the United Kingdom and Japan?

is the name for the 1970s, when research money and hopes shrank. But the years it covers differ from source to source. Japan's Ministry of Internal Affairs and Communications white paper (2016) calls the 1970s a (translated), and an online summary gives 1974–1980. Nilsson (2010), who wrote a history of AI, does the opposite and calls roughly 1975–1985 the of AI.

The figure on the right puts events from three countries on one timeline. In the United States: the 1966 machine translation report, the 1969 limits on how defense money could be used, and the 1976 end of the speech program. In the United Kingdom: the 1973 Lighthill report. In Japan, however, a large national project, the “Pattern Information Processing System” (translated), began in 1971, and research that leads to today kept going: the Associatron in 1972 and the Neocognitron in 1979.

Switch the winter band from one source to another and the band moves a lot. is a name that changes depending on what you use as the yardstick.

The phrase first appears in 1984, as a way of worrying about a winter that might be coming. Calling the 1970s the is a name added afterward.

What the figure shows:The dates of a winter shift greatly with what each source measures. On the same timeline, years called a winter in the United States saw research that leads to today's technology beginning one after another in Japan.

021966 · Machine translation

The ALPAC report on machine translation

If you swap in dictionary words one at a time, can you translate?

In 1966, at the request of three U.S. government agencies, a National Academy of Sciences committee (ALPAC) reviewed machine translation research. The report said that .

In the figure on the right, try the simplest method: replacing a sentence word by word with a dictionary. When one word has several possible translations, the number of ways to translate the whole sentence grows by multiplying the numbers of translations. You can't tell which one is right without knowing the meaning of the sentence and the situation.

But the report did not say to stop all research. It recommended funding the study of how language works (computational linguistics) and tools that help human translators.

number of translations = n₁ × n₂ × … × nk
ni
number of translations of the i-th word
k
number of words in the sentence
What you think you knowThe popular story:The ALPAC report dismissed machine translation as impossible and stopped research
The original source says:The report recommended funding computational linguistics and machine tools that help human translators. The Academy itself had put a cover letter in front of the report, worried that only part of it would be read and that funding would be cut too far.

What the figure shows:Replacing words one by one using a dictionary makes the number of possible translations multiply. Choosing the right one requires understanding the sentence's meaning and situation.

Number of words and number of ways to translate (vertical axis in steps of 10 times)
031969 · Linear separability

The wall of one line

Is there a problem a learning perceptron simply cannot solve?

In 1969, in their book Perceptrons, MIT's Marvin Minsky and Seymour Papert used mathematics to study the limits of the 1958 perceptron (a learning machine that multiplies inputs by weights, adds them up, and answers “yes” when the total passes a set value).

The simplest example is XOR (the answer is 1 only when exactly one of the two inputs is 1). Among the 4 points on the right, try to separate black (answer 1) from white (answer 0) with one straight line. AND and OR can be separated, but XOR cannot be separated however you draw the line. The only kind of boundary a one-layer perceptron can draw is this “one line”.

Press "Use two lines (stack layers)" and you can gather the black points between two lines and separate them. This is why stacking layers lets a machine learn XOR (Chapter 8). The view that extending the result to machines with stacked layers would be was something the book itself called , and it treated it as a question still to be checked.

y = 1 (when w₁x₁ +w₂x₂ +b>0), otherwise 0
x₁, x₂
inputs (0 or 1)
w₁, w₂
weights
b
bias. w₁x₁ +w₂x₂ +b=0 gives the boundary, the “one line”
What you think you knowThe popular story:Perceptrons proved that neural networks cannot solve XOR (so they are useless)
The original source says:What the book proved was the limit of one-layer machines in which each part can only see a limited range. The guess that machines with stacked layers would be useless was, even within the book, an intuitive judgement.

What the figure shows:A perceptron with 1 layer can draw only 1 straight boundary, which can separate AND and OR but never XOR. Using 2 lines can separate XOR.

041969 · How it learns

Even with learning, XOR stays unsolved

What happens if you keep training a perceptron on XOR?

The perceptron's learning method nudges the weights a little toward the correct answer, only when it makes a mistake. For a problem that one straight line can classify, repeating this correction means the errors will always reach 0 someday (the perceptron convergence theorem).

The figure on the right is an example where the 4 points are shown one pass at a time for training. With AND and OR, the errors reach 0 in a few passes and the boundary line stops. But with XOR, the line keeps moving back and forth forever, because wherever you draw it, some point is always left on the wrong side. This is what “not linearly separable” looks like from the side of learning.

w ← w+η (t − y) x
w, η
the weights and the learning rate (eta)
t, y
the correct answer and the perceptron's output
x
the input. w is updated only when it makes a mistake (t ≠ y)

Before 1969, in 1967, Shun'ichi Amari of Kyushu University had published a learning theory that adjusts the weights little by little according to the error and approaches the best weights.

What the figure shows:Adjusting weights only after mistakes is guaranteed to reach 0 errors if 1 line can separate the groups. With XOR, the line keeps moving back and forth without settling.

Number of errors in each pass
051973 · Combinatorial explosion

Dozens of times more branches per move

Where does the method of “reading all the way ahead” get stuck?

The basis of AI that solves games and puzzles is to list every move you can make, then list everything after each of those, and search for the best path (search). In tic-tac-toe there are 255,168 move sequences to the end of the game in all. A computer can count that at once.

But as the number of moves at each turn (the number of branches) grows and the depth you read grows deeper, the number of sequences grows as the number of branches “to the power of the depth”. In the figure on the right, increase the branches and the depth. If there are 30 moves each turn, even 10 moves ahead gives 30 to the 10th power, about 590 trillion sequences.

The Lighthill report of 1973 named as a major reason AI was not succeeding that researchers had not noticed this combinatorial explosion.

number of sequences ≈ bd
b
number of branches at each move
d
depth read (number of moves)

The numbers are “made-up numbers”. In real games the number of branches changes from move to move, and different move orders can reach the same position.

What the figure shows:With b branches per move and search depth d, the number of sequences grows as b to the power d. With 30 choices per move, looking 10 moves ahead gives about 59 trillion sequences, so searching them all quickly becomes impossible.

Depth and number of sequences (vertical axis in steps of 10 times)
061972–1973 · The Lighthill report

A report that split AI into A, B and C

Did the British report say all of AI was worthless?

At the request of a British funding body, the fluid dynamics giant James Lighthill surveyed AI research on his own. The report split AI into three. A is automation for factories and the like, C is research that uses computers to study the brain and nerves, and B is a bridge that links A and C, centered on building robots.

The report said A and C had produced reasonable results. What it judged harshly was B and the goal of an AI that can do anything. The report wrote: .

The top of the figure on the right shows the report's division into A, B and C. Below is a clock of predictions taken from the report. It places on a scale of years the predictions of scientists that the report presented (the 1980s and 2000) and Lighthill's own outlook (the next 25 years). Move "Current year" with the slider, and predictions whose deadline has passed change color.

What you think you knowThe popular story:The Lighthill report rejected AI completely
The original source says:The report said A (automation) and C (brain research) had produced results, and it cited the Japanese government's plan to automate factory assembly as a promising example along the lines of A.

What the figure shows:The Lighthill report did not reject all AI: it recognized achievements in A (automation) and C (brain research), while sharply criticizing B (bridging the two) and the goal of AI that could do anything.

071973 · Where sources disagree

When was the debate held?

What do you do when sources disagree about the date of the same event?

Over the report, a public debate was held at the Royal Institution in London, and the BBC broadcast it as the TV program . John McCarthy, Donald Michie and Richard Gregory argued against Lighthill.

But the date of the debate differs from source to source. A 2025 technology magazine article says May 9, and the University of Edinburgh's recording page says June 1973. A note in a 1982 historian's paper gives July 4 for the debate and August 30 for the broadcast. A BBC magazine of the time carried a July 4 schedule at the Royal Institution and a TV review that appears to be from an early September issue.

The figure on the right lines up when each source was written (at the time, or many years later). This site adopted July 4 (broadcast August 30), where the sources closest to the time agree. However, the BBC's program listings have not been seen, so the confidence grade stays at “confirmed in a secondary summary”.

When deciding a date, don't just pick one side. Line up all the sources and tell apart which are from the time and which are later.

What the figure shows:When dates disagree, neither should be chosen arbitrarily. Comparing all sources, including whether they are contemporary or written years later, helps identify the date supported by sources closest to the event.

081971–1976 · Spoken language

Cut off despite reaching its goal

How did computers pick out connected speech?

From 1971, for five years, the U.S. Department of Defense (DARPA) paid about $3 million a year to support research on machines that understand connected speech. The goals included 1,000 words, many speakers, and a semantic error rate under 10%. In 1976, Carnegie Mellon University's Harpy handled 1,011 words with a semantic error rate of 5%, meeting the goal.

One of Harpy's tricks was beam search. Instead of checking every word sequence that might match the sounds heard, it keeps only the few highest-scoring ones and moves on. In the figure on the right, change how many to keep (the beam width). A narrow width runs fast, but it can throw away the correct sequence along the way.

Even so, DARPA did not fund a follow-up program, and serious research on spoken language did not restart until 1984.

sequences kept = top W by score
W
beam width (number kept)
score
a value adding up how well the sounds and words match (here, numbers made up by this site)
What you think you knowThe popular story:1970s speech recognition research failed and was cut off
The original source says:Harpy met the goals set at the start (1,000 words, semantic error rate under 10%). Even so, no follow-up program came.

What the figure shows:Harpy kept only a few high-scoring word sequences and moved forward instead of checking every plausible sequence, a method called beam search. A narrow beam is faster, but may discard the correct sequence along the way.

091971 · Japan

Lining up speaking speeds to compare

Even the same “one” (ichi) is said fast sometimes and slowly other times. How do you compare?

Even the same word is said at different speeds from time to time. If you compare a voice you stored with the voice you just heard, lined up directly by time, a small difference in speed makes them stop matching.

In 1971, Hiroaki Sakoe and Seibi Chiba of NEC showed a method that lines up the stretching and shrinking of a voice in time using dynamic programming (a way to find the best of many routes efficiently by reusing partial results) and then compares. In the table in the figure on the right, you search for the route that decides which moments of the two voices correspond. The route can only move right, up, or diagonally, from lower left to upper right.

In the 1971 paper, on 2,400 utterances of single-digit numbers spoken by 5 people, it recognized 99.8% correctly on average.

D(i, j) = d(i, j)+min{ D(i−1, j), D(i, j−1), D(i−1, j−1) }
d(i, j)
the difference between the i-th point of voice A and the j-th point of voice B
D(i, j)
the smallest total of differences along a route up to that point

Today it is also called DTW (dynamic time warping). The same idea is used in today's speech research and in comparing data with other data.

What the figure shows:Even 2 recordings spoken at different speeds can be recognized as the same word by using dynamic programming to stretch and compress time before comparing them.

101971–1980 · Japan's national project

A big pattern recognition plan in winter

When budgets were cut in the United States and the United Kingdom, what began in Japan?

In 1971, Japan's Ministry of International Trade and Industry added the “Pattern Information Processing System” to its list of large projects run on national funds. It was a plan to develop computers that recognize characters, figures and the like (pattern recognition), centered on the Electrotechnical Laboratory with private companies, and in the Diet it was also described as a (translated).

The basis of recognition is to compare with a template stored in advance. In the figure on the right, add noise to a character or shift its position. Compared directly with the template, the score drops after only a slight shift. Comparing while shifting makes it stronger. How to handle this “shift” leads on to the later Neocognitron (item 12 in this chapter).

When the plan began, the Diet explanation said that (translated). According to a 1985 reply in the Diet, the commissioned research costs for fiscal 1971–1980 were about 22 billion yen.

The site has not yet been able to confirm the report on the plan's contents (what kind of devices were built and what was achieved).

What the figure shows:As budgets were cut in the United States and Britain, Japan began pattern recognition through a major national project. Recognition compares input with stored patterns and is vulnerable to small shifts, but comparing at shifted positions makes it more robust.

Amount of noise and recognition rate
111972 · Japan

Show a part, and it recalls the whole

Can we build a neural network that recalls the whole from a part of a memory?

In 1972, Kaoru Nakano of the University of Tokyo presented the , a memory mechanism that stores information as 0-and-1 patterns spread across the whole network and recalls the whole when shown a part. The same year, Shun'ichi Amari also published a theory in which patterns are stored as stable states of a network.

The figure on the right is a network that has memorized three patterns. Press squares to erase parts of a pattern, or lower the share shown, then press "Recall (5 times)". The larger the part you show, the more accurately it recalls; the smaller, the vaguer. Add more stored patterns and it starts to mix them up with other patterns and make mistakes.

The way it memorizes is: “if two squares are black together or white together, strengthen the link between them”, and weaken it if they are opposite together. This has the same form as the idea (Hebb, 1949) that the connections between nerves in the brain get stronger the more they are active at the same time.

wij = Σp xip xjp  xi ← sign (Σj wij xj)
xi
the i-th square (black +1, white −1)
p
number of the stored pattern
wij
strength of the link between squares i and j
What you think you knowThe popular story:The associative memory model was first made by Hopfield in 1982
The original source says:Kaoru Nakano and Shun'ichi Amari had published one ten years earlier, in 1972. The Kyoto Prize (2025) calls Amari's model mathematically the same as Hopfield's model, and the 2024 Nobel committee's explanation also lists it among its references (the body text does not name him).

What the figure shows:A network trained to strengthen connections when points are both black or both white can recall a whole pattern from just part of it. Storing too much mixes different memories and causes errors.

121975 · Japan

A network that builds itself, no teacher

Can a network grow without telling each cell “respond like this”?

In 1975, Kunihiko Fukushima of the NHK research laboratories showed a mechanism by which a neural network of many layers assembles itself without a teacher (someone who tells each cell in detail how to respond), and named it the .

The key is competition between cells. According to the paper's abstract, the connections to a cell get stronger only when there is no nearby cell responding more strongly than it does. The figure on the right is the simplest version of this idea. Points appear one after another, and only the nearest cell (the colored circle) moves a little toward that point. Repeat this, and the cells settle at the centers of the clusters of points. Without being told the answer, they come to take charge of things that are alike.

Only the nearest cell k: mk ← mk +η (x − mk)
x
the incoming point
mk
the place cell k is in charge of
η
how fast it moves closer

When tried on a computer, deeper layers took charge of wider areas, and cells in the last layer responded only to particular patterns. The idea of “only the winner learns” also connects to the later k-means (Chapter 9).

What the figure shows:Cells compete, and only the closest cell moves a little closer to the input. Without being given answers, the cells divide up responsibility for groups of similar things.

131979 · Japan

Telling shapes apart despite a shift

Does a machine stop being able to read a character that has only moved slightly to the right?

In 1979, Kunihiko Fukushima developed the cognitron further and presented the “Neocognitron”, a neural network that can recognize characters even if they shift position or their shape is slightly distorted. Modeled on brain research on vision, it stacked many stages of S-cell layers that pick up shape features and C-cell layers that absorb shifts in position.

An S-cell looks for features such as a “corner” or a “line” through a small window. Cells in the same plane hold the same window, only shifted in position (what we now call convolution). A C-cell responds if any of the nearby S-cells responds (what we now call pooling). In the figure on the right, even if you move the character 1 square left or right from the center, the response of the C-cell in the selected box stays the same. If you cross the box's boundary, even a shift of 1 square changes the response.

The explanation of the 2024 Nobel Prize in Physics cites this work as the source of today's image recognition AI (CNN).

S-cell: s(x, y) = Σ window × input (around position x, y) C-cell: c = max (nearby s)
window
a template of a shape feature (3×3)
max
the largest value
What you think you knowThe popular story:Image recognition AI (CNN) began around 1989 in the United States
The original source says:A network that uses the same connections while shifting position was published by Fukushima in 1979. However, the Neocognitron used unsupervised learning, and it was LeCun and colleagues who combined it with backpropagation.

What the figure shows:S cells look for lines through small windows, and C cells respond if any nearby cell responds. Stacking these layers keeps C cell responses much the same even when a letter shifts slightly.

141970–1973 · Japan

A computer finds eyes, nose and mouth

In a photo, where are the eyes and where is the mouth? How does a computer find them?

At the 1970 Osaka World Expo, the NEC show (translated) photographed visitors' faces with a TV camera. The computer automatically found each part of the face and answered with one of 21 (translated) (there is no scientific basis for the idea that a face reveals personality).

In 1973, Takeo Kanade of Kyoto University built a program that automatically finds the eyes, nose and mouth in a face photo, and tested it on about 800 photos (688 of them faces collected at the Expo). One of the clues Kanade's paper used again and again was the sum of the darkness in a thin strip of the photo (integral projection). Eyes and mouths are dark, so when you add across, a peak appears in the graph at that height.

In the figure on the right, move the face parts and the peaks in the horizontal and vertical sums move, with lines marking the positions found. Another feature of Kanade's paper was a way to go back to an earlier stage and try again when things do not work.

horizontal sum H(y) = Σx darkness(x, y)
darkness(x, y)
darkness of the photo at position (x, y)
height where H(y) is large
height where the eyes or mouth are
What you think you knowThe popular story:Takeo Kanade's 1973 paper was the “world first” in face recognition
The original source says:Research on identifying faces by computer also existed in the early 1960s in the United States. What marks Kanade's paper is that it tested automatic analysis, including retries, on about 800 face photos.

What the figure shows:Adding up a face photo across horizontal strips creates graph peaks at the heights of the dark eyes and mouth. Finding those peaks reveals the eyes' and mouth's positions.

Darkness summed horizontally (at each height)
151973 · Japan

Walking on two legs without falling

Why doesn't a two-legged robot fall over?

In 1973, a group led by Ichiro Kato at Waseda University built the humanoid robot WABOT-1. It walked on two hydraulic legs, grasped objects with both hands, found the positions of objects with artificial eyes, and understood Japanese commands spoken in separate phrases and answered by voice. According to the report, carrying a 20 kg load, it could walk straight and turn as told by voice commands.

The basis of why a slowly walking robot does not fall is that the point directly below the center of gravity is inside the area where the feet touch the ground (the support area). In the figure on the right, move the center of gravity. If the point below it goes outside the area, the robot falls. Lifting one foot narrows the support area, so first shift the center of gravity over the supporting leg, and then lift the other foot.

no fall ⇔ the point below the center of gravity is inside the support area
support area
the area enclosed by the soles of the feet touching the ground

What moves here is a “slow walking” figure that considers only the center of gravity. When walking fast, you also need to consider momentum.

What you think you knowThe popular story:WABOT-1 was the world's first humanoid
The original source says:That is Waseda University's own assessment. The 1973 report itself does not claim to be the “world first”; it defines a robot as a machine with hands, legs and a head that all move by themselves, and says it built something that meets those conditions.

What the figure shows:A slowly walking robot stays upright because the point directly below its center of gravity remains inside the area supported by its feet. Before lifting a foot, it first shifts its center of gravity over the supporting foot.

161970 · Japan

Is it creepy when it looks too human?

Is a robot friendlier the more it looks like a person?

In 1970, Masahiro Mori of the Tokyo Institute of Technology wrote an essay, , for a special feature in a magazine published by an oil company. The closer a robot's look and movement get to a person's, the more affinity grows. But just before it becomes almost exactly human, there is a valley where it suddenly turns eerie. Mori showed this idea in a graph.

The figure on the right draws the shape of that idea (this site drew it based on the shape of Mori's original figure. The numbers express Mori's intuition; they are not measured values). Move "Human likeness" with the slider to see where it enters the valley. Mori wrote that adding "Movement" makes the valley even deeper.

On top of that, Mori advised robot designers to aim for , a moderate human likeness, rather than trying to cross the valley toward a perfect human copy.

What you think you knowThe popular story:The uncanny valley is a scientific law confirmed by experiments
The original source says:It began as a 3-page essay in an oil company's magazine in 1970, and the graph came from Mori's intuition. In 2012 he himself said it was less a scientific claim than advice for people who design robots.

What the figure shows:Mori wrote from intuition that familiarity rises as something looks more human, but drops into a valley of unease just before it looks fully human. Adding movement deepens the valley.

171969 · Symbolic AI

Must we list what doesn't change?

If you write “moved the box”, what happens to everything else?

In AI that describes the world in logical formulas and plans actions, you have to write down not only what changes with an action but also what does not change, one by one. In 1969, John McCarthy and Patrick Hayes named this trouble the . With n actions and m quantities describing the state, you could end up having to write m × n conditions saying “it does not change”.

In the figure on the right, increase the objects in the room and the actions. When “the robot pushes the box”, the box's position changes. But the color of the light, whether the door is open or closed, and the position of the desk do not change. If you write all of that, the number you write grows by multiplying actions and objects.

number of “does not change” statements to write ≈ m × n
m
quantities describing the state (number of objects, etc.)
n
kinds of actions
What you think you knowThe popular story:The frame problem is the hard problem that AI cannot tell what is relevant from what is not
The original source says:In the original 1969 paper it appeared as a technical problem: having to write what does not change one item at a time. The broader meaning is an interpretation philosophers added later.

What the figure shows:AI that plans with logical formulas needs each thing that stays unchanged after an action written down, as well as what changes. The number of statements grows as the number of objects multiplied by the number of actions.

181973–1978 · The yardstick

In winter, membership tripled

When research money shrank, did the number of researchers shrink too?

The historian Thomas Haigh (2023) argued that , pointing among other things to the membership of SIGART, the AI special interest group of the computing society ACM, which nearly tripled, from 1,241 in 1973 to 3,500 in 1978.

The figure on the right lays each source's band over the membership line. Switch the bands and you see that the years when membership was growing overlap with the years called winter. It is true that in the 1970s funding got tight for some labs in the United Kingdom and for speech and robot research in the United States. But you cannot say the whole research world shrank.

Change the yardstick, and the answer changes. Do you look at the money of big labs, the number of people doing research, or how words were used?

Membership was confirmed for only two points, 1973 and 1978. This site has not confirmed the numbers for the years between, so the line simply joins the two points.

What the figure shows:Membership in AI societies nearly tripled during years called a winter. Whether it was a winter depends on whether money or people are counted.

191980 · Meaning

Rule-following answers: understanding?

Does a machine that returns correct answers understand meaning?

In 1980, the philosopher John Searle presented a thought experiment. Suppose he, not knowing Chinese, shuts himself in a room and, using only a rule book written in English, answers Chinese questions passed in to him, in Chinese. From the outside he cannot be told apart from a person who understands Chinese, yet the person inside the room understands nothing. So he argued that a computer that merely manipulates symbols by following a program also cannot be said to understand meaning.

The figure on the right is that room. Choose a question, and the person inside looks only at the shapes of the symbols, looks them up in the rule book, and sends back the symbols of the answer. You can also look inside the rule book, but nowhere does it say "meaning".

This paper was published in a journal together with 27 replies and comments. The question is aimed just as much at today's text-generating AI, and it is still not settled.

Around the same time, Joseph Weizenbaum, who made ELIZA, wrote in his book (1976) that, separate from whether it can be done, there are jobs we should not let machines do.

What the figure shows:A person who knows no Chinese can give correct answers to Chinese questions using only a rulebook, appearing to understand from outside while understanding nothing inside. Searle argued from this that a machine manipulating symbols alone cannot be said to understand their meaning either.

Closing

What this chapter still doesn't know

No one has yet found figures that line up AI research funding in the 1970s by country and by year. Whether it was changes with the yardstick you use (the money of big labs, society membership, the number of words).

Whether Perceptrons stopped neural network research also depends on which source you read, and it cannot be pinned down. Whether a machine that only arranges symbols by rules can be said to “understand meaning” has been debated from 1980 to today.

And the seeds that grew in Japan during this winter (the Associatron, the Neocognitron, DP matching) hardly appear by name in the leading English-language histories of AI. In the next chapter, the second boom begins, with AI that has experts' knowledge written into it.

Other events in this chapter (1; all with original sources and confidence grades)
1977Confirmed in summariesSources disagreeJapan

Yaskawa Electric's all-electric arc welding robot “Motoman-L10”: what do the years 1975, 1976, and 1977 in the sources each mean?

Yaskawa Electric (then Yaskawa Electric Manufacturing Co.) began developing electric robots around 1972 and exhibited the first Motoman at a robot show in 1974. The company describes it as Japan's first all-electric industrial robot (one driven only by electric motors, not by hydraulics or compressed air), but because of its high price and other issues it did not reach commercial use. Yaskawa then built the Motoman-L10, a vertically articulated 5-axis robot whose joints are stacked like a human arm, able to carry up to 10 kg (the 10 in L10 is this weight), and specialized it for arc welding (joining metal by melting it with the spark of a discharge between electrodes). It used a microprocessor (a small computer) for control. In 1977 the Nakatsu plant of Yorozu Automobile (now Yorozu) in Nakatsu, Oita Prefecture, decided to buy one; the first order was closed, and the robot was shipped as a product. The year of the L10 is a point of disagreement: the Japan Institute of Invention and Innovation's summary says 1975, while the Japan Society of Mechanical Engineers' Mechanical Engineering Heritage (certified in 2015, No. 76) says 1977. When the sources are opened and sorted out, 1975 and 1976 are written as years of development, and 1977 as the year of the first order and shipment.

The popular story:The Motoman-L10 is often written up as Japan's first all-electric industrial robot (Mechanical Engineering Heritage, the National Museum of Nature and Science database, Yaskawa Electric 2021)
The original source says:Yaskawa's own Technology Story and a 2017 article in the Journal of the Japan Society of Mechanical Engineers by a Yaskawa employee name the first Motoman shown at the 1974 robot show (a different machine from the L10) as Japan's first all-electric robot. They describe the L10 as a redesign made after that first model, which never reached commercial use, and as the first machine that was actually sold (shipped), in 1977. The first machine shown and the first machine sold are different. The years also differ: 1975 and 1976 are written as development years, and 1977 as the year of the order and shipment.

What we still don’t know:It is not known what 1975 stands for (the start of design, the completion of a prototype, or a public showing). Kusuda (2004)'s source (a 1978 article in the magazine “Robot” vol.19) and Yaskawa's 1978 technical report () could not be opened for this site. The number of units sold (2,000 in two years, or about 1,700 afterward) also differs by source.

8 sources and how they were checked

Where sources disagree:Year: 1975 (Kusuda 2004's “(1975)”; the Japan Institute of Invention and Innovation's “100 Postwar Japanese Innovations” cites it and gives “(1975)”)/developed in 1976 (Kodaira 2025; National Museum of Nature and Science, fiscal 2024 edition)/1977 (Yaskawa Technology Story: closing of the first order; Yaskawa Electric 2021: shipment; Journal of the Japan Society of Mechanical Engineers 2017: productization and shipment as a product; Mechanical Engineering Heritage No. 76: development and sales; National Museum of Nature and Science database: year of manufacture). Units sold: 2,000 in two years (Kusuda 2004)/about 1,700 afterward (Journal of the Japan Society of Mechanical Engineers 2017). Announcement of the other company's electric articulated robot used as a model: 1973 (the Yaskawa Technology Story does not name the other company; Kodaira 2025 says a European maker, the IRB 6)/1974 (Kusuda 2004, ASEA's IRB-6). First all-electric robot in Japan: the first Motoman of 1974 (Yaskawa Technology Story, Journal of the Japan Society of Mechanical Engineers 2017)/the L10 of 1977 (Mechanical Engineering Heritage and Yaskawa Electric 2021's “Japan's first all-electric industrial robot” refers to the shipment of the L10).

  1. Robots – Technology Stories – Technology – Yaskawa Electric (The Birth of MOTOMAN) (Yaskawa Electric Corporation · The birth of MOTOMAN; the first MOTOMAN announced to the pu… · The person’s own later recollection)
  2. Mechanical Engineering Heritage No. 76: All-electric industrial robot “Motoman-L10” (Journal of the Japan Society of Mechanical Engineers, vol. 120, no. 1183, June 2017, pp.42-43) (Kenichi Yasuda (Robotics Technology Department, Development & Research Laboratory, Yaskawa Electric Corporation) · 2017 · p.42 1. Motoman-L10; 2. Background of the development · The person’s own later recollection)
  3. Cumulative shipments of MOTOMAN industrial robots reach 500,000 units (Yaskawa Electric announcement, 2021-03-30) (Yaskawa Electric Corporation · 2021 · First paragraph of the main text; 1. History of the company… · The person’s own later recollection)
  4. Mechanical Engineering Heritage No. 76 (certified 2015): All-electric industrial robot “Motoman-L10” (Japan Society of Mechanical Engineers) (Japan Society of Mechanical Engineers (incorporated association) · 2015 · Main text · Secondary summary)
  5. MOTOMAN-L10 (Industrial Technology History Materials Database, material no. 101890081011) (Industrial Technology History Materials Information Center, National Museum of Nature and Science (surveying organization: Japan Robot Association) · Year of manufacture; features · Secondary summary)
  6. Systematic Survey of the Development of Industrial Robot Technology (National Museum of Nature and Science, Survey Report on the Systematization of Technology, vol. 4, March 2004) (Yoshihiro Kusuda · 2004 · p.21-22 4.3 The stagnation period (late 1970s); photo 4.18; note 12 · Secondary summary)
  7. Systematic Survey of Industrial Robot Technology (fiscal 2024 edition) (National Museum of Nature and Science, Survey Report on the Systematization of Technology, Vol.34, March 2025) (Norio Kodaira · 2025 · p.134 4.1.3 Competition among Japan's top makers to develop elect… · Secondary summary)
  8. 100 Postwar Japanese Innovations: the high-growth era, background to the innovation of the “industrial robot”; references (Japan Institute of Invention and Innovation, public interest incorporated association) (Japan Institute of Invention and Innovation (public interest incorporated association) · Background to the innovation (notes 17–19); references · Secondary summary)