# What was Honda's ASIMO, and why did a walking robot matter so much?

Date: 2020-10-02 · Author: Robert Scales · https://guidetoartificialintelligence.com/en/learn/what-was-honda-asimo/

**Answer:** ASIMO is a child-sized humanoid robot that Honda presented in Tokyo in 2000, able to walk smoothly on two legs, turn while walking and climb ordinary stairs. It was the result of 14 years of research into two-legged walking, and it showed that a robot could move through spaces built for people rather than for machines.

Walking looks easy because we learned it before we can remember. For a machine, it is one of the hardest things to do. Every step means lifting one foot, shifting a heavy body over a single point of support and catching yourself before you fall. ASIMO, the white humanoid robot Honda introduced in 2000, was the first robot many people saw doing this smoothly, in a body roughly the size of a ten-year-old.

The name stands for Advanced Step in Innovative Mobility. Honda's press release presenting it is dated 20 November 2000 and says the robot was demonstrated that day at the company's global headquarters in Tokyo; Wikipedia gives October 2000 as the unveiling. Either way, the year is 2000, and the robot came out of Honda's research centre in Wako, Japan.

## What Honda built

ASIMO stood 120 cm tall and weighed 43 kg, according to Honda's own specifications. That was a dramatic shrink from its predecessor, the P3, which was 160 cm tall and weighed 130 kg. Honda chose the height on purpose. Its researchers decided that a helper robot should be somewhere between 120 cm and an average adult, so that it could flip light switches, turn doorknobs and work at a table or bench.

The robot had 26 joints that could each move in one direction, which engineers call degrees of freedom: two in the neck, five in each arm, one in each hand and six in each leg. It walked at up to 1.6 km/h, ran on a nickel-metal hydride battery and was steered by an operator using a workstation or a handheld controller. Sensors in each foot measured the forces pressing on the sole, and a gyroscope in the torso tracked how the body was tilting.

Honda's president, Hiroyuki Yoshino, framed the goal in social terms. He said Honda hoped "to create a partner for people, a new kind of robot with a positive function in society."

## Fourteen years of learning to walk

ASIMO did not appear from nowhere. Honda's history page traces it to 1986 and a pair of mechanical legs called E0. That first machine needed about 15 seconds for every step, and it could only walk in a straight line.

The key difference is between two styles of walking:

- **Static walking** keeps the body's centre of gravity above the sole of a foot at all times. It is stable but painfully slow, like someone edging across ice.
- **Dynamic walking** lets the centre of gravity move ahead of the feet and uses posture to stay balanced, which is how people really walk: a controlled fall, caught by each new step.

Here is how the project moved from one to the other:

| Years | Machine | What it added |
|---|---|---|
| 1986 | E0 | First two-legged walking, static, one step every 15 seconds |
| 1987–1991 | E1–E3 | Dynamic walking, based on close study of human and animal gaits |
| 1991–1993 | E4–E6 | Control systems that keep the robot stable while walking |
| 1993 | P1 | A torso and arms; 1,915 mm tall, 175 kg, with external power and computer |
| 1996 | P2 | Computers and batteries carried inside; it could climb stairs on its own |
| 1997 | P3 | Fully self-contained, 1,600 mm and 130 kg |
| 2000 | ASIMO | 1,200 mm and 43 kg, with smoother, more flexible walking |

## How ASIMO kept its balance

The new ingredient in ASIMO was what Honda called "predicted movement control." Earlier robots reacted to their own position after the fact. ASIMO tried to anticipate its next movement and shift its weight ahead of time.

Think of carrying a full cup of coffee around a corner. You do not wait until the coffee sloshes before you adjust; you lean into the turn slightly before you take it. ASIMO's controller did something similar, which let it change direction while walking instead of stopping, turning and starting again. Honda later described the improved system under the name i-WALK.

> **Try it:** Walk slowly across a room, then stop halfway and try to freeze on one foot mid-stride. Notice how your body had already started leaning into the next step. That forward lean is what a dynamic walking robot has to calculate, many times per second.

## Why ASIMO mattered

ASIMO became a global ambassador for robotics. Honda produced 20 units of the first model in 2002, rented robots to businesses, and sent ASIMO to perform for audiences around the world. Later versions recognised faces and gestures (2002), ran at 6 km/h (2005), worked in coordinated teams (2007) and, in 2011, ran at 9 km/h, hopped on one leg and poured a drink from a bottle.

Its larger contribution was a demonstration. Homes, offices and stations are built for human bodies: steps, narrow doors, switches at hand height. A robot that can walk on two legs can, in principle, go anywhere a person goes without rebuilding the world around it. ASIMO made that idea concrete for millions of people.

In July 2018 Honda said it would stop developing new ASIMO robots and apply the technology to more practical products. The know-how from two decades of walking research is now being redirected toward those other uses.

## Is ASIMO artificial intelligence, or just clever engineering?

Mostly the second, with a growing share of the first. The original ASIMO was a superb feat of control engineering. Its walking relied on carefully designed equations and feedback loops, not on learning from data, and a human operator told it where to go. By the definitions most researchers use, that is robotics rather than AI.

The later models moved toward AI. Recognising faces, following a person's pointing gesture, separating three voices speaking at once and planning a path around people walking past all involve perception and decision-making, the kinds of tasks AI tries to solve. Honda's 2011 version was described as able to keep moving without an operator controlling it.

For a beginner, ASIMO is a useful reminder that intelligence and movement are separate problems. Language systems such as GPT-3 can write fluent paragraphs but have no body at all, while ASIMO had a remarkable body with only modest smarts. Researchers who want truly helpful robots need to solve both at once.

## Sources

- Honda Debuts New Humanoid Robot "ASIMO": https://web.archive.org/web/20060314155447/http://world.honda.com/news/2000/c001120.html
- History of Robotics Development: https://global.honda/en/ASIMO/history/
- ASIMO: https://en.wikipedia.org/w/index.php?title=ASIMO&oldid=978388936