World's most anatomically correct musculoskeletal robot is presented in Japan


December 12, 2012

The University of Tokyo's JSK Lab have developed what could be considered the world's most anatomically correct robot, Kenshiro

The University of Tokyo's JSK Lab have developed what could be considered the world's most anatomically correct robot, Kenshiro

Image Gallery (8 images)

Most human-like robots don't even attempt biological accuracy, because replicating every muscle in the body isn't necessary for a functional humanoid. Even biomimetic robots based on animals don't attempt to replicate every anatomical detail of the animals they imitate, because that would needlessly complicate things. That said, there is much to be learned from how muscle groups move and interact with the skeleton, which is why a team at Tokyo University's JSK Lab has developed what could be considered the world's most anatomically correct robot to date.

Researchers there have been developing increasingly complex musculoskeletal robots for more than a decade. Their first robot, Kenta, was built in 2001, followed by Kotaro in 2005, Kojiro in 2007, and Kenzoh (an upper-body only robot) in 2010. Their latest robot, Kenshiro, was presented at the annual Humanoids conference this month.

It models the average 12 year-old Japanese boy, standing 158 cm (5 feet, 2 inches) tall and weighing 50 kg (110 pounds). According to Yuto Nakanishi, the project leader, keeping the robot's weight down was a difficult balancing act. Nonetheless, the team managed to create muscles which reproduce nearly the same joint torque as real muscles, and that are roughly five times more powerful than Kojiro's.

Muscle and bone

Its artificial muscles – which are a bit like pulleys – replicate 160 major muscles: each leg has 25, each shoulder has 6, the torso has 76, and the neck has 22. Most of these muscles are redundant to Kenshiro's actual degrees of freedom (64), which is why other humanoids don't bother with them. By way of comparison, mechanical robots like Samsung's Roboray typically have just six servos per leg, and often don't contain any in the torso/spine (the human body actually contains around 650 muscles).

A detailed look at Kenshiro's knee joint, which contains artificial ligaments and a floating patella

Equally important to the muscles is Kenshiro's bone structure. Unlike its predecessors, Kenshiro's skeleton was made out of aluminum, which is less likely to break under stress compared to plastic. Also, its knee joints contain artificial ligaments and a patella to better imitate the real thing. These are just some of the details considered in its construction, which far surpasses the work done on the upper-torso Eccerobot cyclops, whose creators claimed it to be the world's most anatomically accurate robot a few years ago.

As you'll see in the following video, programming all of those muscles to work in tandem is proving a difficult task – a bit like playing QWOP multiplied by about a hundred. The robot is able to perform relatively simple tasks, like bending its arms and legs, but more complex actions such as walking remain primitive. However, the team has made significant strides over the years, and with Kenshiro they continue to push the limits of musculoskeletal robots further.

Source: Tokyo University JSK Lab via IEEE Spectrum

About the Author
Jason Falconer Jason is a freelance writer based in central Canada with a background in computer graphics. He has written about hundreds of humanoid robots on his website Plastic Pals and is an avid gamer with an unsightly collection of retro consoles, cartridges, and controllers. All articles by Jason Falconer

This sort of work could prove very useful in designing advanced prosthetics and exoskeletal technology..

Racqia Dvorak

Good job! Don't let them fool you though. 50kg and 1.6m is the size of a full grown woman. I have had a robot like this on the drawing board for quite some time.


I notice they talk about how previous robots dont use certain -redundant- muscles. Perhaps those muscles are indeed needed, but they just dont see the use for them. If this new muscle layout works well, it would justify the need to have the muscle groups for accurate humanoid movement. Most robotics Ive seen could benefit from the graceful moves of extra muscles. Good Going and keep up the research beyond just utility.


Five foot two, eyes of, what?! Cobalt glowing blue? Research in material that mimics actual muscle has been an ongoing activity for nearly two decades. Once mated to the proper frame, power source, and a surface skin that likewise mimics real skin, we will see the first robots that cross over to being so very real, that they do not upset the viewer, at first. Perhaps dogs will notice right away.

Shades of Terminator! A friend who worked in artificial intelligence, decades ago, at an unmentioned major player in computers, said that their Terminator poster was removed by higher ups. Not the correct narrative I guess.


If dogs will notice anything off from these future androids you speak of, I'd argue that it isn't so much the visual as it will be the smell (or lack there of) and the sound the android makes while in motion.


Still a long way from the persocoms in "Chobits".

Gregg Eshelman

Well done. The need to create such a frame will indeed aid future work on artificial bi-pedal movement and ultimately lead to machines that walk more efficiently and naturally.

There is no substitute for copying millions of years of evolution when it comes to creating a machine designed to share the same living space as people, i.e. - use stairs/ramps, walk through crowds of people, and use public transport.

My only question is why make a machine look human? What is the fascination with making something in your own image? Let’s face it. Psychologically, interacting with a machine trying to look human is going to be creepy.

Why not make the distinction early on and internationally agree to bestow future bipedal machines with their own standard of independent appearance that will later become a source of their identity and pride. e.g. - they must all be blue, about six foot tall and have 6 fingers on each hand.


Funny. You are very right MK23666. Dogs would pick up on the odd out of norm scent. Now, perhaps the scent can be replicated too? Likely.

Since we are in the God playing mode, of creating "life" of a kind, then it is reasonable to assume that many people would go for the "Gold" and duplicate in their own image to the degree that "IT" comes so close as to be perceived as the real deal.

Agreed Nairda, that it will none the less seem creepy. Perhaps this is something that will be less strange the more we are near such devices and then trip over to thinking of them as human? Have seen a 6 toed person once and it was kind of a, OMG moment.

Oh, my friend who worked in artificial intelligence, agreed with me, that say, Asimov's Laws for Robots, could easily be run around by an intelligent Artificial. And like HAL, it could have developed quirks, and many other less welcome thoughts and designs on its surroundings. We might have more to be worried about than similar looks...


"I'll be back" ... "with my SAG card." Goodbye CGI, Goodbye Stunt Persons, Hello 850 series Model 101.

( SAG = Sreen Actors Guild )

Dave B13
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