Stress Testing Robots…with Baseball Bats


When you are working on constructing the first Cyberdyne Systems Model 101 prototype a super-robust robotic arm, you’ve got to test it somehow, right?

You probably recognize the robot being abused in the video below, as we have talked about the construction of its hand once once before. The German Aerospace Center has been working on the DLR Hand Arm System for some time now, and are obviously really excited to show you how their design performs.

In case you are not familiar, the arm you see there uses 52 different motors, miniaturized control electronics, and a slew of synthetic tendons to behave like a human arm – only much better. The system’s joints not only provide for an incredible amount of articulation, they are specially designed to allow the unit to absorb and dissipate large amounts of energy without damaging the structure.

We think that any human would be hard pressed to retain their composure, let alone be able move their arm after suffering a blow from a baseball bat, yet the robot arm carries on just fine. It’s awesome technology indeed.


39 thoughts on “Stress Testing Robots…with Baseball Bats

  1. KYLE NO!! This thing looks pretty small, how much does it weigh, it could be used for amputees if its light enough. (Not that I would aprove beating amputees with baseball bats, we should save that for when the robots revolt.)

  2. Seems like he didn’t hit it extremely hard. In addition, he hit it at what seems like the least likely point to cause damage. I understand the idea that the joints move somewhat to redistribute the force. But I wouldn’t have expected a blow like this to damage it to begin with.

  3. Yet the problem is, that while the parts are stronger and can take more abuse, the damage is cumulative and doesn’t go away.

    Aluminium parts are especially vulnerable to fatigue. You make a robot leg out of aluminium parts, and unless you seriously over-engineer it, it’s going to develop fractures and then fail.

    That’s why airplanes are glued instead of riveted when they make them out of aluminium. The idea is to spread the load without causing hots spots like on the rivet holes, where the material would fail under repeated cyclic stress.

    And that’s why you can’t easily make a car chassis out of aluminium either. People have tried, but they usually end up having the wheels pop off at inconvenient times.

  4. @Dax “You make a robot leg out of aluminium parts, and unless you seriously over-engineer it, it’s going to develop fractures and then fail.”

    While aluminum does have poor fatigue characteristics, it is still a great engineering metal. I would disagree with the assertion that you have to “seriously over-engineer it” to make parts that won’t develop fractures and fail (in a reasonable and useful lifetime).

    An incredible number of things are made out of aluminum that don’t fail, like mountain bikes, and even car frames. Audi has been using aluminum frames for a long time, and I’ve never heard of any Audi’s wheel popping off.

    There are some valid concerns with aluminum fatigue, and like you said things like airplanes may use glue instead of rivets on thin pieces like sheet metal, but for general machined parts, aluminum is great, and you could make a great robot leg out of it.

  5. I work on 30+ year old planes made with aluminum sheets riveted to the frame and they only fall out of the sky occasionally ;) ….and those times are usually due to pilot error/engine failure not airframe failure.

  6. the thing is, university materials courses in engineering degrees have a way of making everything sound very alarmist.

    my impression now is that it’s not even possible to build a vehicle to travel outside the atmosphere, because as soon as you get there, it’ll evaporate, or be torn to pieces my micrometeroids, or the crew will die because of solar radiation. That, and any plane I build will fall to bits because aluminium has such poor fatigue performance compared to steel, but it’s all we can use because steel’s too heavy.

  7. critic:
    >take the weight off the arm and do it again!

    That has been my first thought when I watched the video! The “hand” is just a metal bar and not very fragile and the weights attached to it absorb most of the energy. It’s the same principal when in shows people lay on the ground and get a stone plate laying on their stomach smashed by a sledge hammer. They don’t get hurt because the plate absorbs the energy.
    So – nothing special here – even a human could do it ;-)

  8. D-Lite > i agree, i’m pretty sure I could hold a metal bar and have someone strike it with a bat without me getting hurt.

    i’d like to see them smack the shoulder or hang it from something and let children use the arm as a swing ^^

  9. I think you’re missing the point. The robot took a significant blow and didn’t lose registration, as demonstrated by touching the ball. It shows that this robot doesn’t need recalibration after a jostle or crash.

  10. At minute 1:03, notice that the batter does two things to minimize the force of the impact. First he relaxes and bends his wrists and arms, allowing the bat at its point of impact to slow down significantly, and he loosens his grip on the bat, further affecting the force of the bat’s impact point.

    Yes, the bat hit the robot, but as others also pointed out, it was not a homerun swing by any means.

  11. @ Dax: Aluminium Rules!! :0) There are so many alloy options, that to think of anything as being made of just Aluminium is a bit crackers. It’s like saying Humans are made of just Carbon or just Water.

    I trust Aluminium way more than new fandangled composites, largely because Aluminium’s fatigue properties over time and it’s heat treatment/temper conditions are well documented. I won’t generalise by saying all composite materials will unpredictably shatter into a million pieces but keep your eyes peeled for the next plane to fall out of the sky and the reasons why…

  12. So, unlike Robocop whose targetting systems can become misaligned due to mistreatment, this one will still be able to accurately shoot you in the ball.

    I like it.

  13. This arm is probably like a child to it’s creators, one of whom is probably the guy hitting it, so it’s no wonder he doesn’t want to hit it too hard (it’s like a reflex).

    When an arm like this reaches mass-production it would probably have more shielding for the now-visible parts.

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