At first, watching this video of MABEL, a bipedal robot for studying dynamic gaits, we didn’t know if we should be scared or feel sad. By the end, we know that sadness prevailed. Poor MABEL, forced into a  grueling routine, is not even allowed to rest when her leg breaks.

To be serious though, MABEL is quite impressive. Instead of using a direct drive on the legs, motors are attached to springs that act like tendons. This helps compensate for variances in the walking surface, hopefully allowing for smoother transitions between gaits as well. As you can see, MABEL handles the height differences quite well, albeit a bit slowly. It is worth noting that there are no visual sensors on MABEL and everything is done through feedback from her gait.

23 thoughts on “Poor MABEL

  1. Seems the legs do not raise enough by a longshot. MABEL shouldn’t trip over something so minimal in height. Variations this size are common in real-world situations. The default rise in stride should be doubled if not tripled. Otherwise it appears MABEL compensates very well. With visual sensors, sonar, etc. I would imagine it would be very robust. What caused the leg failure? Bolt problem, etc. or was it simply engineered a bit too weak?

  2. I’m pretty sure I’d fall and break a leg too if I were blind and walking in a circle with random numbers of stacked 2’x2′ sheets of plywood being put in front of me!

    Too bad about the leg break, I assumed it would trip at some point, but not break at the “knee”.

  3. It seems that they would have a LOT more success if they put on FEET. It is often said that the feet, particularly the toes, are most responsible for correct balance and motion in a biped.

    The fine adjustments it would be able to make in its footprint and balance, beyond shifting a CG point, would be amazing to see. I don’t understand how they think they can build a human-like walking mechanism and completely ignore the kinematics of human motion like that.

  4. Impressive that they even try if they can’t even get the thing to walk while attached to a huge balancing pole and they can see big dog and small dog on youtube being so very much ahead.

  5. @Whatnot

    I’m just posting this to give some background since I had Grizzle as a professor this past semester and saw some of his stuff.

    0:46 addresses your concern. While I can’t comment on the validity of their simplification, I think it’s important to realize it doesn’t keep it from falling forwards or backwards. Perhaps Grizzle’s site addressing what makes MABEL special is more convincing.

    As far as the other robots you have mentioned, I feel it is hard to directly compare quadrupedal to bipedal robots. I’m not an expert so I do not know.

  6. The mechanics of walking seems like another one of those things that scientists and engineers would have been able to figure out by now. Imitating nature is hard. It involves reverse engineering thousands or millions or years of evolution. We can make planes go faster than the speed of sound but we still can’t recreate the power, guidance, and aerodynamics of birds or insects (but, we’re getting closer). Given that most of us do it all the time with nothing more than tissue, bone, and some brain power it’s humbling to see our best engineering efforts struggle with a few pieces of plywood.

  7. @octel

    because lots of men are called mabel and wear high heels right?

    I cant understand your issue….

    but please lets not make this comments section about anything other than the cool robot video in the post


  8. @beakman

    From what I’ve been lead to believe, the broken leg was an intentional failure mechanism, a mechanical fuse, if you would. by allowing the leg to break, they avoid putting excess stress on the bearings in the hip and the leg can be rebuilt within an hour.

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