A Servo Powered Robotic Arm, But Like You’ve Never Seen Before

We’ve written about a lot of DIY robotic arms. Some of them are high-performance, some are inexpensive, and some are just uniquely fun. This one certainly falls into the last category; whilst watching an episode of Black Mirror, [Gear Down For What] was struck by inspiration for a thin robotic limb. After some iterations he has a final prototype, and it’s quite something to see in action.

To make a robotic arm as slender as possible, the actuators can’t be mounted on the arm itself but must instead drive the arm remotely. There are a number of ways of doing this, and though [Gear Down For What] considered using pneumatics or hydraulics, he opted to keep it simple with RC servos which produced a nifty solution that we really like.

The arm is made out of a series of 3D printed ball joints, allowing rotation in any direction. The tricky bit is transferring the force from the servos to each joint. Initially bare fishing line was considered, but this made the remote joints difficult to control when lower joints were moving. The solution was to use the fishing line inside of tubing, similar to the way that bike brakes operate. This allows the force to be carried to the appropriate joint regardless of lower movement. Each joint needs an x and y tension to allow it to rotate in any direction, which means an army of sixteen servos is needed to operate the eight segment arm.

Robotic arms are always fun to build and we’ve seen some pretty neat uses for them, such as mapping magnetic fields in 3D, or teaching sign language.

26 thoughts on “A Servo Powered Robotic Arm, But Like You’ve Never Seen Before

    1. On land sure, the approx 9ft tough fibrous penis of the blue whale could knock an adult elephant out as not only is it prehensile but, incredibly it levers strongly against the female to hold her position, something similar to Japanese cults exercise regime extending male penile length and orgasms to 20mins. It’s also interesting the blue whale’s brain is much less in mass than its penis, that ratio in mammals might offer clues to some human’s potential evolutionary path depending on their socio-economic-intellectual motivations through life ;-)

  1. Although a nicely executed build, I take exception to the way the guy seems to be implying throughout that he came up with the tentacle mechanism, which has been around since at least the 70s and used in countless films for props such as the chestburster in Alien, through to all manner of tails and elephant trunks

    1. I do not think his intention is to claim to have “invented” the “tentacle mechanism”. He just tries to explain his reasoning on how his robotic leg build iterated to a robotic pen.. holder..

  2. I know recently there were the articles here on how to build a similar manipulator controlled by multi-axis “control stick”, care to post in the comments more examples of this kind of tentacle-like mechanism? There was a neat one for tentacles in the Hell-Boy movie, but I could not find the video again.

    Repeat for ADD folks:
    More build examples in the comments please!

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