What are some good cheap, silent, motors for mannequin robots and what kind of controller should I use?

I'm creating mannequin robots that require 24 motors: 2 neck, 4 shoulder, 2 elbow, 4 wrist, 2 waist, 4 hip, 2 knee and 4 ankle motors. The mannequins will be bolted via a horizontal post from the lower back to a wall. This means they can run, dance, and pose. I may also do something with the horizontal beam so the robots can do side flips, and moves like the twist, jumps and crouches. They will not stand up, but be bolted as I've described to a wall. They could even spin around completely to face the wall.

I've tried using 6v hobby servos for the joins. These are too weak for lifting fibreglass mannequin body parts. They are too loud. They also make noise when poses are held, and they drop and smash when power is shut off. I have been using a handheld remote control for testing with only 5 channels. The robot must be programmable though. Lets say the objective is to make a mannequin dance to 'Thriller' like Michael Jackson.

I am open to using kinnect technology as the controller (so that a dancer can simply dance in front of my robot, who can copy and remember) but I'm also open to controllers that allow me to force the mannequin into a pose at specific time codes in the song. If necessary, I am also willing to program the poses using some kind of lighting desk type controller (such as tech crews use in rock concerts to sync everything to go with the music).

I have noticed that a power drill or winch is very loud whereas my fan is very quiet. I live in an apartment in which neighbours can hear footsteps from other apartments. I would not dare turn on a drill at 4am because it would wake up everyone in the whole building, but I would have no guilt in turning on a fan. I need my robot to be as quiet as a fan. The voltage does not really matter for this project. I'm happy to use up to 240v from the wall socket.

Please let me know which motors and controllers are best for my mannequin robots, taking cost into account. Thanks so much for any help :)

Two standard mannequins - these will be cut at certain joints to allow for mobility.

  • $\begingroup$ Here is the answer to the question: Servos for most joints will be rotating hobby servos. The shoulders will need an actuator setup like this: youtube.com/watch?v=vWn5nc5AS9s. The microcontroller required is this one: pololu.com/product/1356. I'm sorry I couldn't answer this question properly after weeks of research but someone closed the post because we were discussing solutions (?) $\endgroup$
    – Zxen
    Jun 16 '14 at 18:40
  • $\begingroup$ A well-lubricated gearbox helps reduce the noise significantly! $\endgroup$
    – Paul
    Feb 21 '15 at 22:20

The majority of the noise you're hearing is not from the motor itself but from gearing, which both servo motors and drills have a lot of. However, if you don't have a gearbox then when power is cut the torque exherted by the motor will become zero and your arm will fall. I would reccomend a standard brushed DC motor with an encoder for precise control, however a special gearbox designed for less noise. An example of this are the segway gearboxes, which are supposedly designed to be quiet and harmonic. Here's a cheaper example, however it does not have the torque or speeed you are looking for.


Another option are stepper motors, which at certain sizes can offer huge amounts of torque with no gearing. If your mannequin is mounted to a wall would it be possible to mount motors behind the wall, having them run winches through pulleys to manipulate the appendages? This would eliminate the issue as it would allow some form of shield inbetween the noise and the application.

Finally, if you're simply articulating appendages pnuematics may be the better option

Hope this helps.

  • $\begingroup$ Thanks for your reply :) I emailed RobotShop with the link to this page and so far they have said that they do not really sell any equipment which is suitable to my task (building a robot). They have not mentioned servos with brakes yet (which I assume locks the servo when the servo has reached it's desired position or when power is cut but I haven't found a working example for hobby servos). I think they must exist, because these do: en.wikipedia.org/wiki/Electromagnetic_lock. This servo controller robotshop.com/en/lynxmotion-ssc-32-servo-controller.html is perfect for $\endgroup$
    – Zxen
    May 21 '14 at 16:02
  • $\begingroup$ moving servos at varying speeds to end up where you want them at specific time codes. DC, stepper, pneumatic and hydraulic solutions all seem like they would not be able to achieve the accurate movements to make my mannequins moonwalk to the beat of 'Beat it'. 6 Volts seems like a very low voltage to me. I would prefer 240 Volts, which I think might be necessary if mannequins are made of fibreglass and wearing big jackets and carrying accessories. At the moment I cannot get my biggest hobby servo to lift a mannequin arm at the shoulder. Please consider that a winch can lift a truck. I need $\endgroup$
    – Zxen
    May 21 '14 at 16:08
  • $\begingroup$ much less power than that. Also, my servos need to fit inside wrists. Honestly, the wrists are the easiest appendages to animate, so shoulder servos can be bigger. Even so, all servos will probably need the same voltage as each other if they will run from the same controller. And they must lock, either as a programmed function because they will pause for a while, or better still, automatically when a servo reaches it's endpoint (without delays when re-animating). The strain throbbing of servos bearing weight is intolerable - they sound like they're going to break. Instead, they need to brake. $\endgroup$
    – Zxen
    May 21 '14 at 16:13
  • $\begingroup$ "If your mannequin is mounted to a wall would it be possible to mount motors behind the wall, having them run winches through pulleys to manipulate the appendages?" This would involve either poles or wires or both, and seems highly susceptible to fragility. The robots should be able to take a beating, or they will be easily broken - probably not needing some kid to yank an arm to destroy the alignment - but simply from the jolting the robot endures from it's own movements. Seems very fiddly and would probably wobble like Batman's ears during the end credits of Batman & Robin. Good idea though. $\endgroup$
    – Zxen
    May 21 '14 at 16:20
  • $\begingroup$ @Zxen It wouldn't have to be fragile if you use string, all you would need are strong and secure hinges to ensure strength. In fact it would probably be more fragile to have the motors directly mounted to the mannequin, as their shafts and bearings would be susceptible to breaks. $\endgroup$
    – nanogru
    May 21 '14 at 16:30

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