Is there such a thing as a "Silent Servo?"

jtrz

Hi all,

Been experimenting with servos lately.· Just wondering if there was such a thing as a "silent servo?"· Or something like that?· It might be a type of servo or a feature of a servo (i.e. brushless, ball-bearing, etc) that I don't know about yet.

Here's what I'm wondering...

Say I were to build a small circuit that had 2 servos in it and place it in a small project box (where everything was self-contained incl a battery power supply).· If I handed that to someone to hold and the servos were activated (they would be moving IN the box...nothing outside the box), I'm thinking they would hear them working and possibly feel the movement (depending on the mounting situation).

I'd like someone to NOT hear or feel the movement of the servos at all.

Also, does anyone have a good source for small gears?

Thanks,

John

erco

There's a certain amount of gear noise in any transmission. The more gear reduction, the more more gears, the more noise. Brushless motors are quieter than brushed, certainly. You can reduce motor noise by running at lower voltages, and fewer gears your tranny if you want to heavily mod a servo at a major loss of torque. You can also use silicone grease to quiet geartrains, but that also eats into the power. Single stage worm gears are fairly quiet, but also remarkably inefficient.

For reference, the makers of new PLEO dinosaur promised "silent running" gearboxes by using umpteen custom-designed gears, but failed to deliver. PLEO is just as noisy as i-Cybie and every other production robot out there. Making reliable, efficient·gearboxes to transmit real-work torque loads is a science, and noise is a common by-product.

Small gears are available through Vigor Precision in Hong Kong, but unless you're a·master machinist·it would be hard to improve upon their preassembled gearboxes, essentially the Solarbotics-type.

IMHO, custom mechanical prototyping is almost a lost·art these days. Tons of electronics and software help is available, but·guys·who can pick the right motor/battery combo and give you a properly-working·geartrain are few & far between. If you find a guy you can afford, support him!

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·"If you build it, they will come."

FireHopper

I have a animatronic costume with 6 servos, but being hard of hearing. I can't hear it operate.

sylvie369

Not knowing the application, I don't know if this would help, but there's a possible non-engineering solution: add a fairly loud constant noise generator that operates independently of the servos.

Steve Joblin

depending on the force you need, and amount of movement, you can use "muscle wire" which contracts when a voltage is applied. completely silent.

FireHopper

Steve Joblin said...
depending on the force you need, and amount of movement, you can use "muscle wire" which contracts when a voltage is applied. completely silent.

but, dosent muscle wire get hot when activated, and for it to return, it needs to be able to cool off..·so you would need ventilation holes.. and that might give it away, not sure if the person wants ventilation holes.

Steve Joblin

It might get a bit warm, but not hot... I don't think vent holes would be needed, but I haven't tried it, so I can only surmise.