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I'm using a couple of continuous rotation servos to drive the wheels on a mobile robot. One issue I have is that the servos produce a loud, whining sound when in use. Do higher quality servos exist that make less noise? It would also be great if the robot could move a bit faster - are speedier servos available?

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  • \$\begingroup\$ Which servos are you using? \$\endgroup\$
    – tyblu
    Commented Jan 3, 2011 at 22:58

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Any standard PMDC motor would work for this, brushed or brushless.

Continuous rotation servos if I recall correctly are basically just a hack. The typical servo has a radial pot, motor, gearing, and a little controller to get the position right. Their goal is to provide repeatable, precise control, not be efficient or very fast. The reason they make so much noise is because you have a tiny, tiny motor spinning a massive step-down transmission.

Using "just a motor" and gearing it down yourself (or with an integrated gear head on the motor) is the best solution.

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If it doesn't have position feedback, it's not a servo. Continuous rotation "servos" are just gearmotors in the hobby-servo form factor.

So what you want to do is get proper gearmotors to run the wheels. There are lots to choose from.

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  • \$\begingroup\$ If I recall correctly, based on the PWM you give them they will go forwards/reverse; so they still have a controller of some sort left in them. \$\endgroup\$
    – Nick T
    Commented Jan 4, 2011 at 5:18
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I believe you just need separate(and more powerfull) brushless motors + reductors for this. This way you can control speed, not spefic angle of each whell.

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The noise comes from the gearbox. You won't reduce this unless you go for a different gearbox design or belt drive.

The motors used in hobby servos are small and light - originally designed for airplanes.

It is easier to make and control a small, low current high speed motor than a big high current one. Hence the design.

There are high torque servos 'Monster truck servos' which can speed up your robot to a degree.

So unless you are prepared to pay BIG bucks for an industrial drive and controller (which might have a brushless motor) with a good gearbox, sorry, its noise you have to put up with.

I use motor car and truck windshield wiper motors on larger projects where I want more oomph. Automotive and BLDC are good next starting points.

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