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Less noisy alternative to servo. Muscle / nitinol wire?
perik:
I´m looking for a less noisy alternative to using servos for a project and I was thinking of using musclewires (Flexinol / nitinol wire) as an replacement. I havnt worked with musclewires before and wonder if this is possible or if they are very slow (I know they are driven by heat so slow cooling might be a problem)
Basically my project need to pull and push a small weight with a thin ironstick as arm. I need something that goes two ways. When I applies current to it I want it to pull and when I decrease the current again I want it to gradually go back depending on the current. Im using a pwm signal from my raspberry pi to control the current.
I wounder if anyone has some experience with doing the same? Basically replacing a servo with musclewire?
For example this one:
https://www.sparkfun.com/products/12096
I guess the thinner the wire the faster it reacts since it cools off faster?
soldar:
An electromagnet should work if you control the current gradually.
perik:
I had electromagnets in mind for a while but in my case the heating is a problem. As well as I need to pull and push around 3 cm
beanflying:
Not all servos are that noisy when you get into the really tiny ones. Do you need no noise or just really low noise? You could also take a look at things like the steppers used on CD drives or even the internals of a hard drive.
This will get you started for a look. Single gear reduction (standard servos are 5-8 reductions) only and even drop the motor voltage a touch to reduce the speed and noise. https://www.horizonhobby.com/helicopters/aircraft-servos/20-gram-performance-linear-long-throw-servo--15mm-lead-spmsh2025l
artag:
As usual, it's a tradeoff of power, cost, speed, noise. You can get quiet geared DC motors - try Maxon. The more expensive servos are also quieter : it's a question of how good the tolerances are on the gears, so metal-geared servos tend to be better.
Thermal actuators are quiet, slow, and take a lot of power. That's fine in some applications.
Steppers are noisy if the steps are large. Use small steps above audio frequency and they're a lot better : try the drivers from Trinamic.
CD drives, as beanflying says, are also good : you can hear a CD drive move but not usually at the individual step level. They use a very long pitch leadscrew so the step rate is low.
Pneumatic and hydraulic actuators are extremely quiet but the pumps and air-release valves are not. Try the murata micropumps or the piezo aquatic aerators for silent operation (the muratas produce surprisingly high pressure) and pump the air both ways (as you would with hydraulics) rather than letting it escape.
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