Another ROV Question -Tilt

[bdickens]

I'm spending a lot of effort keeping my UW ROV level so to speak. I would like to add a simple circuit to sense pitch and roll and correct automatically. <p>Any ICs out there for that ? I have a tilt switch from a pinball but it's a bit too "mechanical". <p>Recommendations ?

[Chris Smith]

Mercury switches are small, and reliable, and cheap, and you can even make them out of plastic tubing and a couple of contacts, and custom fit them inside the structure. A 4 in 1 is easy to make.

[Externet]

Agree, mercury.
If placed inside a sealed concave dish, maybe 1" Ø with one single central contact at the bottom and peripheric contacts as many as resolution wanted (maybe 8 or every 45 degrees) will yield a signal at the heading down one.
Problem: will misread under acceleration.<p>An upside-down weighed joystick would suffer of the same problem.
Check what the radio control helicopters use as stabilizers, if any toy gyroscopes for them?<p>If gets too complex, just make it more buoyant at the center top and more ballast at the center bottom. It will correct itself.<p>Miguel

[ELMBONSAI]

why dont you try something alittle more stable.
no moving parts.
The ADXL210 is a low cost, +/-10 g, dual-axis accelerometer with a digital output, all on a single monolithic IC. The ADXL210 will measure accelerations with a full-scale range of ±10g, making it suitable for tilt measurement.
-from Analog Devices website
http://www.analog.com/index.html

I havent actually used the chip,but i plan to see how it works when i come to thet stage of building my ROV<p>i hope this helps

[bobsRAC]

You can try an inclinometer. They are made specifically for this purpose.

[bobsRAC]

Memsic has thermal accelerometers, offering greater ruggedness and lower cost, with the tradeoff of lower band-width (160ish Hz). For inclinometers, they are rather ideal, because bandwidth is not at all demanding. Their parts are $12 pretty much across the board. They offer 1 and two axis accelerometers in 1, 2, 5, and 10g ranges. Their outputs can be aselected as ratiometric, absolute, and pwm output. They can withstand up to 50,000gs as opposed to Analog Devices ADXL line (1,000gs). The ADXL210JE is a $12.75 part (comarable).<p>The main advantage to Memsic is the increased robustness. If you drop an ADXLxxx on a hard surface even once, it's got a good chance of being destroyed ( I've had this happen ). The Memsics on the other hand, although not impossible to destroy, are much more durable.

[bobsRAC]

And b.t.w. Memsic charges a flat $15 shipping fee within US. You can get a part sampled to you for $15 including shipping, or buy a few for $12 + flat $15 for shipping within US.

[Dean Huster]

An accelerometer won't correct for static pitch and roll. It can only sense movment. So if you start out from a stationary point when you power up and you're already in a pitched position, the accelerometer won't know the difference and assume zero and take it from there. It'll take a dose of V8 juice to correct it.<p>Dean