Homebuilt ROVs Forum

I was just thinking has anyone ever thought of using an accelerometer to keep an rov level using vertical motors?

Any ideas, anyone?

Was thinking along that line also as the mark two version of my ROV. A friend send me this link: http://dx.com/p/premium-motionplus-for- ... hite-32506 should contain a very good chip and there are plenty rescources how to connect it to an arduino.

My idea was to use the arduino to read the chip and do the math and the logic off keeping line in the Raspberry PI.

You can use a auto leveling 3 axis gyro used in quadcopters.

How about a tilt compensated compass these have a 3 axis accelerometer,

Im messing with a lsm303 at the moment which is working quite well with an arduino

Accelerometers by themselves aren't great, especially the ones that you and I can afford.
A slightly better method is to use a gyro, but those tend to drift.

What you really want to do is use an IMU with both a gyro and an accelerometer. Just a little accelerometer input keeps the gyro from drifting, at least in roll and pitch.

I used an accelerometer for just this purpose on my last MATE competition ROV. I used a $10.00 3-axis accelerometer.... can't remember the manufacturer/part number though.

There's a couple of things to overcome though. First, though gravity pulls down, the accelerometer will respond to the acceleration forces caused by activating thrusters. I solved this problem by making the the system completely ignore acceleration spikes, and only pay attention to fairly steady forces. After that I mixed in a little hard-coded compensation for the effects of off-center thrusters. Since ROVs typically accelerate quickly but for short periods of time this method works after a fashion. For the ROV I used it on, you couldn't tell it didn't have a gyro.

Seawolf is right though; the only perfect way is to use both an accelerometer and gyro in conjunction.