I'm not sure I agree with you on that. Have you ever gone scuba diving? When a current is ripping and you're in it, things on the bottom fly by you even though you feel like you're stationary. It's not turning or rolling you like a wave, it's just all moving in one direction. It's just like being on a moving vehicle, after the initial adjustment of starting, you feel like you're sitting still unless there is another adjustment (turn, accell/decel). I'm not sure your system will be more accurate than dead reckoning and in cases where you *think* it's better you sometimes start to trust it more than it should be trusted if you know what I mean.perfo wrote:Yep setting a heading or setting an end location are different things.. Just because you maintain a certain degrees of heading then you may not end up at the expected destination as the craft may have been crabbed by the current. I am expecting though that the current won't act on the whole craft at the same time and thus unless it's a prevailing or head on current it will try and rotate the ROV and this should be detectable and correctable. I'm not expecting it to be pin point accurate but as long as I know the direction it was heading when it left the Buoy and the distance from the buoy then I should be able to plot it's rough position on a screen. In any case what I'm trying to achieve is a replacement for a direct joystick connection.
A joystick would be constantly adjusted by the pilot to keep the ROV heading towards something. If that thing is visible then great but if not then it is probably going to be done against the returned compass data. So id being doing the same with the exception of I don't need to constantly adjust the joystick. I just aim the ROV at the object/location (if it's visible) or adjust it so its facing a certain heading and press a button and the on-board controller would look after any adjustments. So if the compass feed back is so vague I have to end up correcting every now and then, I'm no worse off than doing it all manually anyway...so really the accuracy of the sensors don't affect my plan any more than a manually operated one but stand a chance to be a bit better.
The giros may be able to compensate for it and maybe it's just a matter of reacting and continually reacting when the current initially starts acting on the ROV, I don't know.
I'm curious to see how this will play out. (and hope you don't think I'm throwing rocks at your design, just playing devil's advocate).