Hello everyone
I am building an ROV dynamic model but ideally I would like it to be informed by reality. The "problem" is that I do not have access to an ROV…and I can’t experience its real behaviour which to me is important when you build a model of a vehicle.
Therefore, I am starting this topic here with a few questions that have come to my mind while working on this project and I would appreciate your help with.
1) I understand that the typical controls of an ROV are: Vertical (i.e. depth), Yaw (i.e. rotate around vertical axis), Lateral (i.e. move side to side), Pitch (i.e. nose up, nose down). But I have also read about the use of "Ballast". Is ballast used to keep the vehicle at a particular attitude (for example pitched down 15 degrees or rolled left 20 degrees) or is ballast used to control the depth only?
2) What is the weight ratio of an ROV to a typical gripper? Suppose that the ROV is trimmed for depth and is stable, how much reaction does the gripper impose on it? So, if I could swivel the gripper to the right, how much is the ROV expected to swivel to the left? Negligible amount? Considerable amount? (I suppose that hydrodynamic effects are negligible (?))
3) Are there standard grippers? How many degrees of freedom are they expected to have? I have seen simple systems which are just extend-and-grab or just grab but I have also seen pairs of grippers where the left is different from the right. The left gripper looks like a standard arm but the right gripper is much simpler. Is there a reason for this?
4) What sort of thrust are typical thrusters expected to provide? From a brief survey across manufacturers websites, I have something like 20kg, is that the general case?
5) How much of a factor in the vehicle movement is the tether? Can you turn around unhindered or do you have to constantly correct for the tether’s pull?
6) What other sort of automatic systems can be found on an ROV besides Automatic Depth Control and Automatic Bearing Control? Also, does the Automatic Depth Control operate on the ballast or the vertical thrusters?
7) What sort of positive buyoancy are ROVs trimmed for? What sort of rate of ascent is expected?
8) Why do you need 3-phase 400V power specifications? Is it purely because of the long length of the tether? (I suppose that the thrusters are simple DC motors (?))
I think that these would be my questions at the moment, short of asking for access to an ROV system 😀
Looking forward to hearing from you
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