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i know buoyancy and apply ed it ; my ship is float on the water now. but i don't know how to apply force to control and navigate my speed boat ?

i'm using havok physics engine. my code's like this

body->applyForce( stepInfo.m_deltaTime,forwardWorld, pointx );

pointx = my apply force point (-75,0,0); this point is a 3d point in back side of my ship

forwardWorld = force value and direction of it (100,0,0); apply 100Nm to back side of my ship

my pointx value is always static.

my forwardWorld values change every time for exam :

when i want to my ship go to front set it to (100,0,0)

when i want to my ship go to right i set it to (0,0,100)

when i want to my ship go to left i set it to (0,0,-100)

but this is'n a good way because my ship will drag and shift to left or right in upper speed and this is mistake please help me.

Mantro Loman
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  • Using a physics engine doesn't mean you can get away with being completely ignorant about physics. Forget about your programming problem; physics is how the world works. How do you live without knowing something about it? – duffymo Jul 21 '12 at 14:35
  • what's your mind ? true my problem is not physic engine. my problem is calculation hydrodynamic physic and understanding it in a limit time.. i know hydro static equations but this is hydrodynamic and i need to some one know enough physic... can u guide me? – Mantro Loman Jul 21 '12 at 16:40
  • Nope, not me. This isn't the place to teach someone physics. We're talking Newtonian mechanics. Grab a book, any book. – duffymo Jul 21 '12 at 17:40
  • I'd like to help, but "my ship will drag and shift to left or right in upper speed" makes no sense to me. What is your native language? – Beta Jul 25 '12 at 00:57

1 Answers1

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You didn't say what you need the model for. If it's a game then perhaps my advice will not satisfy you but if it's for some sort of engineering problem solving then I recommend building your own manoeuvring model. This may sound intimidating but in reality it boils down to solving three differential equations (roll, yaw and surge; you can also add sway depending on what you are interested in). You can easily solve them by integration using, say, Range-Kutta method.

Here is a paper giving a nice overview of what I'm talking about (there are lots on-line): https://scl.snu.ac.kr/SCL_Research/data/research/science.pdf

You will need to find coefficients for your equations of motion. There are some in the paper I listed above, many more can be found on the web. For a start, I recommend going for the KRISO data, they are widely available and well presented in the literature.

Edit: I don't like MatLab but if you have access to it then you can solve your equations really easily by building a Simulink model.

Artur
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