osrf / vorc

Virtual Ocean Robot Challenge (VORC) resources
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CORA: Experimenting with a single thruster! #48

Open dholukeval opened 1 year ago

dholukeval commented 1 year ago

I want to simulate cruiser boat with single thruster. So instead of using WAM-V model. I decided to use CORA model. I am experimenting by attaching one single thruster as shown in figure.

I know that I have to change hydrodynamic parameters because the _usv_gazeboplugin is not suitable for single thruster. I want to know how these values have been decided?

For e.g. mass is way too much.

<inertial>
      <mass value="33000.0"/>
      <inertia ixx="21700.0" ixy="0.0" ixz="0.0" iyy="420000.0" iyz="0.0" izz="420000.0"/>
</inertial>

How do these hydrodynamic parameters calculated? What do I need to change?

<!-- Added mass -->
<xDotU>0</xDotU>
<yDotV>26000</yDotV>
<zDotW>31000</zDotW>
<kDotP>0.0</kDotP>
<mDotQ>0.0</mDotQ>
<nDotR>0.0</nDotR>

<!-- Linear and quadratic drag -->
<xU>120.0</xU>
<xUU>240.0</xUU>
<yV>240.0</yV>
<yVV>2600</yVV>
<zW>50000.0</zW>
<zWW>0.0</zWW>
<kP>50000.0</kP>
<kPP>5000.0</kPP>
<mQ>500000.0</mQ>
<mQQ>5000.0</mQQ>
<nR>400000.0</nR>
<nRR>0.0</nRR>

For my project, I need the mass to be 3100 kg.The length, width, height should be (6.83 m, 1.8 m, 1.4 m). I simply scale it down to these values in gazebo. I calculated inertia matrix for the same. but problem is that with the mass of 3100 kg, it stays afloat as shown in second picture. How do I solve this?

cora_with_single_thruster

Cora_floating