Marine systems simulation
Ship local connection
+ Collaboration diagram for Ship local connection:

The "LocalConnection" SimObject defines a body fixed point which travels and rotates with the parent body. The main application of a body fixed point is to measure the position, acceleration and velocities on a particular point on a rigid body, and to calculate provide position and velocity data for calculation of forces. The body fixed point can also be used to translate a force on a particular point to a force and torque pair which acts on the origin of the parent body.

Definition of the axes directions and rotation angles

A Body fixed point defines a local coordinate system attached to the parent body. The initial orientation of the local coordinate system is a right handed system parallel to the axes of the parent body. The global orientation of the three axes can be obtained from the output and the relative orientation of the axes can be controlled form input ports. The rotation of the local coordinate system is defined as successive rotations about the first (x), second (y) and third axis (z).

Input ports

Name Width Description
ParentPositionNED 3

The position of the parent body in north-east-down

ParentQuaternionNED 3

The orientation quaternion of the parent body in north-east-down

ParentVelocityNED 3

The linear velocities of the parent body in north-east-down

ParentOmegaNED 4

The rotational speed of the parent body in north-east-down

ForceNED 3

Translate an input force to force-torque pair around the parent origin

Output ports

Name Width Description
PositionNED 3

The position in north-east-down coordinates

VelocityNED 3

The Linear velocity in north-east-down coordinates

VelocityBody 3

The velocity in the parents local axis system

OmegaNED 3

The rotational velocity in north-east-down coordinates

QuaternionNED 4

The rotation quaternion. The orientation quaternion is the rotation of the parent body rotated by any axis rotations of the 1,2,3 axes, in succession

Axis1NED 3

The normal vector of the 1. axis in north-east-down coordinates

Axis2NED 3

The normal vector of the 2. axis in north-east-down coordinates

Axis3NED 3

The normal vector of the 3. axis in north-east-down coordinates

ForceNED 3

The force output in north-east-down coordinates

TorqueNED 3

The torque output around the parent body origin of the force input in body coordinates

Configuration parameters

Name Width Description
Offset 3

The offset in the parents axis system

ForceCalculator 1

Use the object to translate forces to force-torque pairs

ForceInBodyFrame 1

Set the input force in the parents body frame

Todo:
ensure that documentation and implementation are synced