Matrix Rotation Query: Inertia Tensor D (+90y, -90z)

In summary, to translate an inertia tensor D from an old Cartesian system to a new one, it needs to be rotated through +90 in y and -90 in z, using the right hand rule notation. This can be achieved by pre-multiplying N_y by N_z to get N_R, and the transpose of N_R, N'_R, would then be used to obtain the new system tensor N_RDN'_R.
  • #1
bugatti79
794
1
I have an inertia tensor D in the old Cartesian system which i need to rotate through +90 in y and -90 in z to translate to the new system. I am using standard right hand rule notation for this Cartesian rotation.


[tex]D= \mathbf{\left(\begin{array}{lll}I_{xx}&I_{xy}&I_{xz}\\I_{yx}&I_{yy}&I_{yz}\\I_{zx}&I_{zy}&I_{zz}\\\end{array}\right)}[/tex], [tex]N_y(+90)=\mathbf{\left(\begin{array}{lll}0&0&1\\0&1&0\\-1&0&0\\\end{array}\right)}[/tex], [tex]N_z(-90)=\mathbf{\left(\begin{array}{lll}0&1&0\\-1&0&0\\0&0&1\\\end{array}\right)}[/tex]


If we let


[tex]N_R=N_z N_y[/tex] (I am pre-multiplying [tex]N_y[/tex] by [tex]N_z[/tex] because that is the order) and the transpose [tex]N'_R=N_R^T[/tex].


Is the the new system tensor [tex]N_RDN'_R[/tex] or [tex]N'_RDN_R[/tex]...?
 
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  • #2
bugatti79 said:
Is the the new system tensor [tex]N_RDN'_R[/tex] or [tex]N'_RDN_R[/tex]...?

This page would seem to indicate the former.
 

FAQ: Matrix Rotation Query: Inertia Tensor D (+90y, -90z)

1. What is a matrix rotation query?

A matrix rotation query is a mathematical representation of a transformation that rotates an object or coordinate system in three-dimensional space.

2. What is the purpose of the inertia tensor in a matrix rotation query?

The inertia tensor is used to calculate the distribution of mass and rotation of an object around different axes. It is an important component in determining the stability and motion of a rotating object.

3. How does the (+90y, -90z) notation in a matrix rotation query affect the rotation?

The (+90y, -90z) notation indicates that the object will be rotated 90 degrees clockwise around the y-axis, followed by a 90 degree counterclockwise rotation around the z-axis. This results in a final rotation of 180 degrees around the combined y-z plane.

4. Can the inertia tensor change in a matrix rotation query?

Yes, the inertia tensor can change depending on the shape and mass distribution of the object being rotated. It can also change if the object experiences external forces or moments.

5. What are some practical applications of matrix rotation queries and the inertia tensor?

Matrix rotation queries and the inertia tensor are commonly used in fields such as physics, engineering, and computer graphics. They are used to simulate and analyze the rotational motion of objects, such as in the design of vehicles or in predicting the behavior of celestial bodies.

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