Euler Angles to Direction Cosines (G Dataflow)

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Last Modified: June 25, 2019

Converts Euler angles into a 3-by-3 matrix of direction cosines.

Euler angles

Euler angles in radians.

This input accepts both proper and Tait-Bryan angle types.

phi

Rotation angle about the first axis in radians.

Default: 0

theta

Rotation angle about the second axis in radians.

Default: 0

psi

Rotation angle about the third axis in radians.

Default: 0

rotation order

Order of the axes to rotate the coordinates around.

Name	Value	Description
X-Y-Z	0	The first, second, and third rotations are about the x-, y-, and z-axes, respectively.
X-Z-Y	1	The first, second, and third rotations are about the x-, z-, and y-axes, respectively.
Y-X-Z	2	The first, second, and third rotations are about the y-, x-, and z-axes, respectively.
Y-Z-X	3	The first, second, and third rotations are about the y-, z-, and x-axes, respectively.
Z-X-Y	4	The first, second, and third rotations are about the z-, x-, and y-axes, respectively.
Z-Y-X	5	The first, second, and third rotations are about the z-, y-, and x-axes, respectively.
X-Y-X	6	The first, second, and third rotations are about the x-, y-, and x-axes, respectively.
X-Z-X	7	The first, second, and third rotations are about the x-, z-, and x-axes, respectively.
Y-X-Y	8	The first, second, and third rotations are about the y-, x-, and y-axes, respectively.
Y-Z-Y	9	The first, second, and third rotations are about the y-, z-, and y-axes, respectively.
Z-X-Z	10	The first, second, and third rotations are about the z-, x-, and z-axes, respectively.
Z-Y-Z	11	The first, second, and third rotations are about the z-, y-, and z-axes, respectively.

Default: Z-X-Z

rotation type

Type of rotation to perform.

Name	Value	Description
Passive and Intrinsic	0	The rotation occurs about the axes of a rotating coordinate system, which is initially aligned with the fixed one, and modifies its orientation after each elemental rotation. The coordinate system rotates, while the coordinate is fixed.
Passive and Extrinsic	1	The rotation occurs about the axes of a fixed coordinate system. The coordinate system rotates, while the coordinate is fixed.
Active	2	The rotation occurs about the axes of the same coordinate system. The coordinate system is fixed, while the coordinate rotates.

Default: Passive and Intrinsic

error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error	error in contains an error

If no error occurred before the node runs, the node begins execution normally. If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.	If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

direction cosines

A 3-by-3 direction cosine matrix.

If rotation type is Passive and Intrinsic or Passive and Extrinsic, the matrix maps points in the old coordinate frame to points in the new coordinate frame. If rotation type is Active, the matrix maps the coordinates of the original points to the coordinates of the rotated points. Each element must be in the range of [-1, 1].

error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

error in does not contain an error	error in contains an error

If no error occurred before the node runs, the node begins execution normally. If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.	If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Algorithm for Converting Euler Angles into Direction Cosines

Direction cosines and Euler angles are two different ways of expressing a rotation. The following equations describe how this node converts Euler angles into direction cosines:

Let R_x(α), R_y(α), and R_z(α) be the rotation matrices of rotating the coordinate system by α angles about the x-, y-, and z-axes, respectively. R_x(α), R_y(α), and R_z(α) are defined as follows:

R_{x} (α) = [\begin{matrix} 1 & 0 & 0 \\ 0 & \cos α & \sin α \\ 0 & - \sin α & \cos α \end{matrix}]

R_{y} (α) = [\begin{matrix} \cos α & 0 & - \sin α \\ 0 & 1 & 0 \\ \sin α & 0 & \cos α \end{matrix}]

R_{z} (α) = [\begin{matrix} \cos α & \sin α & 0 \\ - \sin α & \cos α & 0 \\ 0 & 0 & 1 \end{matrix}]

This node calculates direction cosines using the following equations:

$R = {\begin{matrix} R_{C} (ψ) R_{B} (θ) R_{A} (ϕ) & if rotation type is Passive and Intrinsic \\ R_{A} (ϕ) R_{B} (θ) R_{C} (ψ) & if rotation type is Passive and Extrinsic \\ R_{C} (- ψ) R_{B} (- θ) R_{A} (- ϕ) & if rotation type is Active \end{matrix}$

where

R_A, R_B, and R_C are the rotation matrices of the first, second, and third rotations, respectively. For example, if rotation order is Z-X-Z, R_A, R_B, and R_C correspond to R_z, R_x, and R_z, respectively.
ϕ (-π < ϕ ≤ π), θ (0 ≤ θ ≤ π), and ψ (-π < ψ ≤ π) are Euler angles.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application

Table Of Contents

Euler angles

phi

theta

psi

rotation order

rotation type

error in

direction cosines

error out

Algorithm for Converting Euler Angles into Direction Cosines

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