Inertia

Mass m (kg), centre of mass com (m) and the six independent tensor entries (kg·m²).

Import

from robot_msgs.geometry import Inertia

ROS 2geometry_msgs/msg/Inertia

Fields

Name	Type	Default
`m`	`float`	`0.0`
`com`	`Vector3`	`Vector3()`
`ixx`	`float`	`0.0`
`ixy`	`float`	`0.0`
`ixz`	`float`	`0.0`
`iyy`	`float`	`0.0`
`iyz`	`float`	`0.0`
`izz`	`float`	`0.0`

Example

One instance from the package's own test catalog; the output is its real repr().

Inertia(m=0.75, com=Vector3(x=0.0, y=0.01, z=0.04), ixx=0.0012, ixy=1e-06, ixz=-2e-06, iyy=0.0011, iyz=3e-06, izz=0.0004)

to_dict() as JSON

{
  "_type": "geometry/Inertia",
  "m": 0.75,
  "com": {
    "_type": "geometry/Vector3",
    "x": 0.0,
    "y": 0.01,
    "z": 0.04
  },
  "ixx": 0.0012,
  "ixy": 1e-06,
  "ixz": -2e-06,
  "iyy": 0.0011,
  "iyz": 3e-06,
  "izz": 0.0004
}

Long arrays are cut after 16 values and say so with “…”.

Functions

Constructors

Classmethods and staticmethods: ways to build one.

`from_array`

from_array(array: Any) -> Inertia

No docstring.

`from_matrix`

from_matrix(m: float, com: Vector3, matrix: Any) -> Inertia

From a symmetric (3, 3) tensor; an asymmetric one is refused, never averaged.

`from_dict`

from Msg

from_dict(data: Mapping[str, Any]) -> M

No docstring.

Methods

Return new values; messages are never mutated.

`as_array`

as_array() -> np.ndarray

(10,) = m, com xyz, ixx ixy ixz iyy iyz izz.

`is_physical`

is_physical() -> bool

Positive mass, a positive semi-definite tensor and the triangle inequality on its

`rotated`

rotated(rotation: Quaternion) -> Inertia

Re-expressed in a frame turned by rotation: I' = R·I·Rᵀ, com' = R·com.

`to_matrix`

to_matrix() -> np.ndarray

The symmetric (3, 3) tensor.

`replace`

from Msg

replace(**changes: Any) -> M

A copy with some fields changed. Validation runs again.

`to_dict`

from Msg

to_dict() -> dict[str, Any]

JSON-safe dict with a "_type" key; arrays keep their dtype and shape.

Uses

Types its fields refer to.

Vector3