Inertia

class compas_fab.robots.Inertia

Bases: object

The moments of inertia represent the spatial distribution of mass in a rigid body.

It depends on the mass, size, and shape of a rigid body with units of [mass * m**2]. The moments of inertia can be expressed as the components of a symmetric positive-definite 3x3 matrix, with 3 diagonal elements, and 3 unique off-diagonal elements. Each inertia matrix is defined relative to a coordinate frame or set of axes.

Notes

Assuming uniform mass density, inertial data can be obtained using the free software MeshLab, refering to this great tutorial.

Examples

>>> inertia = Inertia([[0] * 3] * 3, 1., Point(0.1, 3.1, 4.4))
>>> inertia
Inertia([[0, 0, 0], [0, 0, 0], [0, 0, 0]], 1.0, Point(x=0.1, y=3.1, z=4.4))
>>> inertia.principal_moments
[0, 0, 0]

Attributes:

inertia_tensorlist of float

A symmetric positive-definite 3x3 matrix: | ixx ixy ixz | | ixy iyy iyz | | ixz iyz izz | with [ixx, iyy, izz] as the principal moments of inertia and [ixy, ixz, iyz] as the products of inertia.

mass: float

The mass of the object in kg.

center_of_massPoint

The center of mass of the object in meters.

Methods

calculate_inertia_tensor

Returns the inertia tensor.