newton.State

class newton.State

Time-varying state data for a Model.

Time-varying state data includes particle positions, velocities, rigid body states, and anything that is output from the solver as derived data, e.g.: forces.

The exact attributes depend on the contents of the model. State objects should generally be created using the newton.Model.state() function.

Methods

__init__()
clear_forces()	Clear all forces (for particles and bodies) in the state object.

Attributes

body_count	The number of bodies represented in the state.
joint_coord_count	The number of generalized joint position coordinates represented in the state.
joint_dof_count	The number of generalized joint velocity coordinates represented in the state.
particle_count	The number of particles represented in the state.
requires_grad	Indicates whether the state arrays have gradient computation enabled.
particle_q	Array of 3D particle positions with shape (particle_count,) and type vec3.
particle_qd	Array of 3D particle velocities with shape (particle_count,) and type vec3.
particle_f	Array of 3D particle forces with shape (particle_count,) and type vec3.
body_q	Array of body coordinates (7-dof transforms) in maximal coordinates with shape (body_count,) and type transform.
body_qd	Array of body velocities in maximal coordinates (first three entries represent angular velocity, last three entries represent linear velocity) with shape (body_count,) and type spatial_vector.
body_f	Array of body forces in maximal coordinates (first three entries represent torque, last three entries represent linear force) with shape (body_count,) and type spatial_vector.
joint_q	Array of generalized joint coordinates with shape (joint_coord_count,) and type float.
joint_qd	Array of generalized joint velocities with shape (joint_dof_count,) and type float.

__init__()

particle_q: array | None

Array of 3D particle positions with shape (particle_count,) and type vec3.

particle_qd: array | None

Array of 3D particle velocities with shape (particle_count,) and type vec3.

particle_f: array | None

Array of 3D particle forces with shape (particle_count,) and type vec3.

body_q: array | None

Array of body coordinates (7-dof transforms) in maximal coordinates with shape (body_count,) and type transform.

body_qd: array | None

Array of body velocities in maximal coordinates (first three entries represent angular velocity, last three entries represent linear velocity) with shape (body_count,) and type spatial_vector.

body_f: array | None

Array of body forces in maximal coordinates (first three entries represent torque, last three entries represent linear force) with shape (body_count,) and type spatial_vector.

Note

body_f represents external wrenches in world frame and denotes wrenches measured w.r.t. to the body’s center of mass for all solvers except FeatherstoneSolver, which assumes the wrenches are measured w.r.t. world origin.

joint_q: array | None

Array of generalized joint coordinates with shape (joint_coord_count,) and type float.

joint_qd: array | None

Array of generalized joint velocities with shape (joint_dof_count,) and type float.

clear_forces()

Clear all forces (for particles and bodies) in the state object.

property requires_grad: bool

Indicates whether the state arrays have gradient computation enabled.

property body_count: int

The number of bodies represented in the state.

property particle_count: int

The number of particles represented in the state.

property joint_coord_count: int

The number of generalized joint position coordinates represented in the state.

property joint_dof_count: int

The number of generalized joint velocity coordinates represented in the state.