phyz-model

Articulated model and state types for phyz.

The static description of a mechanism (Model) and its time-varying configuration (State). Built with a fluent ModelBuilder; consumed by phyz-rigid, phyz-diff, phyz-gpu and the rest of the workspace.

Types

• Model — bodies, joints, actuators, gravity, dt, nq, nv
• ModelBuilder — add_revolute_body, add_prismatic_body, add_spherical_body, add_free_body, add_fixed_body, add_body
• Body, Joint, JointType, Geometry, Actuator
• State — q, v, ctrl, time, body_xform, qfrc_external

Example

use phyz_math::{GRAVITY, Mat3, SpatialInertia, SpatialTransform, Vec3};
use phyz_model::ModelBuilder;

let model = ModelBuilder::new()
    .gravity(Vec3::new(0.0, -GRAVITY, 0.0))
    .dt(0.002)
    .add_revolute_body(
        "upper",
        -1,                              // parent: -1 is the world
        SpatialTransform::identity(),    // parent frame -> joint frame
        SpatialInertia::new(
            1.0,
            Vec3::new(0.0, -0.5, 0.0),
            Mat3::from_diagonal(&Vec3::new(0.083, 0.0, 0.083)),
        ),
    )
    .add_revolute_body("lower", 0, SpatialTransform::identity(), /* ... */
        SpatialInertia::new(0.8, Vec3::new(0.0, -0.4, 0.0),
            Mat3::from_diagonal(&Vec3::new(0.043, 0.0, 0.043))))
    .build();

let state = model.default_state();
assert_eq!(model.nq, 2);

Bodies form a kinematic tree: each body names its parent by index, -1 meaning the world. Joint transforms are Plücker transforms from the parent body frame to the joint frame.

Part of phyz

phyz is an open-source differentiable multi-physics simulation workspace in pure Rust. Each crate is independent — adding this one does not pull in the rest.

Licensed under MIT.