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novaphy.actuators

Minimal actuator framework. The current public surface is the smallest data-path compatible subset needed by the Newton container contract: a PD controller that accumulates effort into Control.joint_f.

Data Flow

Actuators sit between the application's control loop and the solver. Per step:

  application target ──▶ Actuator.step(state, control)
                                       │
                                       ▼ writes effort into
                              Control.joint_f[indices]
                                       │
                                       ▼ consumed by
                         solver.step(state, state, control, contacts, dt)

The actuator never touches SimState directly; it only writes to the Control buffer's joint_f channel for the configured DOF indices, and the solver reads that channel during its step call. This keeps actuator logic, state integration, and constraint resolution cleanly separated.

Minimal Example

import novaphy
from novaphy import actuators

ctrl     = actuators.ControllerPD(kp=[10.0], kd=[0.5])
actuator = actuators.Actuator(indices=[0], controller=ctrl)

state    = model.state()
control  = model.control()
pipeline = novaphy.CollisionPipeline(model)
contacts = pipeline.contacts()

for step_idx in range(steps):
    control.joint_target_pos[0] = q_des(step_idx)
    actuator.step(state, control)              # writes Control.joint_f[0]
    pipeline.collide(state, contacts)
    solver.step(state, state, control, contacts, dt)

Classes

Class Description
Actuator Composed actuator that writes effort into control.joint_f.
ControllerPD Per-DOF proportional-derivative controller.

Compatibility Notes

Newton's newton.actuators library is significantly larger; NovaPhy does not yet provide:

  • Controller base class abstraction
  • PIDController, MLPController, LSTMController
  • Clamper / SymmetricClamper / DCMotorClamper / LookupTableClamper
  • ActuatorDelay (per-DOF command input delay)
  • ActuatorSpec, ComponentSchema, parse_usd_actuator, register_usd_schema (USD actuator parsing)