HillModel#

class HillModel( simulation_time__ms: Quantity__ms, time_step__ms: Quantity__ms, muscle_parameters: Dict[str, Any], n_motor_units_type1: int, n_motor_units_type2: int, initial_joint_angle__deg: float, initial_muscle_length__L0: float = -1.0, muscle_role: Literal['flexor', 'extensor'] = 'flexor', )[source]#

Bases: object

API wrapper for the Hill muscle model.

This class provides an intuitive interface for creating Hill muscle models with user-friendly parameter names that are internally mapped to the correct format expected by the underlying Hill implementation.

Parameters:

simulation_time__ms (float) – Total simulation time in milliseconds
time_step__ms (float) – Integration time step in milliseconds
muscle_parameters (Dict[str, Any]) – Dictionary containing Hill muscle model parameters
n_motor_units_type1 (int) – Number of type I motor units
n_motor_units_type2 (int) – Number of type II motor units
initial_joint_angle__deg (float) – Initial joint angle in degrees
initial_muscle_length__L0 (float, optional) – Initial muscle length normalized to L0. If -1, automatically calculated from joint angle. Must be between 0.7 and 1.3 if specified.
muscle_role (str, optional) – Muscle role for antagonist pairs (“flexor” or “extensor”), by default “flexor”. Used for joint dynamics calculations and result organization.

Methods

`__init__`
`add_spike`	Add a spike event for a specific motor unit.
`create_default_muscle_parameters`	Create default muscle parameter dictionary.
`integrate`	Integrate the muscle model for one time step.

Attributes

`F0`	Get maximum isometric force (F0) in Newtons.
`L0`	Get optimal muscle length (L0) in meters.
`motor_unit_forces`	Get individual motor unit forces matrix (N_units x time_points).
`muscle_acceleration`	Get muscle acceleration time series (L0/s^2).
`muscle_force`	Get muscle force time series (normalized to F0).
`muscle_length`	Get muscle length time series (normalized to L0).
`muscle_torque`	Get muscle torque time series (F0*m).
`muscle_velocity`	Get muscle velocity time series (L0/s).
`signed_muscle_torque`	Get muscle torque with correct sign for joint dynamics (F0*m).
`time_vector`	Get simulation time vector in milliseconds.
`type1_activation`	Get Type I motor unit activation time series.
`type2_activation`	Get Type II motor unit activation time series.

add_spike(motor_unit_id: int, delay__ms: float = 0.0) → None[source]#

Add a spike event for a specific motor unit.

Parameters:

motor_unit_id (int) – ID of the motor unit (0-based index)
delay__ms (float, optional) – Spike delay in milliseconds, by default 0.0

Return type:

None

integrate(joint_angle__deg: float) → tuple[float, float, float][source]#

Integrate the muscle model for one time step.

Parameters:: joint_angle__deg (float) – Current joint angle in degrees
Returns:: Muscle length (normalized to L0), velocity (L0/s), acceleration (L0/s^2)
Return type:: tuple[float, float, float]

property muscle_length: ndarray#: Get muscle length time series (normalized to L0).

property muscle_velocity: ndarray#: Get muscle velocity time series (L0/s).

property muscle_acceleration: ndarray#: Get muscle acceleration time series (L0/s^2).

property muscle_force: ndarray#: Get muscle force time series (normalized to F0).

property muscle_torque: ndarray#: Get muscle torque time series (F0*m).

property signed_muscle_torque: ndarray#: Get muscle torque with correct sign for joint dynamics (F0*m).

property type1_activation: ndarray#: Get Type I motor unit activation time series.

property type2_activation: ndarray#: Get Type II motor unit activation time series.

property motor_unit_forces: ndarray#: Get individual motor unit forces matrix (N_units x time_points).

property time_vector: ndarray#: Get simulation time vector in milliseconds.

property F0: float#: Get maximum isometric force (F0) in Newtons.

property L0: float#: Get optimal muscle length (L0) in meters.

static create_default_muscle_parameters( muscle_type: str = 'FDI', ) → Dict[str, Any][source]#

Create default muscle parameter dictionary.

Parameters:: muscle_type (str, optional) – Type of muscle model (“FDI”, “Sol”), by default “FDI”
Returns:: Dictionary of muscle parameters
Return type:: Dict[str, Any]
Raises:: ValueError – If muscle_type is not recognized