pytrebuchet.trebuchet module

Module defining the Trebuchet class.

Provides methods for calculating positions, velocities, and accelerations of trebuchet components.

class pytrebuchet.trebuchet.Arm(length_weight_side: float, length_projectile_side: float, mass: float, inertia: float | None = None, d_pivot_to_cog: float | None = None)

Bases: object

Dataclass representing the trebuchet arm.

length_weight_side: float
length_projectile_side: float
mass: float
inertia: float | None = None
d_pivot_to_cog: float | None = None
property total_length: float

Calculate the total length of the arm.

Returns:

total length of the arm (m)

__init__(length_weight_side: float, length_projectile_side: float, mass: float, inertia: float | None = None, d_pivot_to_cog: float | None = None) → None
class pytrebuchet.trebuchet.Weight(mass: float)

Bases: object

Dataclass representing the trebuchet counterweight.

mass: float
__init__(mass: float) → None
class pytrebuchet.trebuchet.Pivot(height: float)

Bases: object

Dataclass representing the trebuchet pivot.

height: float
__init__(height: float) → None
class pytrebuchet.trebuchet.Sling(length: float)

Bases: object

Dataclass representing a trebuchet sling.

length: float
__init__(length: float) → None
class pytrebuchet.trebuchet.Trebuchet(arm: Arm, weight: Weight, pivot: Pivot, sling_projectile: Sling, sling_weight: Sling, release_angle: float = 0.7853981633974483, projectile: Projectile | None = None)

Bases: ABC

Class representing a trebuchet.

The trebuchet’s position is defined by three angles: - angle_arm: angle of the arm w.r.t. the horizontal (radians) - angle_projectile: angle of the projectile sling w.r.t. the horizontal (radians) - angle_weight: angle of the weight sling w.r.t. the horizontal (radians)

__init__(arm: Arm, weight: Weight, pivot: Pivot, sling_projectile: Sling, sling_weight: Sling, release_angle: float = 0.7853981633974483, projectile: Projectile | None = None) → None

Initialize a Trebuchet instance with the given parameters.

Parameters:

  • arm – Arm instance

  • weight – Weight instance

  • pivot – Pivot instance

  • projectile – Projectile instance

  • sling_projectile – Sling instance for the projectile

  • sling_weight – Sling instance for the weight

  • release_angle – angle at which the projectile is released (radians)

init_angle_arm: float
init_angle_weight: float
init_angle_projectile: float
abstractmethod _initialize_angles() → None

Calculate the initial angles of the trebuchet based on its configuration.

abstractmethod classmethod default() → Trebuchet

Create a Trebuchet instance with default parameters.

calculate_arm_cog(angle_arm: float) → tuple[float, float]
calculate_arm_cog(angle_arm: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x and y coordinates of the arm center of gravity.

calculate_arm_endpoint_projectile(angle_arm: float) → tuple[float, float]
calculate_arm_endpoint_projectile(angle_arm: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y coordinates of the projectile arm endpoint.

Parameters:

angle_arm – angle of the arm (radians)

Returns:

x, y coordinates of the projectile arm endpoint, respectively

calculate_arm_endpoint_weight(angle_arm: float) → tuple[float, float]
calculate_arm_endpoint_weight(angle_arm: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y coordinates of the weight arm endpoint.

Parameters:

angle_arm – angle of the arm (radians)

Returns:

x, y coordinates of the weight arm endpoint, respectively

calculate_weight_point(angle_arm: float, angle_weight: float) → tuple[float, float]
calculate_weight_point(angle_arm: ndarray[tuple[Any, ...], dtype[floating]], angle_weight: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y coordinates of the weight point.

Parameters:

  • angle_arm – angle of the arm (radians)

  • angle_weight – angle of the weight sling (radians)

Returns:

x, y coordinates of the weight point

calculate_projectile_point(angle_arm: float, angle_projectile: float) → tuple[float, float]
calculate_projectile_point(angle_arm: ndarray[tuple[Any, ...], dtype[floating]], angle_projectile: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y coordinates of the projectile point.

Parameters:

  • angle_arm – angle of the arm (radians)

  • angle_projectile – angle of the projectile (radians)

Returns:

x, y coordinates of the projectile point

_abc_impl = <_abc._abc_data object>
calculate_projectile_velocity(angle_arm: float, angle_projectile: float, angular_velocity_arm: float, angular_velocity_projectile: float) → tuple[float, float]
calculate_projectile_velocity(angle_arm: ndarray[tuple[Any, ...], dtype[floating]], angle_projectile: ndarray[tuple[Any, ...], dtype[floating]], angular_velocity_arm: ndarray[tuple[Any, ...], dtype[floating]], angular_velocity_projectile: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y components of the projectile velocity.

Parameters:

  • angle_arm – angle of the arm (radians)

  • angle_projectile – angle of the projectile (radians)

  • angular_velocity_arm – angular velocity of the arm (radians/s)

  • angular_velocity_projectile – angular velocity of the projectile sling (radians/s)

Returns:

x, y components of the projectile velocity

calculate_projectile_acceleration(angle_arm: float, angle_projectile: float, angular_velocity_arm: float, angular_velocity_projectile: float, angular_acceleration_arm: float, angular_acceleration_projectile: float) → tuple[float, float]
calculate_projectile_acceleration(angle_arm: ndarray[tuple[Any, ...], dtype[floating]], angle_projectile: ndarray[tuple[Any, ...], dtype[floating]], angular_velocity_arm: ndarray[tuple[Any, ...], dtype[floating]], angular_velocity_projectile: ndarray[tuple[Any, ...], dtype[floating]], angular_acceleration_arm: ndarray[tuple[Any, ...], dtype[floating]], angular_acceleration_projectile: ndarray[tuple[Any, ...], dtype[floating]]) → tuple[ndarray[tuple[Any, ...], dtype[floating]], ndarray[tuple[Any, ...], dtype[floating]]]

Calculate the x, y components of the projectile acceleration.

Parameters:

  • angle_arm – angle of the arm (radians)

  • angle_projectile – angle of the projectile (radians)

  • angular_velocity_arm – angular velocity of the arm (radians/s)

  • angular_velocity_projectile – angular velocity of the projectile sling (radians/s)

  • angular_acceleration_arm – angular acceleration of the arm (radians/s^2)

  • angular_acceleration_projectile – angular acceleration of the projectile sling (radians/s^2)

Returns:

x, y components of the projectile acceleration

class pytrebuchet.trebuchet.HingedCounterweightTrebuchet(arm: Arm, weight: Weight, pivot: Pivot, sling_projectile: Sling, sling_weight: Sling, release_angle: float = 0.7853981633974483, projectile: Projectile | None = None)

Bases: Trebuchet

Class representing a hinged counterweight trebuchet.

_abc_impl = <_abc._abc_data object>
_initialize_angles() → None

Calculate the initial angles of the trebuchet.

Calculate:

  • angle_arm such that the projectile arm end just touches the ground. If the arm is too short to reach the ground, set a default angle of 55 degrees.

  • angle_weight such that the weight hangs vertically downwards.

  • angle_projectile such that the projectile just touches the ground. If the sling is too short to reach the ground, set the sling angle such that it hangs vertically downwards.

classmethod default() → HingedCounterweightTrebuchet

Create a hinged counterweight Trebuchet instance with default parameters.

These parameters are taken from https://virtualtrebuchet.com/.

class pytrebuchet.trebuchet.WhipperTrebuchet(arm: Arm, weight: Weight, pivot: Pivot, projectile: Projectile, sling_projectile: Sling, sling_weight: Sling, release_angle: float, arm_angle: float = 1.0471975511965976, weight_angle: float = 0.17453292519943295)

Bases: Trebuchet

Class representing a whipper trebuchet.

A whipper trebuchet features a hinged counterweight system, but with the counterweight hanger positioned at the top of the throwing arm. When cocked, the arm points forward in the direction of the throw. At the start, the weight and projectile ‘rest’ on the trebuchet arm.

_abc_impl = <_abc._abc_data object>
__init__(arm: Arm, weight: Weight, pivot: Pivot, projectile: Projectile, sling_projectile: Sling, sling_weight: Sling, release_angle: float, arm_angle: float = 1.0471975511965976, weight_angle: float = 0.17453292519943295) → None

Initialize a WhipperTrebuchet instance with the given parameters.

Parameters:

  • arm – Arm instance

  • weight – Weight instance

  • pivot – Pivot instance

  • projectile – Projectile instance

  • sling_projectile – Sling instance for the projectile

  • sling_weight – Sling instance for the weight

  • release_angle – angle at which the projectile is released (radians)

  • arm_angle – initial angle of the arm as measured from the horizontal (radians).

  • weight_angle – initial angle of the weight sling as measured from the arm (radians).

_initialize_angles() → None

Calculate the initial angles of the trebuchet.

Calculate:

-angle_arm based on the specified arm_angle parameter. -angle_projectile such that the projectile rests on the arm. -angle_weight based on the specified weight_angle parameter.

classmethod default() → WhipperTrebuchet

Create a whipper Trebuchet instance with default parameters.