Lifting Surfaces

Description

Mathematical Model

Class Description

class PyFlyt.core.abstractions.LiftingSurface(p: BulletClient, physics_period: float, np_random: RandomState, uav_id: int, surface_id: int, lifting_unit: ndarray, forward_unit: ndarray, Cl_alpha_2D: float, chord: float, span: float, flap_to_chord: float, eta: float, alpha_0_base: float, alpha_stall_P_base: float, alpha_stall_N_base: float, Cd_0: float, deflection_limit: float, tau: float)

Used to represent a single lifting surface.

The Lifting Surface component is used to simulate a single lifting surface based on “Real-time modeling of agile fixed-wing uav aerodynamics, Khan et. al.”.

Args:

p (bullet_client.BulletClient): PyBullet physics client ID. physics_period (float): physics period of the simulation. np_random (np.random.RandomState): random number generator of the simulation. uav_id (int): ID of the drone. surface_id (int): an integer for the link ID for this lifting surface. lifting_unit (np.ndarray): (3,) unit vector representing the direction of lift. forward_unit (np.ndarray): (3,) unit vector representing the direction of travel. Cl_alpha_2D (float): lift coefficient slope under a no-stall condition. chord (float): chord of the lifting surface. span (float): span of the lifting surface. flap_to_chord (float): ratio of the wing that is an actuated flap, can be in [0, 1]. eta (float): correction factor for viscosity effects, usually 0.65. alpha_0_base (float): zero lift angle-of-attack. alpha_stall_P_base (float): positive stall angle in degrees. alpha_stall_N_base (float): negative stall angle in degrees. Cd_0 (float): drag coefficient at zero angle-of-attack. deflection_limit (float): maximum deflection limit of the actuated flap in degrees. tau (float): actuation ramp time constant.

get_states() → float

Gets the current state of the components.

Returns:

float: the level of deflection of the surface.

physics_update(cmd: float)

Converts a commanded actuation state into forces on the lifting surface.

Args:

cmd (float): normalized actuation in [-1, 1].

Returns:

tuple[np.ndarray, np.ndarray]: vec3 force, vec3 torque

reset()

Reset the lifting surfaces.

state_update(surface_velocity: ndarray)

Updates the local surface velocity of the lifting surface.

Args:

surface_velocity (np.ndarray): surface_velocity.

class PyFlyt.core.abstractions.LiftingSurfaces(lifting_surfaces: list[LiftingSurface])

Handler for multiple lifting surfaces.

This is a convenience class for handling multiple lifting surfaces as a single object. Simply pass it a list of LiftingSurface objects.

Args:

lifting_surfaces (list[LiftingSurface]): a list of LiftingSurface objects.

get_states() → ndarray

Gets the current state of the components.

Returns:

np.ndarray: a (num_surfaces, ) array representing the actuation state for each surface

physics_update(cmd: ndarray)

Converts actuation commands into forces on the lifting surfaces.

Args:

cmd (np.ndarray): the full command array, command mapping is handled through command_id and command_sign on each surface, normalized in [-1, 1].

reset()

Resets all lifting surfaces.

state_update(rotation_matrix: ndarray)

Updates all local surface velocities of the lifting surface, place under update_state.

Args:

rotation_matrix (np.ndarray): (3, 3) OR (num_surfaces, 3, 3) array rotation_matrix