State

File: state.py

Author: Marcelo Jacinto (marcelo.jacinto@tecnico.ulisboa.pt)

License: BSD-3-Clause. Copyright (c) 2023, Marcelo Jacinto. All rights reserved.

Description: Describes the state of a vehicle (or rigidbody).

Classes:

State

Stores the state of a given vehicle.

class pegasus.simulator.logic.state.State

Bases: object

Stores the state of a given vehicle.

Note

• position - A numpy array with the [x,y,z] of the vehicle expressed in the inertial frame according to an ENU convention.

• orientation - A numpy array with the quaternion [qx, qy, qz, qw] that encodes the attitude of the vehicle’s FLU body frame, relative to an ENU inertial frame, expressed in the ENU inertial frame.

• linear_velocity - A numpy array with [vx,vy,vz] that defines the velocity of the vehicle expressed in the inertial frame according to an ENU convention.

• linear_body_velocity - A numpy array with [u,v,w] that defines the velocity of the vehicle expressed in the FLU body frame.

• angular_velocity - A numpy array with [p,q,r] with the angular velocity of the vehicle’s FLU body frame, relative to an ENU inertial frame, expressed in the FLU body frame.

• linear acceleration - An array with [x_ddot, y_ddot, z_ddot] with the acceleration of the vehicle expressed in the inertial frame according to an ENU convention.

Methods:

__init__()	Initialize the State object
get_angular_velocity_frd()	Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the angular velocity expressed in the body frame to the NED-FRD convention used by PX4 and other onboard flight controllers
get_attitude_ned_frd()	Method that, assuming that a state is encoded in ENU-FLU standard (the Isaac Sim standard), converts the attitude of the vehicle it to the NED-FRD convention used by PX4 and other onboard flight controllers
get_linear_acceleration_ned()	Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the linear acceleration expressed in the inertial frame to the NED convention used by PX4 and other onboard flight controllers
get_linear_body_velocity_ned_frd()	Method that, assuming that a state is encoded in ENU-FLU standard (the Isaac Sim standard), converts the linear body velocity of the vehicle it to the NED-FRD convention used by PX4 and other onboard flight controllers
get_linear_velocity_ned()	Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the linear velocity expressed in the inertial frame to the NED convention used by PX4 and other onboard flight controllers
get_position_ned()	Method that, assuming that a state is encoded in ENU standard (the Isaac Sim standard), converts the position to the NED convention used by PX4 and other onboard flight controllers

__init__()

Initialize the State object

get_angular_velocity_frd()

Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the angular velocity expressed in the body frame to the NED-FRD convention used by PX4 and other onboard flight controllers

Returns:

A numpy array with [p,q,r] with the angular velocity of the vehicle’s FRD body frame, relative to an NED inertial frame, expressed in the FRD body frame.

Return type:

np.ndarray

get_attitude_ned_frd()

Method that, assuming that a state is encoded in ENU-FLU standard (the Isaac Sim standard), converts the attitude of the vehicle it to the NED-FRD convention used by PX4 and other onboard flight controllers

Returns:

A numpy array with the quaternion [qx, qy, qz, qw] that encodes the attitude of the vehicle’s FRD body frame, relative to an NED inertial frame, expressed in the NED inertial frame.

Return type:

np.ndarray

get_linear_acceleration_ned()

Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the linear acceleration expressed in the inertial frame to the NED convention used by PX4 and other onboard flight controllers

Returns:

An array with [x_ddot, y_ddot, z_ddot] with the acceleration of the vehicle expressed in the inertial frame according to an NED convention.

Return type:

np.ndarray

get_linear_body_velocity_ned_frd()

Method that, assuming that a state is encoded in ENU-FLU standard (the Isaac Sim standard), converts the linear body velocity of the vehicle it to the NED-FRD convention used by PX4 and other onboard flight controllers

Returns:

A numpy array with [u,v,w] that defines the velocity of the vehicle expressed in the FRD body frame.

Return type:

np.ndarray

get_linear_velocity_ned()

Method that, assuming that a state is enconded in ENU-FLU standard (the Isaac Sim standard), converts the linear velocity expressed in the inertial frame to the NED convention used by PX4 and other onboard flight controllers

Returns:

A numpy array with [vx,vy,vz] that defines the velocity of the vehicle expressed in the inertial frame according to a NED convention.

Return type:

np.ndarray

get_position_ned()

Method that, assuming that a state is encoded in ENU standard (the Isaac Sim standard), converts the position to the NED convention used by PX4 and other onboard flight controllers

Returns:

A numpy array with the [x,y,z] of the vehicle expressed in the inertial frame according to an NED convention.

Return type:

np.ndarray