Backend

File: backend.py

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

Description:

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

Classes:

Backend	This class defines the templates for the communication and control backend.
BackendConfig	This class represents the configuration for the communication and control backend.

class pegasus.simulator.logic.backends.backend.Backend

Bases: ABC

This class defines the templates for the communication and control backend. Every vehicle can have at least one backend at the same time. Every timestep, the methods ‘update_state’ and ‘update_sensor’ are called to update the data produced by the simulation, i.e. for every time step the backend will receive teh current state of the vehicle and its sensors. Additionally, the backend must provide a method named ‘input_reference’ which will be used by the vehicle simulation to know the desired angular velocities to apply to the rotors of the vehicle. The method ‘update’ is called on every physics step and can be use to implement some logic or send data to another interface (such as PX4 through mavlink or ROS2). The methods ‘start’, ‘stop’ and ‘reset’ are callbacks that get called when the simulation is started, stoped and reset as the name implies.

Methods:

__init__(config)	Initialize the Backend class
initialize(vehicle)	A method that can be invoked when the simulation is starting to give access to the control backend to the entire vehicle object.
input_reference()	Method that when implemented, should return a list of desired angular velocities to apply to the vehicle rotors
reset()	Method that when implemented, should handle the reset of the vehicle simulation to its original state
start()	Method that when implemented should handle the begining of the simulation of vehicle
stop()	Method that when implemented should handle the stopping of the simulation of vehicle
update(dt)	Method that when implemented, should be used to update the state of the backend and the information being sent/received from the communication interface.
update_graphical_sensor(sensor_type, data)	Method that when implemented, should handle the receival of graphical sensor data
update_sensor(sensor_type, data)	Method that when implemented, should handle the receival of sensor data
update_state(state)	Method that when implemented, should handle the receival of the state of the vehicle using this callback

Attributes:

vehicle

A reference to the vehicle associated with this backend.

__init__(config)

Initialize the Backend class

initialize(vehicle)

A method that can be invoked when the simulation is starting to give access to the control backend to the entire vehicle object. Even though we provide update_sensor and update_state callbacks that are called at every physics step with the latest vehicle state and its sensor data, having access to the full vehicle object may prove usefull under some circumstances. This is nice to give users the possibility of overiding default vehicle behaviour via this control backend structure.

Parameters:

vehicle (Vehicle) – A reference to the vehicle that this sensor is associated with

abstract input_reference()

Method that when implemented, should return a list of desired angular velocities to apply to the vehicle rotors

abstract reset()

Method that when implemented, should handle the reset of the vehicle simulation to its original state

abstract start()

Method that when implemented should handle the begining of the simulation of vehicle

abstract stop()

Method that when implemented should handle the stopping of the simulation of vehicle

abstract update(dt)

Method that when implemented, should be used to update the state of the backend and the information being sent/received from the communication interface. This method will be called by the simulation on every physics step

Parameters:

dt (float) – The time elapsed between the previous and current function calls (s).

abstract update_graphical_sensor(sensor_type, data)

Method that when implemented, should handle the receival of graphical sensor data

Parameters:

• sensor_type (str) – A name that describes the type of sensor (for example MonocularCamera)

• data (dict) – A dictionary that contains the data produced by the sensor

abstract update_sensor(sensor_type, data)

Method that when implemented, should handle the receival of sensor data

Parameters:

• sensor_type (str) – A name that describes the type of sensor

• data (dict) – A dictionary that contains the data produced by the sensor

abstract update_state(state)

Method that when implemented, should handle the receival of the state of the vehicle using this callback

Parameters:

state (State) – The current state of the vehicle.

property vehicle

A reference to the vehicle associated with this backend.

Returns:

A reference to the vehicle associated with this backend.

Return type:

Vehicle

class pegasus.simulator.logic.backends.backend.BackendConfig

Bases: ABC

This class represents the configuration for the communication and control backend. Every backend has a configuration, which is used to customize its behavior. The configuration is used to instantiate the backend at the simulation start.