uav-api 0.0.4

Uav_api is a python package that provides a HTTP interface for MAVLink commands for ardupilot vehicles

Uav_api

This is the repository for Uav_api, an API for UAV autonomous flights. The Uav_api enables UAV movement, telemetry and basic command execution such as RTL and TAKEOFF through HTTP requests, facilitating remote controlled flights, both programmatically and manually. In addition to that, Uav_api supports protocol execution for autonomous flights, oferring the same interface as gradysim-nextgen simulator. At last but not least, Uav_api can be used for simulations based on Ardupilot's SITL.

Installation

Prerequisites

Python 3.10 is required If simulated flights are intended, installing Ardupilot's codebase is necessary. To do that follow the instructions at https://ardupilot.org/dev/docs/where-to-get-the-code.html (Don't forget to build the environment after cloning). In addition to that, following the steps for running the SITL is also required, which are stated at https://ardupilot.org/dev/docs/SITL-setup-landingpage.html

Installing with pip (recommended)

To install uav-api python package run the following command:

pip install uav-api

This will install the package in your current environment. After the installation is over, restart you terminal instance and you are ready to go!

Using git repository

It is also possible to install a local development version of uav_api where you can make changes. Start by cloning the repository

git clone https://github.com/Project-GrADyS/uav_api

Then, inside of the cloned repository, run the command:

pip install -e .

Now close and re-open your terminal instance and you are ready to go!

Executing the api in a real drone

Starting Uav_api

To start the server, run the following command:

uav-api --port [port for API] --uav_connection [ardupilot_connection] --connection_type [udpin or updout] --sysid [sysid for ardupilot]

Alternatively, you can use a configuration file in the following .ini format.

[api]
port = 8000
uav_connection = 127.0.0.1:17171
connection_type = udpin
sysid = 1

And run the command:

uav-api --config /path_to_config

To see more arguments options and to get better insight on the arguments for uav-api run the command bellow:

uav-api --help

And that's it! You can start sending HTTP requests to Uav_api

Executing a Simulated flight

Executing a simulated flight with UAV API is almost exactly the same as in a real drone, the only difference is that simulated flights take a few more arguments.

Starting Uav_api and SITL at the same time

To instantiate the API and Ardupilot's SITL, run the following command:

uav-api --simulated true --ardupilot_path [path to ardupilot repository] --speedup [speedup factor for SITL] --gs_connection [ip:port telemetry routing for groundstation softwares] --port [port for API] --uav_connection [ardupilot_connection] --connection_type [udpin or updout] --sysid [sysid for ardupilot]

This command initiates both the SITL, and the Uav_api API. The connection addres of the SITL instance is the one set in uav_connection argument and the speedup factor of the simulation is set to the value of the speedup argument.

It is also possible to start simulated flights through configuration files.

[api]
port=8000
uav_connection=127.0.0.1:17171
connection_type=udpin
sysid=1

[simulated]
ardupilot_path=~/ardupilot
gs_connection=[172.26.176.1:15630]
speedup=1

With the command:

uav-api --config /path_to_config

Testing and feedback

Testing API initialization

To verify the initialization of the API go to the endpoint localhost:[your_port]/docs.

Once inside the web page, scroll to telemetry router and execute the telemetry/general endpoint.

If everything is fine, the answer should look like this.

Visual feedback with Mission Planner

To get visual feedback of drone position and telemetry use Mission Planner, or any other ground station software of your preference, and connect to UDP port specified in gs_connection parameter.

Flying through scripts

One of the perks of using UAV API is being aple to quickly write scripts that control drone movement. Here are some examples

Running examples

To run the following examples run the following command inside of the flight_examples directory:

uav-api --config ./uav_1.ini

Note that this configuration file contains default values for parameters, change the values such that it matches your envinronment. You can also use your own configuration file or start the api through arguments.

Once the api is up and running, run one of the examples bellow in a new terminal instance.

Simple Takeoff and Landing

This file is located at uav_api/flight_examples/takeoff_land.py

import requests
base_url = "http://localhost:8000"

# Arming vehicle
arm_result = requests.get(f"{base_url}/command/arm")
if arm_result.status_code != 200:
    print(f"Arm command fail. status_code={arm_result.status_code}")
    exit()
print("Vehicle armed.")

# Taking off
params = {"alt": 30}
takeoff_result = requests.get(f"{base_url}/command/takeoff", params=params)
if takeoff_result.status_code != 200:
    print(f"Take off command fail. status_code={takeoff_result.status_code}")
    exit()
print("Vehicle took off")

# Landing...
land_result = requests.get(f"{base_url}/command/land")
if land_result.status_code != 200:
    print(f"Land command fail. status_code={land_result.status_code}")
    exit()
print("Vehicle landed.")

NED Square

In this example the uav will move following a square with 100 meters side. This file is located at flight_examples/ned_square.

import requests
base_url = "http://localhost:8000"

# Arming vehicle
arm_result = requests.get(f"{base_url}/command/arm")
if arm_result.status_code != 200:
    print(f"Arm command fail. status_code={arm_result.status_code}")
    exit()
print("Vehicle armed.")

# Taking off
params = {"alt": 30}
takeoff_result = requests.get(f"{base_url}/command/takeoff", params=params)
if takeoff_result.status_code != 200:
    print(f"Take off command fail. status_code={takeoff_result.status_code}")
    exit()
print("Vehicle took off")

square_points = [
    (100, 100, -50),
    (100, -100, -50),
    (-100, -100, -50),
    (-100, 100, -50)
]

# Moving
for point in square_points:
    point_data = {
        "x": point[0],
        "y": point[1],
        "z": point[2]
    }
    point_result = requests.post(f"{base_url}/movement/go_to_ned_wait", json=point_data)
    if point_result.status_code != 200:
        print(f"Go_to_ned_wait command fail. status_code={point_result.status_code} point={point}")
        exit()
    print(f"Vehicle at ({point[0]}, {point[1]}, {point[2]})")

# Returning to launch
rtl_result = requests.get(f"{base_url}/command/rtl")
if rtl_result.status_code != 200:
    print(f"RTL command fail. status_code={rtl_result.status_code}")
    exit()
print("Vehicle landed at launch.")

NED Square (Polling)

This example does the same thing as the last one but this time instead of using the go_to_ned_wait endpoint we will take a polling aproach using go_to_ned. While more verbose, this way of verifying position allows your program to do other things while the uav has not arrived to the specified location. This file is located at flight_examples/ned_square_polling.py.

import requests
import time
import math

base_url = "http://localhost:8000"

def euclidean_distance(point1, point2):
    return math.sqrt((point1[0] - point2[0])**2 + (point1[1] - point2[1])**2 + (point1[2] - point2[2])**2)

def wait_for_point(point, max_error, timeout):
    start = time.time()
    while time.time() < start + timeout:
        ned_result = requests.get(f"{base_url}/telemetry/ned")
        if ned_result.status_code != 200:
            print(f"Ned telemetry fail. status_code={ned_result.status_code}")
            exit()
        ned_pos = ned_result.json()["info"]["position"]
        print(ned_pos)
        ned_point = (ned_pos["x"], ned_pos["y"], ned_pos["z"])
        distance = euclidean_distance(point, ned_point)
        if distance < max_error:
            return True
    return False


# Arming vehicle
arm_result = requests.get(f"{base_url}/command/arm")
if arm_result.status_code != 200:
    print(f"Arm command fail. status_code={arm_result.status_code}")
    exit()
print("Vehicle armed.")

# Taking off
params = {"alt": 30}
takeoff_result = requests.get(f"{base_url}/command/takeoff", params=params)
if takeoff_result.status_code != 200:
    print(f"Take off command fail. status_code={takeoff_result.status_code}")
    exit()
print("Vehicle took off")

square_points = [
    (100, 100, -50),
    (100, -100, -50),
    (-100, -100, -50),
    (-100, 100, -50)
]

# Moving
for point in square_points:
    point_data = {
        "x": point[0],
        "y": point[1],
        "z": point[2]
    }
    point_result = requests.post(f"{base_url}/movement/go_to_ned", json=point_data)
    if point_result.status_code != 200:
        print(f"Go_to_ned command fail. status_code={point_result.status_code} point={point}")
        exit()

    arrived = wait_for_point(point, max_error=3, timeout=60)
    if not arrived:
        print(f"Error while going to point {point}")
        exit()
    print(f"Vehicle at ({point[0]}, {point[1]}, {point[2]})")

# Returning to launch
rtl_result = requests.get(f"{base_url}/command/rtl")
if rtl_result.status_code != 200:
    print(f"RTL command fail. status_code={rtl_result.status_code}")
    exit()
print("Vehicle landed at launch.")

Follower

In this example one UAV will perform a square flight (shown previously) while another UAV follows it by consuming the leader API. To run this example start 2 different uav-api process with different ports and sysid. Now start the square script using the first UAV port number, then start the follower script (located at flight_examples/follower.py) with the port number of the second UAV.

import requests
from time import sleep, time

base_url = "http://localhost:8001"
leader_url = "http://localhost:8000"
# Arming vehicle
arm_result = requests.get(f"{base_url}/command/arm")
if arm_result.status_code != 200:
    print(f"Arm command fail. status_code={arm_result.status_code}")
    exit()
print("Vehicle armed.")

# Taking off
params = {"alt": 20}
takeoff_result = requests.get(f"{base_url}/command/takeoff", params=params)
if takeoff_result.status_code != 200:
    print(f"Take off command fail. status_code={takeoff_result.status_code}")
    exit()
print("Vehicle took off")

# Follow leader for 30 seconds
start_time = time()
current_time = time()
while (current_time - start_time) <= 30:
    leader_telemetry_result = requests.get(f"{leader_url}/telemetry/ned")
    if leader_telemetry_result.status_code != 200:
        print(f"Leader telemetry fail. status_code={leader_telemetry_result.status_code}")
        exit()
    leader_pos = leader_telemetry_result.json()["info"]["position"]

    print("Got leader telemetry.")

    movement_data = {
        "x": leader_pos["x"] + 5,
        "y": leader_pos["y"] + 5,
        "z": -20
    }
    movement_result = requests.post(f"{base_url}/movement/go_to_ned", json=movement_data)
    if movement_result.status_code != 200:
        print(f"Follower go to ({movement_data['x']}, {movement_data['y']}, {movement_data['z']}) failed. status_code={movement_result.status_code}")
        exit()
    
    print(f"Follower going to ({movement_data['x']}, {movement_data['y']}, {movement_data['z']}).")

    sleep(2)
    current_time = time()

# Return to launch
print("Returning to launch...")
rtl_result = requests.get(f"{base_url}/command/rtl")
if rtl_result.status_code != 200:
    print(f"RTL command fail. status_code={rtl_result.status_code}")
    exit()

print("Landed at launch")