How to record GPS and IMU data of UAV in a certain frequency?

[Kermit Lee (KermitLee)]

I coded the code that controlled the drone to follow the path points and the code that recorded the data.
Running two parts of code using multiple threads is always wrong.
When I use the "MoveOnPathAsync" API, how can I effectively record the status information of the UAV in a certain frequency?

[David Zimmermann (zimmy87)]

There shouldn't be an issue with recording data on one thread while issuing move commands on a separate thread. Can you share the code you're using to control the drone and record data?

[Kermit Lee (KermitLee)]

Thank you for your reply. You can see it here.
issues 3599
Or you can see my simplified code.

"""
airsim  get_uav_fly_data.py
"""
import airsim
# import numpy as np
# import math
import time
# import pprint
import sys
# import threading
import _thread


def write_file(IMU_data, GPS_data, mag_data):

    file_name = 'fly_data' + ".txt"
    all_data = dict()
    all_data['time'] = time.time()
    all_data['angular_velocity'] = [IMU_data.angular_velocity.x_val, IMU_data.angular_velocity.y_val,
                                    IMU_data.angular_velocity.z_val]
    all_data['linear_acceleration'] = [IMU_data.linear_acceleration.x_val, IMU_data.linear_acceleration.y_val,
                                       IMU_data.linear_acceleration.z_val]
    all_data['altitude'] = GPS_data.gnss.geo_point.altitude
    all_data['longitude'] = GPS_data.gnss.geo_point.longitude
    all_data['latitude'] = GPS_data.gnss.geo_point.latitude
    all_data['magnetometer'] = [mag_data.x_val, mag_data.y_val, mag_data.z_val]
    with open(file_name, 'a+', encoding='utf-8') as f:
        data_str = ''
        for d_key, d_val in all_data.items():
            if d_key is 'angular_velocity':
                data_str += ','.join(list(map(str, d_val))) + ','
            elif d_key is 'linear_acceleration':
                data_str += ','.join(list(map(str, d_val))) + ','
            elif d_key is 'magnetometer':
                data_str += ','.join(list(map(str, d_val)))
            else:
                data_str += str(d_val) + ','
        f.write(data_str + '\n')


def log_with_time(sleep_time):
    state = client.getMultirotorState()
    while state.landed_state != airsim.LandedState.Landed:
        write_file(client.getImuData(), client.getGpsData(),
                   client.getMagnetometerData().magnetic_field_body)
        time.sleep(sleep_time)


def fly_by_path():
    z = -40
    path_list = list()
    # fly straight
    for i in range(400):
        path_list.append([i * 0.125, 0, z])
    v_path_list = list()
    origin_z = path_list[-1][-1]
    for p in path_list:
        v_path_list.append(airsim.Vector3r(p[0], p[1], p[2]))
    del path_list

    state = client.getMultirotorState()
    if state.landed_state == airsim.LandedState.Landed:
        print("taking off...")
        client.takeoffAsync().join()
    else:
        client.hoverAsync()

    time.sleep(0.2)

    state = client.getMultirotorState()
    if state.landed_state == airsim.LandedState.Landed:
        print("take off failed...")
        sys.exit(1)

    try:
        _thread.start_new_thread(log_with_time, (0.2))
    except:
        print("thread error")

    client.moveOnPathAsync(v_path_list, 2).join()
    client.moveToPositionAsync(0, 0, origin_z, 2).join()
    # land
    client.landAsync().join()


# connect to the AirSim simulator
client = airsim.MultirotorClient()
client.confirmConnection()
client.enableApiControl(True)
client.armDisarm(True)

fly_by_path()

client.armDisarm(False)
client.reset()
client.enableApiControl(False)

[David Zimmermann (zimmy87)]

We're going to track this investigation in #3624, as this is a duplicate of that discussion