msg文件夾裏共有98個.msg文件、1個CMakelist.txt文件、3個文件夾，如圖：
問：這98個“.msg”文件是做什麼用的呢？
答：這98個文件是多個進程運行時共享數據的橋樑，我們來舉個例子：假設“老師”和“學校”是兩個獨立的進程，老師的任務是發送“我的成績”到“教務系統”，學校的任務是從“教務系統”上獲取“我的成績”，而“教務系統”就是“老師”和“學校”之間的橋樑。
好，下面我們就來實際操作演示一下整個過程：
第一步：首先我們要在msg文件夾裏
源碼1.10.2.msg目錄
actuator_armed（執行器）
actuator_controls
actuator_direct
actuator_outputs
adc_report
airspeed
airspeed_validated （空速驗證）
battery_status （電池電壓電流溫度s數等數據）
camera_capture
camera_trigger
collision_constraints （碰撞約束條件）
collision_report
commander_state
cpuload （cpu使用率、ram使用率）
debug_array
debug_key_value
debug_value
debug_vect
differential_pressure
distance_sensor
ekf_gps_drift
ekf_gps_position
ekf2_innovations
ekf2_timestamps
esc_report
esc_status
estimator_status
follow_target
geofence_result
gps_dump
gps_inject_data
home_position
input_rc
iridiumsbd_status
irlock_report
landing_gear
landing_target_innovations
landing_target_pose
led_control
log_message
manual_control_setpoint
mavlink_log
mission
mission_result
mount_orientation
multirotor_motor_limits
obstacle_distance
offboard_control_mode
optical_flow
orbit_status
parameter_update
ping
position_controller_landing_status
position_controller_status
position_setpoint
position_setpoint_triplet
power_button_state
power_monitor
pwm_input
qshell_req
qshell_retval
radio_status
rate_ctrl_status
rc_channels
rc_parameter_map
safety
satellite_info
sensor_accel
sensor_baro
sensor_bias
sensor_combined
sensor_correction
sensor_gyro
sensor_gyro_control
sensor_mag
sensor_preflight
sensor_selection
servorail_status
subsystem_info
system_power
task_stack_info
tecs_status
telemetry_status
test_motor
timesync_status
trajectory_waypoint
transponder_report
tune_control
uavcan_parameter_request
uavcan_parameter_value
ulog_stream
ulog_stream_ack
vehicle_acceleration
vehicle_air_data
vehicle_angular_velocity
vehicle_attitude
vehicle_attitude_setpoint
vehicle_command
vehicle_command_ack
vehicle_constraints
vehicle_control_mode
vehicle_global_position
vehicle_gps_position
vehicle_land_detected
vehicle_local_position
vehicle_local_position_setpoint
vehicle_magnetometer
vehicle_odometry
vehicle_rates_setpoint
vehicle_roi
vehicle_status
vehicle_status_flags
vehicle_trajectory_waypoint
vtol_vehicle_status
wheel_encoders
wind_estimate