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CSill
Beginner
1,548 Views

Intel aero // Mavros - Clock skew detected

Hi all,

when establishing a mavros connection between my Laptop (Ubuntu 16.04 LTS , running ros), and the Intel Aero RTF via UDP

$ roslaunch mavros px4.launch fcu_url:="udp://0.0.0.0:14550@192.168.0.73:14556" (IP of drone in local network)

the console yields the following

[ INFO] [1505308969.287351579]: MAVROS started. MY ID 1.240, TARGET ID 1.1

[ WARN] [1505308969.372640545]: TM: Clock skew detected (-1505308694.417684555 s). Hard syncing clocks.

[ INFO] [1505308969.393820707]: IMU: High resolution IMU detected!

[ INFO] [1505308969.393991552]: IMU: Attitude quaternion IMU detected!

[ INFO] [1505308969.727654561]: CON: Got HEARTBEAT, connected. FCU: PX4 Autopilot

[ INFO] [1505308970.051755980]: IMU: High resolution IMU detected!

[ INFO] [1505308970.052007967]: IMU: Attitude quaternion IMU detected!

[ INFO] [1505308970.740422861]: VER: 1.1: Capabilities 0x00000000000024ef

[ INFO] [1505308970.740548486]: VER: 1.1: Flight software: 01060500 (000000000181F900)

[ INFO] [1505308970.740654226]: VER: 1.1: Middleware software: 01060500 (000000000181F900)

[ INFO] [1505308970.740712155]: VER: 1.1: OS software: 000000c0 (0000000000000000)

[ INFO] [1505308970.740770259]: VER: 1.1: Board hardware: 0000a4a7

[ INFO] [1505308970.740831751]: VER: 1.1: VID/PID: 0525:a4a7

[ INFO] [1505308970.740884032]: VER: 1.1: UID: 3335511839343335

[ WARN] [1505308970.740974275]: CMD: Unexpected command 520, result 0

[ WARN] [1505308979.375366479]: TM: Clock skew detected (7718063342.435769081 s). Hard syncing clocks.

[ INFO] [1505308979.728118434]: HP: requesting home position

[ INFO] [1505308984.735264665]: WP: mission received

[ WARN] [1505308989.471157623]: TM: Clock skew detected (-7718063342.437295914 s). Hard syncing clocks.

[ INFO] [1505308989.728430551]: HP: requesting home position

[ WARN] [1505308999.473095008]: TM: Clock skew detected (7718063342.437585831 s). Hard syncing clocks.

[ INFO] [1505308999.728594636]: HP: requesting home position

Executing the mavros topic "time_reference"

$ rostopic echo /mavros/time_reference

yields the following:

header:

seq: 201

stamp:

secs: 1505309160

nsecs: 267349839

frame_id: ''

time_ref:

secs: 1505309160

nsecs: 265019000

source: fcu

---

header:

seq: 202

stamp:

secs: 1505309161

nsecs: 304928103

frame_id: ''

time_ref:

secs: 1505309161

nsecs: 265189000

source: fcu

---

now, my question: what is the reason for the Clock skew, and how can I fix it, as I believe it prevents my /mavros/mocap/pose data to be transfered to the drone, and thus, to appear in the RTFs logfiles.

regards,

Christopher

Issue has also been posted on Github: intel-aero/meta-intel-aero:

https://github.com/intel-aero/meta-intel-aero/issues/275 Intel aero // Mavros - Clock skew detected · Issue # 275 · intel-aero/meta-intel-aero · GitHub

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1 Reply
idata
Community Manager
158 Views

Hi Christopher,

 

 

Thanks for reaching out.

 

 

I was investigating regarding the Clock skew warnings and those warnings can be caused by a difference of milliseconds between your system time and the px4 time because the clock sync tolerances are low, also that the clock synchronization system is for onboard use, so you can disable it.

 

 

Please take a look at the following site for more details:

 

Hope this information helps.

 

 

Regards,

 

-Yermi A.

 

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