Pymavlink: sending optical flow messages

1

I have computed optical flow from a downwards-facing camera.
Now I would like to publish this data with pymavlink.

I’ve tried it like this:

from pymavlink import mavutil
...
self.mavlink_connection = mavutil.mavlink_connection('0.0.0.0:14550', autoreconnect=True, baud=57600)
self.mavlink_connection.wait_heartbeat()
...
self.mavlink_connection.mav.optical_flow_send(timestamp, 77, dx, dy, dx_m, dy_m, 255, z)

However, this doesn’t work:

pxh> listener optical_flow
never published

Why?
How would I do it correctly?
Thanks.

(I’m working with posix gazebo simulation.)

Appendix:

  • publishing distance sensor data works just fine:

    self.mavlink_connection.mav.distance_sensor_send(timestamp, 2, 700, 6, mavutil.mavlink.MAV_DISTANCE_SENSOR_INFRARED, 0, mavutil.mavlink.MAV_SENSOR_ROTATION_PITCH_270, 1)

  • I’ve been able to verify that both messages arrive in the self.mavlink_connection.mav.send(...) method, get handed over to a mavudp file object and are sent successfully in mavutil.py line 917.

  • Also rostopic echo /mavlink/from only shows messages with msgid: 132 (DISTANCE_SENSOR), not msgid: 100 (OPTICAL_FLOW).

  • I’ve figured out that messages sent with optical_flow_rad_send (instead of optical_flow_send) are received. However, they are still ignored by the position estimator (EKF2). iris_opt_flow works though. Maybe it has something to do with the broken MAVROS <-> MAVLink timestamps?
    listener optical_flow states timestamp: 20260000 (18446744073707.664062 seconds ago)
    Everything else seems identical to the messages published by iris_opt_flow.

    • Fun fact: ROS time issued by MAVROS is slower than r̴e͏a̧l time (53 s in 60 s). Simulation time however is even slower. Th͠ree̴ ͜diffe͏ren͏t times … w̢̕h͘y?̴͢͠?

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͏̢͢ ͟r̢͘͜et̡ur̛n̵͘ ̷͏t͘s̨̨_t҉̛o̴͝͞_̡͘͢a̕͝b͘s͏͢t́im͝e̢̕(̧͞&̨̨t̀͘͝s͟͟)̢̧͜;͜҉
C͞H̨A͏̧͜O̧S̷
҉͠#͞e͠l͟͡͞s̨̨e̢͝͝V̕͠ƠI͏D
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̙̯͕̰̪̕͡ ̢̱̱̰̖̬̯͔̗͍͚̖̠͈͜ͅͅ ̵̢̡̥̰̜̹̯̮͚͉̲̲̝̘͕̝̭̀͢p̵̢̧̯͙̗̘̦̥͉͉̟̺̕͠x̢̡̣̙͕͉̭͕̗͔̟͔̝̭̯̲̼͓͞4̴̫̫̳͠͝͠͡ͅ_̴̢̛̜͚͓̘͞c̸̕͢͝҉̼̞̖̻͉̻̘̦l̷̨̩̻͇̩͇̖̠̬͔̘̬͉͘͟ơ̷̶̴̭̖̠̺͔̥͔̙͉̼̞̦̘̣̻̕ć̻̣̹̫̣͚̦͙̺̭̞̪͔̖̣͎̬́͢ͅk̴̷̨̛͉̗̲̞̥͚̪̯̘̺̀ͅ_̖̤̭̟̥̣͖̩͙̙̰͕̰͉̦͕̕̕̕͡ͅg͢͞҉͍͉̪͇̦̱̮̼ḙ̶̤͍̰̼̟͓͘͢͡ͅt̷̼̜̭͈̼̥͍̺̻̯̗̜͙̺̹͚̕͜͜ţ̧̺̣̰̗̫̼̬͙̜i̸̴҉̛̗̯̳͕̩͚̱̺̗̫̣̘̪͕m̛̪̭̖̣͍̮̭̫̺̻̫̕͟e͞͏̡̞̞͕̞̙̩̩͍͙͔͖͕̙̭́ͅ(̜͈̲̟̻͇̀̕Ç̛̗̱͔͈̝͔̖̰̹͚͞͞͠L̟͈̤͕̦̘̪͜͢͢͞͡ͅO̼͇̦͙̦̳̻͔͘͢͞C̴̞͎̩̮̯̩̦̦͉͢͟K̴̗̫͚̪͎͈̺̟̠̘͎̰̹͚̬̠̺͞_̴͠͏̳͔̻͔̤̞͘M̡̠̯̞̘̹̟͎̫̟͚̱̺̗̝̪̫̕͡ͅͅO̧͏̶̴͔̩͇̫̙̦̫͎͚̯͘Ṋ̸̯̭̖̭͉͜Ơ̷̜̩̙̰̰̩͚̖͖̱͖̩̥̙ͅŢ̴̗̫̻̤͈͕̻̳̭̭͕̺̰̠͝ͅO̢̨̦̼̜̘̖̙̮͈̺̖̥̮̰͉͚̻N͙̼̳̜͘͜I̶̝̰̘̼͈̺̗͠C̵̢̘̥̮̰̪̩̺̕͢͠,͠͏̡̢̛̦̜̞̺̲̩̫̺͎̪͚̼̦̭̼͕̣ ̶̵̢͚̟̟̞̣̪̖̻̹̟ͅ&̷̦͍̮̘̟̲̝̪̗̫̀ͅt̛̖̻̘̮̹̜̮̩̣͔̬̝͍̀͠͝s̸̡͎̫͚̦̟͇̞̘͘͜͠)̸̷̢̰̝̰̟̞̯̟́ͅ;̷̹̮̱͉͓͚͔̰̟̺̲̲̰̼̫̕
̵̨̞͉̹͔̲̻͕̳̦͠ ̨͉̲̫͕͔̥̼͎̖̦̹̙̹̼̼ͅ ͡҉̧̧̲̖̟̮͖͖̹̥̣̤̹p̡̧͓̘̼̦͓͠x̧̛̝̲̦̲̖̫̰͉̖̩͔̫̞̺́͞͠ͅͅ4̷̹̝̣̥̰̱̻̭̫̺̩̦͍̜͇͇̟̣_̨͞͏̼̣̲̗̟͓̪̣̬̟̹̗̱͓t̵̵̤͕̝̝̯̺͍͖̲̬̬͓̻̤̬̀í̶̳̼̪̹͕͜ͅm͎̦̤̠̙͘͡͡e̶͍̻͓͍͕̙͓̥̫̞̜̙͢͝͠ͅs҉̢̪͔̖̻t̸̷̵̯̣̰͍͍͎̰̱͓̤̟͎̪͘ͅa҉̴̛́҉̲̱̟͎̮͓ŕ̦̹̩̼͙͡͡ţ̴̥̜͉͖̫̱̠̹͡͡ ̵҉͏͈͖̤͔͍̤̙̺͎̥̫̯͉̲̹̖̠͠=̨͔̘̭̥͔̻͖̘͔͕͙͈͘̕͟͞ ̴̨̩̺͓̻̯̘͈̞̻̮͈̣̻͍̕͝t̶̸̨̲͉͇̜̺̮̬̤̩̲̣̖̟̰̀ͅs̠͍͓͚͖̖̦̳̠̗͔̻̪̘̲̲̗̣͘͡_̵̡̹̭̝̣́͡t̶҉͙̳̤̺̱̳̬̲̤̳͓̙͙̣̯ò̢͎͚̬̠͍̖̜̹͍͍͓̫͖̰̟̯_̰̼̖̹͍̖̟̣̳̤͜͡ͅa͇̭̞͙̫͖͉͉̰̫̬͠b̛͞͏̵͓͚͚s҉̶̨̤͓̦̤t̶̛̝̜̳̯̝̟͈͓̻̖͈̭͔̠͉̳̥͈̝͞í̩͈͙̪̥̮͇̯̩͍̲͉̝ḿ̝̠̙͠ͅé͠͏̤̫̞͚͚(̶̶̠͚̗̼͟͞&̷̱̭͎̤̳̻̫̟̭͔̬̦̝̀͢ͅt͏̵̵̧̜̩͉̫̼͚͖̲̦͍̺͇͝ş̷̛͓̬̦̩̫̠̭̥̟̼̩̮͠͝)̧͏̡͇͓͍̫̱̤̣̞̞̠͠͞;̗͙̤̦̘͔̞̱̥̼̼͈̹͍̥̫́͘
͓̬̥͕̮̫̝̰̯̪͎́̕͞ ͓̮̩̞̣̹͔̀̕}͔̠͔̩͟͡͠ͅ
͕̖̙̺̟̤̲̗̹͉͔̻́̀ͅI̧҉͔̜͎͎̼̮̱͈̯̳͉̦͔̩̤́͘ͅM̢͏̠͇̦͎̯̣͖̝̟̼̘̱̘̗̮͚͉̖̕ ̷̪̹͙̼̕͟͡D̶҉҉̠̼̮̤̥̗͓̺̟͓̮̳͍̮̞̗̫ͅO̵͏҉̢̹͉̞̭̩̲͖͔̩͈̩̣͚̘̺̗̱̀N̴̦̺̟͓̳͇̪͖̰̬͔̰͙͞È̮̟͓͉͚̰͖͕̙̼̗͇͖̭̭͕̝̫̕͟͡
̯̰͓̹̰̩̩̬̀̕ ̶̡̳͓͈̻͉͙̦̝̬̲͉̯̣͚̫͠ṕ͓̲͙̤̦̤͈͕͈̺̬͉̱͈̮x҉̸̣̹̲̭͈̜͙̭͙̳̠͈̺̙̖̪͉̺͜ͅ4̧̝̳̫͚̹̫̜͡_̶̬̟̬̹͉̩͈͔̻̳̩͍̱͓̺͇c̨̛̜̲̪͉̪̀͠͠ͅļ̨̪͕͕̣̮̞͖̼͙̪̤͓͈̱̺͖̺̳͢o̴̯̜̬̣̭̦̦̺̕͢c̕҉̪̝͍̯̳̮̩͔̺̞̹͕̳̲k̶̸̼̲̰̱͖̫̣̦̬͍̗_̣̲͔̘̲͘͜g͞͏̢͕͚̟͔̬̰̮̘̜̦̼͇̹̟̜͈̫̪͢͟e̶̢̧̯͖͖̦̯̦̳͇̳͟͝t̸͎͖͍̟̫̰͇̜̟́t̵̷͢͏͖͍̳͓̙͈͉̺͓̙̺͚̩̭̭i̶̴̧̹͍̭̥͓̬͍̰͕̬̰͉̻̦͜ḿ̷̶̶͎̠̦̠̫͎̱̩̖͔̣̼͠e̶̸̸̟̲͍̝͈̬̣̝̞̪̞̹̗͉͖̤̗͈͢͟ͅ(̡̘̦̩͙͇͎̹̥̮͖̩̹̮̳̙̥͕͈̀̕̕C̸̢̛͖̥̱Ļ̧͈̫̻͕̤̩̪̠̥̠̯͇͙͕̘̳̭Ǫ̴͏̟̰̣̬̻̣̻̘͎C̀͞҉͏̗̜̱Ḳ̛̣̪̠̼̖̦͇̪̺͖̩͓̮̭͕͉͈͟͜_̷̠̲̯̩̺̯̖̣͚͚̕M̞͕̖̯̩̯͙͔͈̘͕͎͇͠͡͝͞Ò̶̞͍͈͉̤͙̠̣̩̥̺̟͘͟ͅN͔̹͚̹̕͜Ó̮͉̘̤͕͓̝͕̻͢Ţ̹̹͈̹̝͕̰̝̹̮̻̬̮̮̣̞O̶̡҉̥͚̻͉̰̩͈̰̫̩̹ͅN͝͏̴̙̣̙̠̗͙̺̰͉͇̩̙̰͎̮͈͡͝ͅĮ̨̧̫̹̮̲͢C̨҉̭͖̤̱͓̜̜͚̖̘͈̜͠͞,̴̤̤̼̺̮̩͉͉̪͖̞̭͠ ̨̧̦̹̝͉̙̣͘&́́͜͏̨͉͍̫t̶͓͖̬͍̰̰̼̻̣̬̱̞͔̫͘͟ͅs̶̨̫̦͚͚̺̰͇̬̭͈͝)͝͏̫̫̻̠;̶̘͓̘̯̯̗̯̪̺̤̩͔͇̕
̷̵͚̼̠̠̭ ̛͚̱͓͖̬̖̱͚̯̫͕̣͍̰̪̹̘̜̙͢r̢̨͍̣̱̱̥͝ȩ̨̩̬͕̞̹́͝͝ͅt̵͏̷̢͍͔͔̙̤͙̖͙̞͖̟̪̥͡ų̷̸̜͇͍̥̟̜͕̤̬̣̀͢ṟ̵̛̣͉͓̦̮̭̫͚̣̭̦̯̞ͅn҉͕̝̗̣͙͕̳̱̭̘́́͘ ̻̞̼̝͇͖̩̦̩̮̳͘͝t̛̳͍̺̖̯̮̞̳̺̺̯̬͎̰ͅs̵̛͙͕̠̣̰͖̘̣̰͍_̡̛̩̻̦̯̰̰̫̜̤͎̯̲̭̮͟t̷̵̢͉̬͖̲̥̤̹̥͕̩̳̥̀ͅó̴̴̸̗̣̳̘̜̪̯͜_̵̧̖͕̣̠̱̦̫̝̺̲̜͍̳̬̺̩͎͟͝a̸̧̧̼̻̺̘̲ͅb̵̪̪̫͇̀s̶͏҉̶̣̭̮̪t̶͟҉̦͈̦̯̟̣̀́ͅì͟͟҉̸̭̲͉̝̖̭̬̜̹̹m̴҉͉͉̱̪͈̦̭̺͕ḛ̵̺̩̻̭͙̭͘͢͡(͠͏̵̛̮̱̖̱̝̪̱&̴̘̲̳͉̱͚͎̬̖̮̀͟͜͝ţ̼͈͕̱s̵̵̻͎̞̱̼͍͢͟ͅͅ)̕͟͢҉̶͎͍͔̮̻͍̖ ̧̛͔̭̣̻̖͇̕͝-̷̱͇̜̲̫͓͍̜͟͝ ̷̵̫̻̬͙͈̝̤̺̖̜͈̱͇̞p̶̝̬̗̰̻̩̻̖͚̙͕͖̪͕̯̰͚͜͡x̸̛͇̹͈͍̕4̵̢̣͙̥̝̦͎̺̘͙̙͕̼͚̕ͅ_̶̵̧̻͉̰̟̹t̷̵̲͍̹̮͖̺̣̼̤̖̯͎̲̹͎̼̗i̛̪̬͎͕͎͕͚̲͍͘͜͟͡m̷̴̝̘̦͇̰͉̦̖̼̼͠e͞҉͙̥͍s͞҉̷̛̫͓̮̙̳͕͍͙̦̥̹̩͔̖̩ţ̜̹͎̩̪͕̤̰̗̗͜͞ą̸̛̺̥̠̹̙̭͙͙̝̖̘͇̀͘ŕ̴̢̖͔̣̩͇̜̦̩̭̜͉̫̳̫̗̤̕͠t̺̞͚̩͕͉͉̙͔̼̤̘͖͍͓͢͞;̨̧̠͍̭̺͓̠̩̰̭̺͓̹
̸̶͏҉̦͎̙̥̼͎͇̤͎̮̩̜̘͇̮̫#̵̸̵̴̹̼̲̳̣̻͎͚͇̯͕̖̙e͡҉̨̡̛̹͙͎̮ǹ̴̹̺̪̜̳̝̞͚̯͙͕͜d̶̶̛̛̬̣̹͎̲̘̲͍͕̗̻̩̼̠͡i̬̞̣̻͇͈̪͍̣͈̬̩̠̘͔̗͍͚̞͡f͕̺̠̕̕͡ ̷̠̣̙̳̖̮͖̜̲͇̫͙͚͚͈͟͜͜T̴̷̶̷̯̥̬́H̶̛̛̜͈̱̰̼̯̜͓͕̟̱̩̞͇̀į̴̶̖̯̥͕͔̖͓̱̲͎͓̰̣͍̣s̵̡̪̩̮̙̰̰͈̦͎̹͔̼̼̣̮͜͡ ̛͖͎̦̯̜̮̻̙̀́i̴͖̝̙͙͙̺͝Ş̶̯̰̭͙̫̖͈̟͚̣͢͢͝ͅ ̷̵҉͓̗͉̘̭̥͕̣͓̲̦̻͎̪̙̀T̶̤̖̫̝͍̺̳͇̞̖͎͇͕̩̥̀̀͘͘Ḩ͙͉̗͈̟̘̫E̢̨͖̖͙͍ ̛̪̥̻̲̘͇̥͞E̶̜͇̞̟̺̗N̛̖̘̬̰͉̼̟̫̠͠D̡̢̡̛̛̬͙͈͈̭̼̯͈̻͚̬̪̙ͅ
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