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Re: [Paparazzi-devel] Problem in sending commands from GCS


From: Gautier Hattenberger
Subject: Re: [Paparazzi-devel] Problem in sending commands from GCS
Date: Thu, 18 Jul 2013 21:44:21 +0200
User-agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130623 Thunderbird/17.0.7

Hi,

If you are using XBee modems in transparent mode, for some weird reason it seams that the bandwidth is limited to 9600 bauds, even if the serial link with the modem is faster.
If you set your modem to use the API mode of the XBee, then the bandwidth is much higher and changing settings/waypoints works much better (at least for me).
I couldn't find any information about this behavior in the datasheet.

Gautier

 
Le 18/07/2013 18:13, Michal Podhradsky a écrit :
Hi,
I would back up Stephen - in other words, if you fill up the downlink bandwidth too much (i.e. too many telemetry messages), the link is full almost all the time, so if you send a command up to the airframe, it will collide with telemetry packets.

A quick solution would be to decrease message rate or number of messages, or crank up the bandwidth.

Michal


On Thu, Jul 18, 2013 at 10:00 AM, Stephen Dwyer <address@hidden> wrote:
Hello,

I have also experienced this: telemetry works well, but it is nearly impossible to change settings without clicking perhaps 10 or 15 times. After some investigation it turned out our modems were configured in a very suboptimal manner. Almost every time a command was sent from the GCS up to the aircraft, it resulted in a packet collision between the ground radio and air radio. Since they both had similar settings for delays and retries, we would occasionally see 5 or 10 collisions in quick succession, after which one or both radios would give up. This behaviour was easily reproducible on the ground (we initially thought it was poor range in the radios).

Not sure if this is the same thing, but something to look into. We used a logic analyzer to test our setup, but you might be able to try something else. Perhaps you could disconnect the tx line between the autopilot and radio, and instead run that directly to the GCS with an FTDI adapter or something, and see if changing settings is more successful.

For energy control settings, try including conf/settings/control/ctl_energy.xml and conf/settings/estimation/ac_char.xml.
(ac_char.xml returns estimates about the aircraft climb, descent and level flight characteristics).

Hopefully that helps.

Thanks,
-Stephen Dwyer


On Thu, Jul 18, 2013 at 3:43 AM, Loic Drumettaz <address@hidden> wrote:
Hi Refik,

I have experienced something similar to you: when trying to move a waypoint using the CGS.


I could move it 1 or 2 times and then the setpoints would'nt move anymore. At this time the downlink was still good.. Is there a way to check the datalink is OK?

About energy control loops, have you seen that the wiki has been updated recently?

Best regards
Loïc



Dear friends,

After take of with auto1, we switch to auto2 mode. The plane goes to standby 
and circles perfectly. We can receive telemetry also. But in some of the 
flights (not all of them), when we send commands (like change altitude or land) 
the plane does not receive the commands. Then we manually land. 

We have umarim_light_v2 board, ets_airspeed sensor and Xbee modem, and the 
session is flightUSB serial 57600.

We changed the example airframe file of umarim_lite and use the energy control 
subsystem. Duing compile, it gave some errors due to settings file therefore we 
removed some of the buttons in the settings file.  Does it create this error?

We can not change some basic parameters like cruise_throttle. Is there an 
example settings file for energy control?

The plane flies perfect therefore I want to continue using energy control. But 
I dont know the details of it so we are using it with trial and error. Is there 
a documentation of it?

In simulation, there is no problem. We are using version of 
v4.9_devel-812-g8f341f0-dirty. I am sending configuration files. Could you 
please send some recommendations?

Regards,
Refik

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