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Re: [Paparazzi-devel] simultaneously using two autopilot systems for rel


From: Sergey Krukowski
Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems for reliability
Date: Mon, 25 Nov 2013 22:26:24 +0100
User-agent: Opera Mail/11.61 (Win32)

Hi!

Want also add my 2 cent.
It looks like a hardware problem of your particular board sample. But definitely it's not a good sign. There is no way to get the AP more stable with an external circuitry rather than to get the AP be stable itself. It just HAS to work for hours in full configuration on the ground before you allow yourself to go flying with it.
Just try to follow all of the recommendations guys suggested here.

Best Regards,
Sergey

Hi Stephen,

Thank you very much for the comments,

Refik


From: address@hidden
[mailto:address@hidden On
Behalf Of Stephen Dwyer
Sent: Monday, November 25, 2013 10:02 PM
To: Paparazzi UAV devel list
Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems
for reliability


Hello,


A couple comments that might help:


It definitely sounds like you have a power problem that causes resets or
brownouts (after which who knows what might happen, given no watchdog
currently). I would really suggest avoiding the use of the 5V linear
regulator onboard Lisa/M v2 unless you are power nothing else. This is a
known design limitation - the regulator can not really handle any peripheral
loads as it is only rated for 250mA. I like to power my board with 5V
directly and bypass the onboard 5V regulator. See
http://paparazzi.enac.fr/wiki/Lisa/M_v20#Powering_the_Board for more
details. My guess is your radio draws perhaps 100mA or more, and if you
consider all the other peripherals and the STM32 draw as well, at 12V input
brownout or thermal shutdown is highly likely.


Regarding i2c, I am not 100% sure the current status of that issue, but I do know trying to talk to the eagle tree sensor before it is ready causes the
i2c hardware to lock up. I also think that you might be able to power the
eagle tree sensor a little bit just over the datalines, especially if there
are pullup resistors letting some current through.


I think setting up a watchdog and resetting the autopilot in flight is
fairly dangerous. You will need to carefully comb through all the code and
check all the initialization. For one, if you are using an internal AHRS,
the AHRS needs be aligned on startup without moving the IMU. This is
difficult if the aircraft is already in the air... If you are only wishing to get back into a mode where you can manually fly the aircraft, that would be much easier. Of course, if you are using an external INS/AHRS then this
alignment isn't required.


I think your best bet is still to look at your power supply and clean that up (also make sure no ground loops), and bench test after that to see if you
still have failures.


Perhaps someone with more knowledge can weigh in as to whether an in-flight
restart is feasible.


Thanks,

-Stephen Dwyer


On Mon, Nov 25, 2013 at 12:04 PM, Refik Sever <address@hidden>
wrote:

Thanks Michal...


From: address@hidden
[mailto:paparazzi-devel-bounces+refiksever
<mailto:paparazzi-devel-bounces%2Brefiksever> address@hidden On
Behalf Of Michal Podhradsky
Sent: Monday, November 25, 2013 8:59 PM


To: Paparazzi UAV devel list
Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems
for reliability


Refik,

just a side note - we have BlackMagic debugger and pretty often we have that flash erase error (both when uploading from Eclipse or Paparazzi center - obviously it is gdb related thing). But you can upload for second time then
it usually works.

Try this command sequence in gdb:
target extended-remote /dev/ttyACM0
monitor jtag_scan
attach 1
monitor vector_catch disable hard
set mem inaccessible-by-default off
monitor option erase
set print pretty

and then load the target
.

monitor option erase should undo the flash write protection, but sometimes
it just doesn't work.

M


On Mon, Nov 25, 2013 at 11:36 AM, Refik Sever <address@hidden>
wrote:

Hello,


Chris, I observed that when the modem tx power is above 25mW, then the
voltage of modem drops to 4V. Thanks for warning. We will give the voltage
from a different supply.


Michal, I was not aware of I2C issue. We are using airspeed and temperature sensors connected to I2C. It seems that the I2C issue is a serious problem.


We bought a BlackMagic probe and today we start working on debugging. We
tried to upload using JTAG cable, but it always gives an error that it can not erase the flash when we upload from GCS. When we upload from terminal,
it usually uploads successfully and sometimes it gives the same error.


We want to have a very reliable system which can work for hours. I am
planning to use a second autopilot which does not have any peripheral. It
will be connected only to GPS, and maybe to modem also. It will always be on standby mode. I ordered an FPGA board. If it works porperly, I hope that
the system will be more reliable.  And I understand that using a watchdog
timer outside of the microcontroller will be better. I am planning to use
the FPGA for that purpose.


Do you have recommendations about the connection of the second autopilot?


1. We can add the second autopilot with a second modem using API mode and
the GCS will see the two autopilots as 2 different airplanes.


2. We can add only one modem and both of the autopilots will receive same
commands from GCS, but only one of them transmits data to GCS.


3. The second autopilot will not have a modem. It will always be on standby mode. If the primary autopilot will freeze, the second autopilot will bring
the plane to the standby.


Regards,

Refik






From: address@hidden
[mailto:paparazzi-devel-bounces+refiksever
<mailto:paparazzi-devel-bounces%2Brefiksever> address@hidden On
Behalf Of Michal Podhradsky
Sent: Monday, November 25, 2013 7:23 PM


To: Paparazzi UAV devel list
Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems
for reliability


Refik,

since you mentioned using I2C, look at the pending issue with I2C causing
the autopilot to freeze (https://github.com/paparazzi/paparazzi/pull/531).
What happens if you disable the I2C sensor, does it still hang?

Also, do you have a debugger (http://paparazzi.enac.fr/wiki/JTAG)? That
would be probably the easiest way to find what happened.

M


On Mon, Nov 25, 2013 at 9:40 AM, Eduardo lavratti <address@hidden>
wrote:

When i do the first test with mine lisa_m it reset or hang.
This occur when i power the board with 12v and the internal regulator work
very hot and then turn off.

To solve this i use a external 7.4volt regulator that power the board.

After this the board not hang anymore.

  _____

From: address@hidden
Date: Tue, 26 Nov 2013 00:51:55 +1100
To: address@hidden


Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems
for reliability

 Although we do not give power to the Ets in the upload, its 7 segment
display works and blinks. I think that it takes power from I2C pins. Does it
create a problem in the upload?

I don't know. Can you remove everything then add them back one by one,
testing in between? That's software-guy thinking, maybe a hardware person
has a more informed idea...


Chris Gough


Refik






From: address@hidden
[mailto:paparazzi-devel-bounces+refiksever
<mailto:paparazzi-devel-bounces%2Brefiksever> address@hidden On
Behalf Of Chris Gough
Sent: Monday, November 25, 2013 2:48 PM
To: Paparazzi UAV devel list
Subject: Re: [Paparazzi-devel] simultaneously using two autopilot systems
for reliability



When the modem TX power is 25mw or higher, then the IMU does not work
properly and also does the autopilot. It still sends messages, but the
behaviour is not normal. The PFD screen does not work properly etc. We can
see it on the bench. When the TX power is 1mW, then it works properly.

That makes me very suspicious of a power supply problem. Increasing the
power supply (or powering the modem independently) is so much simpler than a
failsafe/failover system.


Sorry if you've exhausted this line of enquiry already, but these components
are usually very reliable so something must be going wrong.

Sometimes, it completely freezes and the leds do not blink. I think that we
have also problems in upload.  We haven't yet tried the verification
procedure of uploaded stream.  The autopilot starts working, but when it
jumps to a problematic part of the code, then it stops.

What is the problematic part of the code? Does it correlate with a burst of
telemetry transmission?


What peripherals do you have on the powered from the autopilot?


Chris Gough

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