Re: [Paparazzi-devel] Talking about Camreras and Wind

[Stephen L Hulme]

Hi Christophe

 

Thank you. That clears everything up.

 

I had set measured high wind speeds and directions manually previously on the GCS.

 

Regards

 

Stephen 

On Thu, 29 Jul 2010 23:27:52 +0200 Christophe De Wagter wrote:

 

> Sorry about the confusion.
>
> We always fly with the -DSTRONG_WIND, even with not strong winds...
>
> If the wind is strong, you should make sure that the wind estimate is "set"
> manually prior to takeoff. Once in flight the wind is estimated by the
> groundstation and sent to the plane. But especially during a take-off, the
> wind is not known yet to the groundstation while the groundspeed is reduced
> due to the climbing, so the plane is very prone to get into trouble (flying
> backward). Since it takes a while for the groundstation to have a good
> estimate of the wind, it is (always) better to manually guess the wind and
> set it. (as long as the direction is good, the amplitude is of less big
> importance: set it to something in the range 0.5 x V-CUISE to VCRUISE: if
> there is more wind than VCRUISE you shouldnt fly, and less than half VCRUISE
> there is no need to set is.)
>
>
>
>
> On Thu, Jul 29, 2010 at 1:28 PM, Stephen L Hulme <address@hidden>wrote:
>
>>  Dear Christophe
>>
>> Thank you for the informative reply.
>>
>> But I think I am still missing something.
>>
>> When you say "I would say: if the wind comes close to your cruise speed....
>> you should *set it* prior to takeoff"
>>
>> Do you mean set the flags such as:
>>
>> ap.CFLAGS += -DNAV -DAGR_CLIMB -DLOITER_TRIM -DWIND_INFO -DSTRONG_WIND
>> ap.srcs += nav.c fw_h_ctl.c fw_v_ctl.c
>>
>> or something else?. And if the wind is low remove the flags?
>>
>>
>> Regards
>>
>> Stephen
>>
>>
>> On Wed, 28 Jul 2010 22:16:27 +0200 Christophe De Wagter wrote:
>>
>>
>> Dear Stephen,
>>
>> The wind.xml is redundant as the wind parameters are always present in the
>> gcs - settings - flight parameters.
>>
>> Procedure for strong winds:
>>
>> I would say: if the wind comes close to your cruise speed.... you should
>> set it prior to takeoff. In practice we never set it but always start with
>> at least 1 standby circle.
>>
>> *Without *the "strong wind" procedure when the ground speed becomes zero
>> or negative (e.g. when you climb, that reduces your groundspeed), the MAV
>> keeps turning even when the nose is pointing in the right direction and
>> hereby is blown away. The strong-wind procedure is no miracle but simply
>> adds the estimated wind to the ground speed when estimating angles. Even if
>> the wind estimation is not accurate but just points in more or less the
>> correct quadrant, it makes a huge difference. When the groundspeed becomes
>> close to zero, the strongwind function reduces the nav gain (as a small
>> heading difference makes the plane move laterally which is seen as a (huge)
>> 90 degree error, while the real heading error is only a few degrees). When
>> the ground speed becomes negative, the strongwind function uses the
>> estimated heading instead of the ground track. This enables you to fly
>> backward. Using the formation flight routines in paparazzi you can make a
>> "hovering controller" for planes.
>>
>>  Success.
>>
>> On Wed, Jul 28, 2010 at 12:12 AM, Stephen L Hulme <address@hidden> wrote:
>>
>>>  Hi Everyone
>>> **
>>> *Re: Camera:*
>>>
>>> I have a similar software problem with a Canon IXUS 80IS and CHDK.
>>>
>>> Following a very kind donation from John Stowers of a Booz main, IMU and
>>> power board I have successfully launched a 40cm MK quadrotor.
>>>
>>> I wish to carry the mentioned cradled Canon camera and remotely trigger
>>> still shots using the USB remote configuration.while simultaneously
>>> transmitting  video over a 5.8 GHz transmitter.
>>>
>>> To date I am having great difficulty getting the video to display beyond
>>> three minutes without the default script appearing on the video image.
>>>
>>> Any help with a working script would be appreciated.
>>>
>>> Pascal previously indicated in a PM that one of Antoine's quadrotors was
>>> running this setup.
>>>
>>> *Re :Wind *
>>> After crashing my Funjet last summer I came back to test my old the
>>> airframe.xml code for a rebuilt version and found the settings file wind.xml
>>> has been removed.
>>>
>>> Christophe De Wagter maybe you could kindly set out the proper procedure
>>> to run the strong wind function?
>>>
>>>
>>> Regards
>>>
>>>
>>> Stephen