Re: [Paparazzi-devel] Suggestions: Auto-tuning of gains and upload via modems

[antoine drouin]

Hi Maik

You can try flashing serially yourself, just change the FLASH_MODE=IAP
to ISP in your airframe file. I haven't done that for a while but I
recall it takes an unbearably long time ( maybe in the order of 5
minutes ) . You can't just consider the baud rate to estimate the
duration of the operation are there are many exchanges in the flashing
protocol and the com latency over RF becomes significant.
I still would recommend installing a mini USB connector accessible
from the outside of the vehicle - if size is an issue you might even
install a molex instead

Regards

Poine

On Mon, Jun 21, 2010 at 11:13 AM, Maik Höpfel <address@hidden> wrote:
> Hello,
>
> thank you very much for your clarifications!
>
> Auto-tuning: Okay, as far as I understand it, there's disagreement
> about what method to use to get the gains. Once you have the algorithm
> down to detect oscillations and all that, I feel like implementing
> different methods to get the right gains shouldn't be much effort.
> What method do the other Paparazzi users use? I'm afraid I don't know
> nothin' about control theory (well, I guess I've understood the
> concept of a PID controller by now).
>
> Uploading: How long are we talking about here? I know with our
> airplane it the flashing process takes long, because we have to attach
> a USB cable deep inside the airframe ;) And no, having an outside USB
> connector is not an option for us.
> I don't really know how to go about finding the size of a typical
> upload, sorry. But with 57600 bauds, I can't imagine things can be
> that bad. Thoughts?
>
> Regards,
> Maik
>
>
>
> 2010/6/21 Christophe De Wagter <address@hidden>:
>> Uploading used to be over the serial link in the past (2005). Do not
>> underestimate the time this took to upload new code.
>>
>> On Sun, Jun 20, 2010 at 3:39 AM, Eric Parsonage
>> <address@hidden> wrote:
>>>
>>> Hi Florin, Maik,
>>>
>>> I am sure that ZN would definitely work, but its just how well it works! I
>>> am pretty sure ZN is the only option if you cant derive the Transfer
>>> Function of the system analytically, so for most people who use paparazzi
>>> and haven't learnt that much about classical or modern control, or for
>>> airframes that may have weird Dynamics (like a flying wing), it is
>>> definitely the way to go. ZN based tuning also results in a controller that
>>> is very good at rejecting disturbance, which for level flight is great, I
>>> just worry about the step response of that sort of controller in regards to
>>> setpoint changes, like rolling into or out of a heavy bank, I fear that it
>>> may be very oscillatory. It does of course depend on your aircraft, and
>>> whether or not you are constantly changing its attitude.
>>>
>>> However, Maik does make a very interesting point. the community could
>>> probably develop a little script, or even a simple spreadsheet, that assumed
>>> you had a straight winged monoplane platform, and took inputs about its
>>> geometry, moments of inertia etc. then approximated the  transfer function
>>> of the system based on that, with that it could then analytically calculate,
>>> using at least a couple of PID tuning methods, the appropriate gains for
>>> your system which you could then program in. This could be done without you
>>> even having to leave the ground! of course, you would need to do a little
>>> bit of manual tuning once you got up in the air, but at least you could have
>>> some trust in your controller to begin with. Of course, someone would need
>>> to derive the state-space model for a generic aircraft in terms of variable
>>> regarding its dimensions. Any of you control gurus wish to comment on this
>>> suggestion (I know you are reading)?
>>>
>>> Eric
>>>
>>>
>>> On 19 June 2010 18:15, Florin Mingireanu <address@hidden>
>>> wrote:
>>>>
>>>> Hi Eric,
>>>>
>>>> I've used succesfully ZN on flying wings.
>>>> I haven't used it on other planes.
>>>>
>>>> Florin
>>>>
>>>> On Sat, Jun 19, 2010 at 11:34 AM, Eric Parsonage
>>>> <address@hidden> wrote:
>>>>>
>>>>> Hi Maik, Florin,
>>>>>
>>>>> I would suggest that ZN tuning would not be that effective, This is due
>>>>> to the fact that the ZN algorithms were empirically derived from work with
>>>>> process systems which all exhibited a particular response (time delay, big
>>>>> phase lag, integrator racking up error to a step input). Perhaps a more
>>>>> sensitivity driven algorithm, like kappa-tau, or pole placement, would be
>>>>> more effective since aircraft tend to act a lot more like a 
>>>>> servomotor-style
>>>>> system than a phase-laggy process one.
>>>>>
>>>>> Eric
>>>>>
>>>>> On 19 June 2010 17:54, Florin Mingireanu <address@hidden>
>>>>> wrote:
>>>>>>
>>>>>> Hi Maik,
>>>>>>
>>>>>> The method I tried to describe is called Ziegler-Nichols.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Sat, Jun 19, 2010 at 11:20 AM, Florin Mingireanu
>>>>>> <address@hidden> wrote:
>>>>>>>
>>>>>>> Hi Maik,
>>>>>>>
>>>>>>> As far as I know, tuning P and I-gains is like:
>>>>>>>
>>>>>>> increase P value until you detect instability (oscillation as you
>>>>>>> said) and then decrease P to half and start to increase I until 
>>>>>>> sufficient
>>>>>>> stability is obtained.
>>>>>>>
>>>>>>> If, additionally, you have a D term (d-gain) then you apply
>>>>>>> recursively this algorithm for subsequent I and D.
>>>>>>>
>>>>>>> So tuning gains for a new aircraft is more like a cascaded algorithm.
>>>>>>>
>>>>>>> Florin
>>>>>>>
>>>>>>>
>>>>>>> On Sat, Jun 19, 2010 at 10:12 AM, Maik Höpfel <address@hidden>
>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hello dear community,
>>>>>>>>
>>>>>>>> I recently added two features I would like to see to the Software
>>>>>>>> Wishlist in the Wiki, but did not get any feedback. So I'd like to
>>>>>>>> present them on the list as well:
>>>>>>>>
>>>>>>>> 1) Auto-tuning of gains: as far as I see it, the rules for setting
>>>>>>>> the
>>>>>>>> P-gains on a new aircraft are pretty easy: "turn it up till it
>>>>>>>> oscillates, turn down a little". Now given sufficient height and a
>>>>>>>> bit
>>>>>>>> of trust in the airframe, this should easily be doable by an
>>>>>>>> algorithm
>>>>>>>> instead of the crew on the ground, shouldn't it? Oscillation can be
>>>>>>>> detected via the IR sensors/IMU... I imagine it like a special flight
>>>>>>>> plan block that then sets the correct gains.
>>>>>>>>
>>>>>>>> 2) Flashing via modems: Couldn't the boot loader wait for a special
>>>>>>>> sequence from the modems before starting up the Paparazzi code? And
>>>>>>>> then the GCS just sends that special message and the firmware that is
>>>>>>>> to be flashed? Should be error-checked, of course. But it's possible,
>>>>>>>> right?
>>>>>>>>
>>>>>>>> I'm really looking forward to your thoughts! I think both things
>>>>>>>> would
>>>>>>>> make Paparazzi even easier to use for beginners.
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Maik
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Paparazzi-devel mailing list
>>>>>>>> address@hidden
>>>>>>>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Paparazzi-devel mailing list
>>>>>> address@hidden
>>>>>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Paparazzi-devel mailing list
>>>>> address@hidden
>>>>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Florin Mingireanu
>>>> Romanian Space Agency
>>>> Str. Mendeleev 21-25, et. 5, sector 1, 010362 Bucuresti, ROMANIA
>>>> office tel. +40-21-316.87.22; +40-21-316.87.23;
>>>> cell: +40-757-768971 (primary phone)
>>>> fax +40-21-312.88.04
>>>> address@hidden
>>>> http://www.rosa.ro
>>>>
>>>> _______________________________________________
>>>> Paparazzi-devel mailing list
>>>> address@hidden
>>>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>
>>>
>>>
>>> _______________________________________________
>>> Paparazzi-devel mailing list
>>> address@hidden
>>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>
>>
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>