Re: [Paparazzi-devel] Changing the main loop frequency on the Tiny

[Felix Ruess]

Hi Andreas,

Of course you can... just depending on what you use you might need to
code a bit ;-)
I assume you are using an imu that you can read with a higher rate?
Which one? As a subsystem or module?

For fixedwings you can set the rates of reading imu, propagation and updates:
   <configure name="PERIODIC_FREQUENCY" value="120"/> <!-- IMU FREQ -->
   <configure name="AHRS_PROPAGATE_FREQUENCY" value="120"/>
   <configure name="AHRS_CORRECT_FREQUENCY" value="60"/>
Then you can <define name="AHRS_TRIGGERED_ATTITUDE_LOOP"/> to trigger
the control loops when a new attitude was computed.
I just commited a small fix to the dev branch:
- update the fw_estimator not only after a correction, but after
propagation as well (if correction is running at a lower rate)
- if you use AHRS_TRIGGERED_ATTITUDE_LOOP way it only is triggered if
you actually have a new attitude estimate and not every time you get a
gyro callback.

This is all not especially nice, we should be able to set this more
flexibly (and e.g. also select a lower rates for gyros than accels,
etc...).
So feel free to improve this in main_ap.c
;-)

Cheers, Felix

On Mon, Aug 15, 2011 at 1:49 PM, Prof. Dr.-Ing. Heinrich Warmers
<address@hidden> wrote:
> Hi Andreas,
> i think yes, depending what kind of AHS you use.
> If you use the IR and the DCM for normal plane  there is no problem.
> The processor load is less then 25 %.
> But look to the main time constants.
> It is only necessary  to be  about 8 times  faster then the lowest time
> constant in your feedback control system.
> Regards
> Heinrich
>
> Andreas Gaeb schrieb:
>
>> Hello everybody,
>>
>> is it possible to increase the main loop frequency on the Tiny 2.11
>> beyond 60 Hz? The sys_mon module indicates there is still some headroom
>> in terms of processor load, and my PID experiments would greatly benefit
>> from a higher frequency.
>>
>> Best regards,
>>        Andreas
>>
>>
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