Re: [Paparazzi-devel] fly in the loop

[Pascal Brisset]

Hi,

we could have a

<sleep until="condition"/>

instruction or a new "loop_time" variable. What do you think ?

--Pascal

Steven Wawryk wrote:
> Hi Pascal,
>
> It's not a criticism, it's just a usage that I find more intuitive and 
> readable.
>
> I agree that it makes no sense during any fixed-wing flying phase.  The
> situations I've encountered where I would have liked it are all before launch
> when it doesn't make sense for a controller to be running.
>
> One example was for a delay between control surface position changes during
> pre-launch testing where I wanted:
>
> <while cond="LessThan(stage_time,4)"/>
>
> and worked around it with:
>
> <attitude roll="0.0" throttle="0.0" vmode="throttle"
> until="LessThan(4,stage_time)"/>.
>
> Another was to speed up GPS settling where I wanted a timed out accuracy 
> criterion:
>
> <while cond="And(LessThan(1000,gps_Pacc),LessThan(stage_time,10))"/>
>
> and worked around with:
>
> <attitude roll="0.0" throttle="0.0" vmode="throttle"
> until="Or(LessThan(gps_Pacc,1000),LessThan(10,stage_time))"/>
>
> I personally think that the "while" element is more readable.
>
> The use of empty "while" element works when used with block_time
> (NavBlockTime()) or any other variable for that matter and there are lots of
> examples of this in the flight_plan directory, so it can entice the naive user
> like me to use stage_time and wonder why it hangs and never gets past that 
> stage
> (though the flight plan display doesn't actually show that it is hung up on 
> that
> stage, so it takes a bit of investigating).
>
> Of course, it's not a show-stopper because there is a work around.
>
> Steve
>
>
> Pascal Brisset wrote:
>   
>> Hi,
>>
>> there is a single "stage_time" variable which is reset at the beginning
>> of every stage. Here, there is a hidden empty stage inside the while
>> loop where the variable is reset. It is probably not enough documented.
>>
>> However, what do you expect of doing nothing during 2s ? Except during
>> an initialisation phase (or a perch phase with an heli), on the ground,
>> you probably want to continue to fly ...
>>
>> So the <attitude/> instruction is a good answer
>>
>> --Pascal
>>
>> Steven Wawryk wrote:
>>     
>>> I have noticed previously that stage_time is reset to zero every iteration 
>>> of a
>>> while loop.  It works fine with "until=" attributes in other elements or
>>> "stages", but not while elements.  I think this is a bug.
>>>
>>> Try another element that has an "until" attribute, like <attitude ... 
>>> until="2
>>> <= stage_time">
>>>
>>>
>>> 郭 flying pig wrote:
>>>   
>>>       
>>>> Hi all
>>>>
>>>>   I have try to create a loop flight in the basic.xml (from HOME --> STDBY 
>>>> --->CLIMB ....repeat),  i use the following 
>>>>
>>>>
>>>>
>>>> <block name="loop" strip_button="lop">
>>>>         <while cond="TRUE">
>>>>         <go wp="HOME"/>
>>>>         <go wp="STDBY"/> 
>>>>         <go wp="CLIMB"/>
>>>>         <while cond="2 > stage_time"/>
>>>>         </while>
>>>> </block>
>>>>
>>>>
>>>>   The problem i have is that once i call the block, it will fly from HOME 
>>>> --->STDBY ---->CLIMB , but after that it will not do anything until i call 
>>>> the block again, does anyone one have any idea how to do it right? 
>>>>
>>>>   I have enclosed my basic2.xml for the flight plan.
>>>>
>>>>
>>>> Thanks
>>>>
>>>>                                                                            
>>>>          Chen
>>>>
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