Re: [Paparazzi-devel] 4-Dimensional Trajectories (4DT)

[Reto Büttner]

Hi Chris

The telemetry message you are imagining does exist. It is the ADS-B
message. It is part of the collision avoidance (separation, TCAS)
functionality.

The 4DT part is a simpler and is therefore the starting point of the
contest (L1C). That basic functionality can and should be added to
paparazzi straight forward. Once that is mastered, the a lot harder
collision avoidance functionality can be addressed (L2C).

Regards, Reto

2012/10/22 Chris Gough <address@hidden>:
> I read the draft rules quickly, and needed to google quite a few terms that 
> went familiar to me. 4D trajectory was one of then, and it didn't throw up 
> anything that looked like a conventional meaning. I had Imagined (probably 
> wrongly) that it was a telemetry message that other planes (and ATC) could 
> use as a basis for smart avoiding (or directing) behavior. If it's a 
> telecommand as you suggest, in some ways that's a lot simpler (it's just an 
> extension or adaption of existing flight-planning constructs).
>
> Either way, the harder part of the rules seems to be robustness to spoofing 
> (both GPS and "ghost planes"). Has anybody got experience integrating 
> paparazzi with light weight affordable radar? :) I've started reading up on 
> gnuradio, and passive (SDR) radar solution looks to me like Mount Everest. 
> Maybe _just_ possible for ground/terrain sensing, but other air traffic?
>
> Has anyone used the paparazzi TCAS code recently? Is it up to date with all 
> the code changes from the last year or so?
>
> Chris Gough
>
> On 22/10/2012, at 4:56 PM, Reto Büttner <address@hidden> wrote:
>
>> Here are the draft rules:
>>
>> http://prod.nais.nasa.gov/eps/eps_data/154025-OTHER-001-001.pdf
>>
>> They say:
>>
>> Page 3: "Competition missions will be defined by Four-Dimensional
>> Trajectories (4DTs), which will be comprised of a series of
>> three-dimensional waypoints in space and a specific time of arrival
>> for each waypoint."
>>
>> Page 7: "The five distinct segments of a mission are: aircraft launch,
>> pre-4DT loiter, 4DT flight, post-4DT loiter, and aircraft recovery."
>>
>> There will be an air traffic control ("central puppent master"), as
>> they want to be able to create specific scenarios for the competitors
>> with surrounding air traffic using a combination of real and virtual
>> aircraft working synchronously.
>>
>> Managing air traffic might be the next step in development of
>> paparazzi. I would start out with 4DT. That would be a great new
>> feature!
>>
>> Regards, Reto
>>
>> 2012/10/21 Chris Gough <address@hidden>:
>>> I had imagined the 4d trajectories would be chirped about between vehicles
>>> to enhance 'autonomous sense and avoid' with vehicles at potentially very
>>> different speeds. I need to read the rules more carefully, but I didn't get
>>> the impression that a central puppet master was involved. That wouldn't
>>> scale well.
>>>
>>> Chris Gough
>>>
>>> On 21/10/2012, at 9:50 PM, Gerard Toonstra <address@hidden> wrote:
>>>
>>>
>>> I'd expect this to be interpreted as a starting time when a uav is *allowed*
>>> to be in some location, not so much when
>>> it *must* be in some location. My implication is that it's more about
>>> devising a strategy where the uav can be kept
>>> safely in waiting until it's time to move on. The use case here is that this
>>> allows atc to keep an area void of
>>> other traffic until the landing of special craft X has taken place or other
>>> use cases alike, or that a specific mission
>>> may only commence at time Z.
>>>
>>> There may also be an additional requirement where a NoFlyZone has a
>>> particular time range. You may cross the zone
>>> prior or after, but not during, otherwise you have to go around. These NFZ's
>>> may pop up at any time during a trajectory
>>> and may require substantial replanning of the flight itself.
>>>
>>> Replanning flights isn't necessarily bad, as long as it's clear to the
>>> operator why it is necessary and what will happen in the
>>> new plan. It should also be clear what will happen if the new plan is not
>>> accepted, because sometimes the old plan becomes
>>> totally incompatible with the new situation.
>>>
>>>
>>> Anyway... I'm speculating  :).  The actual rules will define how this should
>>> be interpreted. I do think that here's an excellent opportunity to
>>> impress the judges by thinking ahead of the requirements and demonstrating
>>> that beyond a technical implementation, some
>>> thinking has been undertaken why 4D is a necessity and how operators
>>> 'interact" with uav's to enable this in the best way
>>> possible (maintaining overview of the situation, reducing interaction
>>> complexity, etc.)
>>>
>>> G>
>>>
>>>
>>> On Sun, Oct 21, 2012 at 7:12 AM, Reto Büttner <address@hidden>
>>> wrote:
>>>>
>>>> I do not think that the calculation of an ETA in flight will be enough for
>>>> NASA.
>>>>
>>>> I expect rules similar to the following:
>>>>
>>>> - Before flight you file a flight plan including 4D waypoints
>>>> (position, altitude and time). This calculation must include the
>>>> expected wind.
>>>>
>>>> - In flight the autopilot must control position, altitude and speed to
>>>> hit the filed 4D waypoints.
>>>>
>>>> - Perhaps in flight you are allowed to request a change of the filed
>>>> flight plan, e.g. if a delay in departure has occured or wind is
>>>> completely different than expected. I am sure Air Traffic Control will
>>>> allow only a few changes and only for good reasons.
>>>>
>>>> Therefore Paparazzi should accept 4D waypoints (position, altitude and
>>>> time) and the flight control should be enhanced to hit the time. Has
>>>> anybody done that in Paparazzi?
>>>>
>>>> Regards, Reto
>>>>
>>>> 2012/10/21 Steffen Spies <address@hidden>:
>>>>> I think it means, that the flightplan has position and the time. Like
>>>>> "be at home at 6pm" while the plane always tells if it will be in time or
>>>>> not.
>>>>>
>>>>> Am 21.10.2012 um 11:21 schrieb Chris Gough
>>>>> <address@hidden>:
>>>>>
>>>>>> I noticed that too, and don't really understand what it means. Is does
>>>>>> it mean the telemetry messages that say "I am here now, and expect to be 
>>>>>> at
>>>>>> that place in two minutes"?
>>>>>>
>>>>>> Chris Gough
>>>>>>
>>>>>> On 21/10/2012, at 6:43 PM, Reto Büttner <address@hidden>
>>>>>> wrote:
>>>>>>
>>>>>>> Hi guys
>>>>>>>
>>>>>>> The newest UAS competition of NASA requests 4-Dimensional Trajectories
>>>>>>> (4DT):
>>>>>>>
>>>>>>> "The Level 1 Competition (L1C) would focus on a competitors ability to
>>>>>>> fly 4-Dimensional Trajectories (4DT) to provide a reasonable
>>>>>>> expectation that they will be where they are supposed to be, when they
>>>>>>> are scheduled to be there."
>>>>>>>
>>>>>>> See:
>>>>>>> https://www.fbo.gov/?s=opportunity&mode=form&id=426438809b8348c157fa5b7120c18a45&tab=core&_cview=1
>>>>>>>
>>>>>>> Has anyone in Paparazzi realized 4-Dimensional Trajectories, in other
>>>>>>> words has included the time dimension in flight control?
>>>>>>>
>>>>>>> Regards
>>>>>>> Reto
>>>>>>>
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>>>
>>> --
>>> Gerard Toonstra
>>> -----------------------
>>> http://www.radialmind.org
>>>
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