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

From: Chris Gough
Subject: Re: [Paparazzi-devel] 4-Dimensional Trajectories (4DT)
Date: Mon, 22 Oct 2012 00:23:30 +1100

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.)


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:
>>> Has anyone in Paparazzi realized 4-Dimensional Trajectories, in other
>>> words has included the time dimension in flight control?
>>> Regards
>>> Reto
>>> _______________________________________________
>>> Paparazzi-devel mailing list
>>> address@hidden
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