UAV swarm, anticollision - faa - detect-and-avoid

Since UAV activity is largely constrained by the see-and-avoid issues;

I though it would be appropriate to propose a solution which is compatible for every form of flight from gnat-weight to jumbojets. I've worked this out is a simulator - but here is the jist:

This requires only a single frequency and very short blips.

1. Every plane determines it's location and vector by GPS.
2. Then it transmits this information using one short blip every second or so.
a. The blip timing is based on current GPS location, so that the blips cannot interfere, and their location in Timespace tells us where they are coming from. Since GPS provides a very accurate, shared time base. So let t in microseconds = latitude\1 + longitude\1 * 100 + Alt in Km *1000 .
b. Odd seconds communicate vector (ie destination), Even seconds communicate Location.

3. There is a third variable required - which I call "Density". Each plane calculates the perceived Density of their airspace and sends that as well. Your density is your passenger count divided by the distance between you and other planes multiplied by their perceived density.

4. For manned aircraft nothing further is required - this beacon signal will ward off all unmanned vehicles.

5. For Autopilot or UAV, it is possible to chart a new safe vector by trying random vector changes and calculating their future density based on the vectors and densities of nearby airplanes. The vector which optimizes progress toward destination with lowest density is the vector chosen.

simple calculation requirements (ie Arduino), cheap transmitter/receiver requirements, and low power requirements. cheap unit cost, and no ground control.

Such a system could be demonstrated by coordinating a swarm of Ardu-Planes.


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IIRC, Chris is using the Arduino to poll 4 or more servo inputs. I suspect that is what is taxing the poor thing.

This component of listening for short blips is handled by the interrupt on pin 8, and the hardware timers. As a consequence, the listening load is nearly unnoticeable.

The code required to pick a good path is just a few lines in the simulation.

It would appear the resolution or spatial bandwidth is limited by propogation delays rather than CPU speed. at 18Mhz, the Arduino would provide 18 million points of resolution in a second-based frame width.
If we take the number above as 10,000 target points of resolution per second, we are well under the operating speed of the hardware timers (it would seem).

Given that ard can listen and drive servos in the background, I strongy doubt that you need these higher speeds? What seems to be the bottleneck?


Very interested.

Xbee could be used to send raw data - wouldn't be useful for the low-level pinging. I think there will be room for a swarmable autopilot in the near future - this could result in an Uber low cost example (The xbee for example may be twice the price of the entire system - as simple radios are much less expensive without an IP stack)
The new ATC will be late, over-budget, use tube memories, protect union ATC jobs by requiring "human in the loop", and do nothing to prevent or detect malicious flight - if History and the Airforce experience with UAV is an guide. (Hint: it is). I predict on the day the new ATC is deployed, Burt Rutan will fly the first chartered passenger interspacial flight from New York to Paris - relegating the new Fortran-based ATC quaint and anachronistic on day one. (On the bright side, the FAA has certified that the ATC codebase is 100% free of gay and lesbian code after removing several key programmers and deleting their csv entries en-masse.)
I'm surprised that no one has mentioned ADS-B. MITRE has built prototypes of a transmit-only low power unit using cellphone RF components that could cost under $1000US if built in large enough quantities. Glider pilots in high glider traffic areas use FLARM collision warning systems, which are a bit over $1000US each. FLARM operates using low power on unlicensed frequencies, it is not a certified collision warning device. They could be sold in the US, but glider vs. glider accidents are rare here, glider vs. any other kind of aircraft is the real worry. The best solution would be a low power VFR-only ADS-B unit using inexpensive non-certified GPS receivers. Hopefully, the FAA can be convinced to accept this idea...
Yes, FLARM is the system I referenced. The certification will also be necessary to satisfy the other stakeholders .
The FLARM protocols might be a useful starting point for this project if they weren't proprietary ...

FLARM applies for the radio communication between the units a proprietary patent- and copyright-protected protocol. It is not public, but FLARM Technology offers a license contract where it is accessible in the form of a compatible core design ready for integration into 3rd party systems. These systems are officially declared as FLARM-compatible. Any non-licensed use, dissemination, copying, implementation or reverse engineering of the FLARM radio communication protocol, the FLARM hardware and software or parts of it is forbidden by law and will be prosecuted. FLARM is a registered trademark and can not be used without
These systems should be useful for AG work and such but we should keep in mind that over developed areas none of these systems will suffice for sUAS "Sense and Avoid" unless birds can be convinced to wear them too.

Is that a real issue for small uav's that operate at, relative to birds, low speeds with limited maneuverability ?
Over developed areas, yes.
What goes up usually comes down and WHERE it comes down could be a serious issue.
I have personally observed birds (Red Tailed Hawks) attack a small UAS, likely out of concern for a nearby nest.
An operator observing this can take evasive action with his/her system but there is no on board system that can even come close to this capability at this time.
Over a corn field this may not be such an issue. Over a residential area, you can bet it is.

i have seen birds attack R/C airplanes as well and have heard rumors about one being shot down by an eagle at marymoore park in bellevue ,wa . the real advantage that micro uavs have is that when they go down the energy in fairly small and collateral damage would be minimized that being said . people do die flying r/c aircraft . i heard a story about a kid who was learning and he lost it in the sun as it was diving strait for him . it hit him in the chest and defibed' his heart and he died . that being said you probably have way more deaths from people getting hit in the head by baseballs then airplanes . that all being said and the FAA's intolerance of risk see and avoid will be left to humans for a while to come but people like dGatti are laying the ground work for what is to come .
Pcas systems are already available for under $600 and some are capable of interfacing with other devices (flight computers, GPS, moving maps, etc).

The problem with the proposed new ATC environment (Under an ADS-B type system) is in its current configuration it is set up for a Ground controller ATC in the loop, my understanding is that in its original configuration tested in Alaska since the late 1990's it functioned independently of ATC sort of peer to peer, ATC if available was just another peer.

The new version (I may be wrong here) broadcasts to ATC and ATC re-broadcasts traffic position data as well as weather, flight hazards and other useful information.

Chris is right about the resistance to tracking equipment being mandated for GA. But the Private Pilots assoc. is now pledging to work with the FAA on a ADS-B type system as long as GA pilots will not be required to carry other types of transponders and the ADS-B system will provide pilots with other useful information and data including charts and weather maps with no charge to pilots. (I can find that link if someone wants to see it).

I think all developers of UAV flight control systems should be designing in the ability to interface with transponder, and other approved systems.

If an Arduino based Auto pilot system could see traffic from the output of a Zaon XRX PCAS it could easily calculate waypoints and an avoidance plan.

If it will talk to a "Pocket PC, Windows Mobile cell-phone, Tablet PC, UMPC, notebook, or selected car-nav system" I think it would not be to hard to build an interface.

I think Ben's idea is great but I see no sense in reinventing the wheel and a huge upside to interfacing with systems already in use in the GA community.

We should be designing for the future NOW!
Bill -

Thanks for the info. I found a nice explanation of the TCAS system here -

It does seem that addition of a 1030MHz receiver to low-end autopilot systems such as Chris is building would not be too complicated and have a lot of merit.

The system that Ben proposes probably suits a somewhat different purpose, as it is an active beacon rather than a passive receiver (detecting signals from FAA mandated active transponders), and I'm still thinking about the ramifications. In any case, it is worthwhile to understand what others are doing in related endeavors.

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