Dean Goedde has added a cool feature to the forthcoming AttoPilot: relative waypoints. He explains:
"I have innovated a new method for using waypoint paths: a method to signify a waypoint list as being a "template". In this method, the waypoint list becomes a list of relative coordinates, relative to the 0th WP in the list as an "anchor" that is translated to the actual coordinates of where you happen to boot up the system and get first GPS lock. This way, you have a template type WP file on the SD card of up to 100 WPs, perhaps specifying a 1x1 mile grid with 200 meters between the tracks. You also have an extensive set of triggers defined in this WP template, as to snap a photo every 200 meters along the straight tracks. You boot up in the bush somewhere, fly the path, pack up and move 2 miles away and repeat, ad infinitum. An entire day of Geo mapping with no laptop at the field, and TONS of detailed LOG data for exact location and position of the plane during each photo. The math for converting the relative coordinates takes full care of the actual latitude and how to compress/decompress the longitudes from real-->relative-->real coordinates... path is precisely the same either on the equator or at 85 degrees North."
We've been thinking about a similar approach for a supercheap UAV for kids that would just fly selectable patterns around its launch position: figure 8s, squares, circles, etc. No programming required, and potentially no FAA issues since the waypoints are not programmable. Our unofficial motto: "Turning the military-industrial complex into a toy" ;-)
Interestingly, Dean has also created a "synthetic" NMEA GPS sentence for telemetry data, which is just what Jordi did with his GSP parser. Jordi's was called the "$JORDI", Dean's is called "$ATTO".
For something to be patented, on criterion is that it needs to be non-obvious to someone "skilled in the art". I'm not sure moving from absolute to relative markers is non-obvious.
Dean is brilliant, I was working on almost exactly the same thing, hoping to integrate it with Chris's arduino autopilot. Am I thinking correcty that the 0th waypoint is the first waypoint picked up by the autopilot when you power up? I would love to see the source code.
Using relative coordinates has a real practical drawback (I am living with it now). It is dependent on the 0th WP and if you plan your flight using Google Earth or another mapping program and then find the prospective take off location is no good (power lines, rocks, cow crap etc etc) you have to start from scratch in the field. You want this option but trust me I would rather fly using absolute coordinates and have the ability to take off / land at any location that is suitable.
Comments
Correct: 0th is "launch position". It's a convention with most autopilots.