Version 2.6 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!
Updates to MavLink 1.0 means you will need to use "ArdupilotMegaPlanner10.exe" to connect. If you've updated your mission planner recently you should find this executable in the directory where the mission planner is installed.
The above video is done using a prototype 3dr ublox GPS which seems to have better accuracy than the standard mediatek.
Improvements over 2.5.5 include:
- MavLink 1.0 support (use with ArdupilotMegaPlanner10.exe) [Tridge, Craig]
- Stability improvements especially during level hover [Jason]
- throttle range improvement (higher min and max) [Jason]
- improved standard Loiter PIDs [Alan, Heino, Jason, Angel]
- dataflash erase speed up ('+' messages removed but it only takes 6 seconds now) [Tridge]
- Copter LEDs [Robert Lefebvre]
- RTL loiter stage target set to home to improve final landing position [Jason]
- flip & acro improvements [Jason]
- circle mode target improvement for ground station [Jason]
- Auto Approach [Adam Rivera / Marco]
Bug fixes include:
- UBLOX driver fixes (lock should now be more reliable) [Tridge]
- enable mavlink messages during dataflash erase which resolves issue in which new APMs fresh from the factory appeared unresponsive [Tridge]
- proper printing of lat/lon values in dataflash logs [Randy]
- removed duplicate GPS reads [Jason]
- resolve flooding of telemetry link with low-battery warnings [Tridge]
- RTL bug would land if rtl_approach_alt was more than 1 [Jason]
- WP Radius could not be set larger than 1.3m [Jason/Randy]
PIDs are optimised for the 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.
This time we spent some time optimising the loiter PIDs. Tuning loiter can be tricky so please refer to the discussions which will appear below for more community feedback on what parameters work best.
All feedback welcome below. Enhancement requests and bug reports can be put into the arducopter issues list. When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.6 but tell us anyway!).
The term 'Ground loop' can cause confusion in this application, There is no ground as such on these circuits, just negative return path's. These paths, being wire or pcb track, act like resistances!
Multiple return paths will carry different amounts of current depending on load, so multiple negative paths will have small voltage differences depending where measured, and on what path, the amount depending on current flow, these would normally go unnoticed on pure dc applications but spikey current demands like in alternating power output stages, audio, video systems, Computer and especially automation as in cnc machines, and in our case ESC's are the worse cases. Problems can range from occasional glitching to complete havoc.
Yes there is a small ground loop potential created by individual ESCs drawing power, but it also spreads the current loading and since it is common bussed at the APM board it would actually serve to reduce ground excursions, spread current load and increase (very slightly) battery efficiency.
Still, you are right, it is generally a good idea to avoid ground loops and in this case, in the event of a catastrophic ESC failure, it might be able to damage the APM board.
Following your concept, even if you were using the power from one or more of the ESC built in BEC's or even a standalone you would still only want to use the + 5 volt power wire(s) and not connect any of the BEC output grounds to the APM.
And this is where these discussions always go - into ambiguity. Maybe there aren't hard fast rules on the best way to wire these things, but I certainly wish there were.
Regardless of whether spreading the current load (and battery efficiency and failure syndication) across multiple ESCs is a better or worse idea than potential ground loops, it sounds like nobody argues that powering the APM with a separate BEC is a bad idea?
And if you do that, only the signal line should come from the ESCs? And power to the Tx through only a single line? And maybe the current sensor should only send signal too?
How would you measure ground loop - different voltage measurements across power and different ground points?
Best practice is to connect all the ground wires, ESC, battery, and the Signal grounds, to a common point.
And by that I mean something like the supplied Power Distribution Board.
And if you search a bit to previous posts, you'll see what I did to be able to run the APM from ALL the BEC's, using Shottky diodes.
Really Marco? It causes flight problems if you power by BEC?
Yeah Robert, i think this is the cause of my latest crash during test...
It was the first time I powered my APM2 with esc, never again! :-)
Others my drone have one or more dedicated bec.
Having a "clean power" is important.
I and a friend are each powering our KK X525's APM2 board with the provided ESC's BECs which are all connected power and ground to the ESC out connector on the APM2.
These use linear voltage regulators that seem to work well in parallel and when one of the motors is drawing enough power to pull it's BEC down a bit one of the others can in theory compensate.
They will not provide more than the rated power of a single BEC but can compensate (a bit) for local sag.
This is a controversial approach, but at least in this instance it has worked well, with many hours on each Quad.
A high quality single dedicated BEC is likely a safer alternative.
There are several good reasons not to use the BEC that's part of an ESC...not to mention the fact that it is competing for the same electron flow as the motors.... I also fly 3d type helis and you won't find too many folks flying with ESC BECs most use a stand alone bec hooked to it's own small lipo or they'll use a big nicad flight pack with out a bec all togeter....
I do indeed power my APM2 through and ESC's BEC, not a separate one.
Initially I tried powering it with a dedicated BEC, but I must have done something wrong because I couldn't get enough power (1.3 volts) out of the Receiver pins to power my receiver. So I gave up and just used the ESC.
Maybe I should look into it again.
I really hope that APM3 has better power management, it seems to be very weak in this area.
Assuming the stand alone BEC can deliver sufficient current (2 + watts) and that its power lead is attached to one of the APM ESC connectors center (power) pins it normally should be able to work just fine for an APM2 and most receivers.
An APM1 will need a higher current BEC.
The only possibility I can think of where this might not work is that if it is a switching BEC, it is possible that it might have a ground that is not referenced to it's power input ground and is in fact floating.
If that is the case, the BEC's output ground also has to either be connected to the central ground at the power distribution board or one of the outside pins on the APM board.
I do not think that this is likely and I would avoid a BEC with a floating ground in any case.
Could we join (OR) the positive lines of the BEC's together through Schottkey diodes? On diode on each 5volt line. This would give redundancy and my help reduce the ground loop.