Copter-3.6-dev Loiter with accel feed forward and braking

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This is a demonstration of some recent work by Leonard Hall and I to update the “Loiter” flight mode (aka GPS position hold). What’s been added in “acceleration feed-forward” and “braking”.

The braking part is fairly obvious - instead of a gentle glide to a stop like AC3.5 (and earlier), the new version has a user configurable brake. During this test I have the acceleration and brake to be set fairly aggressively.

The “acceleration feed-forward” part means that the roll and pitch make the vehicle feel much more like it does in AltHold (or PosHold).

The changes need more testing but this improved loiter should go out with AC3.6.

By the way, if you find that the current Loiter is too slow to stop, there’s some advice on the Loiter flight mode wiki page. In particular adjusting the WPNAV_LOIT_MINA, _MAXA and _JERK

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That is awesome! It looks more lively, and slowing to a stop less jerky.

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That’s cool. Does it also work with diagonal flight paths or when using yaw whilst braking?

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Jeff, yes it does. In that way, it’s a little different (and perhaps better) than PosHold.

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Will PosHold mode also be able to take advantage of the braking feature? Or with the new “acceleration feed-forward” feature, will people who were previously using PosHold for its greater responsiveness to pilot input start using loiter mode (and at that point, is there any reason for a separate PosHold mode anymore)?

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Looks good! Question: what is the difference of the new Loiter and Poshold in terms of the flight charateristics. Watching your video and if acceleration, braking and speed can be adjusted it should be possible to mimic both the current Loiter and Poshold modes. In other words is Poshold still required?

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It seems that this feature is progressing well. https://github.com/ArduPilot/ardupilot/pull/7659

When this feature would be available in stable?

I have hope that this feature would help me with freight train stop issue. The drone takes long time to slow down from 10 m/s speed when pilot releases controls.

I have tried to tune Loiter and PID settings to make it behave naturally. But it keeps going on after sticks are released.

It goes like following: Drone tilts a bit to slow down, loses half of the speed. After that it straights itself and glides for over ten meters until stops. Drone is about 4 kg.

Would this help?

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Hello everyone and especially rmackay9:

Wonderful, great job. I wanted to thank you publicly you good job and the other fellow that we belong to this wonderful community, that lasts a long time.

regards to all.

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@nomar, Thanks very much! it’s a lot of fun actually. Best job I’ve ever had by far… can hardly call it a “job”.

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