Airplane mode?

[rktman]

Maybe I should have said that, in N/S mode, the sticks control velocity. Which, then controls position. Roll, throttle and pitch control 'spatial' velocity while yaw controls angular velocity.

If "the flight controller pays absolutely no attention at all to position in response to stick inputs" how is it possible that the FPV holds position in a strong wind and control inputs neutral?

"No control input" is synonymous with "control inputs neutral".

How does it hold position? The FC takes over and does all the twitchy hard work to stay in place.

Give some input, and the FC gets (mostly) out of the way and let's you tell it what to do.

The most obvious sign that your sticks are controlling angle and not speed is wind: Does wind add/subtract from ground speed, or is ground speed proportional to stick position?

We all know speed records are set flying downwind. The aircraft only senses ground speed, so is obviously not controlling speed.

However, angle is pretty closely proportional to pitch angle. So it's easy to mistake angle mode for being speed control.

 

[anethema]

I’d have to test it out but I believe on the FPV drone it factors out wind completely and doesn’t just control angle.

If it is holding position in the wind and you press forward X degrees it will move forward at the same speed regardless of wind level.

 

[BudWalker]

"No control input" is synonymous with "control inputs neutral".

How does it hold position? The FC takes over and does all the twitchy hard work to stay in place.

Give some input, and the FC gets (mostly) out of the way and let's you tell it what to do.

The most obvious sign that your sticks are controlling angle and not speed is wind: Does wind add/subtract from ground speed, or is ground speed proportional to stick position?

We all know speed records are set flying downwind. The aircraft only senses ground speed, so is obviously not controlling speed.

However, angle is pretty closely proportional to pitch angle. So it's easy to mistake angle mode for being speed control.

"No control input" is synonymous with "control inputs neutral".
No, neutral means all stick inputs have a 0.0 value.

The FC takes over and does all the twitchy hard work to stay in place.
Exactly, the FC is computing the angles required to hold position.

Give some input, and the FC gets (mostly) out of the way
How much out of the way? E.g. if roll increases from 0.0 to 0.01 is that enough? Or, maybe increases to 0.0314159?

I'm going to take a chance here and speculate that you don't have much experience with DJI drones prior to the FPV. It's well established that prior DJI drones when in GPS mode will operate as has been described here by others and myself. The FPV in N/S mode does the same.

 

[Kilrah]

How is the drone going to respond differently to stick input to move it, just because the FC takes over to hold position when I'm NOT giving control inputs?

Your description assumes that letting go of the stick "engages" position hold while moving the stick disengages it and gives an angle command, but GPS mode on DJI aircraft does not work that way. There aren't 2 modes that it switches in/out of, GPS mode is constantly a speed control, when the stick is centered that speed just happens to be 0.

In angle / ATTI mode your stick commands a given angle, say you push forward so that it gives a 25° pitch down angle, as long as you hold the stick there the aircraft will be tilted at 25° and its movement relative to ground will be whatever it is given that and external factors e.g. wind.
In DJI's GPS mode the stick does NOT command angle, but ground speed/direction. Your stick forward will give say a 10m/s ground speed command in the current aircraft nose direction, and the FC will give the aircraft whatever angles are needed to achieve that. If you have a 15m/s tailwind and push the stick forward to 10m/s speed the aircraft will actually tilt backwards to slow itself down from how the wind is pushing it and maintain your set speed.

Another way to say it is that it continuously holds position, just that with your sticks you move that position around and the FC does whatever it takes to follow that.

 

[rktman]

"No control input" is synonymous with "control inputs neutral".
No, neutral means all stick inputs have a 0.0 value.

The FC takes over and does all the twitchy hard work to stay in place.
Exactly, the FC is computing the angles required to hold position.

Give some input, and the FC gets (mostly) out of the way
How much out of the way? E.g. if roll increases from 0.0 to 0.01 is that enough? Or, maybe increases to 0.0314159?

I'm going to take a chance here and speculate that you don't have much experience with DJI drones prior to the FPV. It's well established that prior DJI drones when in GPS mode will operate as has been described here by others and myself. The FPV in N/S mode does the same.

Ignore.

 

[rktman]

Your description assumes that letting go of the stick "engages" position hold while moving the stick disengages it and gives an angle command, but GPS mode on DJI aircraft does not work that way. There aren't 2 modes that it switches in/out of, GPS mode is constantly a speed control, when the stick is centered that speed just happens to be 0.

Well, I'm not convinced -- the claims here about controlling for speed, etc. just don't match my experience going back to the P3. After all, the speed record threads on the Mavic forum make the case.

Is this how your DJI drones fly? You're flying with a 20mph tailwind with your Mavic Pro in Sport Mode, stick 9/10 forward. This is telling the FC to go 37 mph. It adjusts pitch to achieve that ground speed, so (just for sake of argument) it's pitched forward 15 degrees. Now, you push the stick forward that last 1/10. What happens? Your drone will go 58mph over the ground. Done it. In fact, I pass the "speed limit" (37mph) way before full stick. How is that mapping stick position to speed?

Does that happen with an abrupt jump in acceleration when you hit the stick limit? None of mine ever have. Rather, they've developed speed smoothly from a standstill, and by the time I get to 9/10 stick, there's no sudden acceleration from 37 mph to 58mph. There's just continuous, smooth, acceleration. Right up through the max spec'd speed of 38mph (or is it 42 on the MP2? Not important). On MY DJI drones, they all go faster (ground speed) downwind than upwind at the same forward stick deflection.

Do your (everyone) drones act differently?

Rather than argue, I'm going to take my MP2 out when it's windy (always is in the evening around here) do some flying around with pitch forward 1/2 full deflection, slowly S around and fly a few lazy circles, all in P mode, then grab the logs and do some graphing. I expect to see variations in average RPM synchronized with the course changes, not pitch stick changes if it's trying to hold speed. If not, I expect to see little variation at all in RPM correlated with course direction, and strong correlation with pitch stick position.

 

[Kilrah]

the speed record threads on the Mavic forum make the case.

Link? The only one I found remapped a switch position to ATTI, it wasn't in GPS mode.

Now, you push the stick forward that last 1/10. What happens? Your drone will go 58mph over the ground. Done it. In fact, I pass the "speed limit" (37mph) way before full stick. How is that mapping stick position to speed?

Rather than argue, I'm going to take my MP2 out when it's windy (always is in the evening around here) do some flying around with pitch forward 1/2 full deflection, slowly S around and fly a few lazy circles, all in P mode, then grab the logs

Definitely post logs because I've never seen that myself or seen it reported with data. I have however seen people getting confused with the speed units multiple times. 37mph just so happens to equal 59km/h...

 

[inno]

Hello All,

I just picked up a DJI FPV combo, going through the motions to set it up I was disappointed to find it lacked an Airplane mode like the Mavic I used to have. I fly real airplanes for work and the control stick logic just doesn't make sense. Everyone knows, if you want to go up you pull on something, a yoke or stick in an airplane and a collective in a helicopter, why DJI chooses push up to go up is beyond me.

So, anyway back to my question, I wonder if DJI will include a custom mode or airplane mode in an update, thoughts?

First off tna9001, Welcome to one of the many DronePilots' Forums. Since your a pilot... you'll understand the logic, it's simple and really old school. The way DJI designed there flight systems is really basic in my mind. they just creatively enhanced all with programing.

It's a helicopter, setup to fly like a helicopter period. Look at an early Bell. The example is about the controls not how a single bladed helicopter with tail rotor vs a four bladed drone work to stay aloft.

The flight controls, lefthand controlled throttle and blade pitch, righthand controlled the cyclic pitch of the blades, your feet the tail rotor or yaw. You pulled up with the left hand to increase pitch for gaining altitude once your rotors were up to speed, your cyclic to control the direction of travel for the entire aircraft, and the pedals (yaw) to control the direction the body of the aircraft faced.3D flying in any direction. What a difficult task all those controls, just don't sneeze and cover your mouth with you hands... LOL

DJI really did nothing different, except add a programable flight controller and a ton of programming to make it is what it is today.

dji remote controller, basically the same, the right stick is your cyclic mixed with throttle, the left stick (left/right motion) is your tail rotor(yaw), up/forward down/backward is your collective pitch mixed with throttle because your blades are a fixed pitch.

Yes, i enjoyed myself the airplane mode in the early Mavic and i was sorry to see it go, But it was only programming that made it fly that way.

Airplane mode is still alive with the DJI FPV they just don't call it that. I flew for the first time with the motion controller yesterday and WOW, totally awesome, Three birds in one flight.


The experience was like flying my VTOL (vertical takeoff and landing and forward flight) and Wing (elevons) and any of my DJI drones with all it's telemetry and functionality and to have real nice FPV all at the same time. With only one stick and a trigger for throttle. Once hovering pull the throttle trigger to start moving pull back to clime, push forward to descend, left/right to turn and bank, the only bummer no rolls, split s's, loops... but i can live with that.

If you want the airplane feel mode, get a motion controller.

Happy and safe flying!
inno

 

[BudWalker]

A while back I was adding wind calcs to DatCon and did several flights with my M2P to obtain test data. One of those flights provided a good test for determining if 1) ctrl_pitch determines velocity or 2) ctrl_pitch determines pitch. For those wanting have a look at the data the .DAT is attached.

The interval [373, 798] secs was chosen because it provides flight both against and with the wind.

It's evident but hard to see that ctrl_pitch determines velocity and not pitch. When the M2P is heading SW it lowers the pitch to compensate for a head wind. Travelling NE the M2 raises pitch because it has the wind at it's back.

To make it easier to see an excel scatter plot was created. The blue scatter represents ctrl_pitch vs velocity and the orange scatter represents ctrl_pitch vs pitch. It's clear that pitch has a bimodal response to ctrl_pitch; i.e. ctrl_pitch does not determine pitch. It's also clear that ctrl_pitch determines velocity.

 

[rktman]

Another big enthusiast for the MC!!! Try some full throttle sport mode 3 ft AGL in a big, open field. Climb, dive.... it's what FPV is all about!

 

[Haggi]

Another big enthusiast for the MC!!! Try some full throttle sport mode 3 ft AGL in a big, open field. Climb, dive.... it's what FPV is all about!

Absolutely!
Comming from the mighty Spark to this FPV drone is certainly a giant step.
When flying the Spark I was always envious at the Mavic pro's and the fixed-wing mode.
I could be wrong but I don't think the mavic banked, it was just some clever camera stuff.
Hopefully after some hours in Sport I will dare to release the M mode!
Anyway, the MC is the golden stick!

 

[FPV Flier]

If you want the airplane feel mode, get a motion controller.

I agree 100%. I use to fly ultra lites in my younger days and the motion controller works same way as the stick in my ultra lite. With the new fpv dji drone I can still have the thrill of flight without the expense and risk that I had with my ultra lite A/C.

 

[FPV Flier]

Another big enthusiast for the MC!!! Try some full throttle sport mode 3 ft AGL in a big, open field. Climb, dive.... it's what FPV is all about!

Buzzing around about 20ft above tree top level is a blast also! I now find myself using the MC all the time....... really do like it.