Drones flying on less than 4 motors.

[BrAinZ]

A couple of bits on the BBC Click programme (22.10.16) regarding drones was interesting.

In particular around 13min in is a piece about making drones that can still fly on less than 4 motors, allowing the drone to land (relatively) safely, or at least not plummeting from the sky!.

They were not using any special equipment to do so, but basically putting the drone into a spin to regain some control if a motor failed.

They were saying that any drone manufacturer could do this, so just wondering what people's thoughts were as to DJI doing something like this?

Click, 22/10/2016: www.bbc.co.uk/iplayer/episode/b08163fg via @bbciplayer


Sent from my iPhone using PhantomPilots

 

[Numone]

Yeah, I saw that and thought the same...

 

[yorlik]

Be prepared for the majority of folks here attacking you for suggesting a quad drone can survive and fly if one prop stops.

I told this forum over a year ago it is not only possible, but it is a rather simple subrountine in software that can be added to ALL quads and was attacked as if I was suggesting perpetual motion. HaHaHa!

PS: If you don't call it perpetual motion, perhaps that too is possible....

Miller Colson Magnetic Motor - Energetic Forum

 

[BrAinZ]

In the programme they showed a flying quad where they poked it with a stick to stop a motor, and it landed relatively OK.

They even demonstrated an extreme situation flying (and actually staying up) with just ONE motor.

So definitely possible!

 

[RC Madman]

You can only watch that video if your are in the UK. Expecting to survive a lose of a motor or prop is unlikely. By the time you figured out what happened the quad is hitting the ground.

 

[BrAinZ]

Just use a VPN to watch it.

The point of the article is that the built in software could kick in and bring the drone down in a more safe manner.

 

[BrAinZ]

The people doing the theory on getting the drones to stay airborne are the the ones who look after the drones in the Vegas Cirque Du Soleill.

Here's a video of the stuff they control:

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[42FrankZ]

I wonder if there has been any conversations about this at DJI during R&D meetings....

 

[With The Birds]

DJI wont fess up if they have tried to implement it as clearly they haven't managed to work it out yet...... Seriously, I'm sure they could do it. Perhaps they have assessed that propulsion system failure is a low probability failure mode.

 

[42FrankZ]

DJI wont fess up if they have tried to implement it as clearly they haven't managed to work it out yet...... Seriously, I'm sure they could do it. Perhaps they have assessed that propulsion system failure is a low probability failure mode.

I supposed if it was a "simple" software solution they would just do it.

That aside, there might be bean counters whispering about liability issues. They make it land in a way you didn't want and it damages it when you know you could "have saved the AC".

I think there is a lot more in play than a TV show that is trying to sell advertisements with drama is letting on.

 

[With The Birds]

I supposed if it was a "simple" software solution they would just do it.

That aside, there might be bean counters whispering about liability issues. They make it land in a way you didn't want and it damages it when you know you could "have saved the AC".

I think there is a lot more in play than a TV show that is trying to sell advertisements with drama is letting on.

Agreed.

It could also me a hardware limitation in the wookong M flight controller (as implemented in P3).

 

[Mako79]

Could be a patent issue and the person creating the algorithm wants $$$ from DJI.
Maybe DJI are just stubborn and assures everyone that there is such thing as motor failure - "we don't need airbags because our cars don't crash".

 

[N017RW]

This was demonstrated as far back as 2013.

The quads were small, compact, and did not have cameras meaning the center of gravity is extremely important.

It's not just software and computing power.
Having the mass of a gimbal and camera below would make this very difficult with a Phantom.

 

[yorlik]

Be prepared for the majority of folks here attacking you for suggesting a quad drone can survive and fly if one prop stops.

I told this forum over a year ago it is not only possible, but it is a rather simple subrountine in software that can be added to ALL quads and was attacked as if I was suggesting perpetual motion. HaHaHa!

PS: If you don't call it perpetual motion, perhaps that too is possible....

Miller Colson Magnetic Motor - Energetic Forum

I rest my case.

Does anyone think the folks are DJI are any less skeptical than the majority of the readers here? "IT CAN'T BE DONE!" It is indeed a simple software routine. The hardest part is the decision tree to decide WHEN to jump to it. Patented software routine? HA! There are 17 ways to do the same thing. The responses are as amusing as they were a year ago!

 

[BrAinZ]

I think there is a lot more in play than a TV show that is trying to sell advertisements with drama is letting on.

It's the BBC, they don't advertise anything

 

[Gearbox]

Well I lost a Prop at 25' & can tell you, you don't have a lot of time to do anything . Even software would be hard pressed to make the correct control .
You can be amused as much as you want .

 

[42FrankZ]

I rest my case.

Does anyone think the folks are DJI are any less skeptical than the majority of the readers here? "IT CAN'T BE DONE!" It is indeed a simple software routine. The hardest part is the decision tree to decide WHEN to jump to it. Patented software routine? HA! There are 17 ways to do the same thing. The responses are as amusing as they were a year ago!

Yes, you were so right. All these attacks on you over this.

 

[BigAl07]

The processor in the Phantom does millions of computations every second. Why would it be difficult for it to realize a lost motor/prop issue and initiate a "limp home" routine? While it may not save the aircraft in every situation it most likely would in many. Granted the Phantom platform isn't nearly as easy & stable as the small micro quads are in terms of rotational mass but I do think it is possible to have some degree of "limp home" to help minimize damage.

 

[brothers]

I think we may be underestimating the complexity of this problem. You lose a prop, the first (and often only) thing that comes to mind is the lift imbalance, which you can sort of deal with by feathering the prop diagonally opposite the failed one, with the loss of most directional control. That only exacerbates a potentially more significant problem: angular momentum/torque imbalance. The bird is going to want to spin, and there's very little you can do to counteract that.

I don't see "limp home" as a viable possibility. At best, you might be able to land before the spin gets out of hand.

The above assumes the Phantom configuration of diagonally opposite props spinning in the same direction. I assume DJI had a good reason for going that way (it allows in-place yaw, which the other configuration doesn't). The alternative configuration, props on the same side spinning the same, does offer more potential for recovery from a "lost prop" situation, including a possible "limp home" capability. The reasons for that are left as an exercise for the student

 

[BigAl07]

I'm not sure how well this will link/play (it's from a FB group) but it shows how quickly things go south with we lose a prop on a QUAD set up:
Inspire Loses a Prop