Why don't we have a better/smarter flight controller?

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It occurred to me that one of the really big hazards is losing GPS signal due to interference or shrouding by tall buildings. But i it really all that hard to recover from? The bird knows the GPS location it took off from, it knows the last known GPS before it lost signal. Simple math to ascertain a heading and distance back towards the point of origin. Give a suitable RTH height and obstacle avoidance it should be trivial to at least bring the bird closer to take off point. I think a valid assumption is that at least you will return to an area you can recover GPS signal - at least it maximizes your odds of recovery.
 
It occurred to me that one of the really big hazards is losing GPS signal due to interference or shrouding by tall buildings.
Unless you are flying in the urban canyons of Manhattan or similar, this should not be an issue.
For most flyers it would be quite rare to fly in an environment that blocks satellite reception.
But i it really all that hard to recover from? The bird knows the GPS location it took off from, it knows the last known GPS before it lost signal. Simple math to ascertain a heading and distance back towards the point of origin. Give a suitable RTH height and obstacle avoidance it should be trivial to at least bring the bird closer to take off point. I think a valid assumption is that at least you will return to an area you can recover GPS signal - at least it maximizes your odds of recovery.
The big problem with that idea is that without GPS, the Phantom has no idea where it is, so it can't tell which way to point towards home or how far it is from home.
Having the home point location stored is no help if you don't know where you are.
 
Actually yes. I took my Spark for a walk the other day between some of the new tall buildings going up and it was quite common losing GPS or dropping below 6 satellites.
Granted that's on the ground but I was trying to get a sense for the effects created by the buildings since many use the new metallized glass for energy savings.

The big problem with that idea is that without GPS, the Phantom has no idea where it is, so it can't tell which way to point towards home or how far it is from home.
Having the home point location stored is no help if you don't know where you are.

I think you missed that point of my logic - as I stated the bird has the home location stored as coordinates. It could keep the last coordinate read (say keep anything over 6 satellites) so then it has a last known position (same as "find my drone"). Even if it travels a short distance before acting on the lost GPS signal the angular error wouldn't amount to much. Triangulate position to get a bearing and distance to take off point. It still has the compass so it can establish a bearing. Simply moving in that general direction is better than either hovering in place, landing or continuing the current path. It should be able to recover GPS as it gets closer to home since it had it when it took off. Basically I'm saying it would be a superior error recovery strategy than what it does currently.
 
I think you missed that point of my logic - as I stated the bird has the home location stored as coordinates. It could keep the last coordinate read (say keep anything over 6 satellites) so then it has a last known position (same as "find my drone"). Even if it travels a short distance before acting on the lost GPS signal the angular error wouldn't amount to much.
I was telling you how/why it works as it does.
Another issue is that losing GPS is very rare unless you are flying in a very dodgy area where you'll likely have a lot of obstacle issues to contend with too.
Fly in those areas and you are going to have to look after yourself.
RTH works just fine with lost signal, which would account for 99% of failsafe RTH incidents.
 
I'm not real sure at this point you're paying attention or just decided to argue. I KNOW how it works and I was simply wondering why there aren't a few more recovery tricks in Dji's bag o'tricks. Simple query.
It is NOT unusual to lose GPS - any number of things can do it. Heck I lost GPS in my driveway and had my Mavic plow into a tree. So let's dispense with that assertion right away. I've also lost it under a bridge and as I stated plainly - while walking between two new towers (about 600 and 800 ft tall).
RTH works with lost signal as long as it has GPS. Lose GPS and what do you have? Nothing except likely a flyaway - which I'm sure you've noticed happens more than a few times.
Truth is satellites come and go as they traverse their geosynchronous orbits and sometimes you just lose the numbers and thus can't get a lock on location.
 
It is NOT unusual to lose GPS - any number of things can do it.
It's very, very unusual to lose GPS in flight.
To lose GPS you either have to:
  1. Fly under cover or terrain that blocks the skyview or
  2. Have a faulty GPS receiver or loose connection or
  3. Mess up your compass by launching from steel or reinforced concrete which forces the drone into atti mode - but in this case, you are probably going to have other more serious control issues as well.
Avoid those and you should never lose GPS in flight.

Heck I lost GPS in my driveway and had my Mavic plow into a tree. So let's dispense with that assertion right away.
See #3 above NEVER launch from or land on reinforced concrete. It's just asking for trouble.

I've also lost it under a bridge and as I stated plainly - while walking between two new towers (about 600 and 800 ft tall)
See #1 above.
Fly in locations like that and you need to be prepared to lose GPS. That's the chance you take.

RTH works with lost signal as long as it has GPS.
Lose GPS and what do you have? Nothing except likely a flyaway - which I'm sure you've noticed happens more than a few times.
Lose GPS and your Phantom doesn't fly away.
It just hovers and is stil fully controllable but subject to drifting on the wind.
If you don't have the situational awareness to deal with that, it comes under the category of operator error.
But as I said above, it's extremely unlikely you will ever lose GPS in flight.

Truth is satellites come and go as they traverse their geosynchronous orbits and sometimes you just lose the numbers and thus can't get a lock on location.
Truth is that if your Phantom has a good skyview, you'll always have plenty more sats than you need for position data.
You should never lose GPS when you are flying with a good skyview.
 
Ok - I'm done with the psssing contest.
I couldn't gives a rats furry behind as to the why, where or when of losing GPS - I was merely discussing strategies the FC could take if it DID happen. But that seems to be zooming past while you preach about shall and shalt nots.
I can 100% guarantee I'll never have an issue if it sits in my closet - but I do indeed fly my birds and I've lost GPS. Doesn't matter what the circumstances were - we're talking strategies the FC could take to mitigate circumstances. After all we have all this stuff on board to tell the FC where it is in 3 dimensions - seems like it could act smarter if something goes south - no matter why or how. Similar to airbags - doesn't matter how or why you find yourself in an accident - we have a strategy to mitigate personal injury. How and why you find yourself in an accident situation isn't pertinent to preventing injury at the moment. You can reflect on causes afterwards.
 
After all we have all this stuff on board to tell the FC where it is in 3 dimensions - seems like it could act smarter if something goes south - no matter why or how.
If you have lost GPS (and I've tried to explain clearly why you shouldn't lose GPS) there will be nothing telling the flight controller where it is.
If you think you've got a great idea and can program the Phantom better, tell DJI.
 
If you have lost GPS (and I've tried to explain clearly why you shouldn't lose GPS) there will be nothing telling the flight controller where it is.
If you think you've got a great idea and can program the Phantom better, tell DJI.
In fact I was for a couple of decades a controls engineer designing and programming machines to be run by computers. I CAN and have coded stuff like this.
One of the things you do with industrial machines is try and design failsafe systems which sometimes means you use what's left operational in creative ways.
This discussion was intended to be simple speculation and I can do without the snark - I thought it might be of interest to other inquiring minds. In fact another member pointed me to a very good discussion of a similar topic that also involved the GPS and compass. THAT was helpful and interesting unlike your repeated assertions of "don't so that" and "ain't possible". The irritating thing is you keep misrepresenting the discussion as one of operator error when I have clearly stated several times this is speculative for those occasions when it happens outside of those boundaries - and it does happen. Obviously the recovery option I discussed doesn't exist - but could it?
You can argue about shouldn't until the cows come home and it still has nothing to do with what I'm discussing which is what's possible for recovery procedures.
As a mod you should be more sensitive to staying OT no matter what your personal beliefs and biases.
Whether you think it's likely, operator error or an act of God has no bearing on the discussion.
 
It’s clear where your thinking is- I was there also. Why can’t the DJI flight controller perform dead reckoning using the information from the onboard sensors absent a GPS lock? A working compass might be expected to provide a heading presumably. The accelerometers and gyroscopes combined with pitch angle might be expected to reveal how far the AC has moved. It’s probably the unknowns that make this difficult to implement. An obvious one is that even if an algorithm was implemented it could not reliably provide distance covered over the ground and that is obviously the critical reference. Even a slight breeze would make it inaccurate.

I should get you in too look at one of my routers. I can’t get the fourth axis to move properly after I replaced the servo motor. That’s my headache this week.
 
That's why I stipulated last known position since between that and the home point you can determine a return vector to get it headed in the right direction.
It does presume a working compass to set a heading...
 
That's why I stipulated last known position since between that and the home point you can determine a return vector to get it headed in the right direction.
It does presume a working compass to set a heading...
You would think so, to return to roughly the same position should be achievable. The simple analogy might be the cutter getting back to the set zero point if the table was moving independently. Where the AC is with respect to the ground will be a monumental problem- compass bearing alone won’t be enough...
 
My assumption was that if it heads back in the general direction it should be able to reacquire GPS somewhere along the line - assuming it had a lock when it left.
 
My assumption was that if it heads back in the general direction it should be able to reacquire GPS somewhere along the line - assuming it had a lock when it left.
Add to that assumption loss of control signal accompanying GPS loss and I think all wouod agree it would be a very useful addition. The alternative being the AC drifts untill autoland at batery depletion, an often reported outcome.
 
My assumption was that if it heads back in the general direction it should be able to reacquire GPS somewhere along the line - assuming it had a lock when it left.
You laid that out pretty well in your original post. I would think this option would be worth testing on the programers end at least to see how it would actually work in the real world. I would also think that it could also be something you could turn off in certain circumstances.
 

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