3 ms·

>Add rotors. The demo video showed an 8-rotor drone, I can imagine that building it as a pair of parallel quad rotors from the power supply point of view would

>Add rotors. The demo video showed an 8-rotor drone, I can imagine that building it as a pair of parallel quad rotors from the power supply point of view would give you quite a bit of control even at a 50% loss. A single-engine loss is obviously fairly small beans. I'm emphatically not an expert so this is armchair engineering. Well, the thing about a multirotor is that a motor failure is going to drastically throw off the stability of the aircraft. The controller would have to be able to recognize the failure, kill the faulty rotor hub, and compensate on the remaining motors in very short order to keep the airframe from getting so far off balance that it tumbles out of the sky. Though, honestly, I'd think the controller or battery failing is a more likely mode of failure than one of the brushless motors suddenly dying.

skorgu 13y ago
Aha! I couldn't find the video quickly for my first post but I finally stumbled on it. Granted this is in ideal laboratory conditions but: http://www.youtube.com/watch?v=bsHryqnvyYA&t=22 http://www.youtube.com/watch?v=bsHryqnvyYA&t=22
m4x 13y ago
The controller is already responding to changes in balance at an extremely high rate. How do you think these things fly in the first place? Like an earlier poster acknowledged, the current hobby grade gear is not really engineered with industrial use in mind, but that's a fairly simple engineering problem which has already been solved by the groups who are using drones commercially (i.e. the military) I have no doubt what so ever that Amazon, Google etc have the engineering chops to bring the software and hardware being used in drones up to an industrial grade. Don't assume that because the first thing that you thought of upon hearing "delivery drones" is infeasible that the whole idea is unworkable. It just needs an engineer with a little more imagination Edit: a couple of obvious solutions to your battery/controller failure mode would be a) use redundant controllers. They're small enough that you could easily have two or more running in tandem and checking eachothers integrity, and b) if you lose main battery you can autorotate down and land somewhere reasonably safe. If you use EDFs/shrouded blades they aren't a safety issue, and building a map of safe landing zones for a city is not a huge ask for somebody like Google. Now for somebody else willing to use their imagination: what do you do about cheeky individuals interfering with your drone during delivery?
- commandar 13y ago
  >The controller is already responding to changes in balance at an extremely high rate. How do you think these things fly in the first place? You really don't see how there's a huge difference between balancing thrust between relatively equal power sources and losing so much thrust that the aircraft is inherently unstable? Because that's kind of a huge issue - multirotors fundamentally rely on having power at each corner for aerodynamic stability. Even brief loss of power to one is going to put you into a tumbling state with no way to compensate for it. >that's a fairly simple engineering problem which has already been solved by the groups who are using drones commercially (i.e. the military) What multirotor UAS systems does the military have in service for reliable flight over moderate distances? I'd also take issue with the suggestion that controlling an aircraft which has become unstable over an axis that you no longer have control over is "a simple engineering problem." >They're small enough that you could easily have two or more running in tandem and checking eachothers integrity I was referring to the speed controllers that convert the battery power to AC for the brushless motors. I'd expect commercial grade ESCs to be overbuilt, but they put out a good bit of heat that has to be engineered around. They're also one of the more common modes of failure for the brushless motor systems used in mutlirotors. >It just needs an engineer with a little more imagination This is the equivalent to saying "we're going to magic away any problems with this idea." EDIT: I missed this. > If you use EDFs Seriously? Do you even realize how terrible a suggestion that is? EDFs are even worse in terms of energy efficiency and they'd compound stability issues since they have relatively poor throttle response. But I suppose we can imagine those problems away too.

skorgu 13y ago

Aha! I couldn't find the video quickly for my first post but I finally stumbled on it. Granted this is in ideal laboratory conditions but: http://www.youtube.com/watch?v=bsHryqnvyYA&t=22 http://www.youtube.com/watch?v=bsHryqnvyYA&t=22

m4x 13y ago

The controller is already responding to changes in balance at an extremely high rate. How do you think these things fly in the first place? Like an earlier poster acknowledged, the current hobby grade gear is not really engineered with industrial use in mind, but that's a fairly simple engineering problem which has already been solved by the groups who are using drones commercially (i.e. the military) I have no doubt what so ever that Amazon, Google etc have the engineering chops to bring the software and hardware being used in drones up to an industrial grade. Don't assume that because the first thing that you thought of upon hearing "delivery drones" is infeasible that the whole idea is unworkable. It just needs an engineer with a little more imagination Edit: a couple of obvious solutions to your battery/controller failure mode would be a) use redundant controllers. They're small enough that you could easily have two or more running in tandem and checking eachothers integrity, and b) if you lose main battery you can autorotate down and land somewhere reasonably safe. If you use EDFs/shrouded blades they aren't a safety issue, and building a map of safe landing zones for a city is not a huge ask for somebody like Google. Now for somebody else willing to use their imagination: what do you do about cheeky individuals interfering with your drone during delivery?

commandar 13y ago
>The controller is already responding to changes in balance at an extremely high rate. How do you think these things fly in the first place? You really don't see how there's a huge difference between balancing thrust between relatively equal power sources and losing so much thrust that the aircraft is inherently unstable? Because that's kind of a huge issue - multirotors fundamentally rely on having power at each corner for aerodynamic stability. Even brief loss of power to one is going to put you into a tumbling state with no way to compensate for it. >that's a fairly simple engineering problem which has already been solved by the groups who are using drones commercially (i.e. the military) What multirotor UAS systems does the military have in service for reliable flight over moderate distances? I'd also take issue with the suggestion that controlling an aircraft which has become unstable over an axis that you no longer have control over is "a simple engineering problem." >They're small enough that you could easily have two or more running in tandem and checking eachothers integrity I was referring to the speed controllers that convert the battery power to AC for the brushless motors. I'd expect commercial grade ESCs to be overbuilt, but they put out a good bit of heat that has to be engineered around. They're also one of the more common modes of failure for the brushless motor systems used in mutlirotors. >It just needs an engineer with a little more imagination This is the equivalent to saying "we're going to magic away any problems with this idea." EDIT: I missed this. > If you use EDFs Seriously? Do you even realize how terrible a suggestion that is? EDFs are even worse in terms of energy efficiency and they'd compound stability issues since they have relatively poor throttle response. But I suppose we can imagine those problems away too.