Danielle Fong 🔆#317
Four rotors create complete control authority. Eight offers redundancy. But can someone explain why in the world you'd want to add weight and complexity to pivot each rotor pair?
Some users appreciate the cool appearance and independent control of thrust-vectoring rotor pairs in medical transport, whereas others view the design as over-engineered, strange, and more failure-prone than gimbals.
@CalebChamberla6 All I see is a lot of math.
@CalebChamberla6 Differential thrust is part of why drones sound so unpleasant, they're constantly making very discordant pitch intervals. Thrust vectoring lets you run the rotors at the same speed and sound nicer in built up areas. In this case though my money's on "it looks cool"
@CalebChamberla6 This seems like a bad way to do it, but I've seen some worthwhile camera drone setups that trade camera gimbal complexity for motor gimbal complexity.
Four rotors can't hover while tilted, this can. If the drone is like half camera it starts to make sense to tilt drone not cam.
@CalebChamberla6 You can't control all degrees of freedom with 4 fixed rotors.
@Michi07f True. A quadrotor's pitch and roll is coupled to body-frame velocity. I hadn't considered that as a desired constraint.
@CalebChamberla6 A lot of people at trade shows are idiots with MBAs and little to no engineering knowledge. Just make something that looks different and they'll all want to buy it, even if it makes no sense whatsoever.
@CalebChamberla6 Much better maneuverability and precise control. There’s a reason why remote control helicopters can do way crazier moves than any normal drone with fixed-pitch propellers. It requires more skill to control though, obviously.
@CalebChamberla6 @grok What can this design do that a typical drone design can not?
@CalebChamberla6 a done is underactuated. as in it cannot hold a 6dof pose in the real world. if you want to hold at a particular pitch and/or roll you need to pivot motors. how useful that is a different question though
@impossible_eng Fun mixing problem, for sure.
@CalebChamberla6 Gimbals might only need small-angle to offer the benefit that 8 fixed propellers can’t. Personally I think this is common sense to start w/ that. The extra weight itself could be interpreted as a regularization in itself; better guarantee that subsystems damp
@CalebChamberla6 You can have complete control authority as well as keep the body at an arbitrary orientation. What if you wanna hover while tilted
@NickParkerPrint @CalebChamberla6 does it work well?
DoF is only half of the problem, the other half is decoupling oscillation of torsion bars and actuation algorithms
@CalebChamberla6 My read: thrust vectoring buys instant attitude control without engine spool-up lag, critical for ICE hybrids. Keeps the fuselage level in cruise too. Clever tradeoff. ⚙️🚁
@CalebChamberla6 @Michi07f The reason we use 4 fixed rotors is simplicity, not performance. There are thousands of ways to improve quad rotor performance, and this is one of them.
@CalebChamberla6 Vectoring?
@CalebChamberla6 counter thrust to hold position while staying dead level in crosswind while supporting a camera?
@CalebChamberla6 It looks cool
@CalebChamberla6 If you want to stabilize a payload, you can use a gimbal, or you can do this. If the payload were heavy or hard to center its mass on a ginbal, i would consider this as a lighter solution than a heavy duty gimbal. Possibly.
@CalebChamberla6 Normally this kind of set up is used with an uneven ammount of rotors, Tri- and Penta-Copters for example.
It allows for smoother camera work when filming.