3 ms·

I thought that too initially, but if you think about the physics it makes sense.. the larger the mass the more stable the object, the lower the frequency of acc

by tomxor 5y ago

I thought that too initially, but if you think about the physics it makes sense.. the larger the mass the more stable the object, the lower the frequency of acceleration needed to adjust it's trajectory. Also even though it's dynamic, it's not articulated or anything like dynamic robots. Take the opposite, a little quad copter, very low mass, will need very high frequencies. I used to manually fly miniature remote control helicopters before all of the automatic control stuff came in, they were extremely, inherently unstable, very tricky to control.

chmod775 5y ago
> the larger the mass the more stable the object Not really. Only when scaling mass, margin of error, and forgetting thrust/gravity. And even if you scaled mass, thrust, and margin of error proportionally, you'd still have an object exactly as stable as before (force X applied to the small object gives you the same acceleration as proportionally scaled force Xs applied to a larger object). Gravity accelerates all things the same, and so do proportionally stronger thrusters. But being off by one meter can destroy a small drone just as well as a large spacecraft, so you don't have the luxury of scaling your margin of error by significant amounts. The only reason larger objects appear more stable to humans is because we, and the environment[1], tend to apply relatively weaker forces to them, and also you don't tend to notice they're already moving at 5m/s because of their size. [1]Larger objects will better compensate for "truly random" forces, if their size causes them to encounter more of them, canceling them out and/or they're generally small.
- 7952 5y ago
  A spacecraft may need to be super accurate at docking, but outside of that precision is far less important.
  - ceejayoz 5y ago
    Docking is also done extremely slowly.
  - deleted 5y ago
    [deleted]
extropy 5y ago
Not mass, size. You can still have a small but massive flying device and would end up with the same acceleration and jerk because need more thrust to zero the gravity out. The bigger your thing is the relatively smaller the 9.8 m/s^2 is.

by tomxor 5y ago

chmod775 5y ago

> the larger the mass the more stable the object Not really. Only when scaling mass, margin of error, and forgetting thrust/gravity. And even if you scaled mass, thrust, and margin of error proportionally, you'd still have an object exactly as stable as before (force X applied to the small object gives you the same acceleration as proportionally scaled force Xs applied to a larger object). Gravity accelerates all things the same, and so do proportionally stronger thrusters. But being off by one meter can destroy a small drone just as well as a large spacecraft, so you don't have the luxury of scaling your margin of error by significant amounts. The only reason larger objects appear more stable to humans is because we, and the environment[1], tend to apply relatively weaker forces to them, and also you don't tend to notice they're already moving at 5m/s because of their size. [1]Larger objects will better compensate for "truly random" forces, if their size causes them to encounter more of them, canceling them out and/or they're generally small.

7952 5y ago
A spacecraft may need to be super accurate at docking, but outside of that precision is far less important.
- ceejayoz 5y ago
  Docking is also done extremely slowly.
- deleted 5y ago
  [deleted]

extropy 5y ago

Not mass, size. You can still have a small but massive flying device and would end up with the same acceleration and jerk because need more thrust to zero the gravity out. The bigger your thing is the relatively smaller the 9.8 m/s^2 is.