3 ms·
I'm always reminded of snap, crackle and pop (https://en.wikipedia.org/wiki/Fourth,_fifth,_and_sixth_derivatives_of_position https://en.wikipedia.org/wiki/Fourt
by andrewingram 11mo ago
I'm always reminded of snap, crackle and pop (https://en.wikipedia.org/wiki/Fourth,_fifth,_and_sixth_derivatives_of_position https://en.wikipedia.org/wiki/Fourth,_fifth,_and_sixth_deriv...) for this topic. Essentially it's not enough to just have continuous acceleration, you have to ease into it (low snap), you can probably go into further derivatives for ultra smoothness but maybe not worth it?
- quietbritishjim 11mo agoAs your link says, acceleration is 2nd derivative of position, so rate of change of acceleration is 3rd derivative, often called jolt. As you say, you want acceleration to vary slowly, so it's low jolt that you want. Snap (or jounce), crackle and pop are 4th/5th/6th derivative. They're probably less of a problem.
- nkrisc 11mo agoI’ve also heard it called “jerk”.
- quietbritishjim 10mo agoOops, that's what I meant to say! So much for my correction. I actually heard, many years ago, the higher derivatives referred to as "jerk" (3rd, as you said), "jolt" (4th) and "jounce" (5th). But that contradicts the Wikipedia article that says "jounce" is 4th derivative.
- andrewingram 11mo agoOops, yeah you’re right!
- rcxdude 11mo agoIt can help because the higher derivatives also tend to promote vibrations in the system, but I doubt it'd be perceptible by people. I have heard of 5th-order smooth curves being used for very sensitive structures, like the movement of big observatory telescopes.