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by pahgawk 324 days ago
This is good! Although I'd also say that initial velocity doesn't quite cover what I was talking about in the post -- even anticipation arguably can start from 0 velocity, accelerate backwards, decelerate, then accelerate in the opposite direction. Imo, any sudden change in velocity should by default be avoided (there are always valid uses where breaking that expectation is good, but I'd want it smooth by default.)

That could possibly be done by incrementally changing force to move it back first, then forward, or to model this as a PD controller following an input with some baked in reversal before moving forward. That can still be closed-form (state response to a known input will be; Laplace transforms can help there), but still would need a bit of effort to model and tune to look right.

1 comments

You wouldn't really need an incremental force: a step-function force (first backward for some time steps, then instantly forward) will still produce a continuous velocity curve.
true! I suppose you'd risk getting some oscillations in the anticipation depending on the scale of the force, but that could be desirable, or might not happen if the scale is small enough, and certainly makes the math a little easier
You can trivially calculate the time-to-peak overshoot using the closed form equation. It’s the first (0-indexed) zero of the velocity response, i.e. happens at t = (pi / scale)

And obviously it would only apply for the underdamped case.