Re: acceleration profille

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:

> There is no "best" acceleration profile.
>
> Linear acceleration is "best" because of simplicity. You just add a
> constant to velocity per unit of time to get linear acceleration.
> Its drawbacks are less than optimum time to speed and a large 2nd
> derivative, called the "jerk factor".
>
> Pretend you are in a car decelerating to a stop at a red light. You
> are braced against the g-force of deceleration and are sitting
> still. The moment the car comes to a stop, deceleration abruptly
> disappears and you are still braced against a force that just
> vanished. Until you adjust yourself, your head and upper body will
> slam backwards.

> This is the jerk factor. A moving piece of machinery will resonate
> or "ring" under the same conditions.
>
> S-shaped acceleration curves take care of the "jerk" factor the
> same way you take care of it in the car in the above example. Just
> before coming to a complete stop you ease off the break to make the
> stop more comfortable. At the start of a move, acceleration is very
> gentle but increases with time to a maximum level. It then
> decreases again, gently tailing off to zero when the target
> velocity is reached. The drawbacks are complexity and an even
> slower time to target speed.
>
> The best time to speed uses an acceleration curve that is the first
> integral of the motor's speed-torque curve. For a DC servo motor it
> would be parabolic, for a step motor it would be a higher order
> parabolic. The drawbacks are complexity and a significant jerk
> factor.

So what type of acceleration curve does EMC use?

Ian