I don't understand the content of this part, why use half of the acceleration? Is there any article that can explain this problem in detail?
Important User Concepts (linuxcnc.org)
1.4. Planning MovesMake sure moves are
long enough to suit your machine/material. Principally because of the rule that the machine will never move at such a speed that it cannot come to a complete stop at the end of the current movement, there is a minimum movement length that will allow the machine to keep up a requested feed rate with a given acceleration setting.The acceleration and deceleration phase each use half the INI file MAX_ACCELERATION. In a blend that is an exact reversal, this causes the total axis acceleration to equal the INI file MAX_ACCELERATION. In other cases, the actual machine acceleration is somewhat less than the INI file acceleration.To keep up the feed rate, the move must be longer than the distance it takes to accelerate from 0 to the desired feed rate and then stop again. Using A as
1/2 the INI file MAX_ACCELERATION and F as the feed rate
in units per second, the acceleration time is
ta = F/A and the acceleration distance is
da = F*ta/2. The deceleration time and distance are the same, making the critical distance
d = da + dd = 2 * da = F2/A.For example, for a feed rate of 1 inch per second and an acceleration of
10 inches/sec2, the critical distance is
12/10 = 1/10 = 0.1 inches.For a feed rate of 0.5 inch per second, the critical distance is
52/100 = 25/100 = 0.025 inches.
