G93 code. Tool path not continuous.

Hello,

I faced an issue when creating 4 axis tool path with reverse time mode. I cannot make LinuxCNC to move the tool continuously without decel/accel of 4th axis.

For example:
g93 Y10 B360 F6 - will finish in 10 seconds having one accel and one decel;

g93 Y5 B180 F3
g93 Y10 B360 F3 - will finish in almost 10 seconds but will have 2x accel/decel

.....

Now consider I have created tool path with 0.1mm distance between points. That tool path will generate a ton of G code and if I execute it it will finish in more than a minute because axis will accel/decel on every line never reaching its programmed speed.

Is there a way how to blend such a tool path in LinuxCNC so it will e.g. look ahead and then make optimized, non-interrupted tool path?

Maksym

Sorry, my latest findings are - it does not accel/decel, but once one turn divided in 400 moves overall speed starts to decrease dramatically.

Found an answer to my question in 1.4. Planning Moves.

But anyway, Is there a way to tell traj planner to look ahead more than one segment?

Below is my test program where #3 is the number of slices one move is divided to. If I keep increasing it then the move slows down as each particular start/stop is less than critical distance d = da + dd = 2 * da = F2/A. It can be fixed with increasing acceleration of B axis but that is not right solution for me

o100 sub

#1 = 1
#2 = 360
#3 = 10
#4 = 0

G93

o101 while [ #4 le #3 ]

Y[ #1 / #3 * #4 ] B[ #2 / #3 * #4] F[ 60 * #3 ]

#4 = [ #4 + 1 ]

o101 endwhile

M30

o100 endsub

G64 P0.05
G0 X0Y0Z0B0
G1 Z20 F600

o100 call

In the normal releases of Linuxcnc the "new" trajectory planner only uses multiple line planning for moves using only the X, Y, and Z axis. Any moves using axis A, B, C, U, V, or W cause the planner to revert to the old speed is limited to the old "must be able to stop by the end of the next line" system. There may have been some experimental branches of Linuxcnc that were working on expanding the new trajectory planner to other axis, but I don't remember where they were left off.