toolhead: Introduce "smoothed" acceleration during lookahead

Update the lookahead code to track both normal toolhead acceleration
as well as a pseudo acceleration to the point of deceleration.  This
reduces the top speed of small zig-zag moves and it reduces printer
vibration during these moves.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/config/example.cfg b/config/example.cfg
index ce6a398d..3574cd44 100644
--- a/config/example.cfg
+++ b/config/example.cfg
@@ -240,6 +240,12 @@ max_velocity: 500
 max_accel: 3000
 #   Maximum acceleration (in mm/s^2) of the toolhead (relative to the
 #   print). This parameter must be specified.
+#max_accel_to_decel:
+#   A pseudo acceleration (in mm/s^2) controlling how fast the
+#   toolhead may go from acceleration to deceleration. It is used to
+#   reduce the top speed of short zig-zag moves (and thus reduce
+#   printer vibration from these moves). The default is half of
+#   max_accel.
 max_z_velocity: 250
 #   For cartesian printers this sets the maximum velocity (in mm/s) of
 #   movement along the z axis. This setting can be used to restrict