diff --git a/docs/Kinematics.md b/docs/Kinematics.md index 07ed3a1b..3face1db 100644 --- a/docs/Kinematics.md +++ b/docs/Kinematics.md @@ -170,7 +170,7 @@ the actual tower. It is then possible to calculate where the head will be along the line of movement after each step is taken on the virtual tower. The key -formula is Pythagorean's formula: +formula is Pythagoras's theorem: ``` distance_to_tower^2 = arm_length^2 - tower_height^2 @@ -198,6 +198,22 @@ Should the move contain only Z movement (ie, no XY movement at all) then the same math is used - just in this case the tower is parallel to the line of movement (its slope is 1.0). +### Stepper motor acceleration limits ### + +With delta kinematics it is possible for a move that is accelerating +in cartesian space to require an acceleration on a particular stepper +motor greater than the move's acceleration. This can occur when a +stepper arm is more horizontal than vertical and the line of movement +is near that stepper's tower. + +Klipper does enforce a maximum ceiling on stepper acceleration that is +three times the maximum acceleration of a move in cartesian +space. (Similarly, the maximum velocity of the stepper is limited to +three times the maximum move velocity.) In order to enforce this +limit, moves at the extreme edge of the build envelope (where a +stepper arm may be nearly horizontal) will have a lower maximum +acceleration and velocity. + Extruder kinematics -------------------