Jerk Limiting Along The Path Through Velocity Reduction; Machine Axis-Specific Jerk Limiting; Compressor Functions - Siemens SINUMERIK 808D Function Manual

Selection and deselection of velocity reduction
Continuous-path mode with velocity reduction according to overload factor can be selected modally in every NC part
program block by means of program code G64 (BRISK active, not SOFT).
Continuous path mode G64 can be
● interrupted non-modally when exact stop G9 is selected,
● de-selected when exact stop G60 is selected.
5.4.3

Jerk limiting along the path through velocity reduction

Introduction
With the jerk limiting along the path, another method of influencing the continuous-path mode is introduced. While the
"Velocity reduction according to overload factor" function limits the rate of velocity change, the "Jerk limitation on path"
function described here limits the acceleration changes (jerks).
When sections of the contour consisting of blocks (e.g. circle straight line transitions) are machined, step changes in the
acceleration rate occur at the block transition in continuous path mode.
Reducing jerk
The severity of such jerks can be reduced by decreasing the path velocity at transitions between blocks containing different
degrees of curvature. A smoother transition is thus achieved between the contour sections.
Jerk limit
The user specifies the maximum jerk, which may occur on a path axis during a block transition, with MD32432
PATH_TRANS_JERK_LIM (maximum axis-specific jerk of a path axis at the block transition).
Activating
Jerk limiting at block transitions becomes active if continuous path mode is programmed with G64 and SOFT acceleration
characteristics. MD32432 PATH_TRANS_JERK_LIM must contain a positive value.
5.4.4

Machine axis-specific jerk limiting

Function
The axis-specific machine data MD32431 MAX_AX_JERK[..] can be used to set individual changes in acceleration for each
machine axis, like those that can already be set for acceleration limits in machine data MD32300 MAX_AX_ACCEL.
MD32431 MAX_AX_JERK acts on the axes interpolated by the path if SOFT (smooth acceleration curve) is active within a
block.
A basic distinction is made between the axis acceleration curve within a block and at the transition between two blocks.
Advantages
The deployment of axis-specific machine data for the path offers the following advantages:
● Immediate allowance is made in the interpolation for the dynamic response of the axes, which can then be fully utilized
for each axis.
● Jerk limitation for separate axes is performed not just in linear blocks, but also in curved contours.
Please refer to Chapter "Acceleration (Page 40)" for more information on the subject of "jerk limiting".
5.5

Compressor functions

Function
COMPON, COMPCURV
The compressor functions
the form: "
G01 X... Y... Z... F...
● : Continuous velocity block transitions
COMPON
Function Manual
01/2017
and generate one polynomial block from up to ten consecutive linear blocks of
COMPON COMPCURV
". The polynomial blocks of the compressor functions have the following properties:
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