FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 163

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

positioning (G00) or specifying an M function alone, the ACDEC signal continues to be output. In this
case, the ACDEC signal is turned off when the time set in parameter No. 1650 has elapsed after execution
of the next block for cutting feed is started.

NOTE

The ACDEC signal is turned off by a reset.

Signal

In-acceleration/deceleration signal ACDEC<Fn520.3>

[Classification] Output signal

[Function] Posted to the PMC during deceleration in a block for cutting feed (G01, G02, G03).

[Operation] If deceleration is performed in a block for cutting feed (G01, G02, G03), this signal is set

to 1 during deceleration. This signal continues to be set to 1 for the time set in parameter
No. 1650 after execution of the next block is started upon completion of deceleration.
This signal is set to 0 when the time set in parameter No. 1650 has elapsed.
This signal is also set to 0 by a reset.

Signal address

Fn520

ACDEC

Parameter

1650

Timer for the acceleration/deceleration signal

[Input type] Parameter input

[Data type] Word path

[Unit of data] msec

[Valid data range] 0 to 32767

Set the output duration of the acceleration/deceleration signal.

Note

NOTE

This function is disabled for look-ahead acceleration/deceleration before
interpolation.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

7.3

JERK CONTROL

7.3.1

Speed Control with Change of Acceleration on Each Axis

Overview

In portions in which acceleration changes largely, such as a portion where a programmed figure changes
from a straight line to curve, vibration or shock on the machine may occur. Speed control with change of
acceleration on each axis is a function to suppress machining errors due to vibration and machine shock
generated by change of acceleration. This function obtains a feedrate so that change of acceleration is
within the parameter-set permissible acceleration change amount for each axis, and performs deceleration
by using look-ahead acceleration/deceleration before interpolation.

Explanation

In the following example, the Y-axis acceleration changes largely at the contact point between a linear
interpolation and circular interpolation, so deceleration is performed.

From linear interpolation (N1) to circular interpolation (N2)

Vibration due to change
of acceleration

Tangential
feedrate

Y-axis
acceleration

Feedrate

Time

Feedrate

Acceleration

Time

Acceleration

Time

Setting the permissible acceleration change amount

The permissible acceleration change amount for each axis is set in parameter No. 1788. When 0 is set in
this parameter for a certain axis, speed control with change of acceleration is not performed for that axis.

Parameter setting example

Suppose a figure shown Fig. 7.3.5 in which a straight line is followed by an arc. Let the specified feedrate
and the arc radius be 6000 mm/min and 10 mm, respectively. Then, the Y-axis acceleration change
amount at the contact point of the linear and arc portions is obtained as follows:

1000

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

Y-axis
acceleration

Acceleration

Time

From straight line to arc

Specified feedrate: 6000 mm/min

Acceleration
change amount:

1000 mm/s

Arc radius: 10 mm

Fig. 7.3.1

To suppress the change of acceleration to 300 mm/sec

, set 300 mm/sec

for the Y-axis in parameter No.

1788.
Note that the change of acceleration is determined from the interpolation data of the CNC, so it may differ
from the theoretical value.
The actual machine is affected by acceleration/deceleration and other factors, so the value to be set in the
parameter should be determined after adjustments are made.

For successive linear interpolations

When there are successive linear interpolations, speed control with change of acceleration obtains the
deceleration feedrate from the change in acceleration between the start point and end point of a specified
block.
When a curve is specified using successive minute straight lines, programmed values are rounded to the
least input increment before issued, so the machining profile is approximated with a broken line. The
error due to rounding may increase change of acceleration, and especially when the line segments
specified by blocks are short, deceleration is performed frequently. As a result, the machining speed
cannot increase enough. In such a case, a relatively large value should be set in parameter No. 1789 as the
permissible acceleration change amount for each axis in successive linear interpolations to improve the
machining speed.
When a value other than 0 is set in parameter No. 1789 for an axis for which deceleration with change of
acceleration is enabled, this setting is regarded as the permissible acceleration change amount at corners
in which linear interpolations meet. (For portions where a linear interpolation and circular interpolation
meet and where circular interpolations meet, the setting in parameter No. 1788 is used.)
When 0 is set in parameter No. 1789 for an axis, the setting in parameter No. 1788 specifying the
ordinary permissible acceleration change amount is used even at a corner in which linear interpolations
meet.
When smooth speed control is used in speed control with permissible acceleration in AI contour control II,
the deceleration feedrate is obtained from the change of acceleration calculated by smooth speed control.
Therefore, the deceleration feedrate may be higher than the ordinary deceleration feedrate.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

When linear interpolation is followed
by circular interpolation, speed
control is performed using the
permissible acceleration change
amount set in parameter No. 1788.

Linear
interpolation

Circular
interpolation

For successive linear interpolations,
speed control is performed using the
permissible acceleration change
amount set in parameter No. 1789.

Linear
interpolation

Parameter

1788

Maximum allowable acceleration change rate in feedrate determination based on acceleration change

for each axis

[Input type] Parameter input

[Data type] Real axis

[Unit of data] mm/sec

, inch/sec

, deg/sec

(machine unit)

[Min. unit of data] Depend on the increment system of the applied axis
[Valid data range] Refer to the standard parameter setting table (D)

1789

Maximum allowable acceleration change rate in feedrate determination based on acceleration change

for each axis (linear interpolation)

[Input type] Parameter input

[Data type] Real axis

[Unit of data] mm/sec

, inch/sec

, deg/sec

(machine unit)

[Min. unit of data] Depend on the increment system of the applied axis
[Valid data range] Refer to the standard parameter setting table (D)

(When the machine system is metric system, 0.0 to +100000.0. When the machine system
is inch system, machine, 0.0 to +10000.0.)
Set a maximum allowable acceleration change rate for each axis in feedrate control based
on acceleration change under control on the rate of change of acceleration in successive
linear interpolation operations.
In feedrate control based on acceleration change at a corner between linear interpolation
operations, the maximum allowable acceleration change rate not set in parameter No.
1788 but set in this parameter is valid.
For an axis with 0 set in this parameter, the maximum allowable acceleration change rate
set in parameter No. 1788 is valid.
Feedrate control based on acceleration change is disabled for an axis with 0 set in
parameter No. 1788, so that the setting of this parameter for such an axis is ignored.

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

7.3.2

Look-Ahead Smooth Bell-Shaped Acceleration/Deceleration
before Interpolation

Overview

In look-ahead

bell-shaped acceleration/deceleration before interpolation performs smooth

acceleration/deceleration by changing the acceleration at a constant rate in specified acceleration change
time.
In look-ahead smooth bell-shaped acceleration/deceleration before interpolation, the jerk change time is
specified in parameter No. 1790 by using the percentage to the acceleration change time for look-ahead
bell-shaped acceleration/deceleration before interpolation, and change of acceleration is also controlled so
that the change is bell-shaped.
This enables smoother acceleration/deceleration, therefore it reduces machine vibration and shock due to
acceleration/deceleration.

(Look-ahead bell-shaped
acceleration/deceleration before interpolation)

(Look-ahead smooth bell-shaped
acceleration/deceleration before interpolation)

Time

Tangential feedrate

Acceleration

Jerk
acceleration

Acceleration change time
Time set in parameter No.
1772

Jerk change time
Time set in parameter No.
1790 by using the
percentage to the
acceleration change time

Tangential feedrate

Time

Acceleration

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

Explanation

Setting the jerk change time

The jerk change time is set in parameter No. 1790 by using the percentage to the acceleration change
time.
The actual jerk change time is represented by the percentage to the acceleration change time set in
parameter No. 1772.
The jerk change time must be within a half of the acceleration change time, so the value to be set in the
parameter ranges 0 to 50 (percent).
If 0 or a value beyond the specifiable range is specified in parameter No. 1790, look-ahead smooth
bell-shaped acceleration/deceleration before interpolation is not available.

Acceleration/deceleration before interpolation for linear type rapid traverse

When look-ahead bell-shaped acceleration/deceleration is used in look-ahead acceleration/
deceleration before interpolation for linear type rapid traverse, enabling look-ahead smooth bell-shaped
acceleration/deceleration before interpolation applies smooth bell-shaped acceleration/deceleration to
acceleration/deceleration before interpolation for linear type rapid traverse.
In this case, the jerk change time is represented by the percentage set in parameter No. 1790 to the
acceleration change time set in parameter No. 1672.

Optimum torque acceleration/deceleration

When bell-shaped acceleration/deceleration is used in optimum torque acceleration/deceleration, enabling
look-ahead smooth bell-shaped acceleration/deceleration before interpolation applies smooth bell-shaped
acceleration/deceleration to optimum torque acceleration/
deceleration.
In this case, the jerk change time is represented by the percentage set in parameter No. 1790 to the
acceleration change time set in parameter No. 1672.

Parameter

1790

Ratio of change time of the rate of change of acceleration in smooth bell-shaped

acceleration/deceleration before interpolation

[Input type] Parameter input

[Data type] Byte path

[Unit of data] %

[Valid data range] 0 to 50

Set the ratio of the change time of the rate of change of acceleration to the change time of
acceleration(*1) by percentage (%) in smooth bell-shaped acceleration/deceleration
before look-ahead interpolation.
If 0 is set in this parameter or a value not within the valid data range is specified in this
parameter, look-ahead smooth bell-shaped acceleration/ deceleration before interpolation
is not performed.

(*1) Parameter No. 1772 for look-ahead acceleration/deceleration before interpolation

(cutting feed).

Parameter No. 1672 for look-ahead acceleration/deceleration before interpolation in
linear rapid traverse, or for optimum torque acceleration/ deceleration.

8. MULTI-PATH CONTROL

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MULTI-PATH CONTROL

8.1

MULTI-PATH CONTROL

Overview

The multipath control function is designed to control the independent simultaneous machining with up to
2 paths, and the peripheral device such as a loader for performing a non-machining operation. (machining
path up to 2, loader path up to 2, up to 4 paths in total). This function is applicable to lathes and automatic
lathes which perform cutting simultaneously with multiple tool posts, combined machine tools which
perform turning and milling simultaneously with multiple paths, and machines which require additional
control paths such as a loader control path.
For multipath simultaneous machining, each machining program is stored in a directory in program
memory for each path. When automatic operation is to be performed, each path is activated after selecting
a program for machining with path 1 and programs for machining with paths 2 from the programs stored
in the respective directories in program memory. Then the programs selected for the tool posts are
executed independently at the same time. When tool post 1 and tool post 2 need to wait for each other
during machining, the waiting function is available.
Other available functions specific to multipath control include interference check for each path, balance
cut, synchronization control, composite control, path spindle control, and memory common to paths.
Just one LCD/MDI is provided for the all paths. Before operation and display on the LCD/MDI, the path
selection signal is used to switch between the paths.

For a system with two paths

Fig.8.1 (a)

Explanation

System configuration

In multi-path control, multiple paths are combined into a single machine group, and such multiple
machine groups, in turn, make up a single system.
Each of the elements making up multi-path control is explained below.

Example)

Configuration of multi-path control

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CNC

Machine group 1

Path 1

Machine group 2

Path 2

Axis

Machine group

If you have multiple paths, you can combine some of them into a group, so that, for example, you can
share data in that group and if an alarm is generated in a certain path, you can stop other paths in that
group. A group that is made up of such paths is called a machine group.
Up to three groups are available, depending on the type of the CNC system.
The main items that depend on the machine group are shown below.
-

Emergent stop signal *ESP <X0008.4,X0008.0,X0008.1>

MDI reset key

Operation during the occurrence of an alarm

Path

A path refers to a group of axes controlled by the same CNC program command.
Up to 2 paths are available for machining, and up to 2 paths are available for loader control. Up to 4 paths
in total are available.
You can specify which machine group a certain path is to belong to, using parameter No. 0980 for that
path. In addition.

NOTE

The number of the machine group to which each path can belong differs
depending on the machine used. For details, refer to the manual issued by the
machine tool builder.

Controlled axes

The number of control axes witch used throughout the entire system is specified with parameter No.0987.
You can specify which path each controlled axis is to be assigned, using parameter No. 0981.
You can assign each path to any controlled axis, provided that you follow the maximum allowable
number of controlled axes.

Example)

For a system with 2 paths and a total of 6 controlled axes:

Settings that cause the system to become a 2-path system with the first path consisting of 3
controlled axes and the second consisting of 3 controlled axes

Parameter No. 0981

Setting value

Application

Logical, axis 1

Path 1, axis 1

Logical, axis 2

Path 1, axis 2

Logical, axis 3

Path 1, axis 3

Logical, axis 4

Path 2, axis 1

Logical, axis 5

Path 2, axis 2

Logical, axis 6

Path 2, axis 3

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