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FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 148

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

NOTE

1 Always specify G05.1, G08, and G05 in an independent block.

(Do not specify other G codes at the same time.)

2  G05 can be specified only for AI contour control II.
3  The AI contour control mode can also be turned off at a reset.
4  The AI contour control mode can be turned on at the start of automatic operation

by setting bit 0 (SHP) of parameter No. 1604.

5 G05.1, G08, and the G05 commands are separate commands respectively.

Please turn off the AI contour control mode by the command that turns on the AI
contour control mode. AI contour control cannot be turned off by a different
command.

6 There are the following conditions when each AI contour control mode on / off is

commanded in the multiple.
(1) The AI contour control mode commands are G05, G05.1, and G08 in the

order of a high-ranking command (G05 > G05.1 > G08). It is necessary to turn
on the AI contour control mode from the subordinate position command
sequentially when the multiple commands are executed.

(2) When the AI contour control mode is turned on by the G05P10000 command,

even if the AI contour control mode ON/OFF command is executed by
G05.1Q1/Q0 command in the mode, the command is ignored.
Example)
G05P10000 AI contour control mode on by G05
G05.1Q1 This command is ignored.
G05.1Q0 This command is ignored.
G05P0 AI contour control mode off by G05

(3) After the AI contour control mode is turned on by the G05P10000 or the

G05.1Q1, if the G08 command is executed in the mode, alarm PS5110
“IMPROPER G-CODE (AICC MODE)” occurs.
Example)
G05P10000(G05.1Q1) AI contour control mode on by G05(G05.1)
G08P1(P0) Alarm PS5110 occurs

(4) When the multiple commands are executed, each command that turns on/off

the AI contour control mode must be nested.
Example)
G08P1 AI contour control mode on by G08
:
G05.1Q1 AI contour control mode on by G05.1
:
G05P10000 AI contour control mode on by G05
:
G05P0 AI contour control mode off by G05
:
G05.1Q0 AI contour control mode off by G05.1
:
G08P0 AI contour control mode off by G08

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

CAUTION

Set bit 6 (AP5) of parameter No.11549 to 1 if AI contour control is executed
simultaneously by more than 5 paths. If AI contour control is executed
simultaneously by more than 5 paths without setting this parameter to 1,
sufficient performance might not be obtained.

Explanation

Look-ahead acceleration/deceleration before interpolation

There are two types of look-ahead acceleration/deceleration before interpolation, the linear
acceleration/deceleration type and the bell-shaped acceleration/deceleration type.
Look-ahead bell-shaped acceleration/deceleration before interpolation produces smoother
acceleration/deceleration.

Setting an acceleration

A permissible acceleration for the linear acceleration/deceleration of each axis is set in parameter No.
1660. For bell-shaped acceleration/deceleration, acceleration change time (B) (period of transition from
constant speed state (A) to constant acceleration/ deceleration state (C)) is set in parameter No. 1772. In
the constant acceleration/deceleration state (C), acceleration/deceleration is performed with the maximum
tangential acceleration not exceeding the permissible acceleration of each axis specified in parameter No.
1660.
The acceleration change time specified in parameter No. 1772 is held constant, regardless of the
tangential acceleration.

Feedrate in tangent direction

Optimum inclination is automatically
calculated from the setting of parameter
No. 1660.

(A)

(B)

(A)

(C)

Time set by parameter No. 1772

Fig. 7.1.11 (a)

Method of determining the tangent acceleration

Acceleration/deceleration is performed with the largest tangent acceleration/deceleration that does not
exceed the permissible acceleration set for each axis.

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

(Example)
X-axis permissible acceleration: 1000 mm/sec

Y-axis permissible acceleration: 1200 mm/sec

Acceleration change time: 20 msec

Program:

N1 G01 G91 X20.0 F6000

Move on the X-axis.

G04 X0.01

N2 Y20.0

Move on the Y-axis.

G04 X0.01

N3 X20.0 Y20.0

Move in the XY direction (at 45 degrees).

Since N3 performs interpolation for the X and Y axes in the 45-degree direction, the acceleration of the Y
axis is controlled according to the X axis to become 1000 mm/s

. Therefore, the combined acceleration is

1414 mm/s

20ms

1000mm/sec

gradient

Tangent feedrate

1200mm/sec

gradient

1414mm/sec

gradient

Fig. 7.1.11 (b)

Acceleration

Acceleration is performed so that the feedrate programmed for a block is attained at the beginning of the
block.
When look-ahead acceleration/deceleration before interpolation is valid for multiple blocks, acceleration
can be performed across more than one block.

Speed control by look-ahead
acceleration/deceleration before interpolation
Programmed speed

Feedrate

Time

Fig. 7.1.11 (c)

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

Deceleration

Deceleration starts in advance so that the feedrate programmed for a block is attained at the beginning of
the block.
When look-ahead acceleration/deceleration before interpolation is valid for multiple blocks, deceleration
can be performed across more than one block.

Feedrate

Time

Deceleration
start point

Speed control by look-ahead
acceleration/deceleration before
interpolation

Programmed speed

Fig. 7.1.11 (d)

Deceleration based on a distance

If the total distance of the blocks read ahead becomes shorter than or equal to the deceleration distance
obtained from the current feedrate, deceleration starts.
If the total distance of the blocks read ahead during deceleration increases, acceleration is performed.
If the blocks of a small amount of travel are successively specified, deceleration and acceleration may be
performed alternately, making the feedrate inconsistent.
To avoid this, decrease the programmed feedrate.

Function for changing time constant of bell-shaped acceleration/deceleration

Look-ahead bell-shaped acceleration/deceleration before interpolation is performed according to the
acceleration and acceleration change time set by the parameters, as shown in the figure below.

T1 :

Time obtained from specified feedrate and specified acceleration
(specified feedrate/acceleration (parameter No. 1660))

T2 :

Acceleration change time (parameter No. 1772)

Specified
feedrate

Feedrate

low

Time

Low specified
feedrate

Fig. 7.1.11 (e)

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

Here, the acceleration change time (T2) remains constant regardless of the specified feedrate, while the
acceleration time for the linear section (T1), which is determined by acceleration, varies with the
specified feedrate. If T1 becomes shorter than T2 when the specified feedrate is low, linear
acceleration/deceleration not achieving the specified acceleration results, as shown in the figure below.

Linear acceleration/deceleration not achieving
specified acceleration/deceleration

Specified
feedrate

Feedrate

Time

T1 : Time obtained from specified feedrate and specified acceleration (specified

feedrate/acceleration (parameter No. 1660))

T2 : Acceleration change time (parameter No. 1772)

Fig. 7.1.12 (f)

In such a case, set bit 3 (BCG) of parameter No. 7055 to 1. Then, the internal acceleration and vector time
constant of look-ahead acceleration/ deceleration before interpolation are changed to make the
acceleration/deceleration pattern as close as possible to the optimum look-ahead bell-shaped
acceleration/deceleration before interpolation based on a specified acceleration/deceleration reference
speed, and so acceleration/deceleration time is reduced.

Acceleration/deceleration curve

Specified
feedrate

Feedrate

T1'

T2'

T1':

The acceleration time by optimal acceleration

T2': Optimal acceleration change time

Fig. 7.1.11 (g)

There are three methods for specifying the acceleration/deceleration reference speed.
(1)  Specifying the speed using an F in a G05.1 Q1 block
(2)  Setting the speed on parameter No. 7066
(3)  Setting the speed specified with the F command issued at the start of cutting as the reference speed
When F is specified in a G05.1Q1 block, the specified feedrate is assumed to be the
acceleration/deceleration reference speed. This command can be used only in the feed per minute mode.
If no F command is specified in a G05.1Q1 block, the feedrate specified in parameter No. 7066 is
assumed to be the acceleration/deceleration reference speed. If 0 is set in parameter No. 7066, the F
command specified in the cutting start block is assumed to be the acceleration/deceleration reference
speed.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

NOTE

When function for changing time constant of look-ahead bell-shaped
acceleration/deceleration before interpolation is enabled (bit 3 (BCG) of
parameter No. 7055 is set to 1), be sure to specify acceleration rate of the
reference axis.

If acceleration rate of the reference axis is not specified, optimum acceleration
rate is not obtained.

Acceleration/deceleration after cutting feed interpolation in AI contour control
mode

For cutting feed in AI contour control mode, in addition to look-ahead acceleration/deceleration before
interpolation, acceleration/deceleration after interpolation can be enabled.
The time constant of acceleration/deceleration after interpolation is set to the parameter (No.1769).
Type of acceleration/deceleration after interpolation is selected by bit 6 (LS2) and bit 3 (BS2) of
parameters No. 1602.
Using exponential acceleration/deceleration: LS2 is set to 0 and BS2 is set to 0.
Using linear acceleration/deceleration: LS2 is set to 1 and BS2 is set to 0.
Using bell-shaped acceleration/deceleration: BS2 is set to 1.
If shape of acceleration/deceleration after interpolation is exponential acceleration/deceleration, FL
feedrate for each axis is set to parameter No. 1763.

Feedrate control function

In AI contour control mode, the feedrate is automatically controlled by the look-ahead of blocks.
The feedrate is determined using the  following conditions. If the specified feedrate exceeds the
determined feedrate, look-ahead  acceleration/ deceleration before interpolation is performed to achieve
the determined feedrate.
(1)  Feedrate changes on each axis at a corner and the permissible feedrate change that has been set
(2)  Expected acceleration on each axis and the permissible acceleration that has been set
(3)  Cutting load that is expected from the travel direction on the Z-axis

Specified tool path

Tool path assumed when
Al contour control is not
used

Tool path assumed when Al
contour control is used

The machining error is decreased
because of the deceleration with
the acceleration.

The machining error is decreased
because of the deceleration by
difference in feedrate.

Fig. 7.1.11 (h)

For details, see the explanation of each function.

Speed control based on the feedrate difference on each axis at a corner

By using the speed control based on the feedrate difference on each axis at a corner, if a feedrate change
occurs on an axis on each axis at a corner, the feedrate is determined so that any feedrate difference
exceeding the permissible feedrate difference on that axis that has been set for parameter No. 1783 does
not occur, and deceleration is automatically performed.

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

(Example)

Program

N1 G01 G91 X100.0 F5000

N2 Y100.0

Tangent feedrate

X-axis feedrate

Y-axis feedrate

The deceleration based
on the feedrate difference
is used.

Tangent feedrate

X-axis feedrate

Y-axis feedrate

The feedrate difference
becomes small, and the
feedrate on each axis
becomes smooth.

The tangent feedrate is
smooth, but the feedrate
on each axis is not.

Parameter No.1783

When speed control based on the feedrate

difference is invalid

When speed control based on the feedrate difference is

valid

Time

Fig. 7.1.11 (i)

The method of deceleration based on the feedrate difference differs depending on the setting made for
parameter FNW (bit 6 of No. 19500).
If parameter FNW is set to 0, the largest feedrate that does not exceed the permissible feedrate difference
set for parameter No. 1783 is assumed to be the deceleration feedrate.
In this case, the deceleration feedrate differs if the travel direction differs, even if the shape is the same.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

Decelerate the X axis

down to 500 mm/min

Decelerate the X/Y axis down to 250

mm/min

(The tangent direction feedrate is 354

mm/min.)

(Example)

If parameter FNW (bit 6 of No. 19500) = 0 and the

permissible feedrate difference = 500 mm/min (on all axes)

Fig. 7.1.11 (j)

In the left-side example in the figure above, the X axis is inverted at the corner from the position direction
to the negative direction, and deceleration is performed so that the feedrate difference becomes 500
mm/min. In other words, the feedrate is 250 mm/min both when the axis moves in the position direction
and when it moves in the negative direction. As a result, the tangent direction feedrate becomes 354
mm/min.

X-axis

feedrate

Time

500mm/min

Y-axis

feedrate

Time

250mm/min

Fig. 7.1.11 (k)

If parameter FNW is set to 1, the feedrate is determined not only with the condition that
the permissible feedrate difference and permissible acceleration on each axis are not exceeded, but also
that the deceleration feedrate is constant regardless of the travel direction if the shape is the same.
If this parameter is set to 1, the deceleration feedrate determined with the feedrate difference may be up to
30% lower than that determined if this parameter is set to 0.

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