Content .. 154 155 156 157 ..

FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 156

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

7.2.5

Optimum Torque Acceleration/Deceleration

Overview

This function enables acceleration/deceleration in accordance with the torque characteristics of the motor
and the characteristics of the machines due to its friction and gravity.
Usually, because of the friction of the machine, gravity, the torque characteristics of the motor, and other
factors, the acceleration/ deceleration performance (torque for acceleration/deceleration) is different with
direction of movement, acceleration or deceleration. In this function, acceleration pattern of rapid traverse
for the following situations, plus movement and acceleration, plus movement and deceleration, minus
movement and acceleration, minus movement and deceleration can be set into parameters according to the
torque for acceleration/deceleration of each situation. Acceleration/deceleration can be performed
according to these parameter setting, so that the most of the capability of the motor can be used and
positioning time can be reduced.

Time

Acceleration

Acc/Dec pattern is the same way in each condition.

Speed

Acceleration

and

+ move

Deceleration

and

+ move

Acceleration

and

- move

Deceleration

and

- move

Fig. 7.2.5 (a) Conventional acceleration/deceleration

Time

Speed

Time

Acceleration

and

+ move

Deceleration

and

+ move

Acc/Dec pattern can be changed in each condition.

Acceleration

and

- move

Deceleration

and

- move

Fig. 7.2.5 (b) Acceleration/deceleration with this function

Explanation

Optimum torque acceleration/deceleration selects the acceleration pattern set with parameters on the basis
of the axial movement direction and the acceleration/deceleration state, determines the acceleration for
each axis from the current speed, and controls the tangential acceleration/deceleration for rapid traverse.

Setting optimum torque acceleration/deceleration

When bit 0 (FAP) of parameter No. 19540 and bit 1 (LRP) of parameter No. 1401 are set to 1, and a value
other than 0 is set for any one of the axes as the reference acceleration in parameter No. 1671 as shown in
the Fig. 7.2.5 (a), rapid traverse is accelerated/decelerated by optimum torque acceleration/deceleration.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

Table 7.2.5 (a) Optimum torque acceleration/deceleration

Bit 0 (FAP) of parameter No.

19540

(Optimum torque acc/dec)

Bit 1 (LRP) of parameter

No. 1401

(Linear type positioning)

Reference

acceleration

Bell-shaped

acceleration
change time

Acceleration pattern

No.1671

No.1672

See "Setting an
acceleration pattern".

To enable bell-shaped acceleration/deceleration in addition to optimum torque acceleration/deceleration,
set the bell-shaped acceleration change time with parameter No. 1672.

NOTE

To use optimum torque acceleration/deceleration, set bit 5 (FRP) of parameter
No. 19501 to 1.

Required conditions in addition to parameter setting

If the conditions for performing AI contour control and for look-ahead acceleration/deceleration before
interpolation are satisfied, optimum torque acceleration/deceleration is performed for accelerating and
decelerating rapid traverse. However, when bit 0 (FAE) of parameter No. 11240 is set to 1, optimum
torque acceleration/deceleration is enabled even if AI contour control is disabled. If rapid traverse is
subject to optimum torque acceleration/deceleration, after-interpolation acceleration/deceleration does not
apply to rapid traverse.

Cases in which optimum torque acceleration/ deceleration is disabled

If optimum torque acceleration/deceleration is disabled by parameter settings, or the required conditions
other than parameter settings are not satisfied, acceleration/deceleration after interpolation is used to
accelerate and decelerate rapid traverse.

Setting acceleration pattern data

Acceleration

Speed

Acceleration pattern

Fig. 7.2.5 (c) Setting acceleration pattern

Set the speed and the acceleration at each of the acceleration setting points P0 to P5 for each condition,
plus movement and acceleration, plus movement and deceleration, minus movement and acceleration,
minus movement and deceleration, and for each axis.
The line joining the acceleration setting points is regarded a acceleration pattern.
For example, while the speed is between Fa and Fb in the Fig. 7.2.5 (c), the acceleration is calculated with
Aa and Ab. Tangential acceleration is controlled not to exceed the calculated acceleration for each axis.

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

NOTE

It is not desirable to set an acceleration pattern in which a large acceleration is
set right at a speed of 0, because this will shock the machine. So,

be sure to set

an acceleration pattern so that a relatively low acceleration rate is applied
at speed 0

as shown Fig. 7.2.5 (c).

Table 7.2.5 (b) Parameters for acceleration pattern

Acceleration
setting point

Speed

parameter

Acceleration parameter

During acceleration

During deceleration

During

movement in

plus direction

During

movement in

minus direction

During

movement in

plus direction

During

movement in

minus direction

(Speed 0)

No.19545

No.19551

No.19557

No.19563

No.19541

No.19546

No.19552

No.19558

No.19564

No.19542

No.19547

No.19553

No.19559

No.19565

No.19543

No.19548

No.19554

No.19560

No.19566

No.19544

No.19549

No.19555

No.19561

No.19567

No.1420

No.19550

No.19556

No.19562

No.19568

The speed at P0 is 0, and the speed at P5 is the rapid traverse rate specified with parameter No. 1420. The
speeds at P1 to P4 are to be set into speed parameters Nos. 19541 to 19544 as ratio to the rapid traverse
speed (parameter No. 1420).
Any acceleration setting point for which the speed parameter (one of Nos. 19541 to 19544) is set to 0 will
be skipped, and the next point whose speed parameter is set to a non-zero value will be joined together
connected with line. The polygonal line is regarded as acceleration pattern.
The accelerations at P0 to P5 are to be set into acceleration parameters Nos. 19545 to 19568 as ratio to the
reference acceleration. If any of the acceleration parameters Nos. 19545 to 19568 is set to 0, the
acceleration is assumed 100% (Reference acceleration). Acceleration parameters should be set to 0 at the
acceleration setting point whose speed parameter is set to 0.
If this function is enabled and parameter No. 1671 for an axis are set to 0, the following values are
assumed as the reference acceleration for that axis:
1000.0mm/sec

, 100.0inch/sec

, 100.0 degree/sec

Example of setting acceleration pattern data

In this example, the machine is equipped with the

S 30/4000.

Motor speed at rapid traverse is 3000 (min

-1

100

120

1000

2000

3000

4000

Speed(min

-1

)

orq

(Nm)

Fig. 7.2.5 (d) Speed-torque characteristics of model

S 30/4000

Specifications of the motor model

S 30/4000

Rotor inertia

:0.0099(Kgm

)

Maximum torque

:100(Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse

:79(Nm)

Speed 3000(min

-1

)

Minimum torque

:58(Nm)

Speed 4000(min

-1

)

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

It assumes that 10 (Nm) is needed for the friction torque, so that the torque for acceleration/deceleration is
shown as the following figure.
Because the friction torque is different on each machine, it is necessary to observe the actual torque
output on the machine for deciding acceleration pattern.
Maximum torque

:90(=100-10)(Nm) Speed 0 to 2000(min

-1

)

Torque at rapid traverse

:69(=79-10)(Nm)

Speed 3000(min

-1

)

Minimum torque

:48(=58-10)(Nm)

Speed 4000(min

-1

)

100

1000

2000

3000

4000

Speed(min

-1

)

orq

(Nm)

Fig. 7.2.5 (e) Torque for Acc/Dec with consideration of friction

Let the torque be x (Nm), the inertia be y(Kgm

), and the ball screw pitch p(mm), then the acceleration A

is calculated as follows:

]

sec

[

]

[

]

[

])

][

sec

([

]

[

]

[

]

[

⋅

Machine specification is assumed as follows,
Ball screw pitch : 16 (mm)
Inertia

: The machine inertia is to be 2.0 times higher than that of the rotor.

(Rotor inertia: 0.0099 (Kgm

))

Assumption magnification as inertia of rotor and machine : 3.0 times
According to the above equation of torque and acceleration, the acceleration at maximum torque is,

]

sec

[

7717

0099

The acceleration when torque 69 (Nm) at rapid traverse rate (3000 min

-1

) is,

]

sec

[

5916

0099

From the above data, the parameters related to acceleration pattern is given in the Table 7.2.5 (c).
The example assumes that the torque for acceleration/deceleration is the same regardless of whether
acceleration or deceleration is in progress or whether the movement is in the plus or minus direction.
-

When setting the speed at P1, use the following value as a rough guide:

If a bell-shaped acceleration change time (parameter No. 1672) is set, use as a rough guide the ratio
of the following speed to the rapid traverse rate:

Reference acceleration

T2/4

where T2 is the bell-shaped acceleration change time (msec).

For example, assume T2 to be 40 msec, then the speed at P1 should be approximately

4124 [mm/sec

]

40 [msec]/4

=4124 [mm/sec

]

602

40 [msec]/60000/4

=2474 [mm/min]

If no bell-shaped acceleration change time (parameter No. 1672) is set, use about 5% of the rapid
traverse rate as a rough guide.

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

Table 7.2.5 (c) Example of setting parameters related to acceleration pattern

Parameter

number

Setting

Unit

Remarks

Rapid traverse
rate

1420

48000.

mm/min

The ball screw pitch is assumed 16 mm, so that
the rapid traverse rate is 48000 mm/min at the
maximum speed 3000 (min

-1

Reference
acceleration

1671

4124.

msec

Reference acceleration is 4124mm/sec

Speed at P1

19541

515

0.01%

- Assuming that parameter No. 1672 (bell-shaped

acceleration change time) is set to 40 (msec),
the speed at P1 will be 2474 mm/min from the
calculation described on the previous page. Set
its ratio to the rapid traverse rate, or 5.15%.

0.0515=2474/48000

- If parameter No. 1672 (bell-shaped acceleration

change time) is not set, set about 5.00%.

Speed at P2

19542

6666

0.01%

Since the torque characteristic is constant (90 Nm)
in speeds reaching 2000 min

-1

, set P2 to the ratio

of the speed (32000 mm/min) at 2000 min

-1

to the

rapid traverse rate (48000 mm/min).
0.6666=32000 / 48000

Speeds at P3 to
P4

19543 to 19544

0.01%

P3 to P4 are skipped because the torque drops
almost linearly from the speed
2000 (min

-1

) to 3000 (min

-1

Acceleration at
P0

19545,19551,
19557,19563

9356

0.01%

Set half the acceleration at P1, or 9356.

Acceleration at
P1

19546,19552,
19558,19564

18712

0.01%

At P1, 90(Nm) can be used for the
acceleration/deceleration, so set the ratio of the
acceleration at 90 (Nm) to the reference
acceleration.
(1.8712 = 7717/4124)

Acceleration at
P2

19547,19553
19559,19565

18712

0.01%

At P2, set the same speed as that at P1.

Acceleration at
P3 to P4

19548 to 19549,
19554 to 19555,
19560 to 19561
19566 to 19567

0.01%

0 is set because P3 to P4 are skipped.

Acceleration at
P5

19550,19556
19562,19568

14345

0.01%

At P5, 69(Nm) can be used for the
acceleration/deceleration, so set the ratio of the
acceleration at 69 (Nm) to the reference
acceleration.
(1.4345 = 5916 / 4124)

With the above parameter settings, the acceleration pattern will be shown as the Fig. 7.2.5 (f). From
speeds from 0 mm/min to 2474 mm/min, the acceleration as calculated in accordance with the
acceleration pattern is applied; from speeds from 2474 mm/min to 32000 mm/min, an acceleration of
7716 mm/sec

; and from speeds from 32000 mm/min to 48000 mm/min, the acceleration as calculated in

accordance with the acceleration pattern.

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

1000

2000

3000

4000

5000

6000

7000

8000

9000

8000

16000

24000

32000

40000

48000

Speed mm/min

ccel

n m

Fig. 7.2.5 (f) Acceleration pattern with consideration of friction

NOTE

The values in the model

S 30/4000 speed-torque characteristic diagram are

just typical ones. The values will change depending on the digital servo software,
parameters, input voltage, and other factors.

The optimum acceleration will, therefore, change due to the characteristics of the
machine.

Examples of setting if the torque of acceleration/deceleration differs
depending on whether acceleration or deceleration is in progress and whether
the movement is in the plus or minus direction

From the effect of gravity and friction, torque for acceleration/deceleration is different on each condition,
such as acceleration, deceleration or plus move (up), minus move (down).
The following example is for the vertical axis and gravity and friction torque are assumed as follows.
Torque of gravity : 20 (Nm)
Torque of friction : 10 (Nm)
Because these value are different on each machine, it is necessary to observe the output torque on the
actual machine for deciding acceleration pattern.
The conditions are the same as the previous example.
(Condition)
Motor speed at rapid traverse

: 3000(min

-1

)

Ball screw pitch

: 16(mm)

Inertia

: The machine inertia is to be 2.0 times higher than that of the rotor.

Rotor inertia

: 0.0099(Kgm

)

Maximum motor torque

: 100(Nm) Speed 0 to 2000(min

-1

)

Motor torque at rapid traverse : 79(Nm)

Speed 3000(min

-1

)

Minimum motor torque

: 58(Nm)

Speed 4000(min

-1

)

(1) In case of plus move (up) and acceleration

Because torque of Gravity and friction work against the output torque of motor, the torque for
acceleration/deceleration is as follows.
Maximum torque

: 70(=100-20-10) (Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse

: 49(=79-20-10) (Nm)

Speed 3000(min

-1

)

Minimum torque

: 28(=58-20-10) (Nm)

Speed 4000(min

-1

)

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7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

1000

2000

3000

4000

Speed(min

-1

)

orq

(Nm)

Fig. 7.2.5 (g) Torque for Acc/Dec in case of + move and acceleration with

consideration of gravity and friction.

Parameter setting is as follows,

Fig.7.2.5 (d)

Parameter

number

Setting

Unit

Remarks

Acceleration at P0

19545

7277

0.01%

Set half the acceleration at P1, or 7277.

Acceleration at
P1-P2

19546,19547

14554

0.01%

At P1 and P2, 70(Nm) can be used for the
acceleration/ deceleration, so set the ratio of the
acceleration at 70 (Nm) to the reference
acceleration.
(1.4554 = 6002 / 4124)

Acceleration at
P3-P4

19548 to 19549

0.01%

0 is set because P3 to P4 are skipped.

Acceleration at P5

19550

10187

0.01%

At P5, 49(Nm) can be used for the
acceleration/deceleration, so set the ratio of the
acceleration at 49 (Nm) to the reference
acceleration.
(1.0187 = 4201 / 4124)

1000

2000

3000

4000

5000

6000

7000

8000

16000

24000

32000

40000

48000

Speed mm/min

ccel

n m

Fig. 7.2.5 (h) Acceleration pattern in case of + move and acceleration with

consideration of gravity and friction.

(2) In case of plus move (up) and deceleration

Because torque of Gravity and friction work forward to the output torque of motor, the torque for
acceleration/deceleration is as follows.
Maximum torque

: 130(=100+20+10) (Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse

: 109(=79+20+10) (Nm)

Speed 3000(min

-1

)

Minimum torque

: 88(=58+20+10) (Nm)

Speed 4000(min

-1

)

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7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

100

150

1000

2000

3000

4000

Speed(min

-1

)

orq

(Nm)

Fig. 7.2.5 (i) Torque for Acc/Dec in case of + move and deceleration with

consideration of gravity and friction.

Parameter setting is as follows,

Fig.7.2.5 (e)

Parameter

number

Setting

Unit

Remarks

Acceleration at
P0

19557

13514

0.01%

Set half the acceleration at P1, or 13514.

Acceleration at
P1-P2

19558, 19559

27027

0.01%

At P1 and P2, 130(Nm) can be used for the
acceleration/ deceleration, so set the ratio of the
acceleration at 130 (Nm) to the reference
acceleration.
(2.7027 = 11146 / 4124)

Acceleration at
P3-P4

19560 to 19561

0.01%

0 is set because P3 to P4 are skipped.

Acceleration at
P5

19562

22662

0.01%

At P5, 109(Nm) can be used for the
acceleration/deceleration, so set the ratio of the
acceleration at 109 (Nm) to the reference
acceleration.
(2.2662 = 9346 / 4124)

2000

4000

6000

8000

10000

12000

8000

16000

24000

32000

40000

48000

Speed mm/min

ccel

n m

Fig. 7.2.5 (j) Acceleration pattern in case of + move and deceleration with

consideration of gravity and friction.

(3) In case of minus move (down) and acceleration

Because torque of Gravity works forward to the output torque of motor and torque of friction works
against the output torque of motor, torque for acceleration/deceleration is as follows.
Maximum torque

: 110(=100+20-10) (Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse

: 89(=79+20-10) (Nm)

Speed 3000(min

-1

)

Minimum torque

: 68(=58+20-10) (Nm)

Speed 4000(min

-1

)

Content .. 154 155 156 157 ..