POINT Examples
7.8 Circular Interpolation Using Center Point Designation
Circular interpolation control by designating the end point and arc center point.
Circular interpolation control using center point designation uses ABS and ABS (absolute data method) and INC and INC (incremental method) servo instructions.
Items Set by Peripherals
Common Arc Parameter Block Others
Servo Instruction
Positioning Method
Number of Controllable
Axes
Parameter Block No. Axis Address/Travel Value Commanded Speed Dwell Time M Code Torque Limit Value Auxiliary Point Radius Center Point Control Units Speed Limit Value Acceleration Time Deceleration Time Rapid Stop Deceleration Time Torque Limit Value Deceleration Processing on Stop Input Allowable Error Range for Circular Interpolation S-Curve Ratio Cancel Start Speed Change
ABS
ABS
Absolute data
INC
INC
Incremental
2 ∆ ! ! ! ∆ ∆ ! ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ OK
! : Must be set
∆ : Set if required
[Control Details]
Details of control with the servo instructions are shown in the table below.
Instruction
Servomotor Direction of Rotation
Max.
Controllable Angle of Arc
Positioning Path
ABS
INC
Clockwise
Positioning path
End point Center point
Start point 0°<θ<360°
ABS
INC
Counterclockwise
0° < θ < 360°
Positioning path
End point Center point
Start point 0°<θ<360°
7. POSITIONING CONTROL
Control with ABS and ABS (absolute data method)
(1) Circular interpolation of an arc with a radius equivalent to the distance between the start point and center point, between the current stop address
(pre-positioning address used as the start point address) and the designated end point address, using the home position as the reference.
Reverse direction 0
Forward direction
End address (X1,Y1)
Movement due to circular interpolation
Start point address (X0,Y0)
: indicates set data Positioning speed
Center of arc Radius(R)
Reverse direction
Forward direction
Fig.7.17 Circular Interpolation Control by Absolute Date Method (2) To conduct positioning control of a full circle, divide the circular interpolation
control into two operations.
0 Forward direction
Forward direction
Reverse direction Reverse direction
1st circular interpolation control
1st end address, 2nd start address
2nd circular interpolation control
1st start address, 2nd end address Center of arc
Fig.7.18 Positioning Control of a Full Circle
(3) The setting range for the end point address and arc center point is −231 to (231−1).
(4) The maximum arc radius is 232−1.
Radius R Arc center point
231-1 231-1
Maximum arc
-231 0
7. POSITIONING CONTROL
Control with INC and INC (incremental method)
(1) Circular interpolation of an arc from the current stop address (start point address, 0, 0) with a radius equivalent to the distance between the start point (0, 0) and center point.
Path of circular interpolation(for INC )
Home position
Forward direction
Forward direction Reverse direction
Reverse direction Start point
Positioning speed
Center of arc
: indicates set data End address
Fig.7.20 Circular Interpolation Control by Incremental Method (INC ) (2) To conduct positioning control of a full circle, divide the circular interpolation
control into two operations.
Forward direction
Reverse direction Reverse direction
1st circular interpolation control
2nd circular interpolation control Center
of circle Forward direction
Radius
Home position
0
0
Fig.7.21 Positioning Control of a Full Circle
(3) The setting range for the center point and travel value to the end point is 0 to
±(231−1).
(4) The maximum arc radius is 231−1.
If the designated end point and center point result in a radius more than 231−1, an error occurs at the start and error code 109 is stored in the data register.
0
Radius R
Maximum arc
231-1 231-1
-231
Center of arc
0
Fig.7.21 Maximum Arc Radius
7. POSITIONING CONTROL
[Program Example]
This program conducts circular interpolation control using center point designation under the conditions below.
(1) System configuration
Circular interpolation control of Axis 1 and Axis 2 using center point designation.
M M M M
A61P A273UH CPU
A278 LX
Axis 1
Axis 2
Axis 3
Axis 4 A61P AX41
Positioning start command (X000)
MR- -B MR- -B MR- -B MR- -B
(2) Positioning details
The positioning by the Axis 1 and Axis 2 servomotors is shown in the diagram below.
0
Axis 2 positioning direction (Forward direction)
Axis 1 positioning direction (Forward direction) Positioning by No. 51 servo program Start address
(11459, 30000)
(78541, 30000)
(45000, 20000)
11459 45000 78541
30000 20000
Center point address End address
(3) Positioning conditions
(a) The positioning conditions are shown below.
Servo Program Number
Item No. 51
Positioning method Absolute data
Positioning speed 1000
(b) Positioning start ... leading edge of X000 (OFF→ON)
7. POSITIONING CONTROL
(4) Operation timing
The operation timing for circular interpolation control using center point designation is shown below.
V
Servo program No.51
PLC ready (M2000)
All axes servo start command (M2042)
All axes servo start accept frag (M2049)
Positioning start command (X000)
SVST instruction Axis 1 start accept flag (M2001)
Axis 2 start accept flag (M2002)
(5) Servo program
The servo program No. 51 for circular interpolation control using center point designation is shown below.
Circular interpolation control using center point designation
⋅ Axis used¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥Axis 1,Axis 2
⋅ End point address
Positioning speed ¥¥¥¥¥¥¥¥1000 Center point address
<K 51>
ABS
Axis 1, 78541
Axis 2, 30000
Speed @1000
Center
point 1, 45000
Center
point 2, 20000
Axis 1¥¥¥¥78541 Axis 2¥¥¥30000
Axis 1¥¥¥¥45000 Axis 2¥¥¥20000
(6) Sequence program
The sequence program which runs the servo program is shown below.
0
Turns ON PLC ready.
Turns ON servo program No.51 start command flag (M53) when X000 turns OFF ON.
Turns ON all axes servo start command.
Servo program No.51 execution request.
Turns OFF M1 on completion of sarvo program No.51 execution request.
7. POSITIONING CONTROL
7.9 1-Axis Fixed-Pitch Feed Control
Positioning control to move the axis designated with the sequence program positioning commands by the designated travel value from the current stop position.
Fixed-pitch feed control uses the FEED-1 servo instruction.
Items Set by Peripherals
Common Arc Parameter Block Others
Servo Instruction
Positioning Method
Number of Controllable
Axes
Parameter Block No. Axis Address/Travel Value Commanded Speed Dwell Time M-Code Torque Limit Value Auxiliary Point Radius Center Point Control Units Speed Limit Value Acceleration Time Deceleration Time Rapid Stop Deceleration Time Torque Limit Value Deceleration Processing on Stop Input Allowable Error Range for Circular Interpolation S-Curve Ratio Cancel Start Speed Change
FEED-1 Incremental 1 ∆ ! ! ! ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ OK
! : Must be set
∆ : Set if required
[Control Details]
(1) Positioning control through the designated travel value from the current stop position (0).
(2) The travel direction is designated by the sign of the travel value, as follows:
• Positive travel value ... forward direction (increased address)
• Negative travel value... reverse direction (decreased address)
V
t Travel value
Commanded speed
Fixed-pitch feed using FEED-1 instruction
Reverse direction
Forward direction Current stop position
Travel direction for Negative sign
: indicates set data Operation timing
Positioing direction
SVST instruction Travel direction
for Positive sign
Fig.7.23 1-Axis Fixed-Pitch Feed Control
POINT
Do not set the travel value to zero for fixed-pitch feed control.
7. POSITIONING CONTROL
[Program Example]
This program conducts repeated 1-axis fixed-pitch feed control under the conditions below.
(1) System configuration
Fixed-pitch feed control of Axis 4.
M M M M
A61P A273UH CPU
A278 LX
Axis 1
Axis 2
Axis 3
Axis 4 A61P AX41
Start command (X000)
MR- -B MR- -B MR- -B MR- -B
(2) Fixed-pitch feed control conditions
(a) The positioning conditions are shown below.
Item Setting
Servo program number No. 300
Controlled axis Axis 4
Control speed 10000
Travel value 100000
(b) Fixed-pitch feed control start command ...leading edge of X000 (OFF→ ON) (c) Fixed-pitch feed control end command ...leading edge of X001
(OFF→ON) (3) Operation timing
The operation timing for fixed-pitch feed control is shown below.
V
t
1 second 1 second
10000
Servo program No.300
PLC ready (M2000)
All axes servo start command (M2042)
All axes servo start accept frag (M2049)
Start command (X000) SVST instruction Axis 4 start accept flag (M2004)
End command (X001)
7. POSITIONING CONTROL
(4) Servo program
The servo program No. 300 for fixed-pitch feed control is shown below.
1-axis fixed-pitch feed control
Axis used Axis 4
Travel value 80000
Commanded speed 10000
Dwell 1000
<K 300>
FEED-1
Axis 4, 80000
Speed 10000
Dwell 1000
(5) Sequence program
The sequence program which runs the servo program is shown below.
0
CIRCUIT END
M2000
SVST 2
4
11
13 M9039
M9074
X000
M300
M9074 M9074
M301
M2049 M9076
M2004
M2042
PLS
SET
RST M300
M301
M301 300 K J4
23 X001
Turns ON PLC ready.
Turns ON servo program No.300 start command flag (M301) when X000 turns OFF ON.
Turns ON all axes servo start command.
Servo program No.300 execution request.
Turns OFF M301 on completion of sarvo program No.300 execution request.