Tangent Motion
M O T I O N C O N T R O L P R O G R A M M I N G
110
Motion Control Programming
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Galil Motion Control, Inc.
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800-377-6329
To accomplish this function, motion controllers read
the potentiometer voltage and adjust the feedrate in pro-
portions. For a specific implementation by the DMC,
consider the following example.
Repeat the motion of the previous example with feed-
rate override. The operators generate a voltage in the range
between 0 and 10 V. This voltage is applied to the analog
input #1 to set the feedrate in proportion to the voltage.
The motion is generated by two programs, #MOVE
and #SPEED. Both programs operate simultaneously in
multitasking. The program #SPEED reads the analog
inputs and adjusts the vector speed continuously. The sec-
ond program, #MOVE, is the same as in the previous
example with the exception that the vector speed is not
specified.
The two programs are listed below.
Instruction Interpretation
#SPEED
Label
A = @AN[1]
Read analog voltage
V = A*2000 Set feedrate
VS V Update feedrate
JP #SPEED Repeat the process
EN End program
#MOVE Label
VM XY Specify XY plane
VP 6000,0 Move to Point B
CR 1000,270,180 Move to Point C
VP -6000,2000 Move to Point D
CR 1000,90,180 Move to Point E
VP 0,0 Return to Point A
VE End of path
VA 100000 Vector acceleration
VD 100000 Vector deceleration
BGS
Start motion
EN End program
When two motors perform coordinated motion in a plane,
it is often desirable to control a third motor in a manner
whereupon its angle remains tangent to the direction of
motion. This feature is useful in applications such as cut-
ting cardboard with a knife. As the knife moves in the
plane, it is necessary to keep the blade angle tangent to
the motion trajectory.
The user must specify several parameters to generate
the tangent motion. First, the user must select the motors
for the different roles. For the rest of this discussion,
assume that X and Y generate the motion in the plane and
Z is the tangent motor.
The second parameter is the resolution of the Z motor
(or the number of units of resolution that will turn the Z
motor one degree). For example, if the encoder resolution is
3600 counts per revolution, the parameter is 10. Finally, the
position of the Z motor at which its angle is 0° in the XY
plane must be given. These parameters define the require-
ments for the tangent motion completely.
To generate tangent motion by the DMC, first the axes
must be selected using the instruction VM. For example,
the instruction
VM XYZ
selects the first two axes, X and Y, to form the motion in the
plane, and the third axis, Z, to form the tangent motion. The
remaining two parameters are defined with the instruction
TN m,n. For example, the instruction
TN 20,700
sets the resolution to 20 counts per degree. This also indi-
cates that when the Z motor is at the absolute position of
700 counts, its angle in the XY plane is zero.
TANGENT MOTION
