Galil Motion Control DMC-18 2 Series, User Manual

Page: 82 / 218

DMC-18x2 Chapter 6 Programming Motion • 71
VELOCITY
(COUNTS/SEC)
20000
10000
5000
15000
20
40 60
80
TIME (ms)
100
X axis velocity profile
Y axis velocity profile
Z axis velocity profile
0
Figure 6.1 - Velocity Profiles of XYZ
Notes on fig 6.1: The X and Y axis have a ‘trapezoidal’ velocity profile, while the Z axis has a
‘triangular’ velocity profile. The X and Y axes accelerate to the specified speed, move at this constant
speed, and then decelerate such that the final position agrees with the command position, PR. The Z
axis accelerates, but before the specified speed is achieved, must begin deceleration such that the axis
will stop at the commanded position. All 3 axes have the same acceleration and deceleration rate,
hence, the slope of the rising and falling edges of all 3 velocity profiles are the same.
Independent Jogging
The jog mode of motion is very flexible because speed, direction and acceleration can be changed
during motion. The user specifies the jog speed (JG), acceleration (AC), and the deceleration (DC)
rate for each axis. The direction of motion is specified by the sign of the JG parameters. When the
begin command is given (BG), the motor accelerates up to speed and continues to jog at that speed
until a new speed or stop (ST) command is issued. If the jog speed is changed during motion, the
controller will make an accelerated (or decelerated) change to the new speed.
An instant change to the motor position can be made with the use of the IP command. Upon receiving
this command, the controller commands the motor to a position which is equal to the specified
increment plus the current position. This command is useful when trying to synchronize the position
of two motors while they are moving.
Note that the controller operates as a closed-loop position controller while in the jog mode. The DMC-
18x2 converts the velocity profile into a position trajectory and a new position target is generated every
sample period. This method of control results in precise speed regulation with phase lock accuracy.
Command Summary - Jogging
COMMAND DESCRIPTION
AC x,y,z,w Specifies acceleration rate
BG XYZW Begins motion
DC x,y,z,w Specifies deceleration rate
IP x,y,z,w Increments position instantly
IT x,y,z,w Time constant for independent motion smoothing
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com