Position Tracking - Galil Motion Control DMC-21 5 Series User Manual

Example - Jog in A only
Jog A motor at 50000 count/s. After A axis is at its jog speed, begin jogging C in reverse direction at 25000 count/s.
#a
SH AC;
AC 20000,,20000;
DC 20000,,20000;
JG 50000,,-25000;
BG A;
AS A;
BG C;
EN;
Example - Joystick Jogging
The jog speed can also be changed using an analog input such as a joystick. Assume that for a 10 Volt input the
speed must be 50000 counts/sec.
#joy;
SH A;
JG 0;
BG A;
#b;
v1=@AN[1];
vel=v1*50000/10;
JG vel;
JP #b;
EN;

Position Tracking

The Galil controller may be placed in the position tracking mode to support changing the target of an absolute
position move on the fly. New targets may be given in the same direction or the opposite direction of the current
position target. The controller will then calculate a new trajectory based upon the new target and the acceleration,
deceleration, and speed parameters that have been set. The motion profile in this mode is trapezoidal. There is not
a set limit governing the rate at which the end point may be changed, however at the standard
controller updates the position information at the rate of 1msec. The controller generates a profiled point every
other sample, and linearly interpolates one sample between each profiled point. Some examples of applications
that may use this mode are satellite tracking, missile tracking, random pattern polishing of mirrors or lenses, or any
application that requires the ability to change the endpoint without completing the previous move.
The PA command is typically used to command an axis or multiple axes to a specific absolute position. For some
applications such as tracking an object, the controller must proceed towards a target and have the ability to
change the target during the move. In a tracking application, this could occur at any time during the move or at
regularly scheduled intervals. For example if a robot was designed to follow a moving object at a specified distance
and the path of the object wasn't known the robot would be required to constantly monitor the motion of the
object that it was following. To remain within a specified distance it would also need to constantly update the
position target it is moving towards. Galil motion controllers support this type of motion with the position tracking
mode. This mode will allow scheduled or random updates to the current position target on the fly. Based on the
new target the controller will either continue in the direction it is heading, change the direction it is moving, or
decelerate to a stop.
The position tracking mode shouldn't be confused with the contour mode. The contour mode allows the user to
generate custom profiles by updating the reference position at a specific time rate. In this mode, the position can
be updated randomly or at a fixed time rate, but the velocity profile will always be trapezoidal with the parameters
Chapter 6 Programming Motion ▫ 40
'program label
'servo A and C axes
'specify A, C acceleration of 20000 counts/sec2
'specify A, C deceleration of 20000 counts/sec2
'specify jog speed and direction for A and C axis
'begin A motion
'wait until A is at speed
'begin C motion
'end program
'program label
'enable A axis
'set in Jog Mode
'begin motion on A axis
'label for loop
'read analog input
'compute speed
'change JG speed
'loop
'end program
rate, the
TM
DMC-21x5 User Manual 1.0a1