Galil DMC-2X00 user manual Motion Smoothing, Sampled Dual Loop, #Dualoop, DE0, Jp#Correct

method splits the filter function between the two encoders. It applies the KP (proportional) and KI (integral) terms to the position error, based on the load encoder, and applies the KD (derivative) term to the motor encoder. This method results in a stable system.

The dual loop method is activated with the instruction DV (Dual Velocity), where DV 1,1,1,1

activates the dual loop for the four axes and DV 0,0,0,0

disables the dual loop.

Note that the dual loop compensation depends on the backlash magnitude, and in extreme cases will not stabilize the loop. The proposed compensation procedure is to start with KP=0, KI=0 and to maximize the value of KD under the condition DV1. Once KD is found, increase KP gradually to a maximum value, and finally, increase KI, if necessary.

Sampled Dual Loop

In this example, we consider a linear slide which is run by a rotary motor via a lead screw. Since the lead screw has a backlash, it is necessary to use a linear encoder to monitor the position of the slide. For stability reasons, it is best to use a rotary encoder on the motor.

Connect the rotary encoder to the A-axis and connect the linear encoder to the auxiliary encoder of A. Assume that the required motion distance is one inch, and that this corresponds to 40,000 counts of the rotary encoder and 10,000 counts of the linear encoder.

The design approach is to drive the motor a distance, which corresponds to 40,000 rotary counts. Once the motion is complete, the controller monitors the position of the linear encoder and performs position corrections.

This is done by the following program.
Instruction	Interpretation
#DUALOOP	Label
CE 0	Configure encoder
DE0	Set initial value
PR 40000	Main move
BGA	Start motion
#CORRECT	Correction loop
AMA	Wait for motion completion
v1=10000-_DEA	Find linear encoder error
v2=-_TEA/4+v1	Compensate for motor error
JP#END,@ABS[v2]<2	Exit if error is small
PR v2*4	Correction move
BGA	Start correction
JP#CORRECT	Repeat
#END
EN

Motion Smoothing

The DMC-2x00 controller allows the smoothing of the velocity profile to reduce the mechanical vibration of the system.

DMC-2X00 Chapter 6 Programming Motion y 69