Elmo HARmonica, HARSFEN0602 - page 139

HARSFEN0602
Start
Will s teady
deceleration at
DC stop motion
before target?
Speed > SP?
Speed = SP?
Yes
No
Yes
Apply AC
Main tain S P
Apply DC
Apply DC
Figure 24 – PTP Decisions Flow Chart
All the parameters of the above flow chart, including AC,DC, SP, and the position target are updated by a
BG command, or by its hardware activated equivalent.
Example – On-The-Fly Change of The Position Target
The acceleration and the final speed are AC=100000,DC=200000,SP=20000.
We begin from PX=0 and set the target position by PA=100;BG.
The position reference has not yet stabilized to the position target, when the target position switched by the
command
PR=-400;BG;
To the position target of (PA+PR)=-300.
The Amplifier calculates the position reference to reach the new target.
Note that in this example the position reference overshoots the original target position of 100. This is since
at the time the target position was changed, the Amplifier was approaching the target using DC. When a new
target is set, the Amplifier exits the state of final approach. It therefore uses the AC acceleration, which in
this example is smaller, than DC. With the reduced acceleration, it cannot avoid the overshoot.