Yaskawa G5 Motion Control - Manual (Page 2)

Motion Control
Date: 08/18/04, Rev: 04-08 Page 2 of 22 TM.G5SW.020
1.2 Different Types of Motion
This software, through parameter P1-01, differentiates between linear or rotary motion and absolute or relative position
coordinates. These four choices will setup the commands needed for various functions outlined below. These choices
will also change the definition of the length of move for any of the 31 move profiles.
Rotary motion, such as winder turrets and dial tables, is defined as motion where the commanded move destination can
be reached in both the positive and negative direction. Linear motion, such as a ball screw or transfer station, is defined
as motion where there is only one direction to reach the commanded move destination.
Absolute positioning is the determination of a position independent of the current position (i.e. positioning related back to
home). An example would be a transfer station or dial table. Relative positioning will use the current position information
and make the next move as an offset from the current position, without relation to home. An example would be a cut to
length application.
This software supports three motion positioning combinations: absolute linear, absolute rotary, and relative. In absolute
linear, each move destination setting in the A2 parameter group is defined as a distance from home (home switch + home
offset).
In absolute rotary, each move destination setting in the A2 parameter group is defined as the move destination from home
(home switch + home offset) in the positive direction within one revolution of the machine. This can be thought of
establishing positions for the hour marks on a clock. The maximum value for a move destination must not exceed one
complete revolution. The move positive and move negative commands are both active since the commanded position
can be reached in either direction.
In relative motion, each move destination setting in the A2 parameter group is defined as a length of move from the
current position. There is no direction implied so both the move positive and move negative commands are needed to
give a move direction. The motion can be rotary or absolute. In relative motion, the drive simply rotates the motor the
commanded number of revolutions in the commanded direction. However, the drive will keep track of the number of
pulses and direction from home and can be commanded to return to the home pulse count even though multiple moves
away from home had been made. Additionally, the drive can be selected to have “relative memory”. This selects if the
drive should begin its move using its actual current position or the position commaned from the previous move.