The Description Of E-Cam Function - Delta ASD-A2R-0221 Series User Manual

Chapter 7 Motion Control ASDA-A2R Series

7.11 The Description of E-Cam Function

E-Cam is a virtual cam which is implemented by software. It includes Master axis and Slave
axis. The illustration is as the following:
In PT mode, the position command (slave) is issued by the external pulse input (master).
The two is merely the linear scaling relation (its scaling equals to e-gear ratio). However,
instead of linear scaling, E-Cam is defined by cyclic curve profile, just like the cam shape. In
physical machine cam, slave axis can operate as variable speed motion, alternating motion,
intermittent motion, etc by master axis with the constant speed motion. It is very extensive
in application. Using E-Cam could have similar effect. The following table describes the
differences between E-Cam and Machine Cam.
Structure Return to the original position
after rotating a cycle.
Smooth It is determined by the fineness
Performance of the real process.
Position Very precise (when it has no
Accuracy vibration)
Long Distance The longer the slave axis is,
Motion the bigger the cam will be. It is
not easy to make.
The Necessity The master axis is necessary.
of Master Axis
Flexibility It is inconvenient to change
and modify and it is expensive
as well.
Maintenance Machine will wear and the No need to maintain.
7-26
Machine Cam E-Cam
It might not return to the original
position after rotating a cycle. The
structure could be in spiral shape like
mosquito coil incense.
It is interpolated by cubic curve via
software
The command is very precise, but the
actual position might have deviation
due to the servo delay.
Change the value of the table will do. It
is easy to realize.
The master axis is unnecessary when
it is applied to constant speed motion.
It will do by using the internal signal of
the servo drive.
It will do by re-setting the parameter.
Revision December, 2014