42 Operation Theory
closed loop control algorithm to make it possible. This increased
the complexity of motion control and not easy to use for a begin-
ner.
4.1.2 Pulse Type Motion Control Interface
The second interface of motion and motor control is pulses train
type. As a trend of digital world, pulse trains type represent a new
concept to motion control. The counts of pulses show how many
steps of a motor rotates and the frequency of pulses show how
fast a motor runs. The time duration of frequency changes repre-
sent the acceleration rate of a motor. Because of this interface,
users can control a servo or stepper motor more easier than ana-
log type for positioning applications. It means that motion and
motor control can be separated more easily by this way.
Both of these two interfaces need to take care of gains tunning.
For analog type position controller, the control loops are built
inside and users must tune the gain from the controller. For pulses
type position controller, the control loops are built outside on the
motor drivers and users must tune the gains on drivers.
For more than one axes’ operation, motion control seems more
important than motor control. In industial applications, reliable is a
very important factor. Motor driver vendors make good perfor-
mance products and a motion controller vendors make powerful
and variety motion software. Integrated two products make our
machine go into perfect.
4.1.3 Network Type Motion Control Interface
Recently, there is a new control interface come into the world.
That’s network type motion controller. The command between
motor driver and motion controller is not analog or pulses signal
any more. It is a network packet which contents position informa-
tion and motor information. This type of controller is more reliable
because of digitized and packetized. Because a motion controller
must be real-time, the nerowrk must have real-time capacity
around a cycle time below 1 mini-second. This means that not
commercial network can do this job. It must have a specific net-
work like Mitsubishi SSCNET. The network may have opto-fiber
type to increase communication reliability.
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