ADLINK PCI-8102 - Manual (Page 51)

40 Operations
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 tuning. 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 industrial 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 network 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.
4.1.4 Software Real-time Motion Control Kernel
For motion control kernel, there are three ways to accomplish it.
They are DSP-based, ASIC based, and software real-time based.
A motion control system needs an absolutely real-time control
cycle and the calculation on controller must provide a control data
at the same cycle. If not, the motor will not run smoothly. Many
machine makers will use PC’s computing power to do this. They
can use simply a feedback counter card and a voltage output or
pulse output card to make it. This method is very low-end and