26
Rev. 1.0
0006302011
SSM23C User Manual
+86-400-820-9661
5 Tuning - Sampling
Being a servo motor, the SSM Integrated Motor employs sophisticated algorithms and electronics
for controlling the torque, velocity and position of the motor to achieve a well behaved operation of
the load.
Because the motor encoder continuously tells the drive what the motor is doing, the drive can
alter the current applied to the motor until the motor achieves the desired operation. This is called
“closed loop control.”
One of these loops controls the amount of current going to the motor. This loop requires no
adjustment other than specifying the maximum current the motor can handle without overheating.
The SSM employs two control loops for the actual motor motion. The fi rst is a Velocity Loop which
is designed to control only the speed of the motor. The second is a Position Loop that controls the
count position of the motor. As shown in the drawing below, the Current Loop is contained in the
Velocity Loop, and the Velocity Loop is contained in the Position Loop. Knowing this is important
as good Position Loop control requires fi rst tuning the Velocity Loop. As mentioned above, Current
Loop tuning is not required as it is already optimized for the motor.
5.1 Velocity Control Loop (V Loop)
The Velocity Control Loop is designed to operate the
motor in a velocity-only type of servo control. This
means that it can control the speed of the motor but
cannot cause the motor to follow a command position.
The Jog commands available in the drive can use this
loop only for operation, the advantage of this is good
stability even with very high inertia loads. The JM
(Jog Mode) command is available to set this feature
or it can be confi gured when selecting the
Velocity
Control Mode. Selecting the
Speed Only
control type
setting causes the Velocity Loop alone to be used in
the various Jog or Velocity control functions. JM2 (Jog Mode 2) does the same.
Position over
time
control type adds in the Position control loop for precise position control during the move and
when stopped, JM1 (Jog Mode 1) also confi gures this setting.
The
Velocity Control Loop
has four terms that can be confi gured for optimum performance with
a given load. This loop can be set and tuned independent of the Position Control Loop. These
control terms are described below.
Position Loop
Velocity Loop
Current Loop
