Chapter 16 Fully Closed Loop System - Mitsubishi Electric MELSERVO-J4 Series Instruction Manual

16
FULLY CLOSED LOOP SYSTEM
The fully closed loop system is available for servo amplifiers with software version A1 or later.
When fully closed loop control system is used with this servo amplifier, "Linear Encoder Instruction Manual" is
needed.
Fully closed loop control system is available with position mode.
When fully closed loop system is configured with MR-J4-_GF_ servo amplifier, the following restrictions will be
applied. However, these restrictions will not be applied to MR-J4-_GF_-RJ servo amplifiers.
• A/B/Z-phase differential output type encoder cannot be used.
• The load-side encoder and servo motor encoder are compatible with only the two-wire type. The four-wire
type load-side encoder and servo motor encoder cannot be used.
• When you use the HG-KR and HG-MR series for driving and load-side encoder, the optional four-wire type
encoder cables (MR-EKCBL30M-L, MREKCBL30M-H, MR-EKCBL40M-H, and MR-EKCBL50M-H) cannot
be used. When an encoder cable of 30 m to 50 m is needed, fabricate a two-wire type encoder cable
according to the following section. Page 606 Two-wire type encoder cable for HG-MR/HG-KR
16.1
Functions and configuration
Function block diagram
A fully closed loop control block diagram is shown below. The fully closed loop system is controlled in the load-side encoder
unit.
Controller
(Servo motor side)
Droop pulses
(Servo motor side)
Cumulative
feedback pulses
Load-side
droop pulses
Cumulative load-side
feedback pulses
*1 Switching between semi closed loop control and fully closed loop control can be performed by changing the setting of [Pr. PE01].
When semi closed loop control is selected, a control is always performed on the bases of the position data of the servo motor encoder
independently of whether the servo motor is at a stop or running.
*2 When the fully closed loop system is enabled in [Pr. PE01], dual feedback control in which the servo motor feedback signal and load-
side encoder feedback signal are combined by the dual feedback filter in [Pr. PE08] is performed.
In this case, fully closed loop control is performed when the servo motor is at a stop, and semi closed loop control is performed when the
servo motor is operating to improve control performance. When "4500" is set as the filter value of [Pr. PE08 Fully closed loop dual
feedback filter], fully closed loop control is always performed.
+
-
+ Servo motor-side cumulative
feedback pulses
+
(load-side encoder resolution unit)
-
+
Fully closed loop
dual feedback
filter
+
*2
([Pr. PE08])
-
Fully closed loop selection
([Pr. PE01] and [Pr. PE08])
Control
Monitor
+
- Servo motor
S
FBN
FBD
-
+
*1*2
Load-side feedback pulses
16 FULLY CLOSED LOOP SYSTEM
Linear encoder
Encoder pulse setting
([Pr. PA15], [Pr. PA16]
and [Pr. PC03])
Fully closed loop control
error detection function
selection ([Pr. PE03])
16.1 Functions and configuration
16
513