Delta MMC120 - Manual (Page 14)

Description MMC120 Linear Motion Control Module
14 Delta Computer Systems, Inc. 360/254-8688
Control Loop
The MMC120 is a targeting controller; each millisecond the onboard microprocessor updates the TARGET
POSITION and target speed values. For point-to-point moves, TARGET POSITIONS are generated so the
target speed follows a profile. The MODE, ACCELERATION, DECELERATION, SPEED, and COMMAND
VALUE (requested position) are used to generate the profile. They are specified by the user, and can be
changed while the axis is moving.
The ACTUAL POSITION measured by the magnetostrictive transducer is compared with the TARGET
POSITION to determine the position error. Every millisecond the position error is used to calculate the closed
loop components of the drive output. It is multiplied by the PROPORTIONAL GAIN to calculate the
proportional component of the drive output. The accumulated position error is used, along with the
INTEGRAL GAIN, to calculate the integral portion of the drive output. The change in position error, along
with the DIFFERENTIAL GAIN, is used to calculate the differential portion of the drive output.
Actual
Position
Position
Error Proportional
Gain
Accumulator
(Integrator)
∆ ∆ ∆ ∆
Error
(Differentiator)
Integral
Gain
Differential
Gain
Feed
Forward
Forward
Position
∆∆∆∆
(Velocity)
Σ
Σ
+
-
Drive
Output
Target
Generator
Target
Position
Command
Processor
Ladder
Logic
DCS120
Accel Feed Velocity
∆∆∆∆
(Acceleration)
Deadband
Eliminator
Time
Speed
Maximum Speed
Deceleration Ramp
Acceleration Ramp