Instruction manual

SI-H Muscle Testers
18
WORLD PRECISION IN STRU MENTS
• Constant Load–This mode maintains a constant load on the tissue sample.
CL Command
receives F
measurement
Force measured by
SI-KG force transducer
(signal may go
through SI-AOSUB)
LabTrax 8/16
triggers Capture
Command
If capture command
triggered, Capture
sets F
0 at level of
captured F
k×F0
calculated
LabTrax 8/16
signal determines
setpoint (F
0 or k×F0)
Control Loop
calculates Linear
Motor command
Linear Motor
response changes
force on muscle
Force Step
sets k (%)
The SI-AOSUB Corrected Output, representative of the force transducer output, is
the SI-COLUB feedback input. The SI-AOSUB Corrected Output is connected to the
CL CMD (constant load command). The digital output of the data acquisition sys-
tem (LabTrax 8/16) that carries the capture command is connected to the Capture
BNC port on the SI-COLUB. When the voltage of the capture command goes from
low (0V) to high (5V), the SI-COLUB reads the force (F
0
) in the muscle, analyzes the
feedback signal, and slacks the muscle until it reaches kF
0
. When the voltage of the
capture command goes from high to low, the SI-COLUB controls the restretch of the
muscle to F
0
.
• External Loop–In this mode, an external signal other than one from the force
transducer (Constant Load mode) is used as the feedback signal for the SI-COLUB to
control the position of the motor.
CL Command
receives
measurement
Alternate Feedback
parameter measured
(ex.: Sarcomere Length)
LabTrax 8/16
triggers Capture
Command
If capture command
triggered, Capture
sets setpoint at level
of captured measurement
Control Loop
calculates Linear
Motor command
Linear Motor
response changes
monitored parameter
When using an External Loop to control the position of the motor, an output of the
LabTrax 8/16, as programmed by MDAC, is connected to the CL CMD input of the
SI-COLUB. This sets the desired level of force (F
0
) that this module will try to maintain
using the feedback signal to control the motor position command (MOT POS CMD
OUT) sent to the SI-MOTDB.
The output of the SI-SARCAM is a good example of a feedback signal from an
external source that would be used to control the position of the motor. Feeding the
output of the SI-SARCAM into the ALT FB input of the SI-COLUB module will control