Delta RMC151 - Manual (Page 813)

8 Command Reference
A Linear Ramp Type will ramp the pressure or force linearly until it reaches the
Requested Pressure/Force. An S-curve Ramp Type will provide a half s-curve ramp to
the Requested Pressure/Force.
If the current Pressure/Force is stopped or is moving away from the Requested
Pressure/Force when this command is issued, the Target Pressure/Force will
immediately be set to the Requested Pressure/Force. This may cause the system to
jerk.
Notice that if the Actual Pressure/Force Rate is very small when this command is issued, a
very slow ramp may be calculated. If this is the case, and you do not want a slow ramp,
consider using the Enter Pressure/Force Control (Time) (45) instead, which will make sure
the axis reaches the Requested Pressure/Force within a specified time. Another option
is to use the Hold Current Pressure/Force (19), which will enter pressure/force control
and hold the current Actual Pressure/Force.
The Integrator Preload specifies the value that the Integral Output Term should be set
to when transitioning into pressure/force control. The Preload is specified as a percentage
of the Output Scale (typically 10V), and is not affected by the pre-transition integrator
state. Typically, this can be left at the default value of 0. If the pressure/force exhibits a
drop upon entering pressure/force, increase this value to help smooth the transition.
Example
Consider a hydraulic press that must move toward the material to be pressed, transition
to force control and hold a certain force.
The user program below shows a possible sequence of steps.
Step 0 issues a Move Absolute command to move the axis to a position beyond where it
expects to encounter the material. The Step 0 Link Type waits for the Actual Force to
exceed 1000, then it goes to Step 1 which issues an Enter Pressure/Force Control (Auto)
command with an S-Curve Ramp Type. The axis will smoothly transition to force control
and go to the Requested Pressure/Force of 5000.
The plot below shows the transition:
deltamotion.com 793