Delta RMC151 - Manual (Page 830)

RMC70/150 and RMCTools User Manual
Mid-Pos and Mid-Neg Details
If the Start Location is Mid-Pos or Mid-Neg, in order to prevent a sudden jump in the
velocity, the frequency will be logarithmically ramped from zero Hertz to the requested
frequency during the first quarter cycle. Therefore, the first quarter cycle will not be a
true sine function, and the first quarter cycle will take longer. See the Mid-Pos and Mid-
Neg images above. If a sine move stops at the middle, the same type of ramping will
occur in the last quarter cycle.
To achieve a different ramping behavior for Mid-Pos or Mid-Neg start locations, do the
following:
• Send the Sine Start command with the frequency set to zero. The sine wave will
start, but there will be no motion.
• Use the Change Target Parameter command to ramp the frequency to the desired
value. The Change Target Parameter command provides great flexibility in defining
the ramp.
Note: For Start Locations Mid-Pos or Mid-Neg, very low frequencies, such as 0.0001 or
less, may cause an irregular Target Position. Test any very low frequencies before using
them.
Note: For Start Locations Mid-Pos or Mid-Neg with a non-zero starting frequency,
changing the frequency with the Change Target Parameter (Prs/Frc) (81) command is not
allowed until the sine wave has reached the first positive or negative peak.
Status Block
The optional Status Block specifies the location in the Variable Table of a block of six
registers that provide read-only information on the sine move. This block will not be
needed by most users and the Status Block parameter should then be set to none. For
more details, see the Sine Move Status section below.
Stopping a Sine Move
If the number of cycles is non-zero, the sine move will automatically stop after reaching
the number of cycles. By specifying the Cycles in various increments of 0.25, you can
control whether the sine wave stops at the bottom, top, or middle. If the Cycles is a
whole number, the sine move will stop at the same location where it started.
The Sine Stop (Prs/Frc) (77) command is especially designed for stopping a
pressure/force sine move. The specific stop location can be specified to be the positive
peak, negative peak, next peak, middle, or after the current cycle completes. See the
Sine Stop (Prs/Frc) (77) command for more details.
If the stop location is the middle, the frequency will be ramped to zero hertz during the
last quarter cycle. This prevents a sudden jump in the pressure/force rate, because the
middle of a sine move otherwise has a non-zero rate.
Of course, as with any motion on an axis, when a sine move is in progress, another
pressure/force command can be issued and the axis will immediately stop the sine move
and start the new motion. For example, a Stop Pressure/Force (43) command will stop
the Pressure/Force target.
Ramping Sine Move Parameters
Use the Change Target Parameter (Prs/Frc) (81) command to ramp the Offset,
Frequency, or Amplitude, or change the Cycles of a pressure/force sine move in progress.
810 Delta Computer Systems, Inc.