Programmable SyncPos motion controller
MG.10.J8.02 – VLT is a registered Danfoss trade mark
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CAM Control
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CAM Control
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How CAM Control with SyncPos operates
In order to realize CAM control, you need –
depending on the application – at least one curve
which describes the slave position in relation to the
master position, as well as the engaging and dis-
engaging behavior. Of course, many additional
parameters are required for a CAM control which,
together with the fixpoints of the curve, produce a
curve profile.
The synchronization in CAM-Mode (SYNCC com-
mand) can also be performed with marker correc-
tion (SYNCCMM and SYNCCMS). This would be
required, for example, if the products are transpor-
ted irregularly on a conveyor belt, or if adding
errors need to be compensated for.
Diagram of the principle
The mechanical cam disc and the mechanical
camshaft are shown on the left, the curves for the
electronic cam control and the electronic cam box
are shown on the right:
In order to create the curve profile, use the
→
"CAM-EDITOR", i
, i
, i
, i
, into which you first load the VLT
parameters that have already been set. Then you
set the fixpoints of the curve and define the para-
meters required for your application. You can enter
all values in physical or user-defined units under a
Windows interface. You can constantly control the
curve profile graphically; in this way, you can check
velocity and acceleration of the slave axis.
Interpolation
The CAM-Editor calculates the curve from fixpoints
with the help of a spline interpolation. This is opti-
mized to a minimum torque. In order to prevent
speed leaps in the case of repeated curve cycles,
the velocity at the beginning and the end is equated.
You can choose between two types of curve for this
calculation. In either type, the interpolation takes
account of the gradient of the curve at the beginning
and the end. In the case of curve type 0, the gradient
at the beginning and at the end is averaged; in the
case of curve type 1, the gradient at the beginning of
the curve is also used for the end of the curve.
Tangent Points for straight sections
For areas where the velocity must be constant and
the acceleration = 0, you need to use tangent
points. A straight line will be drawn instead of a
spline between these points.
Accuracy
The fixpoints are used directly as interpolation
points provided that this is permitted by the inter-
val distance. The CAM-Editor performs a linear
interpolation between the interpolation points. If a
fixpoint is not hit by the selected interval distance,
then the corresponding slave reference value does
not exist in the interpolation table. You can avoid
such deviations if you have activated
→
"SNAP
ON GRID".
Internal realization as array
The curve profiles are realized internally as arrays
which you can call up by means of a DIM instruc-
tion and the SETCURVE command.
