Danfoss MCO 305 Design Manual page 35

MCO 305 Design Guide
CAM Control
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 disengaging
behavior. Of course, many additional parameters are required for a CAM control which, together with the Fix
points of the curve, produces a curve profile.
The synchronization in CAM-Mode (SYNCC command) can also be performed with marker correction
(SYNCCMM and SYNCCMS). This would be required, for example, if the products are transported 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. Then you set the Fix points of the
curve and define the parameters 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, Tangent Points, Accuracy, and Array
Interpolation
The CAM-Editor calculates the curve from Fix points with the help of a spline interpolation. This is optimized
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 three types of curve for this calculation. In
any type, the interpolation takes account of the gradient of the curve at the beginning and the end. Either
the gradient at the beginning and at the end is averaged or the gradient at the beginning of the curve is
also used for the end of the curve, or [0] is used for both the beginning and end gradient.
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 Fix points are used directly as interpolation points provided that this is permitted by the interval
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
Internal realization as array
The curve profiles are realized internally as arrays which you can call up by means of a DIM instruction and
the SETCURVE command.
__ Functions and Examples __
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