Siemens SIMOTION D4x5-2 DP/PN Operating Instructions Manual page 167

Use
The principle and necessity of the immersion point are explained below:
● At point A, the immersion point is set to a value that is located above the "real" deck height
because the spreader is lowered between two container stacks. Below point A, the trolley
will therefore in all probability no longer move faster than the velocity limits set in P46 (see
figure below "Setting the immersion point").
At point A, the immersion point is only a supplementary function. If the container stack is
detected correctly, there will be blocked regions. This means the spreader will move along
a vertical trajectory even without use of an immersion point. Moreover, the immersion point
is not needed when unobstructed travel in the horizontal direction is possible in any case (no
cell guides, walkways, etc.).
● Point B is located approximately at the height of the ship deck, where the cell guides and
container stack begin. The immersion point is also moved there because the container is
lowered vertically along the cell guides to the target position. In this lowering phase, the
trolley is not expected to move, so the immersion point is not lowered any further either.
The immersion point is only a supplementary function at point B because there are also
blocked regions due to the existing container stack.
● At point C, the immersion point is at the same height as point B because, at this point, the
container is also lowered vertically as at point B along the cell guides to the target position.
This is where the necessity for the immersion point becomes clear. In this region, there is no
container stack and therefore no blocked regions because the cell guides are not usually
detected as obstacles. Without a correctly set immersion point, trajectories would be
calculated that would result in inclined travel in the red hatched region (e.g. when picking up
a single container set down on the floor of the hold). In this case, travel in SAM mode could
cause damage to both the ship and the crane.
To ensure the immersion point remains operative, the trolley must not move faster than the
set velocity limit in the red hatched region (e.g. when the rope is slack).
Figure 6-12
SC integrated STS, GSU
Operating Instructions, 07/2019, A5E48271265B AA
Principle of the immersion point
Sway Control function description
6.9 Immersion point
167