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XPS-Q8 Controller
XPSDocumentation V1.4.x (EDH0301En1060 — 10/17)
Figure 25 shows a trajectory example. Every trajectory must have a first element entry
angle (called First Tangent) defined in the head of the trajectory data file. If the first
element is a line, this parameter has no effect. If the first element is an arc, the entry
angle is the tangent to the first point of the arc. Each trajectory element is identified by a
number, starting from 1. The references for synchronizing external events with the
trajectory execution are the starting and ending points of these elements.
Line and arc elements can be sequenced in any order. An arc is automatically placed by
the controller so that its entry angle corresponds to the exit angle of the preceding
element to ensure the continuity of the trajectory. But with every line segment, the user
must choose the (X,Y) end-point in that way that the angle discontinuity to the previous
segment does not exceed the maximum allowed angular discontinuity. The angular
discontinuity is measured in degrees and is defined in the head of the trajectory data
file. In theory, a trajectory can be defined only by straight lines, if two adjacent line
segments have an angular difference smaller than the allowed angle of discontinuity, as
shown in the Figure 26.
In practice this is not recommended since each angle of discontinuity corresponds to an
instantaneous velocity change on both axes, which produces large accelerations. This
can result in a shock to the stages and an increase in the following error. The larger the
angle of discontinuity, the larger the shock and following error will be. Special
consideration must be given to both these effects when increasing the maximum
discontinuity angle from its default value.
8.1.5
Define Lines
A line element is defined by specifying the (X
The succeeding element's starting point is always the end point of the previous segment
(X
, Y
).
i-1
i-1
Note that all line element positions are defined relative to the trajectory's starting point
(0, 0).
As described before, when adding a new line element, the user must make sure that the
discontinuity angle between the new segment and the previous one is not excessive.
Figure 26: Contouring with linear lines only.
Figure 27: Line element to (X
92
Motion Tutorial
, Y
) ending point.
i
i
, Y
) position coordinates.
i
i
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