Newport MM4006, User Manual

Page: 339 / 411

MM4006
Trajectory Functions Tutorial
5.2
Trajectory Description and Conventions
5.3 Geometric Conventions
When defining and executing a trajectory, a number of rules must be fol-
lowed. For the current MM4006 version, these are the conventions that
guide the contouring implementation:
• M u l t i p l e trajectories can be defined in a program but only one is active
at a time. This means that the controller can have only one trajectory
ready to be executed.
• O n c e one trajectory is started, it executes in background allowing the
other axes and peripherals to work independently and simultaneously.
• E a c h trajectory must have a beginning and an end. "Endless" (infinite)
trajectories are not allowed.
• T h e size of a trajectory is limited to 100 trajectory elements. This value
is arbitrary and should satisfy most complex applications.
• T h e trajectory definition process must ensure a continuous motion path
to avoid any excessive accelerations and shocks that could damage the
stages.
• T h e line segments are true linear interpolations:
y = Ax + B
• T h e arc segments must be true arc of circles:
(x - x0)2 + (y - ye)` = R2
• A trajectory is always defined relative to the predefined stage units. To
avoid confusion, it is recommended to use same units of displacement
on both axes.
• E a c h trajectory is defined relative to its starting point. Thus, every start-
ing point has the coordinates 0, 0.
• A l l trajectories start executing from the current X and Y positions. To
execute a trajectory from a desired location, the two axes correspond-
ing to X and Y must be moved using the standard point-to-point com-
mands (PA, PR).
• B e f o r e executing a trajectory, the controller verifies if its definition does
infringe on any predefined motion rules (excessive tangent discontinu-
ity, excessive acceleration, travel limits).
• Trajectories can be defined in both IMMediate and PRoGram mode.
• T h e coordinate system is an X-Y orthogonal system.
• A n y valid motion axis can be assigned to be the X or Y axis.
• A f t e r executing a trajectory, new axes can be assigned to X or Y axis.
• T h e origin of the X-Y coordinate system is in the lower left corner, with
positive values up and to the right.
• A l l angles are measured in degrees, represented as floating points num-
bers.
• A n g l e origin and sign follow the trigonometric convention: positive
angles are measured counter-clockwise.
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EDH0181 En 1020 — 03/0:3
5.4 N e w p o r t .