User`s guide

millimeters of belt travel.
4. An encoder offset, which is used to adjust the origin of the belt frame of reference.
5. Window parameters, which define the working range of the robot along the belt.
These components of belt variables are described in detail in the following sections.
Unlike other V+ data types, belt variables cannot be stored in a disk file for later loading.
However, the location and real-valued data used to define a belt variable can be stored and
loaded in the normal ways. After the data is loaded from disk, DEFBELT and WINDOW
instructions must be executed to define the belt variable. For details, see Belt Variable
Definitions on page 317. (The file LOADBELT.V2 on the Adept Utility Disk contains a
subroutine that will read belt data from a disk file and execute the appropriate DEFBELT and
WINDOW instructions.)
Nominal Belt Transformation
The position, orientation, and direction of motion of a belt are defined by a transformation
called the nominal belt transformation. This transformation defines a reference frame
aligned with the belt as follows: its X-Y plane coincides with the plane of the belt, its X axis is
parallel to the direction of belt motion, and its origin is located at a point (fixed in space)
chosen by the user.
Since the direction of the X axis of the nominal belt transformation is taken to be the
direction along which the belt moves, this component of the transformation must be
determined with great care. Furthermore, while the point defined by this transformation
(the origin of the frame) can be selected arbitrarily, it normally should be approximately at
the middle of the robot's working range on the belt. This transformation is usually defined
using the FRAME location-valued function with recorded robot locations on the belt. (The
easiest way to define the nominal belt transformation is with the conveyor belt calibration
program provided by Adept.)
The instantaneous location described by the belt variable will almost always be different from
that specified by the nominal transformation. However, since the belt is constrained to move
in a straight line in the working area, the instantaneous orientation of a belt variable is
constant and equal to that defined by the nominal belt transformation.
To determine the instantaneous location defined by a belt variable, the V+ system performs
a computation that is equivalent to multiplying a unit vector in the X direction of the nominal
transformation by a distance (which is a function of the belt encoder reading) and adding the
result to the position vector of the nominal belt transformation. Symbolically, this can be
represented as
instantaneous_XYZ =
nominal_XYZ + (belt_distance * X_direction_of_nominal_transform)
where
belt_distance =
(encoder_count - encoder_offset) * encoder_scaling_factor
Basic Programming Concepts
(Undefined variable: Primary.Product_Name_V)Language User's Guide, version
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