Juggling many functions
Now you can control entire automation systems and individual robots within a single integrated control environment.
Three axes of independent
SCARA geometries can be addressed by leveraging the native
articulated independent geometries
configuration; related dialogs and
motion instructions allow designers
to superimpose multiple moves and
instructions as needed.
The control system calculates
translational and dynamic path profile translation and rotation (orientation) as well as orientation offsets
between the two systems. With dynamic rotation, H-Bot gantry robots
can be easily controlled, so a single
controller manages material handling equipment, processing equipment, and robot.
Users can synchronize their robot's motion with other parts of the
application, such as conveyor tracking and vision systems, by superimposing concurrent single and multiple-axis move types and interfacing
with off-the-shelf vision systems
that can be connected to kinematicscapable controllers via an EtherNet/IP network. (This is useful on applications that need conveyor tracking,
for example.) Here, software transforms a specific position from the
source coordinate system into the
target coordinate system and vice
versa, eliminating additional code.
Shared development tools allow for the reuse of engineering resources, and in turn, scalable architecture eliminates repeat work
and retraining. Say a plant needs to
scale from one line to three. In this
case, the house designer needs only
to add the necessary processors and
copy code from one to the next; programming takes just minutes.
Mixing and mingling
Integrated motion control is the
heart of packaging lines, but their
eyes and ears are sensors and safety
components. Here, integrated kinematics-capable platforms offer another advantage: The ability to use
open EtherNet/IP networks to interface with a variety of off-the-shelf third-party vision systems.
Some integrated controls have an
open networking strategy to provide
a common set of services, enabling
users to mix multiple processors,
networks, and I/O. For example,
from a PC on EtherNet/IP, ControlNet, or DeviceNet, designers can
exchange data for fast control, and
collect it for trending and analysis.
System designers also can route and
bridge between networks without
additional logic programming for
communication.
One control engine and programming environment also means that
that the same program developments
can be re-deployed across a variety of
controller platforms.
For example, safety control added
to controllers can include commonality of platform (with the same
control engine, motion, networking
and I/O) for better sharing of information, reduced training costs, and
faster commissioning. Here, safety
control is managed just like standard
control. Software helps manage safety memory, so users are not required
to manually manage the separation
of standard and safety memory, or
worry about partitioning logic to
isolate safety-related data. This coupled with the fact that standard logic
and external devices, such as HMIs
and other controllers, can read safety
memory means that the need to condition safety data from a dedicated
safety device is eliminated.
Support for additional geometries
Kinematics-capable controllers
are currently limited to three axes of
articulated dependent, independent,
or SCARA geometries. Soon, however, new controls will also support
Delta robots. These products will be
released to coincide with that robot's
approaching patent expirations:
2006 in Europe, and 2007 in North
America.
For more information, call (262)
512-2192 or visit rockwell.com
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Discreet note on
discrete |
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Many outputs,
one control On one new packaging line, one of their suctionarm Delta robots takes products from a stationery belt,
groups them, and places them on another continuously
moving conveyor belt that feeds the next station. Here,
besides safety, calibration, and error management,
Rockwell Automation's Allen Bradley ControlLogix choreographs all motion, starting where product is fed into
the grouping unit. The track layout is designed to work around several
limitations: that workspace available to the robot is limited, that the robot's mechanical stress limits must not
be exceeded, and that acceleration of some products
must be kept to a minimum. So, the controller calculates
blending radii for smooth transitions from one movement
to the next. Allowing for gravity, various acceleration values for vertical and horizontal moves can also be selected to optimize cell performance. Memory management works with tags rather than encrypted addresses.
Sometimes this addressing is not only included in the
programming software, but also stored in the control memory, to simplify communication with both decentralized field equipment and higher-level monitoring and visualization systems. Pick-and-place is no easy task for any robot, as product position can vary, and (on a moving belt with variable speed) place position differs from the theoretical
position. So tracking in the robot control compensates
by summing the two vectors to determine the required
movement for the actual situation. A gatekeeper function automatically monitors cavities
in the robot's work area. If a cavity leaves the work area
and is only partially filled (or is emptied, or not filled at
all) the gatekeeper blocks the corresponding feeder. In
this way the robot always has sufficient time to complete
work on a cavity. A set parameter indicates how far down
the robot's work area an empty cavity can travel before a
stop command is activated. Here, the robot kinematics include forwards and backward transformations: Backward transformations calculate the appropriate angle for actual robot axes using
universal X, Y, and Z coordinates. By means of forward
transformation, joint positions are converted into universal coordinates. Programming follows IEC 61131-3 (LAD, FBD, ST, SFC) with a multitasking OS symbol-based CPU. With some simple address mapping, TAG aliasing allows reuse of existing programs over several projects — and even the mapping is straightforward, because the RSLogix 5000 controller automatically identifies which tags do not have actual I/O addresses. |
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© 2012 Penton Media Inc.
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