BNCE PUSAD
2006
'OPENARCHITECTURE ROBOT
CONTROLLERSANDWorkcell
Integration'Ritesh Bhusari
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New PC based open architecture robot controllers and the demand for
improved Man Machine Interfaces (MMI), increased flexibility, and lower
purchasing and operating costs are forcing a paradigm shift in the design,
integration, and servicing of robotic workcells. Improved MMI can reduce the
operator's programming time, shorten system error diagnostic times, and allow for
common user interfaces across many different systems. Lower purchasing and
operating costs can be achieved along with increased flexibility by using standard
hardware and software components. The use of standard PC components in a
robot controller opens the door for third party venders and allows for new workcell
development and customization opportunities. Robot and controller manufactures
have already begun to respond to customer demands by developing "open
architecture" controllers. Note the word "open" is not synonymous with the word
"universal." The phrase "open controller" refers to a controller that is based on
known or published specifications whereas; a "universal" controller refers to a
controller that can be used with several different robot arms. The degree of
"openness" may vary from one manufacture to the next. One definition of an open
architecture controller is "a controller with standard hardware and operating
system with open interface specifications." The PC is an example of an existing
open architecture system that is based on the original IBM® personal computer.
The PC hardware architecture is now a standard piece of computing hardware
that can be found in commercial products and industrial machine tools. The
Microsoft Windows® software is a standard operating system used in millions of
PC systems. Robot controller systems built around the PC hardware and the
Windows® operating system have numerous advantages over closed proprietary
robot control systems.
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2
Proprietary (i.e., closed) robot controllers have improved over the years,
but still have many disadvantages relative to an open architecture controller. Most
proprietary systems are often viewed as "islands of automation" because of the
"closed" nature of these machines and their very limited compatibility and
connectivity with other systems. Some controllers use one or more common
CPU's (i.e., Intel 8088, Motorola 68000) in each system, but the rest of the
hardware and interface specifications are proprietary. Hardware performance
upgrades (i.e., CPU's, memory, etc.) are limited if even possible. Proprietary
system I/O peripherals and interface configurations are also used, which
compound the compatibility and connectivity problems of closed systems. For
example, one controller used a standard floppy drive and diskette. However, it
wrote the data to the disk using a proprietary format (i.e., did not use the standard
MS-DOS format), which prevented the operator from reading the data using
standard software on an office PC. Given these and numerous other limitations of
proprietary robot controllers, the request for open architecture control systems has
been made by end-users such as the "big three" automotive companies as well as
system integrators.
In the remainder of this paper, the integration of PC based open
architecture robot controllers and the Windows® operating system with robotic
workcells is presented. In Section 2.0, a comparison between open architecture
controllers and propriety controller systems is provided. Outlined in Section 3.0 is
an overview of new workcell development and servicing opportunities for the
system integrator of open architecture controllers.
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Hardware and software developers of an open architecture controller
system open themselves to more market resources. They can experience lower
hardware development costs while enjoying a greater number of relatively
inexpensive configuration options. Likewise, software development groups can
benefit from the use of standard software development tools to give them more
flexibility and portability.
The hardware development cost of a proprietary robot controller can easily
outpace the development cost of an open system with the same functionality. The
basic components of a robot controller system are illustrated in the block diagram
in Figure. Shown in this figure, is a robot arm, power supply for the arm, teach
pendent, and controller.
The degree of openness in a robot controller may vary from one system to
the next. The robot system in the block diagram shown in Figure illustrates one
form of an "open architecture" system. For this system, the robot arm, power
system, and teach pendent are considered as proprietary components. The
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controller and communication interface hardware and specifications are labeled as
the open architecture components. The "Open" label refers to the PC's open
hardware architecture, a standard operating system (e.g. Windows®), and
standard software libraries. The quotations around the word open signify that
there is a degree of openness (i.e., open relative to other systems, but how
open?). In this example, the external I/O communication interface is also based on
open architecture hardware (i.e., can-bus, Ethernet, com ports, parallel ports).
A PC based controller system can more easily integrate many
commercially available add-on peripherals such as; modems, Ethernet cards,
mass storage devices, card scanners, sound cards and other I/O and multimedia
devices. These types of peripherals are readily available at the household
consumer price level. Depending upon the controller cabinet design, commercial
rather than industrial PC equipment can be utilized. Well-ventilated, air filtered,
shielded cabinets help provide a "safe" electronic environment. Note, electronic
PC equipment is relatively no more susceptible to problems as electronic
proprietary equipment. Developers of a PC based controller system benefit from
development expenditures and resources spent by other companies.
In other words, by using PC technology in the robot controller, developers
are able to minimize costs by capitalizing on current and future hardware devices
in the market and on the drawing boards. The PC hardware is relatively
inexpensive and readily available (i.e., motherboards, CPU's, memory, etc.) and is
usually supplied by numerous venders (i.e., no more single source venders going
out of business). In addition, this hardware did not have to be individually
designed and tested by the developers of the controller. As a result, the human
resources and technical talent requirements to build and update a controller are
reduced.
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5The software developer of an open architecture system has an equally
great number of available market resources to take advantage of as the hardware
developer. Software development on a PC based system can be less expensive,
faster, and more portable than with proprietary systems. Standard development
tools (e.g. Visual C++®, Visual Basic®, Delphi®, etc.) can be utilized. These tools
are less expensive, allow for rapid prototyping techniques, and allow existing
source code to be recompiled and optimized for different CPU's and PC platforms.
In addition, the talent resource pool of people who are experienced with using
these programming tools and the PC platform is greater than the number of those
who are knowledgeable about a particular microprocessor and associated
compiler tools (i.e., proprietary development tools).
Portable controller software running on a PC based system can simplify
system emulation hardware, given that a PC is a PC. Simplified emulation
hardware leads to reduced training costs, improved simulation, and off-line testing
and debugging capabilities.
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The system integrator is a company that designs and manufactures robotic
workcells and lines. They purchase a robotic system (i.e., arm and controller) and
integrate these arms with positioners, application specific technologies (i.e.,
welders, laser systems, water jet systems, vision systems, etc.), and safety
devices (i.e., light curtains and beams, fences, gates, etc.). System integrators
have limited opportunities to cleanly add custom hardware and software
components to proprietary robot control systems. However, the integrator has
relatively many opportunities to add components to open controller systems.
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A PC based open architecture controller can be used with or without a
traditional programmable logic controller (PLC) hardware (i.e., SLC500, etc.).
When a PLC function is required for a given system, it can be integrated with the
controller. Workcell control logic can be implemented more easily and cheaper
when integrated with the robot controller. The robot controller has a high-level
programmable language that can be used to control many workcell functions. If
needed, a “Soft-PLC” (Software Programmable Logic Controller) can be installed
on the system. Placing a Soft-PLC in the robot controller focuses the cell control
to a centralized location. PC based PLC's can still provide the familiar
programming control logic interface for the maintenance personnel on the factory
floor. A Soft-PLC also reduces the physical wiring interconnections between
traditional robot controllers and typical hardware PLC. As future enhancements
are made, Soft-PLC can be easily upgraded on the controller. Physical I/O (i.e.,
inputs and outputs) are no longer related to a few proprietary choices because the
open architecture controller can communicate with standard bus systems.
Many standard workcell sensors, which include; light curtains, gate
switches, and tooling proxies, can be integrated and controlled directly by the
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7robot controller software, or controlled by a reside Soft-PLC program. Other
workcell sensor components, such as real-time vision seam tracking systems,
through-the-arc seam tracking systems, and vision systems for part detection and
placement can be implemented in open architecture controllers. A standard PC
system will have several ISA and PCI slots open which can be used for special
vision hardware. Arc data monitoring hardware and software could be
incorporated into the controller itself. Software modules for collecting data can be
resident on the robot controller platform or an external processing board
connected to the controller using a standard communication interface. Processing
of the data can take place on the controller or exported to another computer for
post-processing. The data manipulation software can be written by the integrator
or end user using standard off-the-shelf development software or even purchased
from a third party source.
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Robotic systems are designed for and applied to a variety of tasks in the
work area. These tasks include; spot and
arc welding, material handling, gluing,
water and laser cutting, and others.
Manufactures of robot systems
traditionally develop a core set of
controller functions that only provide the
robot with a basic set of motion control
and programming functions. When a robot is applied to perform a particular type
of job (i.e., arc welding), additional functionality must be added to the robot
system. For example, some welding related functions (i.e., wire feed rate, weld
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voltage, etc.) must be correlated to the motion of the robot arm or more specific,
the welding torch. In most cases, it is expected that these functions be integrated
into the user interface (i.e., the teach pendent).
Therefore, a given line of robots from a single manufacture may be applied
to several types of applications and tasks that may require several different user
interfaces. When applying a proprietary system to a new job, which requires a set
of unique controls or a user interface, only the robot manufacture can add these
features to the controller software. The system integrator must go back to the
manufacture of the propriety controller to add more functionality or to correct
problems in the existing controller software. In addition, changes to the controller
may only be implemented if they are viewed as a worthy investment of resources
and also viewed as needed for the good of all who will buy the new controller
interface (i.e., custom functions and user interfaces are unlikely for a given system
integrator). On a PC based open architecture system, which uses a standard
operating system (e.g. some version of Windows®), the system integrator has the
ability to develop new functions and customized user interfaces. The "value added
components" refer to these unique customizable software and hardware modules
than can be added by the system integrator with little to no help from the
developer of the controller. The system integrator reaps many of the same
benefits as the developer of the robot controller software. For example, most robot
controllers do not have a built in production screen.
A "production screen" is an information screen for the operator to be used
during the production cycle to display pertinent system and production
information. With an open architecture controller, the system integrator could
develop a custom production screen and other "value added" components (e.g.
built-in electronic documentation, system error notification and diagnostic
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modules, statistical packages, etc.) for a given type of job or even for a given
customer.
As mentioned in earlier, the developer of a PC based system is open to an
array of low cost, commercially available hardware peripherals. Likewise, the
system integrator can take advantage of these resources to provide the end-user
with relatively low cost parts. More importantly, the system integrator can easily
upgrade the robot controller system by just plugging in standard, off-the-shelf
components (i.e., a faster CPU, more memory, faster modem, etc.).
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System integrators using an open architecture PC based controller system
can reduce the short and long term expenses incurred in their service department,
change the way service is conducted, and respond to the customer quicker and
more directly than ever before while reducing costs and losses for each party.
Typically, the system integrator builds up a robot workcell and ships the system to
a customer. Included with the system, may be a service contract that gives a
warranty covering some extended period of time. The number of service calls by
the customer to the system integrator is dependent upon the customer's prior
robotic experience and the amount of training received on the new system.
Service calls made within the warranty period are recorded as an expense for the
integrator otherwise they are an expense for the customer. Traditionally, when the
customer has a problem they call for service. If the system integrator is unable to
correct the problem via vocal instructions over the telephone, they must send
service personnel to the site. In the mean time, the customer is losing because of
lost production time (i.e., losing finical and competitively--market influences) and
the system integrator is losing money because of the expenses of sending a
representative into the field (i.e., rental cars, airline tickets, etc.).
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It is well known that some problems leading to a field service call are
corrected shortly after the service person arrives at the site. The expenses and
lost revenue by the integrator and customer can be greatly reduced by changing
the way service calls are conducted. This can be achieved by taking an advantage
of the available hardware devices and software programs that are readily
available for the standard PC system. For example, the connectivity possibilities,
when using either a modem or an Ethernet card in conjunction with commercially
available peer-to-peer graphical communications software packages, provide
service personnel with new tools to perform their job quicker, easier, and cheaper,
by eliminating the need to leave their desk.
This remote tele-robotic servicing approach is one of the business changes
that are emerging as part of the shift to open architecture controllers. Many
customer service calls can be solved by simultaneously conversing with the
customer and actively viewing and controlling the customer's teach pendent
hundreds of miles away. A service person physically located at either the system
integrator's site or locally in-house to the customer would have the ability to
interact with the robot controller (without moving the robot -- i.e., safety issue). In
some cases, live videos snapshots of the robotic work cell may be needed to
communicate some work cell problems to the service person.
With these tools, they would be able to visually instruct the operator on the
procedural "how-to's" with almost everything on the teach pendent. They can also
check system errors and log files, install new or updated software modules, and
perform many other functions.
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Presently, thousands of PC based robot controllers, developed by KUKA,
are now in production and a considerable amount of research and development
efforts are being expended by other manufactures. The customization and
development opportunities for system integrators dramatically increase when
using open architecture robot controllers which are based on standard PC
hardware and the common Windows® operating system. System integrators are
now able to provide improved man-machine interfaces, improved
communications, customer service, and productivity.
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BBBIIIBBBLLLIIIOOOGGGRRRAAAPPPHHHYYY
Ø Fiedler P. and Schilb C., "Open Architecture Systems for Robotic
Workcells," IWACT 1997 Conference Proceedings, Columbia Ohio, 1997
Ø Specification Sheet, KUKA Roboter GmbH, "KR C1, Kuka Robot Control
System," Augsburg, Germany, 1996.
Ø Advertisement, Nimbl Incorporated, Robotics World: The end user's
magazine of flexible automation, Vol. 15, Number 3, pg 5, Fall 1997.
Ø News Release, RWT - Robotic Workspace Technologies Inc., "Universal
Robot Controller," Contact: Sandra Brooks, Fort Myers Beach, FL, July
1997.
Ø Robotics World: The end user's magazine of flexible automation, Vol. 15,
Number 3, Fall 1997.
Ø Brochure, Hitachie 3242Y800 704, Hitachie LTD. Narachino Works, Japan
Ø Service Manual, ASEA Service Manual, 6397-020-105, CK 09-1564E Sept.
1987
Ø Brochure, Accudata Inc., 9700 Myers Road, Jackson, IM., Sales literature.
Ø Technical Description, Servo-Robot Inc., 1380, Graham Bell, Boucherville,
Quebec, Canada J4B 6H5
Ø Technical flyer, Technosoftware AG Germany
Ø Technical Documentation, Sybase Inc., 15721 College Blvd, Lenexa, KS
66219
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AAACCCKKKNNNOOOWWWLLLEEEDDDGGGEEEMMMEEENNNTTT
We take this opportunity, to express our deep sense of gratitude towards
Prof. B. B. Patel (H.O.D. mechanical) and Prof. N. S. Walimbe (Mechanical)
PVG’s COET, for their expert guidance during the preparation of this paper
presentation.
We are also thankful to Prof. D. S. Patil (mechanical) PVG’s COET, Pune &
the entire library staff without whom; we wouldn't have been in a position to
present this paper.
We are also grateful to MESA for giving us the opportunity to present this
paper.
We also express our thanks to all of them who directly or indirectly have
helped us to prepare this presentation.
OMKAR V KARANDIKAR
AMIT H KHAMKAR
(B. E. MECHANICAL)
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