Energy resource sharing method and apparatus

A resource-sharing system enables multiple work areas to share an energy resource on a real-time, asynchronous basis in order to perform manufacturing processes. A specific embodiment involves a communication and control structure for a distributed laser processing system wherein the work areas, in communication with a cell controller via a cell-level LAN, share high-power lasers through beam multiplexers and optical fibers. The cell controller, typically in communication with a factory information system computer over a factory-level network, receives information relating to processes to be performed in the workareas, and makes this information available to the workareas as a node in the cell-level LAN. With such an arrangement, tools requiring the laser energy within the work areas may be controlled in real time by their associated station controllers, as cell controller need only be responsible for coordinating more global activities. The implementation of a digital switching network enables a particular work area to assume direct, real-time and asynchronous control of one of the laser resources in accordance with the requirements of a given materials processing application.

FIELD OF THE INVENTION 
This invention relates generally to systems wherein an energy resource may 
be shared by multiple work areas and, in particular, to methods and 
apparatus which allow lasers associated with manufacturing processes to be 
shared on a real-time basis. 
BACKGROUND OF THE INVENTION 
The expense of certain types of materials processing equipment resources 
can render such resources economically difficult to justify for smaller 
organizations, and, as such, may leave a manufacturer with no choice but 
to employ more traditional and less productive methods. One solution, 
however, is to share more costly resources among several operators or work 
areas, thereby permitting greater utilization of such equipment and 
enhancing the financial aspects of the overall system through shorter 
payback periods. Such resource sharing also permits improved productivity, 
reduced component fabrication cost, an ability to process a greater 
variety of components simultaneously, and a more flexible system, better 
able to meet changing schedules. Overall, in many circumstances, sharing 
of costly resources may lead to a more competitive position in desired 
marketplaces. 
In recent years, significant progress has been made in the application of 
lasers to materials processing. This progress has been two-fold, through 
developments in higher-power laser sources and, additionally, through more 
innovative approaches to beam-delivery problems. Efficient beam delivery, 
which is crucial to any industrial laser processing application, has been 
improved through the introduction of low-loss industrial-type optical 
fibers which, in turn, have introduced new system design possibilities. 
These novel fiber-based beam-delivery techniques are capable of reducing 
system cost and, consequently, such approaches may directly affect the 
economics of laser-based materials processing. 
One advantage of fiber-based beam-delivery in the realm of materials 
processing is its adaptability to modern flexible-manufacturing 
techniques. Time multiplexing and energy multiplexing may be carried out 
with fiber-based beam delivery in a relatively straightforward conceptual 
manner, with distributed computer control being applied to realize full 
system potential. An optimal configuration would include an architecture 
and interfaces to provide real-time control over various laser functions 
while supporting necessary communication between work areas and 
factory-information systems. 
As it happens, however, the sharing of multiple resources among multiple 
work areas demands much more than a straightforward interconnection scheme 
and time multiplexing. To achieve desired computer control and 
coordination of activities associated with all system elements, a complex 
communication and control structure must necessarily be imposed with 
hardware and software exhibiting the bandwidth and response time required 
for efficient operation at all system levels. In some cases, distributed 
communication via local-area network may be appropriate, whereas direct, 
real-time digital input/output may be necessary between the hardware 
resources and the tools which benefit from those resources. 
With specific regard to laser-based processing, once energy is directed to 
a particular work area by selecting the proper output fiber, the equipment 
controller must be able to assume control of the laser, including the 
ability to fire the laser quickly, with a circuit delay time between the 
request and the actual time at which the laser fires of milliseconds or 
less. This is practically impossible in conventional hierarchically 
designed process control systems, wherein instructions must be distributed 
and interpreted at multiple levels before control of resources may be 
relinquished or assumed. The required signaling speed may be achieved by 
direct hardware connection of digital control between equipment 
controllers and lasers, but with multiple resources and work areas 
demanding those resources, contention between competing control signals 
must be properly arbitrated. 
SUMMARY OF INVENTION 
The present invention provides the required real-time time control over 
various resource functions and supports the necessary communication and 
coordination required of a fully integrated distributed energy-sharing 
system. In one embodiment, laser energy is shared, though the system is 
applicable to any resource capable of being time-multiplexed. To achieve 
the desired interaction of all system elements, the invention implements a 
distributed cell-control architecture operating over a local area network. 
In the case of two workstations competing for multiple laser resources, 
the control system uses a central cell controller which interfaces to the 
lasers and beam multiplexers and acts as a file server for the workstation 
nodes. The workstation nodes interface with local controllers over serial 
and parallel I/O lines. 
In order to facilitate high-speed, real-time control over the laser 
resources, an inventive real-time digital signal network is implemented 
with hardware switches which connect control signals between the lasers, 
equipment controllers and the cell controller in accordance with control 
software. Energy redirection through the multiplexers, laser control 
signal arbitration, and control signal routing through this hardware 
switch are managed by software resident on the cell controller. 
Software is preferably included to minimize "makespan," which is the time 
required from the beginning of a schedule through completion of the last 
job in the sequence. Resource allocation software is additionally 
preferably included to arbitrate contending requests for system resources, 
allocate those resources by controlling the real-time digital network 
hardware and fiber-beam multiplexers, and apprise an operator of the 
current system configuration. A job scheduling algorithm may be included 
to determine the sequence of jobs, chosen from a queue, to be processed 
through the multiple work areas using one or more of the lasers, which may 
be from different manufacturers. A method utilizing structured 
programming, in conjunction with digital I/O, supports limited interrupt 
capabilities.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is directed toward the sharing of resources, 
particularly those associated with manufacturing processes. Generally 
speaking, an objective of the invention is to allow multiple work areas to 
take advantage of energy-based resources which otherwise might not be used 
to their fullest extent. By enabling multiple operators to take advantage 
of such equipment, productivity is enhanced, and the expenses associated 
with these resources is reduced. 
In one embodiment, the present invention takes the form of a communication 
and control structure for a distributed laser processing system, wherein 
high-powered lasers of the type used for materials processing are shared 
in a manufacturing environment. Such lasers may be used for various 
functions, including welding, drilling, cutting and the like. In 
particular, the present invention allows different laser systems from 
different manufacturers to be shared over a time-multiplexed beam-delivery 
system in conjunction with serial and parallel networking and software 
components which will be described in detail in subsequent sections. 
It should be understood, however, that although the following detailed 
description concerns the sharing of laser resources within a materials 
processing application, the present invention is by no means limited to 
this specific implementation. Broadly, the advantages and techniques made 
available by the present invention are readily transferrable to any 
environment wherein multiple work areas must take advantage of multiple 
resources on a real-time basis. One can imagine applications wherein other 
forms of energy must be shared on a similarly high-speed basis, including 
other forms of optical energy, radiant energy, or electrical energy. For 
example, any type of system which might require multiple operators to use 
a specialized energy resource associated with a costly generation means 
associated with that energy may advantageously implement the communication 
and control structures delineated and implied by the present invention, 
particularly if in sharing these resources, it is necessary that control 
be relinquished by a more centralized hierarchy in order for the various 
work areas to assume direct, real-time and asynchronous control of the 
energy or other capabilities which may be derived from a particular 
resource. 
Now making reference to the figure, there is depicted generally a block 
diagram of a hierarchical communication and control structure applicable 
to a resource-sharing system, in this case, a distributed laser processing 
system. At a high informational level, a cell controller 38, implemented 
as a personal computer, typically communicates with a factory computer 
(not shown), receiving data, for example, from a factory database. At a 
lower point in the hierarchy, the cell controller 38 coordinates the 
activities which take place in various workareas. There are two such 
workareas, 21 and 24 in the embodiment shown, though a greater number of 
such areas may be accommodated by the invention. 
Advantageously, the various workstations may include identical tools or 
equipment of varying design. Workarea 21, for example, includes a Moroman 
K10AS laser cutting robot 46 and associated controller 45; a workstation 
control personal computer 44, and an RS-232 communication connection 36 
between the robot controller and the workstation controller PC. Moroman is 
located in West Carrolton, Ohio. Laser energy from either of the 
fiber-optic beam multiplexers 23 or 29 is delivered to the workarea over 
fiber optic cables 47 and 48. A digital control signal connection 32 is 
established between the robot controller and a digital I/O switch 28, and 
a local area network connection 43 is maintained among workstation 
controllers and the cell controller 38. The digital switch 28 is 
preferably the asynchronous bidirectional node switch described in the 
parent to this application, and is incorporated herein in its entirety by 
reference. 
Workarea 24 includes an Anorad custom 5-axis computer numerical controller 
(CNC) machining center 26, and controller 25, a workstation controller PC 
27, and an RS-232 communication connection 35 connected therebetween. 
Anorad Corporation is based in Hauppauge, N.Y. As with workarea 21, fiber 
optic cables 49, 50, digital control signal connection 34 and a local-area 
network connection 42 are similarly provided. With the exception of the 
different type of motion equipment in this workarea, in all respects, its 
operation is identical to the workarea 21 described previously. 
The preferred embodiment includes two lasers, 22 and 30, and respective 
fiber-optic beam multiplexers 23, 29 which provide a resource, in this 
specific case, laser energy. There may be any number of resources and they 
may be fundamentally different. Each resource, however, provides something 
to the workcell shown in the figure to be shared between the various 
workareas so as to increase the utilization of the resource. This approach 
reduces the total cost of the workcell when compared to an otherwise 
identical system with independent workareas, each requiring a copy of that 
resource if it were not shared. 
Digital control signals connect each resource, 22 and 30, including its 
associated fiber optic beam multiplexer 23 or 29, to the digital I/0 
switch 28, thereby providing switchable control of the resource. If the 
resource is programmable, as are the lasers in the preferred embodiment, 
they are connected to the cell controller PC 38 via RS-232, or equivalent, 
connections 51, 52, thereby allowing reconfiguration before or during 
operation. 
The digital I/0 switch 28 is configured by software resident on the cell 
controller PC 38. This software can change the state of the digital I/O 
switch by signalling over the connections 37, such that at any given 
instant, control of a specified laser is provided by, and distribution of 
its energy is directed to, a specified workarea. A third state is provided 
whereby a resource may be entirely disconnected from the system. 
Additionally, one or more resources may be connected to one or more 
workareas simultaneously. 
The software resident on the cell controller also arbitrates resource 
contention, and allocates resources based on requests from the workstation 
controllers 44 or 27 in the designated workareas 21 or 24 and the 
availability of the requested resource. This operation is unique to the 
configuration of the invention because the cell controller PC only 
switches control and energy distribution. Actual control of the allocated 
resource is managed by the equipment controller over digital control 
signals that are established between the requesting equipment controller 
45 or 25, and the allocated resource; i.e., a laser. Unlike conventional 
hierarchal control structures that route such signals through a next level 
controller (the cell controller 38, for example), this configuration 
provides instantaneous real time control of the allocated resource by the 
requesting controller. 
Using workarea 21 and laser 22 for illustration purposes, in operation an 
equipment operator indicates that a particular operation will be run at 
the workarea according to an application chosen from a list supplied on 
the workstation controller PC 44. The appropriate files are fetched by the 
workstation controller 44, which then downloads the appropriate code to 
the equipment controller 45 over the RS-232 serial communication link 36. 
Once this is complete, the operator is notified that the application is 
ready to run. Before starting execution of the application program at the 
workarea, the workstation controller determines which, if any, resources 
are needed, then initiates a request for allocation of the needed 
resources by sending a request message to the cell controller. 
If the requested resource is available, it will be allocated to the 
workarea. Once a resource has been allocated, the software resident on the 
cell controller PC 38 reprograms the resource to the requirements of the 
application by sending command sequences over the RS-232 connection 51. 
Once configured, the digital control signals 33 will be switched at the 
digital I/O switch 28 by the software running on the cell controller PC 
38. In this case, the digital I/O switch control connections 37 are used 
to connect the equipment controller 45, via path 32 to the laser 22, and 
the laser energy will be switched via multiplexer 23, so as to direct 
energy to the requesting workarea 21. This process is identical for each 
request. 
Once requested and granted, a particular configuration will remain in 
effect until the workstation controller 44 is notified by the equipment 
controller 45, that the resource is no longer needed. The workstation 
controller 44 then informs the cell controller PC 38 by sending a complete 
message in the same manner as the request message, that it no longer needs 
the allocated resource. At this time the software will de-allocate 
(disconnect) the resource from the equipment controller by switching the 
digital I/0 switch 28 and switch the fiber-optic beam multiplexer 23 so 
that energy is no longer directed to that particular workarea. 
An application directory structure provides each workstation and cell 
controller 38 with a separate working directory which contains run-time 
and start-up files for each computer, these directories being located on a 
hard disk associated with cell controller 38. Also included in the 
applications directory are a series of subdirectories which contain files 
for downloading to each equipment controller and laser. 
Using the directory structure just described, system support is simplified 
by maintaining all files and data on one system. This, in conjunction with 
the network configuration, allows distribution of processing between 
multiple computers, thereby enabling tasks to run in parallel, which tends 
to decrease contention for CPU time. Once an application is loaded to a 
workstation, cell controller 38 is entirely freed from any activity 
required to manage the application, allowing another application to be 
developed or to run simultaneously on another workstation, or the cell 
controller, without any effect on run time. 
Each workstation also preferably includes workstation management software 
from which an operator may load and run any application applicable to that 
workstation, and queue up jobs for a resource which may be currently 
unavailable. Generally, the workstation manager software includes a visual 
interface in menu form, the queuing structure just mentioned, and an 
equipment server which provides an interface to the equipment controller.