Patent Application
20080082196
Referring to
The automated manufacturing system 2 is an automated system insofar as it includes at least one process controller that governs the operation of the manufacturing process, or at least a portion of the process, and more particularly governs the operation of one or more controllable devices that are active in performing the process. In the present embodiment, the automated manufacturing system 2 in particular includes a process controller 4 that is a programmable logic controller (PLC) such as one of the ControlLogix PLCs available from Rockwell Automation, Inc. of Milwaukee, Wis. As shown, the process controller 4 is capable of controlling several controllable devices within the automated manufacturing system 2. In particular, the process controller 4 is in communication with, by way of first, second, third, fourth and fifth communication links 6, 8, 10, 12 and 14, respectively, a first moving device 16, a first clamping device 18, a second clamping device 20, a welding device 22, and a second moving device 24.
By way of the communication links 6-14, the process controller 4 is able to control the operation of the devices 16-24 to perform a welding process such as that described in accordance with
The automated manufacturing system 2 shown in
In alternate embodiments, for example, the automated manufacturing system could employ devices for performing operations other than (or in addition to) a welding operation including, for example, heating or cooling operations, painting or spraying operations, various physical operations such as pushing components together or pulling components apart from one another, bending components, applying torques or other types of forces (e.g., shearing forces) upon components, connecting or fastening components together, and a variety of other operations. It should further be mentioned that the process controller 4 in the present embodiment is designed to be capable of interaction with other programmable logic controllers or other process controllers (not shown) by way of one or more networks or other communication links 32, which could be, for example, DeviceNet or ControlNet networks. Thus, the automated manufacturing system 2 of
Further as shown in
As shown, the sensors 34-42 typically are positioned close to a path 58 along which the target item 26 travels as it is moved into the room 30 for the welding operation and subsequently moved out of the room. That is, each of the sensors 34-42 is positioned proximate to the target item 26 as it proceeds through the room 30 and at least some of the sensors are positioned close to a location at which a welding operation performed by the welding device 22 occurs in relation to the target item 26. For this reason, the sensors 34-42 are likely to be exposed to repeated stresses over time as the automated manufacturing system 2 operates with respect to the target item 26 and other target items. In particular, the sensors 34-40 are situated within a substantially circular region demarcated by a dashed line 60 in which relatively high-energy electromagnetic fields occur due to operation of the welding device 22 during the welding operation (albeit the sensor 42 is located somewhat outside this region). Further, one or more of the sensors 34-42 also are likely to be exposed to other stresses during the manufacturing process including, for example, temperature-related stresses, physical impulse or impact-related stresses, and stresses related to exposure to various chemicals.
Although the sensors 34-42 are likely to be exposed to various stresses during manufacturing, this is in contrast to the intermediate controller 54, which is located sufficiently far away from the welding device 22 and, indeed, is located outside of the room 30 and on the opposite side of the wall 28 defining the room 30 relative to the sensors, such that the intermediate controller is not exposed to the same degree of stresses. In particular, as illustrated by the dashed line 60, the intermediate controller 54 is located outside the region in which there are relatively high-energy electromagnetic fields during the welding operation. The dashed line 60 can be understood as demarcating an inner region extending from the welding device 22 up to points at which the electromagnetic field intensity is 10% or less than a maximum level generated by the welding device 22 (in at least some embodiments, the radius of this region could be 12 inches). Thus, in the present embodiment the intermediate controller 54 is located in a region where the electromagnetic field intensity is 10% or less than a maximum generated by the welding device 22.
Further as shown, in the present embodiment the intermediate controller 54 not only is positioned so that it is less likely to be exposed to high-energy electromagnetic fields than some or all of the sensors 34-42, but also is positioned so that it experiences (or is likely to experience) less stresses of other types including, for example, high heat intensities and potentially-damaging physical impacts or impulses, to name a few. Thus, the present invention is intended to encompass a variety of embodiments in which one or more sensors are located in positions where those sensors are potentially subject to moderate or high stress levels of one or more types and at the same time are coupled to an intermediate control device (or possibly multiple intermediate control devices) that is located in a position at which it is less likely to be subject to those same types of stresses. The types of stresses to which the sensors, but not the intermediate control device(s), are significantly subjected can include not only those associated with exposure to high-energy electromagnetic fields, high temperatures, or physical impacts or impulses, but also other types of stresses such as those associated with extreme low temperatures, great or rapid temperature fluctuations, high (or low) pressures, or centrifugal forces.
Referring additionally to
In alternate embodiments, the sensor 34 (and the other sensors 36-42) can be any of a variety of types of sensors having an appropriate sensing component (or components) and output circuit (or circuits) including, for example, a photoelectric sensor, a photosensor, a magnetic sensor, a laser sensor, a pressure sensor, a temperature sensor, a vibration sensor, a proximity sensor, a position sensor, a flow sensor, an ultrasonic sensor, a capacitive sensor, a RF sensor, a humidity sensor, a transducer and/or a variety of other types of sensors, including a variety of other types of condition sensors. Also, while the sensor 34 of
While the sensors 34-42, in contrast to conventional sensors, employ only minimal components/circuits, much of the circuitry that ordinarily is provided in conventional sensors instead is provided as part of the intermediate controller 54. Referring to
Further, the circuitry 70 includes output switching circuitry 76, for example, maximum current circuitry. The output switching circuitry 76 in particular as shown is coupled to the additional output ports 67. The output switching circuitry 76 by way of the output ports 67 (as well as external communication link(s), not shown) is thus capable of providing control signals or other signals to controlled devices (e.g., valves, motors, relays, etc.) as well as to other devices, including devices that provide additional monitoring or control functions (e.g., remote computer terminals). In some alternate embodiments, the output switching circuitry 76 can include (or be replaced with) additional circuitry allowing for the input of additional signals into the intermediate controller 54, that is, the output switching circuitry can be replaced with circuitry capable of both input and output functionality (or merely input functionality).
In addition to including the circuitry 70, the intermediate controller 54 additionally as shown in
Additionally, the processing device 78 includes fault management software, which in the present embodiment is shown as weld field immunity management software 82. The weld field immunity management software 82 enables the processing device 78 to monitor the signals received from the sensors 34-42 by way of the communication links 44-52 (which, in at least some embodiments such as the present embodiment, are hardwired links that do not employ any protocol) and to make determinations based upon those signals as to whether one or more of those sensors have experienced a fault or failure that is severe enough so as to warrant a change in the automated manufacturing process being controlled by the process controller 4. Depending upon the particular determinations that are made by way of the weld field immunity management software 82, the processing device 78 in turn provides signals via the additional communication link 56 to the process controller 4, in response to which the process controller 4 can take various actions such as causing a modification of the automated manufacturing process or even a complete cessation of the automated manufacturing process.
The weld field immunity management software 82 can make a variety of determinations, in a variety of manners, depending upon the particular embodiment. In at least some embodiments, the weld field immunity management software 82 determines whether a given one of the sensors 34-42 has experienced an unacceptable failure as follows. First, when a welding operation is about to begin, the process controller 4 sends a signal to the intermediate controller 54 by way of the additional communication link 56 indicating this to be the case. The intermediate controller 54 at that time observes/records the signals that are being provided from the sensors 34-42. The signals that are being provided in at least some such embodiments are merely indicative of the presence or absence (or proper positioning) of a target item such as the target item 26 that is to be the subject of the welding operation.
Subsequently, after the welding operation has been performed, the process controller 4 again sends a signal to the intermediate controller 54 indicating that the welding operation has been completed, and in response the intermediate controller 54 again observes/records the signals that are being provided from the sensors. If a sensor signal has changed sufficiently in its value/level relative to its value/level prior to the welding operation, then this potentially is indicative of a failure of the sensor. In some cases, merely the occurrence of such a change would be sufficient basis for a determination by the weld field immunity management software 82 that an unacceptable failure has occurred. In other, more preferred, embodiments, the weld field immunity management software 82 is configured to determine that a sensor failure has occurred based upon not only whether an inappropriate sensor signal value has appeared but also whether that inappropriate sensor signal value continues to occur for a threshold length of time after the welding operation has been performed, for example, for more than a single weld cycle (e.g., approximately 1 second).
Typically, if the weld field immunity management software 82 determines that any one or more of the sensors 34-42 have experienced a failure, the processing device 78 sends a signal to the process controller 4 that causes a complete cessation of the automated manufacturing process. However, in some alternate embodiments it can instead be the case that the processing device 78 will only send a signal to the process controller 4 precipitating a shutdown if the weld field immunity management software 82 determines that more than one of the sensors 34-42 (or even a majority of those sensors) have experienced a failure. Further, in some alternate embodiments, the particular signal output by the processing device 78 will vary depending upon the particular failure circumstance.
For example, the sensor 40 of
Because the intermediate controller 54 includes the circuitry 70 that previously would be positioned within the discrete sensors 34-42, the sensors 34-42 themselves have less (or at least different) componentry. Removal of the features such as weld field immunity management software 82 and/or related circuitry from the sensors can allow for the sensors themselves to be reduced in size or allow for a same-sized sensor to have available additional room for other sensor features. Such other features can include, for example, additional structures allowing for improved sensing techniques to be implemented, such as techniques that allow for increased sensing ranges, as well as additional structures that improve the durability of the sensing packages, for example, metal face sensors. Such features can make it possible to mount the sensors farther away from the target(s) they are sensing, such that the sensors are less susceptible to physical damage during the manufacturing process. For that reason, in comparison with conventional sensors, the sensors 34-42 are less susceptible to damage due to stresses such as heat-related stresses or physical impact stresses. Further, when the sensors do need to be replaced or repaired, the cost of repairing or replacing the sensors is reduced relative to what it ordinarily would be in a conventional system. Likewise, although not all conventional sensors have circuitry that determines (or assists in determining) whether the sensors have experienced failures, to the extent that some conventional sensors do have such circuitry, the inclusion of the weld field immunity management software 82 within the processing device 78 of the intermediate controller 54 eliminates the need for such circuitry in the sensors and so, for that reason as well, the sensors 34-42 can be less susceptible to damage and, when damage does occur, the sensors can be repaired or replaced at relatively less cost than conventional sensors.
It should further be mentioned that, while the intermediate controller 54 (unlike the sensors 34-42) in the present embodiment is desirably positioned sufficiently far away from heat, physically moving items, chemicals, and/or other potential manufacturing-related hazards or sources of stress that could potentially damage its internal circuitry and/or other components so as to largely if not completely eliminate the risk of damage to its internal components, this does not mean that in all embodiments the intermediate controller is positioned so far away as to remove all risk of damage. Rather, the present invention is also intended to encompass embodiments in which the intermediate controller is largely removed away from the hazards/sources of stress but yet there remains some risk that damage could occur. In at least some such embodiments, as indicated by a dashed line 55 shown in
Although
In addition to the circuitry 70 and the weld field immunity management software 82 employed in the processing device 78 shown in
Also for example, in various embodiments the intermediate controller 54 can include additional circuitry as represented by a box 86. In at least some embodiments, the intermediate controller 54 is coupled to the sensors 34-42 by way of a wireless communication network/wireless communication links rather than by way of hardwired communication links as are represented by the communication links 44-52. In such embodiments, the additional circuitry represented by the box 86 can be a wireless transceiver controlled by the processing device 78. Also in such embodiments, the output circuitry of the sensors such as the output circuit 64 of
Turning to
In the present embodiment, upon starting the process 90 at a step 88, the process controller 4 provides a command to the first moving device 16 to transfer in a target item such as the target item 26, at a step 92. Then, in response to the command, the moving device 16 transfers in the target item, at a step 94. Next, at a step 96, the sensors 34-42 (or at least a subset of those sensors) detect the presence of the target item within the room 30 and further, at a step 98, the sensors output signals indicative of that presence to the intermediate controller 54, which in turn causes the intermediate controller 54 to send a signal indicating the presence of the target item to the process controller 4, at a step 100.
Upon receiving confirmation that the target item is present, the process controller 4 sends commands to the first and second clamping devices 18 and 20 to clamp the item in place, at a step 102, which subsequently results in the clamping devices taking such action at a step 104. Then, upon completion of the clamping at step 104, at a step 106 the process controller 4 then sends a signal to the intermediate controller 54 that welding is about to take place. At a step 108, the intermediate controller 54 then observes/records the present values of the sensor signals being received from the sensors 34-42. At a step 110, the process controller 4 next provides a command to the welding device 22 to commence the welding process and, at a step 112, the welding device 22 performs the welding upon the target item. The time during which the welding process occurs generally is a blackout period for the sensors 34-42, in which they are unable to properly operate, and the intermediate controller 54 does not make any determinations based upon the sensor signals it may receive during this time.
Once the welding is completed, at a step 114 the process controller 4 provides a signal to the intermediate controller 54 indicating this to be the case. In response, at a step 116 the intermediate controller 54 observes the values of the sensor signals occurring at that time and detects any changes that have occurred in those sensor signals since they were previously observed at step 108. The exact changes that are detected can depend upon the embodiment and, in some embodiments can be highly nuanced. For example, in at least some embodiments and as described above, the intermediate controller 54 detects in particular whether any changes in the sensor signals that are occurring immediately following the welding operation continue to occur for a threshold amount of time thereafter.
If, at a step 118, the intermediate controller 54 determines that a sensor failure has occurred based upon the detected changes, then an additional signal is provided from the intermediate controller to the process controller 4 alerting the process controller that the failure has occurred, at a step 120. Upon receiving the additional signal, the process controller 4 then takes appropriate action at a step 122, after which time the process ends at a step 124. The particular action that is taken again can be highly nuanced depending upon the embodiment or circumstance, albeit in at least some embodiments the action that is taken is simply the complete stopping of the automated manufacturing process. If, however, at step 118 the intermediate controller 54 does not determine that a sensor failure has occurred, then the process continues to completion. Thus, at a step 126, the process controller 4 provides a command to the clamping devices 18, 20 to unclamp the target item and, at a step 128, the item is unclamped by the clamping devices. Then, at a step 129, the process controller 4 provides a command to the second moving device 24 that the target item be transferred out and, at a step 130, the item is transferred out, after which time the process again is ended at the step 124.
Although
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.
