TECHNICAL FIELD

[0001] The present disclosure is directed, in general, to computer-aided design, visualization, and manufacturing ("CAD") systems, product lifecycle management ("PLM") systems, product data management ("PDM") systems, and similar systems, that manage data for products and other items (collectively, "Product Data Management" systems or PDM systems).

BACKGROUND

[0002] In the planning of industrial processes, computer simulation techniques are used where a physical scene of a physical environment is modeled by a virtual scene of a virtual simulation environment. The physical or real scene may, for example, be a facility, a manufacturing plant, an industrial scene, or any other physical scene which may benefit from being modeled in a virtual environment for industrial simulation purposes. [0003] The real scene may include a variety of real objects which are related to a facility. Examples of real objects include, but are not limited to, equipment pieces, tools, containers, material pieces, finished or semi-finished products, and other objects present in the real scene. Real objects are represented in the virtual simulation environment by virtual objects. Virtual objects are typically defined through three-dimensional (3D) virtual models, examples of which include, but are not limited to, CAD models, CAD- like models, point cloud models, and other types of 3D computer models.

[0004] In the real scene, the real objects have a position and an orientation, which can change/move as the real object is moved or re-positioned within the real scene. When modeling industrial facilities in the virtual simulation environment, it is often a common requirement that the position and the orientation of the virtual objects in the virtual scene accurately reflect the position and the orientation of the real objects in the real scene.

[0005] It is assumed that light weight robots, which are designed to work around humans with no safety guards, are at a certain risk of hitting humans, such that safety mechanisms are provided to reduce any possible damage.

SUMMARY

[0006] It is difficult to design the environment and plan the process, to reduce the risk that when the robot actually collides with the human, the damage from the impact will be kept to a minimum. Furthermore, the human's behavior is not deterministic and often not exactly predefined, such that it is hard to accurately time the robot's and human's movement so that all possible hits will be calculated. Therefore, improved techniques are desirable.

[0007] Various disclosed embodiments include simulation and handling methods and corresponding systems and computer-readable mediums. A method for simulating and certifying safety management for an area of a production plant performed by a data processing system is disclosed, wherein at least one collaborative robot performing robotic operations and at least one human performing human operations operate at least partially simultaneous in said area, the method comprising:

a) defining a table comprising human body parts and a threshold injury level related to the respective human body part;

b) simulating the robot's operations thereby determining a robot swept volume; c) simulating the human's operations thereby determining a human swept volume, d) comparing the robot swept volume to the human swept volume and determing a volume of robot-human intersections where the robot swept volume and the human swept volume overlap; e) using kinematic and/or physical data for the movements of the robot in the volume of robot-human intersection for calculating hit parameters for a number of points in the volume of the robot-human intersection;

f) using the hit parameters for calculating the actual injury level on the human body parts present in the volume of robot-human intersections;

g) identifying whether the calculated actual injury level infringes the threshold injury level; and

h) in case of infringement, re-arranging the robot's operations and/or the human operations and repeating the steps b) and/or c) and d) to f) until non-infringement of the threshold injury level is achieved.

[0008] In another example, a data processing system is disclosed. Said data processing system comprises a processor and an accessible memory. The data processing system is particularly configured to simulate and certify safety management for an area of a production plant, wherein at least one collaborative robot performing robotic operations and at least one human performing human operations operate at least partially simultaneous in said area, the data processing system further configured in detail for: a) defining a table comprising human body parts and a threshold injury level related to the respective human body part;

b) simulating the robot's operations thereby determining a robot swept volume; c) simulating the human's operations thereby determining a human swept volume, d) comparing the robot swept volume to the human swept volume and determing a volume of robot-human intersections where the robot swept volume and the human swept volume overlap;

e) using kinematic and/or physical data for the movements of the robot in the volume of robot-human intersection for calculating hit parameters for a number of points in the volume of the robot-human intersection;

f) using the hit parameters for calculating the actual injury level on the human body parts present in the volume of robot-human intersections;

g) identifying whether the calculated actual injury level infringes the threshold injury level; and h) in case of infringement, re-arranging the robot's operations and/or the human operations and repeating the steps b) and/or c) and d) to f) until non- infringement of the threshold injury level is achieved. [0009] In another example, a non-transitory computer-readable medium is disclosed. The non-transitory computer-readable medium is encoded with executable instructions that, when executed, cause one or more data processing systems to:

simulate and certify safety management for an area of a production plant, wherein at least one collaborative robot performing robotic operations and at least one human performing human operations operate at least partially simultaneous in said area, further causing the data processing system in detail to:

a) defining a table comprising human body parts and a threshold injury level related to the respective human body part;

b) simulating the robot's operations thereby determining a robot swept volume; c) simulating the human's operations thereby determining a human swept volume, d) comparing the robot swept volume to the human swept volume and determing a volume of robot-human intersections where the robot swept volume and the human swept volume overlap;

e) using kinematic and/or physical data for the movements of the robot in the volume of robot-human intersection for calculating hit parameters for a number of points in the volume of the robot-human intersection;

f) using the hit parameters for calculating the actual injury level on the human body parts present in the volume of robot-human intersections;

g) identifying whether the calculated actual injury level infringes the threshold injury level; and

h) in case of infringement, re-arranging the robot's operations and/or the human operations and repeating the steps b) and/or c) and d) to f) until non-infringement of the threshold injury level is achieved. [0010] The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that those skilled in the art may better understand the detailed description that follows. Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure in its broadest form.

[0011] Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words or phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "associated with" and "associated therewith," as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term "controller" means any device, system or part thereof that controls at least one operation, whether such a device is implemented in hardware, firmware, software or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases. While some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which: [0013] Figure 1 illustrates a block diagram of a data processing system in which an embodiment can be implemented; [0014] Figure 2 illustrates a schematic view of a production environment wherein a human and a robot perform simultaneously production activities;

[0015] Figure 3 illustrates a schematic view of human operations in the production environment thereby defining a human swept volume;

[0016] Figure 4 illustrates a schematic view of a robot operations in the production environment thereby defining a robot swept volume;

[0017] Figure 5 illustrates a schematic view on the addition of the human swept volume and the robot swept volume thereby determining a volume of robot-human intersections where the robot swept volume and the human swept volume overlap;

[0018] Figure 6 illustrates a schematic view on the process where the human body parts in the volume of robot-human intersections are checked against being crushed by a force F between the robot and any other part present in the volume of the robot-human intersections; and

[0019] Figure 7 illustrates an embodiment of acts for simulating and certifying safety management for an area of a production plant performed by a data processing system, wherein at least one collaborative robot performing robotic operations and at least one human performing human operations operate at least partially simultaneous in said area.

DETAILED DESCRIPTION [0020] FIGURES 1 through 4, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged device. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0021] Previous techniques for a proper handling of anti-collision management for an area of a production plant were based on an on-site analysis where robots are taken to the shop floor and production engineers tried to visually assess the robot's operations in order to figure out whether a robot may hit a human during the course of its operations. This analysis is cumbersome, tedious, error-prone, and otherwise ill-suited for the task of avoiding damage to humans operating with robots within the same production area.

[0022] Embodiments according to the present disclosure provide numerous benefits including, but not limited to: providing a user- friendly manner for simulating the collision management systematically by checking the robotic path and the human interactions in the area of the robot. Further, the production process involving robot operations and human operations within the same area of a production plant can be planned systematically, thereby avoiding collisions at least partially while or for performing modification of the production process within the simulation environment; enabling a user-friendly control of the position and of the orientation of the robot's and the human's operations in an intuitive manner so that the industrial simulation and planning is an accurate simulation of the real world process; facilitating, for non-expert users, the usage of industrial simulation packages on a shop floor (such as Process Simulate and Human Simulation provided by Siemens Product Lifecycle Management Software Inc. (Piano, Texas)) to execute the virtual simulation for ongoing production simulation. Further, the application of the present invention will allow a certification of the safety for the operations where robots and humans act within the same area. [0023] Embodiments may be particularly beneficial for software packages which incorporate CAD environments, including, but not limited to, NX, Process Simulate, Solid Edge, and others provided by Siemens Product Lifecycle Management Software Inc. (Piano, Texas) or packages offered by other software suppliers. Embodiments combined with a CAD system may conveniently supply a complete design and simulation environment.

[0024] Figure 1 illustrates a block diagram of a data processing system 100 in which an embodiment cam be implemented, for example as a PDM system particularly configured by software or otherwise to perform the processes as described herein, and in particular as each one of a plurality of interconnected and communicating systems as described herein. The data processing system 100 illustrated can include a processor 102 connected to a level two cache/bridge 104, which is connected in turn to a local system bus 106. Local system bus 106 may be, for example, a peripheral component interconnect (PCI) architecture bus. Also connected to local system bus in the illustrated example are a main memory 108 and a graphics adapter 1 10. The graphics adapter 1 10 may be connected to display 1 1 1.

[0025] Other peripherals, such as local area network (LAN) / Wide Area Network / Wireless (e.g. WiFi) adapter 1 12, may also be connected to local system bus 106. Expansion bus interface 1 14 connects local system bus 106 to input/output (I/O) bus 1 16. I/O bus 1 16 is connected to keyboard/mouse adapter 1 18, disk controller 120, and I/O adapter 122. Disk controller 120 can be connected to a storage 126, which can be any suitable machine usable or machine readable storage medium, including but not limited to nonvolatile, hard-coded type mediums such as read only memories (ROMs) or erasable, electrically programmable read only memories (EEPROMs), magnetic tape storage, and user-recordable type mediums such as floppy disks, hard disk drives and compact disk read only memories (CD-ROMs) or digital versatile disks (DVDs), and other known optical, electrical, or magnetic storage devices. [0026] Also connected to I/O bus 1 16 in the example shown is audio adapter 124, to which speakers (not shown) may be connected for playing sounds. Keyboard/mouse adapter 118 provides a connection for a pointing device (not shown), such as a mouse, trackball, trackpointer, touchscreen, etc.

[0027] Those of ordinary skill in the art will appreciate that the hardware illustrated in Figure 1 may vary for particular implementations. For example, other peripheral devices, such as an optical disk drive and the like, also may be used in addition or in place of the hardware illustrated. The illustrated example is provided for the purpose of explanation only and is not meant to imply architectural limitations with respect to the present disclosure.

[0028] A data processing system in accordance with an embodiment of the present disclosure can include an operating system employing a graphical user interface. The operating system permits multiple display windows to be presented in the graphical user interface simultaneously, with each display window providing an interface to a different application or to a different instance of the same application. A cursor in the graphical user interface may be manipulated by a user through the pointing device. The position of the cursor may be changed and/or an event, such as clicking a mouse button, generated to actuate a desired response.

[0029] One of various commercial operating systems, such as a version of Microsoft Windows™, a product of Microsoft Corporation located in Redmond, Wash, may be employed if suitably modified. The operating system is modified or created in accordance with the present disclosure as described.

[0030] LAN/ WAN/Wireless adapter 1 12 can be connected to a network 130 (not a part of data processing system 100), which can be any public or private data processing system network or combination of networks, as known to those of skill in the art, including the Internet. Data processing system 100 can communicate over network 130 with server system 140, which is also not part of data processing system 100, but can be implemented, for example, as a separate data processing system 100.

[0031] Figure 2 illustrates a schematic view of a production environment 200 wherein a robot 202 and a human 204 perform simultaneously production activities. In this production environment 200 a number of other production equipment 206, such as conveyors, mounting platforms and the like, is arranged. For the production equipment 206 exists a 3d model as well as the physical attributes, such as elastic, fluffy etc., associated with the respective production equipment. For both the robot 202 and the human 204 a 3d model exists as well as the physical attributes, such as soft, hardened, mass, center of gravity etc., and kinematic attributes associated with the respective production activities, such as velocity, acceleration, torque, kinematic chain information (which joint/human body is based on other joint/human body, how each movement impacts on others, minimum and maximum values of movement etc.

For the simulation and the certification of the production activities, a table is defined comprising human body parts and a threshold injury level related to the respective human body part. Said threshold injury level thereby defines the threshold for the effect of a collision event between the robot and the human in a volume of human-robot intersection 500 (see Figure 5) that is still considered to be harmless for the human and is therefore considered allowable. In one embodiment, the possible calculation of the threshold injury level may comprise a hit damage index that can range from 0 to 10, wherein the head of a human operator is assigned the highest hit damage index 10. The palm of a human operator has an assigned hit damage index of 8. The arms and the legs of the human operator have a hit damage index of 5, while the chest area has the lowest hit damage index of 3, in this example. The hit damage index therefore represents an indication for the weighing factor when determining the severity of a collision event of a robot with the respective part of the human operator in order to determine the actual body injury level. The values for the hit damage index can be present in form of a table comprising the body part and the value for the respective body part. The numbers are not limited and additional number/areas of the body can be utilized as well as other weighting factors. [0032] Figure 3 illustrates a schematic view of human operations in the production environment thereby defining a human swept volume 300. This human swept volume 300 shows for example the movements of the complete body, the head 302 and the right arm 304 during the course of human operations, such as grabbing a part, mounting the part to an assembly provided temporarily by the robot, assembling a part in cooperation with the robot and the like.

[0033] Analogously, Figure 4 shows a schematic view of robot operations in the production environment thereby defining a robot swept volume 400. The robot swept volume 400 is given by the registration of all planned movements of the robot 402 during the robot's production activities.

[0034] Figure 5 illustrates a schematic view on the addition of the human swept volume 300 and the robot swept volume 400 thereby determining a volume of robot-human intersections 500 where the robot swept volume 400 and the human swept volume 300 overlap. In the overlapping volume of robot-human intersection, the main problem with respect to the certification of the productions activities consists in the presence of the head and the chest in the volume of the robot human intersections 500 which require an educated investigation of the physical parameters during these production activities.

[0035] When running a simulation of a mixed environment of a production area in which a human and a robot will operate simultaneously, a number of different parameters can be observed, such as:

a) Considering that the mixed environment includes CAD models which are available for the data processing system. The CAD models can be generated from mechanical scans, Point cloud and manually modelled;

b) Considering the robot's CAD model is available in the data processing system;

c) Considering the human's model and the threshold injury level table to the data processing system; d) the industrial production process can be planned which represents the actions/operations of the robot;

e) the human's operations can be planned or predicted in the same environment;

f) a swept volume of each body part of the human can be determined, which represents all the places and positions that the human will be present, during the production process; g) the simulation can be run and all the collision events between the robot's swept volume and the swept volume of the human can be tracked;

h) optionally, the speed of the specific part of the robot while hitting the swept volume of the human can be considered;

i) based on the path and velocity of the robot's parts (i.e. the impact angle) and the body part which will be hit during the collision event, the actual injury level value can be calculated that represents the "Safety Score" for that specific production area. As mentioned above, the "Safety Score" can be provided as 2D or 3D collision injury map representing the potential severity of an injury, in case there is one, for the human caused through the collision event;

j) a high. score for the actual injury level can mean for example a potential severe injury. The score S can be calculated in different ways. For example: Rs ² + Bp ² = S, where Rs G R is the robot's speed, Bp G {1, . . ,10}, is the hit damage index and S G R is the Safety Score, wherein the hit damage index represents the sensitivity of the body part for a robot hit.

[0036] In addition, different models of different humans with different body types can be simulated in parallel, so that the Safety Score for one area will be the maximum score which was calculated for different humans and/or robots.

[0037] Finally, a collision damage map (the safety score map) can be visually presented in the 3D computer environment by coloring/animation of that area/volume in an appropriate color that represents the score. The collision damage map can for example indicate the severity of a damage such as in a heat map, where redder colors indicate potentially more severe damage and greener colors indicate a potentially less damaging strike, etc. [0038] Consequentially, the robot's operation program and/or the human's operation program can be changed so that the safety score (the actual injury level) and the associated color will change and the respective environment is then displayed a safer area. For example, this can be achieved by reducing the speed of the robot in areas in which the safety score shows that the area is not safe yet or is above a pre-defined threshold for the severity of the collision event.

[0039] The embodiments disclosed provide a reliable method to check the robot swept volume and the human interactions simultaneously in the same production area. Disclosed embodiments help verify that the industrial process is safe without the use of cumbersome, time consuming, and error-prone tests that fail to accurately reflect the position and speed of the robot's and human's movements during the production process. When applying standardized calculation methods to determine the potential injury levels to the human, such as according to ISO 15066:2016 or another standard derived thereof, the production process can be simulated and certified to satisfy the respective standard.

[0040] The embodiments disclosed provide reliable methods for robotic engineers to design a robot's activity in close proximity to human activities, as is often required in common industrial environments. The combination of precise human activity based on ergonomic behavior and identification of body parts with a precise robotic path provides for an accurate simulation of the industrial environment to minimize the risk of a human being injured. [0041] Optionally, embodiments may further include: 3D environment models that define the constraints and object of activities for robots and humans as well as the precise simulation of robot motion, the path and various elements of arms, manipulators, combined with target parts (in case of pick-and-place handling robots) can be utilized in some embodiments to identify the precise trajectory and speed of rigid bodies in the space resulting in reliable, ergonomic, and anatomical correct, human body simulation that predicts the precise movement and trajectory of various parts. Some embodiments further identify and score human body parts for severity of potential injury, based on the impact conditions (e.g. force, angle, speed, body part, hit damage index).

[0042] The combination of the kinematic simulation behavior with a visual dynamic mapping of zones with threshold injury levels provides numerous benefits for industrial production planning. Some embodiments utilize the actual injury maps for static analysis of hazards or for identifying motion of objects through such zones. Some embodiments provide such information dynamically to robotic/ergonomic engineers to allow a continuous modification of the path/position/movements enabling more efficient planning due to continues feedback.

[0043] By means of the threshold injury level an upper threshold for the severity of a collision event can be defined and a warning attribute can be assigned to those collision events exceeding the upper threshold. In addition, for collision events receiving a warning attribute, the robot operations and/or the human operations involved are identified and the order of the robot operations and/or the human operations involved are rescheduled in order to remove those collision events or lower the collision impact below the upper threshold. Further, for collision events receiving a warning attribute, the robot operations and/or the human operations involved are identified and the execution of the robot operations and/or the human operations involved are amended, i.e. by lowering accelerations values for the robot operations and/or amending the course of the robot activities. But other ways to lower the collision impact are also possible.

[0044] It is also possible determine the speed of the robot or a specific part of the robot during a collision event. This measure can be used advantageously when the severity of a collision event is calculated using the speed of the robot or a specific part of the robot and the hit damage index of the respective human body part most probably hit during the collision event. [0045] Figure 6 schematically shows the process where the human body parts, here an arm 602, in the volume of robot-human intersections 500 are checked against being crushed by a force F between the robot 600 and any other part 604 present in the volume of the robot-human intersections 500 thereby determining for all relevant human positions within the volume of robot-human intersections 500 a crush parameter by simulating for the period of the presence of the robot 600 in the volume of robot-human intersections 500 the movement of the robot 600 with respect to the presence of the human body part 602 and any other part present in the volume of the robot-human intersections.

[0046] Further, a first time can be determined being representative for the time the robot enters the volume of robot-human intersections. Of course, a second time can be determined being representative for the time the robots leaves and never enters back into the volume of robot-human intersections. Both, the first time and the second time limits the time period that needs to be considered by the simulation in order to reach the safety certification for the complete production activity.

[0047] In order to satisfy the required confidence level of the simulation for the resulting certification, for points in the robot-human intersections where different human body parts are present, the human body part having the highest hit damage index is taken for the identification of a possible infringement of the required safety level (i.e. always proceed with the more risky value may be a principle). Analogously, the robot activity having the highest impact force shall be applied for the calculation when the same body part will be potentially hit at least two times during the course of the robot operations and the human operations in the volume of the robot human intersections 500. Further, for each human body part a tolerance value can be defined considering the possibility of smaller unexpected movements of the respective human body part in the volume of the robot-human intersections 500.

[0048] In addition, the human swept volume 300 can be weighted with the respective threshold injury level prior to the addition of the robot swept volume 400 in order to receive from the addition an already potential injury-related volume of robot human intersections.

[0049] Furthermore, the robot swept volume 400 can be weighted with the kinematic and/or physical data for the movements of the robot. Therefore, also the robot swept volume 400 already provides a potential injury related statement prior to the addition of the human swept volume 300 and the robot swept volume 400.

[0050] In order to improve the possibility to analyze the evolution of the volume of robot-human intersections 500 in time, the volume of robot-human intersections 500 can be timely structured.

[0051] Figure 7 illustrates a flowchart 700 of a method for simulating and certifying safety management for an area of a production plant performed by a data processing system, wherein at least one collaborative robot performing robotic operations and at least one human performing human operations operate at least partially simultaneous in said area, the method comprising the following acts:

[0052] At act 710 a table is defined comprising human body parts and a threshold injury level related to the respective human body part.

[0053] At act 720 the robot's operations are simulated thereby determining a robot swept volume. [0054] At act 730 a table is defined comprising human body parts and a hit damage index related to the respective human body part.

[0055] At act 740 the robot swept volume is compared to the human swept volume and a volume of robot-human intersections where the robot swept volume and the human swept volume overlap is determined. [0056] At act 750 kinematic and/or physical data for the movements of the robot in the volume of robot-human intersection are used for calculating hit parameters for a number of points, preferably all points, in the volume of the robot-human intersection. [0057] At act 760 the hit parameters are used for calculating the actual injury level on the human body parts present in the volume of robot-human intersections.

[0058] At act 770 it is identified whether the calculated actual injury level infringes the threshold injury level.

[0059] At act 780 in case of infringement, the robot's operations and/or the human operations are re-arranged and the acts 720 and/or 730 and the act 740 to 770 are repeated until non-infringement of the threshold injury level is achieved. [0060] One or more of the processor 102, the memory 108, and the simulation program running on the processor 102 receive the inputs via one or more of the local system bus 106, the adapter 1 12, the network 130, the server 140, the interface 114, the I/O bus 116, the disk controller 120, the storage 126, and so on. Receiving, as used herein, can include retrieving from storage 126, receiving from another device or process, receiving via an interaction with a user, or otherwise.

[0061] Of course, those of skill in the art will recognize that, unless specifically indicated or required by the sequence of operations, certain steps in the processes described above may be omitted, performed concurrently or sequentially, or performed in a different order.

[0062] Those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all data processing systems suitable for use with the present disclosure is not being illustrated or described herein. Instead, only so much of a data processing system as is unique to the present disclosure or necessary for an understanding of the present disclosure is illustrated and described. The remainder of the construction and operation of data processing system 100 may conform to any of the various current implementations and practices known in the art.

[0063] It is important to note that while the disclosure includes a description in the context of a fully functional system, those skilled in the art will appreciate that at least portions of the mechanism of the present disclosure are capable of being distributed in the form of instructions contained within a machine-usable, computer-usable, or computer- readable medium in any of a variety of forms, and that the present disclosure applies equally regardless of the particular type of instruction or signal bearing medium or storage medium utilized to actually carry out the distribution. Examples of machine usable/readable or computer usable/readable mediums include: nonvolatile, hard-coded type mediums such as read only memories (ROMs) or erasable, electrically programmable read only memories (EEPROMs), and user-recordable type mediums such as floppy disks, hard disk drives and compact disk read only memories (CD-ROMs) or digital versatile disks (DVDs).

[0064] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0065] None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims.