Systems Engineering und PLM
From the Perspective of Siemens PLM Software
The basis of this background document was a discussion with Dr. Stefan Jockusch, Vice President, Automotive Industry Strategy Siemens PLM Software. Prior to holding this position he was Research & Development Manager at Dematic and before that General Manager Solution Provider at Siemens Production & Logistics Systems. One of the main subjects he has worked on in recent years is the support of system-driven product development in the automobile industry. (photos Sendler, all screenshots Siemens PLM Software)
At a glance:
- Siemens PLM Software has concerned itself with Systems Engineering for many years and Teamcenter Systems Engineering (TCSE) is currently being used by a number of large companies. In addition to customers from the aircraft industry, automobile manufacturers and their Tier I suppliers have become increasingly interested in Systems Engineering methods, and machine and plant builders have also become target markets for the model-based development of multidisciplinary systems.
- For Siemens PLM Software, the most important aspect of tool support by Systems Engineering is the effective management and fast availability of all data associated with the technical system and the interrelationships of the data itself. The coming version, Teamcenter Unified Architecture (TCUA) Version 9.1, supports this, and moreover permits the systematic model-based definition of functionality and logical architecture. Active Workspace will be the window onto this data.
- Because all – and particularly the complex – industries utilize a multiplicity of models and IT tools to develop parts of the technical systems, simulate their functions and validate their agreement with the requirements they must meet, Siemens sees the openness of the IT tools towards each other as the main basic prerequisite for successful Systems Engineering.
- Siemens perceives the inclusion of the software and the various system models in the management of the system data as being a special challenge. The goal is a representation of software components similar to that already available for mechanical components. To this end, Siemens is cooperating closely with suppliers of corresponding tools.
- With Mechatronic Concept Designer, Siemens has brought to market one of the first integrated mechatronic development platforms for the parallel development of design and behavior. It is rapidly growing in popularity in the machine building field.
Systems Engineering has a long history at Siemens
The acronym “RFLP” (Requirements, Functional, Logical and Physical view) has been since the 80s a known description of the core elements of Systems Engineering. A presentation by Boeing at PLM Connections 2006 bore the title “What is Functional Integration?” The subtitle was “Integrate Requirements, Functional, Logical, and Physical Architectures”.
At that time Boeing took an apparently simple but highly efficient measure to reduce failure rates for the interaction of the many thousands of components in an aircraft. Everyone involved in development had two “views” arranged in a matrix: He could register as a “Subscriber” for certain components in order to ascertain the status of those components that were important to him. He was also able to register as a “Publisher” for his own development. The sensational results given by this simple setting up of factual relationships was that from one product range to the next, the number of failures determined went from approximately 16,000 to zero!
“You don't need to explain to aircraft manufacturers” says Stefan Jockusch “why Systems Engineering is a necessity. They've been doing it for a long time and can't do it any other way. And initially they only considered the relationship between “R” and “L”, i.e. between the requirements and the logical components or assemblies. The functions and their simulation and validation were not yet part of overall system development.
Until recently, Systems Engineering methods were regarded skeptically by the automobile industry, being seen as being too bureaucratic and much too slow. It was felt that the product structure of a vehicle was well under control. This viewpoint, however, has changed radically over the last three years. The complexity of the complete vehicle and the continually increasing necessity of packing more and more components into an ever-smaller space at increasingly lower weight, combined with continually increasing quality requirements, was one reason for this. The other is that today every mid-range vehicle contains more source code than an aircraft. In the aerospace and defense industries, it was the long lifecycles and the size of the systems that led to new methodical approaches. In the automobile industry, the increasing pressures to find the right path to address conflicting requirements and the increasingly important role of the software have led to the same result.
To complete Siemens’ perspective across the various sectors: Machine and plant builders, and also high-tech, medical technology and a vast number of other industries, are now searching for practical methods of keeping their increasingly complex technical systems under control. For Siemens PLM Software this resulted in a demand for the development of appropriate IT tools that could support this in the best possible fashion.
In doing so, the supplier did not have to start from the very beginning and reinvent the wheel, because through cooperation, initially with aircraft manufacturers and then with the automobile industry, numerous steps in this direction had already been taken. The system that Boeing used for development was initially called SLATE. That was the original basis for the TCSE module in Teamcenter UA 9.1.
From being purely mechanical to a technical system
As with other suppliers of IT for Engineering and PLM, the original core of the software can be clearly discerned at Siemens PLM Software: It was about the organization, administration and the secure management of product data – in particular here the product geometry. Getting the geometry under control solved a problem important to survival, since the functions and properties of the products above all depend on the correct physical linking of the individual parts and assemblies.
This has fundamentally changed for multidisciplinary technical systems. Only a very few functions are today realized purely mechanically. Most are a combination of software, electronics and mechanics and this increasingly includes systems external to the vehicle – for example that of the Car-to-Car-Communication-Consortium initiated by the automobile industry. For this reason, the focus for Product Lifecycle Management has also changed in recent years at Siemens PLM Software: In the future, IT must help to completely record and manage the lifecycle of complex technical systems. These include the mechanical components as well as the electrical and electronic components – and above all the software.
(Dr. Stefan Jockusch, photo Sendler)
Stefan Jockusch notes “What is decisive, and this is what was found out at Boeing, is that consistency of the hundreds or thousands of components must be maintained in order to know what was developed, by whom, and for what purpose – or, even more importantly, modified – and how it interoperates with other parts. This is what we do very well. There is hardly any other discipline that has achieved the same level of sophistication in managing data as CAD and digital manufacturing, and the things that we have mastered very well in the mechanical domain we now use for software and electronics."
He names revision management as an example. Many management systems, whether for simulation or software development, manage versions – if what is meant is the counting up of version numbers. But the ability to differentiate between a variant in which only one part has changed but which, for example, continues to be used as a spare part instead of the newer variant, and a new version that is no longer backwards compatible, is much more advanced in PDM systems since it is a necessity in CAD, CAE and CAM.
However, as well as the extension of data management to cover components from other specialized areas such as electro-technology/electronics/software (E/E/SW) there is another fundamental change: The taking into account and analysis of a system and design of a suitable system architecture are now included in the development of the components, and this must be managed just as much as the components themselves.
According to Stefan Jockusch, PLM software is positively predestined to take on this role. This is because for systems it is all about securely managing and making available at all times data (requirements, functional descriptions, logic schematics) and above all their interrelationships. In the course of the last ten years, Siemens PLM Software has extended today's Teamcenter platform with a number of modules and functions in close cooperation with large aerospace and automobile sector customers.
In particular, the data model itself has been modified to fit the new requirements step-by-step. As Jockusch observes “today there are not only datatypes for every kind of geometric element but also, for example, a processor datatype, a signal datatype, a message datatype or a firmware datatype, to only mention a few that are necessary for a mechatronic system. In order to be able to make the correct decisions, engineers must be able to understand the dependencies between these artifacts and easily determine how one change affects the main characteristics of the vehicle. All of these datatypes may have attributes associated with them. These contain, for example, the revision number, specific characteristics, dependencies on other elements and so on. As for all mechanical products, the system must produce a bill of materials in which all the components of each product variant are listed with the correct revision, because in the end the technical system itself must be produced and assembled.”
Model-based system development is open teamwork
The greatest part of the function of modern product systems is to be found in the software in which the components are embedded. How fast the vehicle runs, how well the brakes work, assistance systems for the driver – the software controls almost everything. This fact will be strengthened according to the degree in which the intelligence of the system further develops into the “Internet of Things”. The communication of products with one another, with their users and the environment via the Internet or special networks may well change our world, our forms of transport and our behavior more dramatically than the computer has in the last 50 years. It is therefore even more important that IT tools used in product development work just as well with software as, for example, mechanical 3-D models have up until now.
Siemens has for several years been working intensively with, amongst others, IBM, the manufacturer of Rational ClearCase, one of the leading (and oldest) systems for software development. This has created a functionality that goes farther than the usual integration of metadata. Stefan Jockusch comments “the integration with ClearCase goes so far that users can directly handle source code from within Teamcenter using ClearCase. In the same way as I can edit a 3-D model with NX or another system via Teamcenter, I can now open, check out, edit and check back in source code using ClearCase. In this case, Teamcenter has more or less taken over remote control of the software development environment, even though maintenance of the data is still carried out in ClearCase. It is, however, Teamcenter that manages the relationships between the software components and the other parts of the system.”
Development of the systems not only includes the software but also numerous models, each of which describes specific aspects of a system. Under certain conditions, these could also be executable models that then permit the simulation and testing of the described systems or subsystems.
Today there is still no comprehensive model that comprises all aspects of the system and then enables views from various perspectives or sub-perspectives. Instead, Stefan Jockusch estimates that there are a good 50 different types of applications in industry that permit the generation and/or simulation of different models. Of the IT tools in use, around two-thirds are commercial, the rest being internal developments. But even the standard systems are often so comprehensively modified to meet company-specific needs that they almost have the quality of an internal development. For this reason, a closed mechatronic development system is still a long way off. It should be added that, completely separate from this, the resulting dependency on a single supplier may well be undesirable for industrial customers.
Siemens in any case sees it as its duty to help customers integrate all important systems well, so that they can be used with one another. In this regard, this includes several items that have only recently been further developed. For example the integration of Matlab & Simulink (the manufacturer is Mathworks) allows the management and data maintenance of the models down to the building block level. By doing this, larger models can again be generated from the stored building blocks. For many Siemens customers this step means immediate progress. Until now they have managed the Matlab models in ClearCase, which is not particularly suitable for data management. The importance can also be found in the fact that thousands of specialists in industry – both aerospace and automotive – have been working with these systems for decades.
Taking a leading automobile manufacture as an example, Stefan Jockusch explains what the consequences of this integration could be in the future: “There they tell us that they are developing models that describe parts of the system. Then they simulate these models so that they know that their perception of how the software should work is correct. They subsequently write a text document that contains the functions, the description of interfaces and the test cases, and give that to the supplier. The supplier has now to develop the software on his ECU and prove that it is tested and validated. If they could give the supplier a model instead of a text file and he could realize his tests using this, the manufacturer would save 50% time.”
Mathworks is now working with Siemens on the realization of such a vision. Other important suppliers in this regard include, according to Siemens, LMS Engineering Innovation, a Belgian manufacturer of software tools for test and mechatronics simulation.
Research delivers important results
The importance of science and research, and also R&D areas in industry, continuing to carry out basic research in Systems Engineering can be seen in a relatively new product from Siemens PLM Software that was brought to market two years ago – the Mechatronic Concept Designer (MCD). It was first developed in the Siemens Corporate Technology development laboratory before being made into a market-ready product that is increasingly being used by companies.
Siemens took a bold step in the direction of gaming software in this system. The Physics Engine from Nvidia, a module for the simulation and calculation of physical relationships that occur in the world of computer games, is used here for the first time to represent mechatronic machine reality. The curtailments in accuracy that its use entails are suitable for the early phase of product development, which is concerned with the principle, not the detail.
With Mechatronics Concept Designer, the engineer can very simply define objects or select from a library that, in contrast to CAD models, not only contains the geometry but also its physical properties. Weight, dynamics, friction and kinematics are the most important parameters that can be set. The system therefore knows how an object behaves under the influence of gravity or other forces. A conveyor belt, for example, transports a workpiece up to the sensor of a photoelectric barrier that in its turn drives the motor of a robot arm that grips the workpiece and places it on a pallet. The electronics, software and mechanics have finally entered the digital world of symbiosis offered by machine builders in their products for many years, but in general entirely without computer support.
In other industries such as aircraft construction or the automobile industry, the simulator is still evidently missing many other properties that need to be simulated, such as thermodynamics or flow behavior. A great deal, therefore, remains to be done, and this is why Siemens is working intensively with many of those involved in science and research and with their corresponding organizations.
This is also why IBM has initiated Open Services for Lifecycle Collaboration (OSLC), which is intended to contribute to standardization and better interoperability in software development. Numerous suppliers and users are already active in this initiative. The development of software systems and the management of their lifecycle, the Application Lifecycle Management (ALM), suffer, in much the same way as PLM, from various inconsistencies and incompatibilities between the tools being used in practice. One of the application cases for which better cooperation is being sought is the link between ALM and PLM. Siemens sees itself as currently being the only PLM supplier that is in reality attempting to contribute something.
Siemens is also an active member of the International Council on Systems Engineering (INCOSE). This organization is a manufacturer-independent neutral organization that is flying the flag for the development of Systems Engineering methodologies in a number of fields.
There have also been many years of cooperation with various institutes and universities, for example the H. Milton Stewart School of Industrial and Systems Engineering at Georgia Tech, where Aerospace & Defense and the SYSML play a big role. Several initiatives connect the Technical University of Munich, especially the Chair of Informatics under Professor Broy, with Siemens. On one hand, Siemens PLM Software makes its Systems Engineering developments available for test purposes and assesses the experience gained there. On the other, there is cooperation with the extramurally- founded Institute fortiss (Münchner Forschungs- und Transferinstitut für Software-intensive Systeme – Munich Research and Transfer Institute for Software-intensive Systems).
There is also intensive exchange with other professors such as the Systems Engineering specialists Prof. Anderl, TU Darmstadt, Prof. Eigner, TU Kaiserslautern and Prof. Stark, TU Berlin.
As well as the extensions to the data model and the integration of various models and the software, there will be of further innovation that also promises enormous benefit the more complex the multidisciplinary systems become. With Active Workspace, Siemens PLM Software offers a new user interface that is above all characterized by its Google-like search mechanisms that can find what the user is looking for in seconds. This search engine is one of the innovations that Siemens would also like to introduce in the Teamcenter Unified Architecture.
Teamcenter Unified Architecture 9.1 is the name of the next version of the core Siemens PLM offering. It will contain many of the innovations mentioned. For Stefan Jockusch, this is a step along the way towards an ever-expanding tool that is intended to enable all industries to use Systems Engineering methods productively in the future.