Rules for Four Wheels

Manufacturers of cars, machines, or electronic devices have to react quickly to new requirements with new product variants. The role of the ERP software here is to map all the characteristics of the different variants with their interdependent relationships, and enable users to manage the complex configuration logic of the products.
Even the initial steps in defining basic characteristics are complicated. For example, a class with up to 1000 configuration characteristics that define the product must first be created in SAP ERP for a vehicle. Model-specific characteristics, such as optional extras, are defined in the product class itself. Characteristics that apply across several models – for example the country, engine or drive type – are inherited from a higher-level class, for example the class for the product family. Configuration characteristic values that are not required for the specific product must be removed using value range restrictions. For example, the “Drive Type” characteristic may be restricted to front-wheel drive or four-wheel drive for certain models.
In addition to the basic characteristics of a product, the variant configurations must also map the available standard features and optional extras. Here, the individual characteristics must be defined using procedures, a form of SAP object dependencies. With up to 100 features and up to 100 product types in each product family, this process is extremely time-consuming, as the data is not maintained in tables but in a description language. The distinction between standard features and optional extras may also change over time, making it necessary to redefine the characteristics.

No soft-top with sunroof

It not only takes a huge amount of time to maintain the configuration logic and its rules, it also requires a great deal of expertise in the area of object dependencies, which describe the interdependencies between the characteristics. If, for example, different features of a product are mutually exclusive, this dependency must be mapped using constraints, another form of SAP object dependencies. The fact that a soft-top cannot have a sunroof is obvious and is therefore relatively easy to record in the configuration logic, but in the case of more complex configurations with numerous characteristics, only specialists are able to model the rules accurately.
The variant configuration also ties up the capacities of costly specialists because the rules for defining characteristics and classes and for restricting value ranges or selecting characteristic values have so far been maintained in separate SAP transactions in the classification system and in the variant configuration. This distributed maintenance makes it difficult to obtain an overview of the complete configuration of a particular product and to ensure consistent rules. An automatic check is not possible, as this would require the configuration of all combinations of all characteristics, which would take up too much time and computing power. IT experts are therefore needed to ensure the consistency of the configuration logic. The company cannot risk cutting back on personnel in this area: shortcomings could lead to production faults and even warranty claims by customers if incompatible features cause faults in product functioning.

Enhancement for iPPE

SAP’s partner CaRD PLM developed the Rule Designer solution to simplify maintenance of the configuration logic for different product variants. This software allows different rules to be maintained in table form and integrated in the variant configuration. “We designed configuration applications for customers from the mechanical engineering and automotive industries. When developing our solution package, we took account of these customers’ requirements relating to data transparency, ease of use, and the modeling of rules,” says Eckhard Behr, managing partner of CaRD PLM GmbH.
From a technical point of view, CaRD Rule Designer is an add-on for SAP ERP programmed in ABAP Objects. The add-on is encapsulated and can therefore also be integrated in other SAP solutions, for example SAP Customer Relationship Management. The starting points for CaRD Rule Designer in SAP ERP are the “classification system,” in which products are described using characteristics and are grouped into classes, and “engineering change management” as the central logistical function for changes to product data.
As a result, CaRD Rule Designer can be used not only in the classical “BOM” and “routing” environments, but also within Integrated Product and Process Engineering (iPPE). iPPE is particularly suitable for the repetitive manufacturing of multivariant products, as all it draws together data from the life cycle of these products into an integrated model. “We have developed a solution that is independent of the product structure, so that customers can continue to use Rule Designer without the need for a data migration if they switch from ‘BOM’ to ‘iPPE’,” says Behr.

Analyses made easier

Standard features and optional extras for a product can be mapped with CaRD Rule Designer, and characteristics, requirements, and exclusions can be determined. It is also possible to hide characteristics on the configuration dialog on a rule basis. However, the main advantage of the new solution is that it is easy to use and provides an overview of the variant configuration. The rules of the configuration logic can be maintained in a table view based on Excel and the environment is therefore familiar even to users who have not received special training. The characteristics that belong to a configuration rule are mapped in the first columns of the table, and the later columns are used for assignment to the various products.
With CaRD Rule Designer, distributed maintenance of the configuration logic is also a thing of the past: All the rules are displayed centrally in an interface and they can all be maintained simultaneously in one transaction. Central, table-based maintenance means that operations in the variant configuration are easier to analyze. For example, if a characteristic value is missing in the configuration dialog, all rules for the characteristic value can be loaded as additional information.

Cause identified, conflict eliminated

One special feature of CaRD Rule Designer makes it easier for users to maintain the dependency syntax, including complex configurations in SAP ERP, without expert knowledge of the system. Additional messages, providing information about requirements and exclusions for example, have been incorporated in the configuration dialog. These messages inform the user of the exact cause of an inconsistency – for example, that two optional extras are mutually exclusive – instead of displaying the source text of a constraint, which is often difficult for the end user to understand. “These messages provide clear information on the affected characteristics. In future, was also want to propose different ways a user can eliminate a conflict,” states Behr. The check on the configuration logic during the consistency check is also easier thanks to CaRD Rule Designer, because the logic stored in table form can be checked effectively using algorithms.
In its current form, CaRD Rule Designer provides different rule types for the variant configuration. The rules for the definition of the basic scope of a product category specify the basic characteristics involved, the possible optional extras, and the defined standard features. The “simple rules” make it possible to manage requirements and exclusions based on these and – in the next development phase – to manage the origin of characteristics. CaRD PLM GmbH also plans to integrate rules for the definition of complex requirements or package definitions in the solution.

Johannes Frevert
Johannes Frevert