PLANNING AND INTEGRATION OF PRODUCT DEVELOPMENT:ELEMENTS OF RAPID PRODUCT DEVELOPMENT

ELEMENTS OF RAPID PRODUCT DEVELOPMENT

Process Planning

The goals of RPD are to speed up these iteration cycles, on the one hand, and promote learning within the cycle, on the other. The whole development process involves cooperating development teams that are increasingly distributed globally. The functioning of the cooperation between these teams is essential for the success of the development process. This can only be realized by effective coordination of the partial plans of each of the distributed development teams that are part of the overall product-development chain.

The decentralization of decisions and responsibilities enhances the flexibility and responsiveness of development teams significantly. Hence, planning tools used to coordinate the tasks of development teams have to fit the characteristics of a development process. Consequently, a tool that is designed for central planning approaches will not fit the requirements of a decentralized structure. Specifically, issues needed for RPD, such as coordination of decentralized teams or learning within each cycle, are not supported.

Based on the understanding of planning as the initial step for scheduling diverse processes, the planning of processes involved in complex R&D projects must be possible. The planning system has to be suitable for use in surroundings that are characterized by decentralized and multisited operations. A high grade of expression of the generated plans is based on the ability to process of incomplete and inconsistent data. Therefore, support of documentation and planning has to be integrated, too. Because separate development teams have different tasks, adaptability to the type of the development task and consideration of specific situations have to be ensured. For this reason, open and standardized data storage is fundamental for the planning system. Therefore, the team-oriented project planning system (TOPP) has been developed.

In order to ensure a high grade of expression of the plans, time relations as proposed by Allen (1991) have been used for the phase of plan definition. Logical and time-connected relations between tasks to be planned have to be described within the plan definition phase. Based on 13 Allen time relations, the results of each task are described dependent on the relations to other tasks. Therewith all necessary constraints between related tasks can be represented. This is why TOPP differs from critical path methods. This method only uses the start and the finish to describe time relations.

Each distributed team can define the relations between the tasks to be planned within their re- sponsibility by Allen time relations (internal relations). External relations (interfaces) to other dis- tributed development teams can also be defined. These external relations are additional constraints for the backtracking-planning algorithm that forms the basis for calculating the optimal plan.

Further, the planner uses disjunctive relations to define the constraints between tasks in order to take the requirements of uncertainty into account. For example, the planner can determine whether a task A has to start at the same time as task B, or whether task B can start at the same time as task A is finished.

If all other constraints, such as available resources, can be met, each disjunctive relation will lead to one possible plan alternative. The required resources and the expected duration of the task are added to the task to be planned in order to consider the limits of resources adequately.

The first reason for this approach is the high uncertainty and complexity of R&D and RPD projects. The definition of rules forms the basis for the use of automatic resource assignments. Therefore, abstractions and simplifications are needed, which cannot easily be obtained from complex systems such as R&D or RPD projects. Second, planners are subject to cognitive and mental limi- tations. Hence, the planning system has to support the planner by giving him the ability to compare plan alternatives under various circumstances.

A typical problem in multiattributive decision making is the proposed selection of one plan out of a limited number of plans characterized by specific figures. Since the figures show ordinal quality, the process of selecting the optimum can be supported by using the precedence sum method.

Planning as a complex task can normally not be solved optimally, due to the limited mental capacities of human planners. The use of models to plan projects offers many advantages:

• From a statistic point of view, the probability of finding the optimal plan increases with the number of plans.

• The comparison of plans based on specific figures offers possibilities for finding advantages and disadvantages of each plan. Additionally, the planner is not limited to one plan.

• Failures within obscure and complex structures typical of RPD are detected rather than antici- pated.

• Since sensitivity for the different figures increases, there is a support mechanism with regard to the knowledge about the situation.

• The evaluation of plans based on quantifiable figures contributes to the achievement of plans.

Five different scenarios have been implemented in TOPP. A particular planning aspect is empha- sized by each scenario. The scenario is defined via characteristic figures such as process coordination, process risk, and process logics. Hence, the planner is given the ability to judge all possible plans from a specific point of view.

According to the scenario, the calculation of the order of precedence always takes place in the same manner. First plans are evaluated in view of first-order criteria (FOC). If plans still show the same ranking, second-order criteria (SOC) are taken to refine the order. If a final order of precedence is still not possible, the ideal solution, defined by the best characteristic numbers of all plans, deter- mines the order. The plan with the least difference from the optimal plan will be preferred.

Decentralized planning within rapid product development involves more than simple distribution of partial goals. Since development teams are distributed and are responsible for achieving their partial goals, different coordination mechanisms are necessary. The coordination of TOPP is based on planning with consistency corridors, an integration of phase-oriented and result-oriented planning and task-oriented planning.

By the use of characteristic numbers and planning scenarios, a new approach has been presented to support the selection of the optimal plan within complex R&D projects and rapid product devel- opment (Wo¨rner 1998).

In general, TOPP offers a way to support planners coordinating global engineering projects of rapid product development and R&D.

Physical Prototyping

Rapid Prototyping

In addition to the conventional manufacturing of physical prototypes (e.g., CNC milling) the rapid prototype technologies (RPT) are gaining more and more importance. RPT makes it possible to produce a physical artifact directly from its CAD model without any tools. Thus, it is possible to build the prototype of a complex part within a few days rather than the several weeks it would take with conventional prototyping.

In the past, great effort has been put into developing RPTs, improving their processes, and in- creasing the accuracy of the produced parts. The most common techniques today, like stereolitho- graphy (STL), selective laser sintering (SLS), solid ground curing (SGC), and fused deposition modelling (FDM), are mainly used to produce design or geometrical prototypes. They are used primarily for aesthetic, ergonomic, and assembly studies or as pattern masters for casting or molding processes. However, up to now current materials and process limitations have hindered their use as technical or functional prototypes. To accelerate the development process, technical and functional prototypes are of great importance. Therefore, it is necessary to develop powerful technologies for rapid production of prototypes with nearly serial characteristics, for example, material or surface quality. In addition to new or improved RPTs, there are promising developments in the field of coating technologies and sheet metal and solid modeling, which will be a valuable contribution.

Rapid Tooling

In addition to rapid prototyping, rapid tooling has become increasingly important in recent years. It offers the possibility of building functional prototypes. Here, the material and the process of the series product is used. With rapid tooling it is possible to build tools rapidly and inexpensively for prototypes parallel to the product development process. Rapid tooling technologies help to make the process from the first sketch to the final product more efficient. A range of technologies is available, from cutting to generative methods and from milling to the direct or indirect metal laser-sintering process.

Digital Protoyping

Physical prototypes are often time and cost intensive and thus need to be reduced to a minimum. By the combining of CAD technologies, rapid prototyping, virtual reality, and reverse engineering, pro- totypes can be produced faster and more cheaply then before. The employment of virtual prototypes in the early phases of product development, in particular, optimizes the whole development process (Thomke and Fujimoto 1998). The strategic advantage of digital prototyping is the advancement of decisions from the test phase with physical prototypes to the early phases of product development with digital prototypes. Thus, the process of product development and testing can be considerably ameliorated. The digital demonstration allows early modification and optimization of the prototype. Furthermore, it leads to a cost-saving increase in the variety of prototypes. By means of virtual prototypes product features can be easily verified and thus development times can be reduced enor- mously. Also, faults concerning fabrication or the product itself can be detected in the early devel- opment phases and thus be eliminated without great expenditures. This makes it possible to start product planning at an early stage. Due to the early overlapping of development and fabrication, additional synergy effects can be expected. Prerequisites for digital prototyping are the following three areas: CAD, simulation, and virtual reality. Simulation (Rantzau and Thomas 1996) and CAD data produce quantifiable results, whereas the connection with VR technologies enables a qualitative evaluation of the results (Figure 2).

An important component of digital prototyping is the digital mock-up (DMU), a purely digital test model of a technical product. The objective of the DMU is the current and consistent availability of multiple views of product shape, function, and technological coherences. This forms the basis on which the modeling and simulation (testing) can be performed and communicated for an improved configuration of the design. This primary digital design model is also called the virtual product. The virtual product is the reference for the development of a new product, specifically in the design and testing phase. The idea is to test the prototype regarding design, function, and efficiency before producing the physical prototype. Thus, effects of the product design can be detected in a very early phase of product development. This way, possible weaknesses of the physical prototype can be detected and corrected in the design phase, before the physical prototype is built. An enormous advantage of the DMU is the shortening of iteration cycles. The decisive changes in the digital prototype are carried out while the physical prototype is being built. During this period, the DMU process can achieve almost 100% of the required quality by means of corrections resulting from the simulation processes. The development process without DMU, on the contrary, requires further tests

with several physical prototypes before the end product can be produced. This means that employing the DMU considerably reduces the time-to-market. The DMU platform also offers the possibility for a technical integration of product conception, design, construction, and packaging.

Digital prototyping offers enormous advantages to many different applications, such as aircraft construction, shipbuilding, and the motor industry. Fields of application for digital prototyping in car manufacturing are, for example:

• Evaluation of components by visualization

• Evaluation of design variations

• Estimation of the surface quality of the car body

• Evaluation of the car’s interior

• Ergonomic valuation with the aid of virtual reality

To sum up, creating physical or virtual prototypes of the entire system is of utmost importance, especially in the early phases of the product-development process. The extensive use of prototypes provides a structure, a discipline and an approach that increases the rate of learning and integration within the development process.

The Engineering Solution Center

The use of recent information and communication technology, interdisciplinary teamwork, and an effective network is essential for the shortening of development times, as we have demonstrated. The prerequisites for effective cooperative work are continuous, computer-supported process chains and new visualization techniques. In the engineering solution center (ESC), recent methods and technol- ogies are integrated into a continuous process chain, which includes all phases of product develop- ment, from the first CAD draft to the selection and fabrication of suitable prototypes to the test phase.

The ESC is equipped with all the necessary technology for fast and cost-efficient development of innovative products. Tools, like the Internet, CAD, and FEM simulations, are integrated into the continuous flow of data. Into already existing engineering systems (CAD, knowledge management, databases, etc.) computer-based information and communication technologies are integrated that sup- port the cooperative engineering effectively. Thus, the engineering solution center offers, for example, the complete set of tools necessary for producing a DMU. A particular advantage here is that these tools are already combined into a continuous process chain. All respective systems are installed, and the required interfaces already exist. An important part of the ESC is the power wall, a recent, very effective, and cost-efficient visualization technology. It offers the possibility to project 3D CAD models and virtual prototypes onto a huge canvas. An unlimited number of persons can view the 3D simultaneously. The power wall is a cost-efficient entrance into large 3D presentations because it consists of only one canvas.

Another essential component of the ESC is the engineering / product-data management (EDM / PDM) system. The EDM encompasses holistic, structured, and consistent management of all pro- cesses and the whole data involved in the development of innovative products, or the modification

of already existing products, for the whole product life cycle. The EDM systems manage the proc- essing and forwarding of the produced data. Thus, these systems are the backbone of the technical and administrative information processing. They provide interfaces to CAD systems and other com- puter-aided applications (CAX), such as computer-aided manufacturing (CAM), computer-aided plan- ning (CAP), and computer-aided quality assurance (CAQ). This way, these systems enable a continuous, company-wide data flow. Inconsistent or obsolete information stocks are reduced to a minimum through the use of EDM.

The innovative approach realized here is what makes the engineering solution center so special. The ESC integrates recent technologies into a continuous process chain. By the use of virtual pro- totypes the time- and cost-intensive production of physical prototypes can be considerably reduced. The interplay of all methods and technologies makes it possible to achieve high development quality from the first. The virtual product, together with all the applications of virtual technologies and methods in product development and testing, is a necessary reaction to the rapidly changing require- ments of the market.