Quite often projects show limited success in terms of time, cost and quality. Although not in all 3 points, delays or deviations often arise in at least one of the critical disciplines of the "magical triangle" during the course of a project. To counteract this problem, methodologies have been developed that help to structure and manage projects. With this procedure models, complex tasks are executed according to established, standardized and proven practices.

Fig. 1: Example of a general procedure model

With their regulations, procedure models are organizational tools that divide a process of creative production in different structured sections. Without a doubt, a product development as part of a development project is such a creative production.

The tasks and activities necessary to reach a project objective are presented in a conclusive, logical arrangement and are executed with best practices and proven tools. This reduces the complexity of a project and increases its transparency.

What all procedural models have in common is the step-wise procedure from problem to solution and the systematic execution of the related work packages.

The group of sequential procedure models derives from the development of complex technical Systems. A typical representative of this group is the waterfall model.

This procedural model divides the activities into phases that are then processed one after another (sequentially). As a prerequisite for the transition from one phase to the next, the previous phase has to be completed. However, the use of sequential process models is not limited to the development of complex systems; you can also find them in the development of individual products. The number and content of the phases can vary widely, depending on the type of project and the relevant project manager.

Fig. 2: Sequential procedure model (waterfall model)

Figure 2 shows a sequential procedure model that consists of the seven phases of the MOBA product development process:

- Approval

- Product specification

- Development & design

- Prototype

- Test

- Preparation manufacturing & series production

- Series production

During the ”approval” phase the portfolio management not only checks the technical and economic benchmark data from the project proposal but also the compliance with the company's objectives and makes the final decision about whether the project is generally carried out or not. During the "product specification", the product’s target concept is created via user requirement specification and target specification. Subsequently the requirements are realized until prototypes are available. These are qualified in accordance with the specifications and extensively tested on the premises as well as at the customer’s site. In the "preparation manufacturing & series production" phase, the course is set for the following series production with all its surrounding conditions.

Every phase delivers development results or partial results, which partly are further processed in subsequent phases. The project management defines milestones for each phase, which then serve as proof or legitimacy for the phase transition.

A further development of the waterfall model is the V-model which additionally includes the quality assurance.

In connection with the individual development phases, test phases are defined, in which first the conformity of the product properties to the specification and finally the suitability of the developed product for the intended use is checked.

The figure below shows where the term V-model comes from.

Fig. 3: V-model

The down leading branch at the left shows the stages of granulation and specification of a complex system, with the actual development at its end. The ascending branch on the right shows the test phases associated with the realization and integration.

Each phase of the descending branch is allocated to a test phase. The specification forms the basis of the content and scope of the accompanying tests.

As with the waterfall model, transition from one phase to the next is not performed until the previous stage has been completed. I. e. only after the component test has been successful, the units are brought together and the integration test takes place.

During the system test the function of the entire system is verified with the specification before finally, after the acceptance test, the correctness of the finished product is confirmed by customer approval.

Besides the general procedure models mentioned here, there are also specific procedure models. With these concepts it is tried to avoid the respective disadvantages of the general procedure models by mixing different methods of project Management.