Automotive User Interfaces and Interactive Vehicular Applications

The visual design of the graphical user interface (GUI) plays an
important role for building appealing products. Visual designers
often need to adapt their drafts for the GUI multiple times
throughout the development process in response to feedback from
customer clinics, changes in requirements, or adhering to latest
market trends. Once the implementation of the final HMI software
has begun such design changes need to be integrated with
minimum effort.
1.2 Conventional and Model-Driven HMI
Development Processes
The HMI prototypes and the final HMI-software for the target
system can be created using different approaches based on
cooperation between OEM and first tier suppliers. In the usual
division of tasks the OEM is responsible for creating
specifications that serve as a basis for a call for tenders. The
supplier manually implements the final software based on this
specification (Figure 2).
Figure 2 – Conventional HMI Development Process
The manual implementation involves a great deal of financial
expense and time. This is why HMI prototypes based on the target
hardware are available for evaluation very late. Until then the
OEMs have to develop prototypes for management presentations
and customer clinics, but not on the target hardware. The source
code of these prototypes cannot be reused as it is not scalable,
does not meet the requirements of the target systems and may be
based on unsuitable technologies 1 . Additional prototypes that use
close-to-series hardware and software are vital for evaluating user
experience aspects such as the look-and-feel of animations.
However, if the HMI software is implemented manually the
supplier can only provide such prototypes in late stages [4]. In the
remaining time the OEMs can perform only a small number of
iterations. All resulting corrections have to be performed
manually, which is particularly costly when done in these late
stages [5].
A major part of the HMI specification serves to describe the
system’s graphical design with pixel accuracy. The usage of
1 These prototypes are often based on Adobe Flash. However, no
sufficient support for this technology is available for all target
platforms so far.
conventional requirement formats is unsuitable for this purpose.
The effort to create such specifications for modern HMIs is very
high because it is difficult to describe things like animations and
the dynamic layout of the GUI. In order to complement the HMI
specification documentation, OEMs can give the prototypes that
they have created to the supplier. However, this means that the
OEMs have to spend effort on maintaining and extending these
prototypes throughout the development process.
Model-driven approaches can be applied in order to avoid the
drawbacks of the manual implementation (Figure 3). The basic
idea is to specify the HMI in a machine-readable form using
formal models. These models are executed by code generators or
interpreters [6]. This allows for updated prototypes to be created
right after changing the source models. HMI prototypes are
available for evaluation without expensive and time-consuming
manual programming [7]. The shortened turnaround time yields
more iteration cycles during the same period of time and thereby
achieving a higher quality of the final product.
Furthermore, the model-driven development processes boost the
OEM’s flexibility because they enable major modifications to be
made to the HMI even in late development phases [8]. The
automated processing prevents misunderstandings due to wrong
interpretation of the models [9]. The prototypes created by the
OEMs can be passed to the supplier to serve as reference for
implementing the code generators or interpreters for the target
hardware.
Figure 3 – Model-Driven HMI Development Process
2. CURRENT STATE OF THE ART
The advantages of model-driven HMI development are well
known in the automotive domain (e.g. [10]) and the corresponding
processes are applied in industrial practice. However, a modeldriven
approach requires the availability of adequate model types
and tool support for their creation and processing. The most
important tools and scientific approaches which are used in the
automotive domain and are available on the market today are
presented below. Furthermore the problem of adopting updated
GUI designs as well as the associated drawbacks of each tool is
discussed.