1. E DONA / HMI – Modelling of Advanced
Automotive Interfaces
S. Boisg´ rault, E. Vecchie, O. Meunier, J.-M. Temmos
e
March 18, 2010
I NTRODUCTION
In car cockpits, human-machine interfaces (HMI) increasingly use displays
devices at the expense of classic instruments and controls. High-end vehicles
and car prototypes benefit the most from their high flexibility: for a given hard-
ware platform, HMI software may be differentiated to support the needs of
many advanced car applications. The models and tools that contribute to the
design of such HMIs are the subject of this article.
This work is a part of the E DONA project1 [2]. E DONA / HMI provides a auto-
motive HMI design platform that addresses the specific issues of the industry:
flexibility of designs, interoperability and standards, safety of embedded sys-
tems.
H UMAN -M ACHINE I NTERFACE M ODELS
The model-driven approach that we have adopted is a key factor that en-
hances interoperability. Our E DONA / HMI model offers a large range of pos-
sible HMI designs ; it is structured into 3 layers: graphics, components and
signals, and functional model.
Its graphics layer is a 2D scene graph – a structured collection of graphic
nodes commonly used in vector graphics. Among these nodes, groups are
node containers: they define the tree structure of the document that determines
the order in which graphics nodes are rendered. The other nodes are graphics
elements: shapes, images and text. Every node is characterized by style and
geometric properties whose exact nature may depend on the node type. For
example, the main geometric property of shapes is the numeric data that de-
scribes their boundary whereas for groups, it is the geometric transformation
that is applied to all of its content during the rendering. The most common
style properties control color and visibility of the graphics elements but sev-
eral additional properties – font family, size and weight – may for example be
used to control text rendering.
1 E DONA is a french project of N UM @ TEC A UTOMOTIVE , a thematic group of the competitive
cluster S YSTEM @ TIC. It gathers major actors of the automotive industry to deliver an open tech-
nological platform hosting specialized development environments for the automotive industry.
E DONA is funded by the Direction G´ n´ rale des Entreprises, the Conseil R´ gional d’Ile de France,
e e e
the Conseil G´ n´ ral des Yvelines, the Conseil G´ n´ ral de l’Essonne and the Conseil G´ n´ ral des
e e e e e e
Hauts de Seine.
1

2. This graphics model is compatible with the Scalable Vector Graphics (SVG)
XML language [7], a W3C standard for the description of 2D vector or mixed
vector/raster graphics. Subsets of the full format are commonly used to de-
scribed HMIs on mobile platform such as mobile phones. We defined our own
SVG subset as the basis of our serialization format [1]. Non-graphic model
elements extend this language.
HMIs being dynamic, the model has to provide means to modify the graphic
state. We have adopted a data-driven approach to this issue: the data of the
graphics model – geometric and style properties of the graphics nodes – may
be exposed as readable and/or writable signals while the document structure
remains the same. Encapsulation is provided by a component model: only sig-
nals that are explicitely exposed in a component interface are visible outside of
its scope. The component hierarchy is structurally consistent with the graphics
own tree hierarchy.
This partially described component model would still expose directly raw
graphic data into interfaces, a strategy that does not allow high-level compo-
nent modelling and reuse. The complete HMI model [5] therefore includes a
functional layer that solves this issue: a synchronous language connects inter-
face and graphics signals. Synchronous programming languages are domain-
specific languages dedicated to the design of real-time embedded systems and
are amenable to formal analysis. The specific design of the E DONA / HMI func-
tional model is strongly inspired by the synchronous programming language
L USTRE [4] whose declarative style complements well our data-driven graphic
model.
E DONA / HMI P ROTOTYPING T OOLCHAIN
Tool support is crucial to ensure the succes of the E DONA / HMI model. Our
E DONA / HMI Prototyping toolchain includes a set modelling tools, a generator
of HMI software components and a runtime architecture based on J AVA. This
platform is specialized for simulation in the design loop, component testing
and deployment on car prototypes, particularly hosts of intelligent systems
transportation (ITS) applications.
The modelling tools provide a domain-specific XML data binding that en-
ables easy creation, loading and serialization of HMI models, as well as model
analysis and transformation. This library is a suitable foundation for higher-
level tools such as a graphical model editor or translators to and from external
HMI formats.
The HMI component generator uses a mixed strategy: J AVA code is gen-
erated for the functional layer whereas the graphics model is interpreted and
rendered using the B ATIK SVG toolkit (a part of the A PACHE XML G RAPH -
ICS project). This strategy allows – at any time during execution – to serialize
the state of a HMI component as a new model. Several graphics backends are
available: no graphics (mainly for testing purposes), J AVA AWT and image
buffer.
The runtime functional component follows a synchronous model of com-
putation and is triggered (conceptually instantly) by updates of the interfaces
signals. It manages a copy of the graphics state that allows it to be decou-
pled from the graphics runtime update loop. The graphics may be rendered –
2

3. among other strategies – synchronously with the interface signals or on a fixed
frame rate.
Finally, to adress the needs of intelligent transportation systems (ITS) em-
bedded applications, we extended the B ATIK SVG toolkit to support the dis-
play of graphic and textual information on top of video as well as the inclusion
of embedded controls. A full-fledged HMI was also designed for the LOV E
[3, 6] project. LOV E aims to use multi-sensor tracking system to improve the
road safety for pedestrians. Our HMI interface was used to display video
streams and – through specifically designed interfaces – data such as pedes-
trians location and risk of collision.
R EFERENCES
[1] S. Boisg´ rault, M. O. Abdallah, and J.-M. Temmos. SVG for automotive
e
user interfaces. In SVG Open, Nuremberg, Germany, 2008.
[2] EDONA: Environnements de d´ veloppement ouverts aux normes de
e
l’automobile – website. http://www.edona.fr.
[3] G. Gate, A. Breheret, and F. Nashashibi. Centralized fusion based algo-
rithm for fast people detection in dense environment. In Proc. of the IEEE
International Conference on Robotics and Automation, Kobe, Japan, May 2009.
[4] N. Halbwachs, P. Caspi, P. Raymond, and D. Pilaud. The synchronous
dataflow programming language LUSTRE. Proceedings of the IEEE,
79(9):1305–1320, September 1991.
[5] Human Machine Interface – Work Package 4. EDONA HMI Format. Re-
port, EDONA, 2008.
[6] LOVe: Logiciel d’Observation des Vuln´ rables, project website. http://
e
love.univ-bpclermont.fr.
[7] Scalable Vector Graphics (SVG) 1.1 specification. W3C recommendation,
W3C, January 2003. http://www.w3.org/TR/SVG.
3