AUTOSAR proof-tests vehicle electrical design at every level
Bill Chown, Michael Seibt, Mentor Graphics Corp.
7/23/2010 5:01 AM EDT
It’s no secret: the methodology
known as “simulation” is a cornerstone of many engineering disciplines these
days. Simulation is a tool that enables designers to meet the time, cost and
complexity challenges common in today’s development projects, from passenger jets
to paint sprayers… and, of course, automobiles. It is also a means to detect
emerging design flaws or avoid them altogether.
Simulation is applied at diverse
levels: systems, circuits, multi-body, or Finite Element (FEM) simulation. It works
with software-based models that enable emerging designs to be verified
independently of tangible hardware prototypes. Test vectors or parameters can
be changed easily within a simulation model, and the same model provides easy
access to internal variables that would be difficult or impossible to extract
in hardware tests.
It all adds up to a natural fit
for automotive design applications. Especially in the development of electronic
control units (ECUs), model-based development practices are now widespread, and
becoming more so.
Of course, what “works” can
always be improved, and what is good can always be made better. Openness and standardization
have the potential to take productivity to a new level, and industry thought
leaders are responding. The emerging automotive design software standard known
as AUTOSAR (Automotive Open System Architecture) began as the product of a
standardization effort among European auto makers and their suppliers. Its
objectives are to bring structure, clean interfaces and implicit methodologies
to a process—in this case, the design of distributed systems within
AUTOSAR is a set of standards
encompassing interfaces and software module definitions. It establishes a
structure for the embedded software within a vehicle’s complex network-based
distributed system. AUTOSAR frees designers to focus on unique, innovative
functions while insulating them from implementation details of integration.
In an AUTOSAR-compliant system,
automotive functions ranging from door locks to engine controls are built up
from one or more software components (SWCs) that can be executed on AUTOSAR-compliant
ECUs. SWCs are the means to deliver differentiated features in an end product.
A continuum of verification scenarios
AUTOSAR places a host of new
demands on simulation and verification processes as the design evolves. To reap
the benefits of AUTOSAR standards, OEMs and suppliers must communicate
accurately and interact efficiently.
The AUTOSAR flow includes the
software component and behavior design, the software architecture design, the
ECU and topology definition, and the function distribution. Figure
1 depicts the progression of these steps, with the chronology going
essentially from left to right. Depending on agreements between OEMs and
suppliers, diverse scenarios, work divisions, and packages for the individual
participant affect the nature of the development process. Innate in the process
is the series of consistency checks symbolized by the check marks in Figure
1. The simulation levels, too, progress from single-function SWCs to
top-level architectural models as follows:
1: Consistency checks and simulations along the design flow