Image Processing Reference
In-Depth Information
which facilitates composability (i.e., ability to integrate individually developed components) and
deterministic real-time behavior of the system.
Dashboard, wipers, lights, doors, windows, seats, mirrors, and climate control are increasingly
controlled by software-based systems that make up the body domain. This domain is character-
ized by numerous functions that necessitate many exchanges of small pieces of information among
themselves. Not all nodes require a large bandwidth, such as the one offered by CAN; this leads
to the design of low-cost networks such as local interconnect network (LIN) and TTP/A (see Sec-
tion .). On these networks, only one node, termed the master, possesses an accurate clock and
drives the communication by polling the other nodes—the slaves—periodically. he mixture of dif-
ferent communication needs inside the body domain leads to a hierarchical network architecture
where integrated mechatronic subsystems based on low-cost networks are interconnected through a
CAN backbone. The activation of body functions is mainly triggered by the driver and passengers'
solicitations (e.g., opening a window, locking doors, etc.).
Telematics functions are becoming more and more numerous: hand-free phones, car radio, CD,
DVD, in-car navigation systems, rear seat entertainment, remote vehicle diagnostic,etc.hesefunc-
tions require a lot of data to be exchanged within the vehicle but also with the external world through
the use of wireless technology (see, for instance, Ref. []). Here, the emphasis shifts from messages
and tasks subject to stringent deadline constraints to multimedia data streams, bandwidth sharing,
multimedia QoS where preserving the integrity (i.e., ensuring that information will not be acciden-
tally or maliciously altered) and confidentiality of information is crucial. HMI aims to provide HMI
that are easy to use and that limit the risk of driver inattention [].
Electronic-based systems for ensuring the safety of the occupants are increasingly embedded in
vehicles. Examples of such systems are impact and roll-over sensors, deployment of airbags and belt
pretensioners, tyre pressure monitoring or Adaptive Cruise Control (the car's speed is adjusted to
maintain a safe distance with the car ahead). These functions form an emerging domain usually
referred to as “active and passive safety.”
13.1.3 Different Networks for Different Requirements
The steadily increasing need for bandwidth
∗
and the diversification of performance, costs, and
dependability
†
requirements lead to a diversification of the networks used throughout the car. In ,
the Society for Automotive Engineers (SAE) defined a classification for automotive communication
protocols [,,] based on data transmission speed and functions that are distributed over the
network. “Class A” networks have a data rate lower than kbit/s and are used to transmit simple
control data with low-cost technology. hey are mainly integrated in the body domain (seat control,
door lock, lighting, trunk release, rain sensor, etc.). Examples of class A networks are LIN [,]
and TTP/A []. “Class B” networks are dedicated to supporting data exchanges between ECUs
to reduce the number of sensors by sharing information. They operate from to kbit/s. The
J [] and low-speed CAN [] are the main representations of this class. Applications that need
high speed real-time communications require “class C” networks (speed of kbit/s to Mbit/s) or
“class D” networks
‡
(speed over Mb/s). Class C networks, such as high-speed CAN [], are used
for the powertrain and currently for the chassis domains, while class D networks are devoted to
multimedia data (e.g., media oriented system transport (MOST) []) and safety-critical applications
∗
For instance, in Ref. [], the average bandwidth needed fortheengineandthechassiscontrolisestimatedtoreach
kbit/s in while it was kbit/s in and kbit/s in .
†
Dependability is usually defined as the ability to deliver a service that can justifiably be trusted, see Ref. [] for more
details.
‡
Class D is not formally defined but it is generally considered that networks over Mb/s belong to class D.
