Automotive electronic systems are the product of decades of fiercely competitive evolution which has resulted in highly optimized solutions for engine control, antilock braking, etc. Each system by itself provides enough added value in terms of customer satisfaction, compliance with government standards, or reduction in manufacturing cost to justify its use by the automotive industry.
Further progress will be made by integrating information across these various systems, so that each can optimize its behavior using data from other systems, as well as external sources. For example, if the GPS system knows the vehicle is in Denver at an altitude of 1,600 meters, the engine control system could compensate by injecting less fuel, and an airbag system with selective deployment could decrement its force level on the seat occupant.
However, one automotive system is by far the largest waste of energy and the greatest source of avoidable repair and maintenance cost. Serious design effort can be spent improving power train reliability or body aerodynamics, but all of that improvement can be blown away by misbehavior of this other system. This system is, of course, the driver.
The greatest untapped resource for further progress lies in optimizing the behavior of the driver by integrating information from sources both inside and external to the vehicle and providing a user interface for effectively using that information.
For example, avoiding an unnecessary trip to the supermarket for baby food or coffee saves both gasoline and the consumer’s time. Alerting a hard-driving consumer to the need for an early oil change might save an engine. Optimizations abound in this integration of information, and the technologies for its implementation are already available.
The fundamental technology for this revolution in the human-automotive interface is the gateway processor, which provides a central access point for wired and wireless networks. By using standard hardware interfaces and communication protocols, it provides a technology-independent platform for building applications which unleash the potential which already exists in automotive and cellular networks.
Converging trends in telematics infrastructure
Three critical technologies for enabling new telematics applications are already emerging as independent solutions for other problems in automotive design:
Hands-free car kits: Concern over the safety of talking on the cell phone while driving stimulated development of systems built into vehicles to allow hands-free use of cell phones. The hands-free car kit in its simplest form uses Bluetooth short-range radio to interface a cell phone brought into the vehicle with a vehicle-mounted microphone and speaker.
The hands-free car kit takes control of the cell phone and uses it to connect to the cellular network, while replacing its other functions (voice input/output, dialing, and switch hook control). Although this may seem like an undemanding application, a high-quality implementation will include advanced techniques such as voice recognition and echo cancellation which require significant DSP horsepower.
GSM modules: More advanced designs include a vehicle-mounted Global System for Mobile Communications (GSM) module for interface to the cellular network. The car’s power system can be tapped for the cellular radio, while the handset unit is recharging. A vehicle-mounted antenna has a more stable position than a handset antenna, and it is less obscured by metal body panels, so reception is less subject to sudden dropouts or loss of connection.
The GSM module could be configured to work directly with a Bluetooth-enabled headset or a vehicle-mounted microphone and speaker, however the GSM module still would require a mechanism for identifying the subscriber to the cellular network. This can be provided by giving the module its own SIM card and subscriber account, however Bluetooth technology already includes a standard access method for retrieving SIM card data from a cell phone, which allows the GSM module to assume the cell phone’s identity.
In-vehicle networks: The cost of electrical wiring is being dramatically reduced by replacing multiconductor cable bundles with a Controller Area Network (CAN) two-wire differential pair. In-vehicle networks typically will have multiple CAN networks: low-speed networks for serving devices like door locks and tail light clusters which use CAN to reduce wiring, and high-speed networks for critical high-performance functions such as power train control.
The 7 Series BMWs implement three CAN networks: A CAN power train network as well as the CAN body network are linked to the central gateway module, which is connected to the Byteflight star network. The Byteflight star coupler is the safety-critical control and information module. The third CAN network links the CAS (car access system) to the door control units and to the seat controllers (up to a maximum of 11 units). The CAS also provides an interface to the CAN body network, which consists of up to 20 nodes.
The foundation of the telematics infrastructure is the gateway processor, which provides transparent access across the different wired and wireless networks. A gateway processor that handles automotive wired networks, Bluetooth wireless networking, and hands-free car kit functions is seen below.
Automotive technologies form a telematics infrastructure.
Because of the need for networks with varying degrees of reliability and bandwidth, multiple network types will be used in future in-vehicle networks. There are a number of emerging automotive networks to address the ongoing revolution in vehicle electronics architecture. Multimedia devices in automobiles, such as CD/DVD players and digital TV sets, demand networks with high bandwidth. Other applications require wireless networks or other special demands.
Future in-vehicle networks are likely to include:
Bluetooth piconets: Medium-bandwidth, wireless networks already standard for communication with cell phones and mobile computers
Low-bandwidth RF network: Low-overhead wireless network for simple sensor and control applications, such as tire-pressure sensors, door locks, etc.
CAN network: Medium-bandwidth, high-reliability wired network already standard in the automotive industry
Audio/video network: High-bandwidth wired network for entertainment media. Several protocols are competing for this niche, including Domestic Data Bus (D2B), FireWire (IEEE 1394), Media Oriented Systems Transport (MOST), and Mobile Media Link (MML).
Low-Overhead Networks: UART-based wired networks (Local Interface Network, LIN) and chip-to-chip buses such as Inter IC (I2C), Serial Peripheral Interface (SPI), and Microwire support low-cost interface to keypads, displays, sensors, etc.