A manager's guide to FlexRay: here's what you need to know about the new communications protocol that will make X-by-wire more pervasive. (Manage).A not-so-funny thing is happening as all the automakers work toward installing "X-by-wire" systems, such as drive-by-wire and brake-by-wire. Conventional mechanical and hydraulic systems Noun 1. hydraulic system - a mechanism operated by the resistance offered or the pressure transmitted when a liquid is forced through a small opening or tube can only go so far. Likewise, the in-vehicle serial data buses that pass electronic signals between a vehicle's electronic control units (ECU ECU See: European Currency Unit ECU See European Currency Unit (ECU). ) and associated electronic devices can no longer cut it. So, a change is afoot, and that is FlexRay--a new communications protocol Hardware and software standards that govern data transmission between computers. The term "protocol" is very generic and is used for hundreds of different communications methods. A protocol may define the packet structure of the data transmitted or the control commands that manage the designed for the high data transmission rates required by advanced automotive control systems. These are the same control systems that, in the next few years, are expected to replace nearly every hydraulic line and mechanical cable in today's automobiles with wire-based networks, sensors, and actuators. By the way, FlexRay should also simplify automotive production. GETTING TO THE LIMITS OF TECHNOLOGY? Today's braking systems have evolved from electro-hydraulic systems to hybrid brake-by-wire systems. (Actually, current brake systems are mostly "wet-brake-by-wire," slowly evolving into fully electrical "dry-brake-by-wire.") These systems consist of three communications "protocols": hydraulic, electrical (sensors on each wheel for ABS skid control), and, in at least 80% of the cars, mechanical (a parking brake cable). In the not-too-distant future, says Ben Baker, director of Electrical Product and Processes for General Motors Corp. (Warren, Ml), sensors on the vehicle might detect a panic situation--a stopped object, whether another car, a tree, or a person--approaching at a rapid rate while you're twiddling with the radio, Intelligent, electronically based "anticipatory braking" might "decide" to initiate a 0.2-g stop to get your attention--and to help stave off a major collision. Doing this with hydraulics hydraulics, branch of engineering concerned mainly with moving liquids. The term is applied commonly to the study of the mechanical properties of water, other liquids, and even gases when the effects of compressibility are small. is difficult. Keeping brake pressure balanced on all brake pads brake pad n. A flat block that presses against the disk of a disc brake. Noun 1. brake pad - one of the pads that apply friction to both sides of the brake disk in a vehicle is so much easier in a system of sensors, actuators, servos, electronic controls, and software. Another automotive system going electronic is powertrain. For example, very fast, very reliable electromagnets, not a camshaft, will eventually control the valves in tomorrow's powertrains. In the meantime Adv. 1. in the meantime - during the intervening time; "meanwhile I will not think about the problem"; "meantime he was attentive to his other interests"; "in the meantime the police were notified" meantime, meanwhile , more and more sensors are being sprinkled throughout vehicles, especially sensors that look outside: at street surfaces and at obstacle in front, beside, and behind the vehicle. These sensors include video, radar, and photo-electrics, which both capture and transmit a colossal amount of data in real time for the ECUs within the car. Last, there's the reality that the automakers, says Baker, "haven't been able to figure out how to do diagnostics through hydraulic fluid hydraulic fluid toxic because of its high content of industrial triaryl phosphate. ." Electronic diagnostics will provide a "higher fidelity level on each of the components," he continues. Better diagnostics through electronics will become tomorrow's maxim. Some of these advanced applications exist now. Throttle-by-wire, also called "drive-by-wire," has been in diesel-fueled cars for about five years. Some high-performance gasoline-fueled cars, like the Corvette corvette, small warship, classed between a frigate and a sloop-of-war. Corvettes usually were flush-decked and carried fewer than 28 guns. They were widely employed in escorting convoys and attacking merchant ships during the great naval wars of the late 18th and , have had it for three years now. Luxury carmakers such as BMW BMW in full Bayerische Motoren Werke AG German automaker. Founded as an aircraft engine manufacturer in 1916, the company assumed the name Bayerische Motoren Werke and became known for its high-speed motorcycles in the 1920s. , Mercedes, and Audi are planning to introduce brake-by-wire in the 2004 model year. WHAT IS FLEXRAY? For these automotive applications to become commonplace, a number of protocol requirements must exist. Enter FlexRay. FlexRay is a communication system developed by a consortium founded in 2000 by BMW, DaimlerChrysler, Motorola, and Philips Semiconductors. In 2001, Robert Bosch GmbH Robert Bosch GmbH [1] is a German corporation which was started in 1886 by Robert Bosch in Stuttgart, Germany. [2] Bosch businesses include:
spark plug Device that fits into the cylinder head of an internal-combustion engine and carries two electrodes separated by an air gap, across which current from a high-tension ignition system discharges, creating a spark fire through your aftermarket Aftermarket See: Secondary market. aftermarket See secondary market. AM radio?) FlexRay is an open, common, scalable electronic architecture for automotive applications. It can operate in single-or dual-channel mode, providing redundancy where needed. It allows both synchronous and asynchronous Refers to events that are not synchronized, or coordinated, in time. The following are considered asynchronous operations. The interval between transmitting A and B is not the same as between B and C. The ability to initiate a transmission at either end. data transmissions. With the former, other nodes on the network receive time-triggered messages in a predefined latency time. With the latter, messages get to their destinations quickly or slowly, depending on their priority. Currently, FlexRay can handle communications at 10 Mbps--the speed of your typical low-end home-computing local area network. Motorola's Both is quick to add that this standard doesn't mean that 10 Mbps is enough forevermore for·ev·er·more adv. Forever. Adv. 1. forevermore - at any future time; in the future; "lead a blameless life evermore" evermore . Instead, it is fast enough for the foreseeable future, given the applications automakers have envisioned thus far. Last, FlexRay's clock synchronization Clock synchronization is a problem from computer science and engineering which deals with the idea that internal clocks of several computers may differ. Even when initially set accurately, real clocks will differ after some amount of time due to clock drift, caused by clocks mechanism aptly handles cheap clock oscillators, namely those made out of quartz. And that synchronization (1) See synchronous and synchronous transmission. (2) Ensuring that two sets of data are always the same. See data synchronization. (3) Keeping time-of-day clocks in two devices set to the same time. See NTP. , as with all of FlexRay, is fault tolerant The ability to continue non-stop when a hardware failure occurs. A fault-tolerant system is designed from the ground up for reliability by building multiples of all critical components, such as CPUs, memories, disks and power supplies into the same computer. . For example, FlexRay automatically and digitally compensates for the differences in the variety of quartz clocks running on the network, as well as in their slight changes in clock frequencies. This clock synchronization is a distributed mechanism; there's no master timekeeper here. So if one node fails or for some reason is taken off the network, the other nodes will continue to operate in synchrony synchrony /syn·chro·ny/ (-krah-ne) the occurrence of two events simultaneously or with a fixed time interval between them. atrioventricular (AV) synchrony . (Insofar in·so·far adv. To such an extent. Adv. 1. insofar - to the degree or extent that; "insofar as it can be ascertained, the horse lung is comparable to that of man"; "so far as it is reasonably practical he should practice as the fault tolerance See fault tolerant. (architecture) fault tolerance - 1. The ability of a system or component to continue normal operation despite the presence of hardware or software faults. This often involves some degree of redundancy. 2. of motors and sensors, the normal rules of reliable systems design applies. For example, in a steer-by-wire system, the sensor system in the steering wheel will be a redundant array, with two or three sensors providing the same signal. A judging algorithm in the electronics will then determine the validity of the signals; that is, it will determine whether all three sensors are providing the same information, or at least two of the three.) SIMPLIFICATION=DOLLAR SAVINGS Along with making X-by-wire control possible, FlexRay offers other advantages. First, "any time you can get the control mechanism closer to the actual mechanism you're trying to control, that's a performance enhancer," says Baker. Second, FlexRay helps eliminate the amount of mechanical space required for hydraulic fluid systems--systems that will be totally replaced by electronics. Third, continues Baker, FlexRay "provides the flexibility needed to simplify integration with current control system, reducing overall system complexity." Therein lies a major advantage. Both OEMs and automotive suppliers are saying, says Both, "'We don't need more [communications] technologies. We need less technologies that are more versatile.' They want technologies that can be used over a range of applications." That is, rather than have one by-wire protocol for steering and another for powertrain, FlexRay aims to be the protocol for all the applications. That's one protocol applied across platforms, across assembly plants, ac ross regions. Not only will this simplify automotive electronics and communications architectures, it should also help make automotive electronics more stable. WHAT'S FLEXRAY MEAN TO PRODUCTION? Certainly large dollars savings will come from ripping out hydraulics and hydraulic installation equipment from automobiles and automotive assembly. Granted, today's hydraulic systems and conventional chassis systems perform. "admirably," Baker is quick to point out. But let's be frank: with fluids sloshing around containers, bunches of fittings, and thin steel or plastic pipes, hydraulic systems are complex, moderately fragile, and messy. Hydraulic parts must be connected correctly; absolutely no leaks allowed. In a classic bit of understatement, Baker murmurs that hydraulics are "kind of a pain in the career." Assembling electronic systems is much easier. "We believe there is a benefit to being able to put two snap connectors together rather than having to carry tools to hook up tiny hydraulic lines." If that hydraulic line should get bent or kinked, either the fluid won't pass or eventually the line fails. Compare that to shielded wire. Electrical wires and harnesses can accommodate vibration and a fair amount of abuse. "Electric cable can be bent, even doubled upon itself," explains Baker, "and the electrons still have a way to sneak through." Obviously, if you don't have to put parts in the car--specifically mechanical and hydraulic parts--you don't have to pay for them. So, the betting is that overall, both in component and overall assembly costs, electronic systems will be less expensive than their mechanical and hydraulic counterparts. This is especially true where multiple configurations are involved. Take, for instance, ABS modules for 2-wheel and 4-wheel drives. Rather than have separate modules consuming factory floor space, different FlexRay-based ABS can be configured by some intel-inside computer sitting where inventory and assembly robots used to sit. In conclusion, says Baker, "anytime you're building something, whether kitchen cabinets or cars or trucks, your engineering and design goals should be to make sure the materials and processes you use are forgiving. Generally, FlexRay-enabled electrical systems are a lot more forgiving than hydraulic or mechanical linkages. RELATED ARTICLE: FlexRay's Basic Features * Scalable synchronous and asynchronous data transmission * High net data rate of 5 Mbit/sec; gross data rate approximately 10 Mbit/sec * Deterministic 1. (probability) deterministic - Describes a system whose time evolution can be predicted exactly. Contrast probabilistic. 2. (algorithm) deterministic - Describes an algorithm in which the correct next step depends only on the current state. data transmission, guaranteed message latency and message jitter A flicker or fluctuation in a transmission signal or display image. The term is used in several ways, but it always refers to some offset of time and space from the norm. For example, in a network transmission, jitter would be a bit arriving either ahead or behind a standard clock cycle * Support of redundant transmission channels * Flexible allocation of bandwidth to individual nodes * Configurable number of sending slots per node and cycle * Fault-tolerant and time-triggered service implemented in hardware * Fast error detection and signaling * Support of a fault-tolerant synchronized syn·chro·nize v. syn·chro·nized, syn·chro·niz·ing, syn·chro·niz·es v.intr. 1. To occur at the same time; be simultaneous. 2. To operate in unison. v.tr. 1. global time base * Error containment on the physical layer through an independent "Bus Guardian" * Arbitration-free transmission * Support of optical and electrical physical layer * Support for bus, star, and multiple star topologies [Source: FlexRay Consortium] FlexRay's Benefits for production * Enable re-use of carry-over components and easy future extendibility - Without embedding 1. (mathematics) embedding - One instance of some mathematical object contained with in another instance, e.g. a group which is a subgroup. 2. (theory) embedding - (domain theory) A complete partial order F in [X -> Y] is an embedding if knowledge of future platform partitioning - Without touching not-involved components or reconfiguring them - Only the required receive and transmit buffers should be configured * Compatibility as far as possible - For migration of existing solutions and products - For embedding in-development processes * High dependability for mass production * Power management * Proper error detection and diagnosis [Source: Dr. Horst Brinkmeyer, DaimlerChrysler AG] WHERE'S FLEXRAY NOW? FlexRay is aimed at the automotive market. No royalties will have to be paid For applications. Prototype implementations of FlexRay-based chips are available for FlexRay Consortium members. First silicon of protocol engines will be available in early 2004; qualified silicon is scheduled for late 2004 Engineering samples of the electrical physical layer will be available from Philips Semicondutors in the second quarter of 2003; of 2004. First series product parts by the end production cars with FlexRay are expected around 2006. The price of FlexRay devices, as with any semiconductor device, depends on Silicon size, chip test efforts, commercial relationships with customers, and other criteria. None of these are fixed just yet. For more information about the FlexRay Consortium and its FlexRay communications protocol. trawl trawl - To sift through large volumes of data (e.g. Usenet postings, FTP archives, or the Jargon File) looking for something of interest. over to www.flexray.com. Read the FAQ (Frequently Asked Questions) A group of commonly asked questions about a subject along with the answers. Vendors often display them on their Web sites for use as troubleshooting guidelines. ; it's excellent., For additional information or if you have specific questions, send an email to |
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