techtrends C ble nd h rness EDA
matter of measuring its length and se lecting a gauge. The federal government has turned its attention to the reliability problems inherent in cables and wires, unfortunately only as a reaction to a cou ple of recent air traffic disasters. In No vember 2000, the government issued a report covering the maintenance of wires and cables systems but acknowledging the importance of new technologies for designing such systems as a way of min imizing maintenance problems (Refer ence 1).
In any large system, two or more de velopment teams are likely to use cables to connect their subsystems. Yet, devel opers designed and located each sub assembly in the system with little con sideration of the physical and electronics constraints of cabling. Even a clear ex ample of leading edge design, a Formu la 1 race car, falls prey to the tradition. Designers of suspension systems, for ex ample, know that they have to accom modate sensors that carry signals back to the engine control computer. Yet, these designers often fail to consider the phys ical characteristics of the cable during suspension design, and they likely deter mine its precise routing and length through trial and error on the test track. The common approach to cables seems
AT A GLANCE
Smart products call for sophisticated cables.
Both electrical and mechanical engi neers have had to learn new terms.
Electromechanical design automation is a new discipline with a promising market.
Few vendors and high entry barriers characterize the cable market.
to be: If they do not get in the way, they are good enough. The rapid increase in semiconductor fabrication technology and the Internet are forcing changes. The Internet supports a move toward global design and manufacturing with the goal of reducing costs. Manufacturers have to maintain many variants and options for each design and accommodate the spe cial circumstances of regional manufac turing and design. Many products have long active deployments, requiring de signers to consider the certainty of field upgrades during the life of the product. Electrical systems are evolving: Cars will soon have 42V batteries, flexible cable is becoming a viable alternative and possi bly a preferred medium, and designers
are using multiplexing as a way of in creasing bandwidth.
A commercial wide body jet has more than 150 km of wires; technicians likely determined the wires’ individual lengths and routes by running a rope through the airplane. A helicopter electrical system contains an average of 20,000 wires. Fiber optics will most likely replace many of the wires in both airplanes and helicop ters. The designers of the B 52, for ex ample, expected it to have an operational life of 16 to 18 years; however, it is now scheduled to stay in active duties for 50 years. No one ever considered the effect of aging on the copper and insulation materials in the aircraft’s wires. In satel lites and other space vehicles, the chal lenges are even more daunting. Radiation can be corrosive and generates electro magnetic interference. Such systems can not tolerate slack design rules because every pound of extra weight adds around $70,000 to the cost of a launch. But ex otic products are not the only ones that offer challenges. A typical car today has more than 20 microcomputers on board that need to communicate with each oth er and with sensors and actuators in all types of weather conditions and at ex treme temperatures in certain cases. In a commercial vehicle, the weight of a har ness and its cost is second only to the en gine. Development times are shrinking
CAR MAKERS PUT THE PEDAL TO THE METAL
The AMI C (Automotive Multimedia Interface Collaboration) is an organization of vehicle manufacturers world wide that facilitates the develop ment, promotion, and standardi zation of electronic gateways to connect automotive multimedia, telematics, and other electronic devices to their motor vehicles. After an initial meeting in 1998, the manufacturers formally formed the organization in 1999 as a nonprofit corporation. Members are Fiat Auto, Ford Motor Co, General Motors, Honda, Mitsubishi Motors, Nissan, PSA Peugeot Citroen, Renault, and Toyota. Volkswagen, BMW, and Daimler
Chrysler, which were active in the establishment of the consor tium, are not official members. The AMI C objectives are to:
provide a convenient method to enable con sumers to use a variety of emerging media, comput ing, and communications devices in their vehicles;
foster innovation of new features and functions in automotive media, com puting, and communica tions electronics by creat ing a stable and uniform hardware and software interface in vehicles;
reduce time to market and facilitate upgrades of
evolving electronics in vehicles;
support deployment of telematics by defining specifications for the telematics and information interfaces between the vehicle and the outside world;
reduce relative costs of vehicle electronic compo nents; and
improve the quality of vehicle electronic compo nents through reduction in variations, thus improving first time capability.
The group has recently released a number of specifica tions covering architecture, func
tional requirements, interfaces, and physical specifications, as well as use cases and a common message set. The specifications are for informational purposes only. The group will refine, vali date, and verify these specifica tions. Upon completion of the process, AMI C will release final “build to” versions. Although the German car manufacturers have declined to sign the member ship agreement, they can still provide input to the develop ment of the standards and deploy products that fully meet them. You can find the specifica tions at www.ami c.org.
104 edn | March 29, 2001