远程诊断和汽车维修系统概述.docx

1、远程诊断和汽车维修系统概述英文资料Overview of Remote Diagnosis and Maintenance for Automotive Systems1. INTRODUCTION1.1. Current vehicle diagnosisAll cars and light trucks built and sold in the United States after January 1, 1996 are required to be equipped with On-Board Diagnostics II (OBD-II). While the primary im

2、petus for OBD-II was diagnostics for emission systems, the range of vehicle sub-systems addressed by this standard is quite broad. The OBD-II Diagnostic Trouble Codes (DTCs) are made up of 5 digits 1. While these codes are useful to identify faulty subsystems, they are typically not sufficient to id

3、entify specific faulty components.The trouble codes are typically accessed through a scan tool that is plugged into a special OBD-II vehicle connector. This connector is located in the passenger compartment and can be accessed from the drivers seat.Hand-held scan tools are usually limited to vehicle

4、s from one or more manufacturer. In general, Chrysler products, all European and most Asian imports use the ISO 9141 standard for in-vehicle OBD-II communications. GM cars and light trucks use SAEJ1850 VPWM (Variable Pulse Width Modulation), and Fords use SAE J1850 PWM (Pulse Width Modulation)1.2.Pr

5、oblems with current vehicle diagnosisApproachesFrom above description we can see, there are several problems in the current approach to vehicle diagnosis.1. The diagnosis is not standardized among vehicle manufacturers. This leads to higher costs when vehicles from different manufacturers are to be

6、diagnosed by a given facility.2. The diagnosis requires driving to a repair facility.This is an inconvenience to the driver and a source of uncertainty in scheduling vehicle diagnosis and repair. The driver may be told to leave the vehicle for the day when the problem can be solved in an hour.3. A c

7、omplete diagnosis may need special equipment and trained technician help. This can make the diagnosis very expensive.4. The DTC information is typically not accurate enough to pinpoint the source of the problem.Better vehicle diagnostic algorithms and strategies could reduce the time needed to diagn

8、ose problems.5. With the increased sophistication of electronic control systems in vehicles, there is a concomitant increase in the difficulty of identifying component malfunctions. One symptom of this is the diagnosis of replaced parts as “no trouble found”.1.3.Current vehicle maintenance strategie

9、sCurrent vehicle maintenance strategies generally consist of corrective and preventive maintenance approaches or a combination of these. In the corrective maintenance approach, the vehicle is maintained on an “as-needed”basis, i.e. after a fault has occurred. This can be a risky approach as it may,

10、over time, lead to unexpected breakdowns and more costly repairs due to higher levels of damage. At the other extreme, preventive maintenance relies on replacing components and fluidsbased on a conservative schedule to “prevent” possible failures. Although preventive maintenance programs may increas

11、e system availability, they lead to increased cost of vehicle ownership due to the replacement of parts and fluids well before the end of their useful life. In general, preventive maintenance schedules are typically time or mileage-based strategy and do not account for actual vehicle operating condi

12、tions orsubsystem health. As an everyday example, drivers have little idea of how to trade off the many factors in oil life and are admonished by the oil-change industry to change their oil every 3,000 miles; many vehicle manufacturers, however, recommend much longer intervals for “normal” driving c

13、onditions. Studies have revealed that most the equipment failures are not related to the number of hours of operation . Many drivers use a mix of corrective and preventative strategies,depending on the subsystem involved.1.4. Problems with current vehicle maintenance practicesCorrective and preventa

14、tive vehicle maintenance practices are sub-optimal strategies in terms of the cost of vehicle ownership and driver convenience. Neitherstrategy accounts for actual vehicle driving conditions or current component/fluid health. In addition, vehicle operators often do not read the maintenance schedules

15、 intheir owners manual or, if they do, have difficulty in deciding between moderate or severe operating conditions.According to a September 15, 2003 report published bythe Commission of the European Community, repair and maintenance accounts for 40% of the total lifetime costs of vehicle ownership 5

16、. Thus, the affordability of vehicles depends not only on initial vehicle cost but the cost of repair and maintenance.2. SIGNIFICANCE OF REMOTE DIAGNOSIS &MAINTENANCERecent advances in remote communications, humanmachine interfaces, model-based diagnostics, electronics and embedded system technologi

17、es are leading to a dramatic shift in the way the vehicles is diagnosed and maintained. These advances equip the automobiles with the capability share in-vehicle sensor and diagnostic information with remote computers, enabling vehicle diagnosis and maintenance be performed remotely while the vehicl

18、e is being driven. In addition, vehicle parameters mcan be monitored while the vehicle is being driven todetermine when maintenance is necessary. These capabilities coupled with increased consumer interest are the reasons why vehicle RD&M is drawing increasing attention in the automotive industry.2.

19、1. Remote Diagnosis & Maintenance BackgroundRD&M is a multidisciplinary subject that embodies many vehicle subsystems and their associated diagnostic and maintenance needs, a remote analysis center, andwireless communication. A number of recent patents and articles have addressed a variety of applic

20、ation-specific issues related to RD&M. Examples include a vehicle communication system to establish a two-way communications link between the vehicle and a remote computer, and an automated voice response system to provide a method for remotely diagnosing a vehicle. Also NASA has developed a remote

21、diagnosis server to monitor the health of the space shuttle.Several companies, including GMs OnStar; NEXIQ Technologies Inc., ATX Technologies Inc., Toyota,Vetronix Inc., Jentro AG, BMW, Volkswagen, IBW,and Dearborn Group, either already have or are actively developing RD&M applications . GMs OnStar

22、 system has evolved from being an option on Cadillacs to standard equipment on nearly all GM vehicles. OnStar integrates cell phone service, roadside assistance,emergency service, and simple remote diagnostics based on Diagnostic Trouble Codes (DTCs). GM projects that OnStar system will be installed

23、 in 4 million vehicles by 2005 . A few other car manufacturers, includingToyota, Volkswagen and BMW, are working on similar telematics systems and are rolling out models with integrated early-generation remote diagnosticstechnology as well .2.2 Advantages of RD&MAs described in the scenarios at the

24、beginning of this report, RD&M should have the ability to unobtrusively diagnose vehicle health without the need to drive to a special repair facility. RD&M systems can examine automotive fault codes andinternal sensor values no matter if the car is running on the road or parked in the garage, witho

25、ut the involvement of a vehicle service technician. These readings can be wirelessly transmitted to a remote RD&M server, where vehicle information, such as records of vehicle service and previous repair are stored. A RD&M server can use powerful processing capability to assess vehicle health and re

26、mind owners if maintenance is recommended. If a problem is detected, the driver can be warned of the malfunction, can get help from an advisor to assess the severity of problem and to schedule maintenance or repair. If needed, advanced diagnostic algorithms could be remotely downloaded to the vehicl

27、e for performing complex diagnostic tasks, and recovery and rescue services could be activated to deal with faulty conditions and, possibly, save lives.Remote maintenance program can aid in reducing operating costs and increase safety by, for example,early detection of low tire pressure, determining

28、 when an oil change is needed, or when brake linings are in need of replacement. Early warnings of problems may prevent some on-the-road breakdowns and, in some cases, may avert accidents. RD&M should give drivers peace of mind by taking much of the ambiguity out of the current approaches to diagnos

29、tics and maintenance.Vehicle manufacturers can also use RD&M as an early warning system to detect vehicle warranty problems early in the model year. The authors believe that as the number of automobiles equipped with RD&M increases,consumers will increasingly recognize the long-term cost-to-benefit

30、ratio of these systems.2.3 Potential Consumer Interest in RD&MAutomotive telematics is growing rapidly and RD&M is generally regarded as one of the most important telematics services. According to a recent survey by InfoMove, a Seattle provider of personalized, locationbased applications and wireles

31、s services for automobiles, 73 percent of consumers would like automakers and dealers to be able to diagnose car problems remotely. Projections by Allied Business Intelligence, an Oyster Bay, NY-based research firm, indicate that telematics products and services are expected to grow from an aggregat

32、e $2.2 billion global market in 2001 to more than $12.3 billion by 2007. A good indication of the strength of consumer interest in automotive telematics services is the growth of OnStar subscribers, and the emulation of OnStar type services by other OEMs.2.4 RD&M for X-By-Wire systemsX-By-Wire syste

33、ms were introduced in aircraft well over a decade ago, first in military and then in commercial aircraft. These systems replace hydraulic and mechanical systems with electronically controlled systems. In a true X-By-Wire system, there is no hydraulic backup to the electronic system. X-By-Wire systems ar