Figure 1. AHS Vis-a-Vis Other Systems


At present, advanced information-communications systems are being developed at a rapid pace in Japan. In the area of ITS research targeted at information communications among motor vehicles in transit, action is fully underway pursuant to a concrete master plan. With regard to cruise-assist systems, car navigation systems and vehicle information communications system (VICS) have been accepted by drivers and are disseminating rapidly. The target of our R&D project is real-time driver assistance through coordination between the road and the vehicle.As is widely known, a general ITS plan was adopted in August 1986 by relevant ministries and an agency that are linked to ITS development. The plan is classified into nine development areas. The Advanced Cruise-Assist Highway System Research Association (AHSRA) focuses on the third of the development areas, namely, assistance for safe driving. In this area, research is being conducted on the following 4 of 21 types of user services: provision of driving and road conditions information (No.4), danger warning (No.5), assistance for driving (No.6), and automated cruise (No.7). Efforts are also being made in development area No. 7 of the aforementioned development areas: increasing efficiency in commercial vehicle operations and the related user service of automated platooning of commercial vehicles.


Figure 2. The General ITS Plan and AHS


Figure 3. History of AHS Research and Development


The history of AHS research and development can be classified in three major currents. Research that dates back the longest is that relating to guidance-based automated cruising, which began with the study of guidance cables in the 1950s. More recently, guidance with magnetic markers or radio-wave markers is being studied. Platooning and AHS research in Japan and the United States stems from research in this area. The second current relates to automated cruising without any special road infrastructure but dependent on independent vehicle functions. In this area, Japan's Mechanical Engineering Laboratory developed the world's first intelligent vehicle in 1977, and research on this subject is continuing in research institutes around the world. The third current is directed toward early commercialization based on cruise assistance, because of the extreme difficulties involved in such automated cruising systems. The objective is to develop intelligent roads and vehicles for practical support in motor vehicle driving. Leading examples of this are the Prometheus Project in Europe and the Advanced Safety Vehicle (ASV) Project in Japan. Although there has been more than 50 years of research, there have been two major developments in recent years. One is that research has entered a stage in which all three of these currents are being integrated in more-effective and more-practical research. The second is that research is advancing powerfully due to governmental support in Japan, Europe, and the United States.


Figure 4. A Chronology of AHS Research and Development


Research on cruise assistance at Japan's Ministry of Construction started in 1989 with basic study on cruise-assist system. Later, feasibility tests on automated cruising were conducted for the first time in the world in 1995 at the test track of the Public Works Research Institute (PWRI). In the following year, automated cruising of 11 vehicles was tested on the newly completed but yet-to-be-opened Joshinetsu Expressway. With the success of these two experiments, system feasibility was confirmed, and the Advanced Cruise-Assist Highway System Research Association was established in that same year of 1996.


Figure 5. Establishment of the Advanced Cruise-Assist Highway System Research Association (AHSRA)


AHSRA was established in September 1996 with approval of the Ministry of Construction under the Mining & Industrial Technology Research Association Law. At present, it has 21 member companies and 360 supporting members that include organizations and private individuals. The 21 member companies are private businesses from several industries: electronics, 11; automotive, 7; heavy machinery, 2; and telecommunications, 1.


Figure 6. AHSRA Members


Due to the breadth of research needed, AHSRA has organized 15 research teams for each research theme. These research teams has a total of approximately 180 members. However, the various member corporations have their own researchers supporting activities of the research teams, which results in a grand total of approximately 600 people being involved in the project.


Figure 7. Definition of AHS and Levels of Service


In Japan, the service levels of AHS are defined clearly into three categories, based on advances in the system and the possibility of commercialization. The first level is AHS-i, or support of vehicle cruising with information provided from the road infrastructure to the vehicle. The second level is AHS-c, or support in vehicle control. The third level is a fully automated cruising service, or AHS-a. The term AHS is used to denote these three levels of service collectively. At present, we are directing our energies into commercialization of AHS-i and AHS-c. AHS-a is certainly possible, but only under limited conditions, such as where lanes are devoted exclusively for that use and in automated parking in parking lots. Automated cruising under ordinary conditions that include driving in traffic that includes conventional vehicles is a theme that must be examined at the next level of research.


Figure 8. AHS Service and the Division of Service Roles


This illustrates the relationship between information gathering, cruise control, and cruise control responsibility, and the respective service levels, in order to deepen understanding of these levels. Under current driving conditions, the driver is responsible for all driving tasks. On the AHS-i level, the system covers some of the information-gathering tasks, with the driver held liable for cruise control and cruise control responsibility. On the AHS-c level, the system covers some cruise-control tasks as well as information gathering, with the driver held liable for cruise control and cruise control responsibility. At the fully automated AHS-a level, the system will take over all of these tasks and will be liable for cruise control responsibility as well. Because of that, this system involves not only various technical issues, but an extremely serious social concern regarding cruise control responsibility. The target cruise-assist system that we aspire to actualize is under development, based on needs. In order to analyze needs, to define clearly the user services that are necessary, and to actualize them in the AHS system, the various needs and conditions have been defined quantitatively and in concrete terms as requirements. Because the three levels are vitally important in system design, they are in some instances collectively called requirements in the broad sense.


Figure 9. AHS Services and Requirements



Figure 10. Configuration of Principal User Services

The system of principal user services is a product of research conducted in 1997. It consists of 10 user services in the area of improving driving safety and 9 user services in the area of driving efficiency and environmental control, selected and organized systematically. Our research project places priority on improving driving safety and focuses on perfecting the 10 principal user services relating to safety. Safety-related cruise-assist system is being developed and promoted for commercialization in various parts of the world. One distinctive feature of this research is that safety systems in Europe and the United States focus on self-reliant vehicle systems, while Japan is directing its efforts not only to research concerning on-board systems, in which Japan excels as well, but into development of a safe cruise-assist system based on road-vehicle affinity, a subject regarding which Japan stands at the cutting edge of research.


Figure 11. Scale of the Traffic-Accident Problem



Figure 12. Comparison of On-Board and Infrastructural System


Next, the objectives of research concerning a safe cruising system based on road-vehicle affinity and how this is being implemented are shown as follows. Figure 12 shows the characteristics of both the on-board system and the infrastructural system. Each has its own strengths and weaknesses; for example, with regard to gathering information regarding conditions surrounding the vehicle, the on-board system excels. However, that system is physically unable to gather information regarding remote locations or in blind-spot situations, where the infrastructural system proves to be useful. Regarding the range of system application, the on-board system can function everywhere that a vehicle goes, while the infrastructural system is restricted to locations where it is installed. The former naturally excels in decision-making based on the conditions of the vehicle; the latter is capable of facilitating overall decisions taking into account conditions in the environment. For these reasons, road-vehicle affinity is essential, so that the two systems can supplement each other and compensate for the other's weaknesses.

Research that is under way concerning the cruise-assist system involves coordination of research in three areas: motor vehicles, roads, and communications. The ASV Project focuses on the development of the intelligent motor vehicle known as the Smart Car. AHS research centers on an infrastructure called the Smartway, and the Association of Radio Industries and Business (ARIB) is conducting research concerning radio-communication technologies and other Smart Gateway facilities. Through coordination of these systems, research concerning overall Cruise Assist Systems are being made.


Figure 13. Cruise Assist Systems



Figure 14. Cruise Assist Systems Committee (tentative)


In the area of motor-vehicle and road-infrastructure coordination that has been studied by the Ministry of Construction and the Ministry of Transport, Cruise Assist Systems Working Group (tentative) was formed in 1998 under Cruise Assist Systems Committee (tentative) so as to enable representatives of the ASV Project and AHSRA to conduct joint research.


Figure 15. Updating Service/Requirements


Requirements are updated every year as research results produces are obtained. The year 1997 was Phase 0 of research, which focused on analysis of needs and systematization of the principal user services. In 1998, safety-related services that must be prioritized were selected, and requirements were assessed quantitatively. Figure 15 shows the content of the safety services and priorities of such services, arrived at through collaboration and agreement with ASV researchers. In 1999, practical requirements regarding improvements and basic studies have been incorporated into laws and regulations. The year 2000 is considered to be the ending phase for developing commercialization requirements. The proving tests to be conducted this year are based on primary requirements adopted jointly with ASV researchers.


Figure 16. Priority Safety-Related User Services


The priority user services in the area of safety, including their relative priority, have been selected and agreed upon by the Cruise Assist Systems Working Group. Ten principal user services were initially selected. Due to differences between expressways and ordinary roads, however, priorities have been placed on the services, with four user services for expressways and six for ordinary roads (seven user services in total) being chosen for prioritized development.



2. AHS Requirements

Figure 17. Causes of Accidents


After user services were defined, the causes of accidents were analyzed so as to develop requirements prior to conducting the system design work. Approximately 50% of all accidents are caused by delays in recognition. Among other causes, 9% are errors in judgement, and 16% are errors in operations. Excluding accidents caused by reckless actions such as exceeding the speed limit and drunken driving, it can be said that approximately 75% of all accidents can be averted through suitable cruise assistance.


Figure 18. Driver-Behavior Model and Content of Support


Thus, because the causes of most driver behavior that leads to accidents relate to recognition, judgement, and operation, accidents can be reduced with cruise assist systems regarding driver behavior relating to recognition support, judgement support, and operational support.


Figure 19. The Accident-Occurrence Process and Countermeasures Model


Next, the mechanisms and processes of an accident are shown as follows. If a hazard that is likely to lead to an accident occurs, the problem is how to avert it. First, although an error in recognition can lead to an accident, the AHS system can help to prevent such accidents by providing support in the form of information services. Similarly, the system issues warning to help prevent errors in judgement and operational support helps to prevent errors in operation. In further examining the requirements, one of seven services, Support for prevention of collisions with forward obstacles is introduced as an example. This requirement has been summarized in three points (see Figure 20).


Figure 20. Example of Support for Prevention of Collisions with Forward Obstacles



Figure 21. Example of Support for Prevention of Collisions with Forward Obstacles


The common factors have been organized into six categories (see Figure 21). Regarding methods of cruise assistance, information is to be provided with latitude in time, warnings are to be sounded in a way that does not irritate the driver, and operational support is to be limited only to emergency situations. With regard to the speed covered by the service, a speed that markedly exceeds the speed limit will be excluded. The three meteorological requirements based on normal driving conditions are with visibility of more than 50 meters, precipitation of less than 50 mm per hour, and wind speed of less than 25 meters per hour per second. Road surface conditions for service include those that commonly occur on roads, such as dry, wet, water film, snow-covered, and frozen surfaces. Factor 5, vehicles covered by the service, covers vehicles with four (or more) wheels, such as automobiles, as well as motorcycles. However, service to motorcycles is limited to warnings, and operational support is provided as a common requirement for automobiles and larger vehicles. Also, service hours are 24 hours for all types of vehicles. In actually providing service, a variety of information is necessary (see Figure 22). Information that varies according to the environment, such as obstacles, road surface conditions, vehicle cruising speed, and so on; fixed information regarding a location such as the road shape, and so on; and vehicle attributes, such as model, braking characteristics, and so on. Another type of information that is required but that is extremely difficult to assess concerns driver characteristics. In actually implementing AHS service, it is necessary to take into account such factors as the response time, habits, and preferences of the driver. With regard to timing (see Figure 23), various types of timing are important for real-time control of vehicles that are cruising at high speed. To prevent collisions with forward obstacles, for example, brakes must be applied before reaching the "normal deceleration limit" in order to stop at normal deceleration speed before colliding with the obstacle. Similarly, considering the driver response time that is required after information is provided, the information must be provided before reaching the "information service limit."


Figure 22. Support for Prevention of Collisions with Forward Obstacles



Figure 23. Time Limits in the Deceleration Process

Because emergency deceleration will be executed if warning and operational support is provided, cruising time will be extended. Therefore, the point in time at which emergency deceleration is effective becomes the time limit for initiating emergency deceleration. Similarly, the limit for warning can be determined by issuing a warning prior to the warning response, which varies from driver to driver. There are various time limits that must be defined in detail. Although they cannot be defined uniformly by driver characteristics, cruising speed, or road surface conditions, hypothetical parameters have been established to represent the concept with typical values (see Figure 24). For one example, assuming that the normal deceleration speed is 0.3 G and that the emergency deceleration speed is 0.5 G. The response time and so on have been defined hypothetically, based on the results of driving-simulation research and the like. The next step is how to meet these requirements in a system. The first key point in system development is how to allocate the needed functions between the road infrastructure and the vehicle. Figure 25 shows the four principles that have been adopted and approved through joint research with ASV researchers. Because the service levels are i (information) and c (control), the responsibility ultimate lies on the driver. Second, information from infrastructure that must be provided are determined in part by consideration of vehicles. Because the infrastructure cannot asses control, control itself must be decided by the vehicle. Information provided by road infrastructure is basically information that cannot be gathered easily by the vehicle, such as information concerning curves, intersections, obstacles, road surface conditions in remote locations, and so on. Research is now under way based on the aforementioned four principles.


Figure 24. Example of Support for Prevention of Collisions with Forward Obstacles

Figure 25. Basic Approach regarding Division of Functions Between Road and Vehicle


The basic principles underlying the infrastructural requirements are vitally important concepts in system development (see Figure 26). The first principle is to develop a system that is widely accepted and effective. The second concerns user tolerance, which means that the functions are within the scope of systems that the great majority of users today can accept, and that the systems are widely accepted and not resisted by users. In terms of social acceptance, the system must be widely applicable at reasonable levels of technology and cost. Furthermore, the system must be defined based on statistics and other data.


Figure 26. Principles of Infrastructural Requirements



Figure 27. Basic Approach in Defining Infrastructural Requirements


In the basic approach of defining infrastructural requirements, the first requirement is to provide accident prevention service to drivers who normally drive safely. Drivers who cruise well beyond the speed limit are excluded. When safety is considered the number of warnings and degree of operational support increase. However, excessive frequency of intervention will in fact erode driver trust. For this reason, the service must not intervene excessively with driver operations. Regarding the third policy, service under extreme conditions poses problems in terms of cost efficiency. To achieve a balance between cost and efficiency, service is set within the range of normal driving conditions.



3. Research Activities in 1999

Figure 28. AHS Research and Development: A Chronology


In its first year (1996) of operation, AHSRA conducted research on automated cruising. Subsequently, service classified into i, c, and a levels were defined for future practical application, and research that focused on i and c was conducted . In 1998, research was based on requirements in light of past research results. In 1999, the focus of activities moved particularly to the development of a system for proving tests and formation of a social consensus. This year, proving tests and a public demonstration are scheduled, with the introduction of the AHS in major roads projected for 2003. Research is now under way to achieve this goal through the development of systems and standards, and through the holding of field tests.


Figure 29. Research Policy for 1999


The research policy for 1999 is to combine past research results in a system for proving tests to be ready for commercialization in 2003. Specifically, the first goal is to establish goals for 2015 and to define the processes by which to achieve them. The second goal is to develop Phase-1 Cruise Assist Systems that can be commercialized in 2003, and concurrently to develop a test system for this year's proving tests. The third goal is equally important: to actively disseminate information in Japan and other countries, and to propose international standardization and so on, in order to form a social consensus. As for the framework for research activity (see Figure 30), research is divided largely into five areas due to the breadth of the range.


Figure 30. AHS Research and Development in 1999



Figure 31. Items on AHS in General (Chronology)


Service and requirements (see Figure 31) are very important themes that have been studied since 1996. Starting with research regarding the concept of automated cruising, the 19 principal user services constituting i, c, and a services were systematized into Phase 0 requirements in 1997. Phase 1 requirements were developed in the following year. However, major research achievements were made in 1999, with the development of Phase 2 requirements, the conducting of studies regarding coordination with the ASV Project, probable scenarios, and systems and standards, the refinement of safety-related requirements, and the conducting of basic research regarding efficiency.


Figure 32. AHS in General: Principal Research Themes and Achievements in 1999


Other AHS-related achievements in general (see Figure 32) are summarized as follows. In the study to facilitate the introduction of the system, the principal research results are definitions of safety goals and actions to achieve them. Regarding requirements, studies were conducted, as mentioned earlier, regarding the development of tools for communications within Japan and other countries and disseminating information so as to form a social consensus. Then tests were planned and preparations were made for a proving tests project. With regard to the development of international standards, a strategy has been formulated, and the first proposal is being prepared along with the production of relevant supporting documents. Research has been conducted chiefly concerning what AHS technical literature should be systematized and how to do so.


Figure 33. System Development (Chronology)


Full-scale system development activity (see Figure 33) started in 1997, with system design of user services and review of system control levels for AHS-i and AHS-c. In 1998, studies were conducted regarding the logical and physical architectures of the system for designing the principal safety services. From then on, system design for a number of combinations of the principal safety services was implemented.


Figure 34. System Development (Principal Research and Achievements in 1999)


In 1999 (see Figure 34), research focused on the development of a standard AHS system, and on the design and production of a functional proving tests system. With regard to issues relating to the entire system, design indicators concerning safety and reliability were developed, and analysis of factors affecting system configuration was executed and applied in system design. Furthermore, the greatest achievement was determining how to achieve the vitally important integration of the ITS system architecture with the AHS system. Design of a functional proving tests system has been completed, and work is now at the final stage of installation and adjustment at the test grounds.


Figure 35. Development of Element Technology (Chronology)


In order to develop element technology (see Figure 35), studies concerning the performance of a variety of existing sensors around the world were conducted from the start of research, in order to define the direction of research and identify the relevant issues. In 1997, AHS-i and AHS-c targets were established. An algorithm for each sensor was developed, and systems were selected based on the goals. In 1998, systems for safety services were selected and improved. When the requirements were finalized in 1999, research regarding commercialization began. From a macro-perspective, we have been able to achieve performance for commercialization in 2003 as the target. Specifically, performance of road surface sensors and road condition sensors has been confirmed for nighttime and daytime driving, including under inclement weather conditions. Cruise assist information systems, including the simulation of actual road environments, is now being examined regarding data-processing algorithms based on models covering a number of vehicles. As for lane markers, research is under way concerning the commercialization of markers for use in vehicle-position detection and the provision of information services. With regard to the information-communication system, radio communication requirements and limits have been identified. With regard to test evaluations, production was conducted in 1997 chiefly on developing test-evaluation tools, such as the development of a simulator and data-gathering vehicle. In 1998, the evaluation system was completed, and the completed simulator was employed for use in refining and evaluating AHS system requirements. In 1999, the evaluation content of the proving tests was determined concretely with regard to the design and adjustment of requirements for equipment necessary for proving tests and evaluation.


Figure 36. Test Evaluation (Principal Contents and Achievement of Research in 1999)


In evaluation of simulation (see Figure 36), a simulator was utilized to help evaluate the viability of the system design. A car-driving simulator was used to gather data regarding the behavior of drivers, including elderly drivers. Road traffic environment data regarding vehicle behavior at curves and at junctions was gathered under actual traffic conditions. Also, driver acceptance of information services, timing, and service methods was evaluated. With regard to safety and reliability, a method for evaluating FT-map production was developed. For evaluations under real-life conditions, enormous amounts of data must be gathered in the tests. For this reason, in order to evaluate the performance of infrastructural features, requirements have been defined and designed for devices to gather and evaluate test data, test vehicles, and so on. With regard to safety standards and the facility-use plan that are needed in implementing proving tests, the basic items have been identified, and evaluation indices for each service have been developed and organized in an evaluation plan.



4. Plans for Future Research


Figure 37. Issues concerning Commercialization


AHSRA is scheduled to complete its five-year plan in FY2000. Although study is now under way as to whether AHSRA will be continued in the future, the direction of future research is discussed below. A number of issues must be resolved in order to realize Cruise Assist Systems (see Figure 37). There are problems, particularly in the area of technology, in developing a system that is able to withstand all environments, such as frigid areas and other locales with extreme environmental conditions, difficult road conditions, and so on. There also are issues relating to the vehicle, the infrastructure, and the broader application of services with Smartway and the like in the future. In the future, issues concerning not only the human behavior inside the vehicle, but also the human interface with roadside display boards and the like are expected to become very important. There also are issues relating to the social environment, such as the acceptance of an AHS system by drivers and by society in general, how to prevent driver overconfidence and a decline in awareness and alertness, driver education, the division of responsibility between the driver and the system, and international and domestic standards. The guidance and support of many persons and organizations in our efforts to resolving these issues are essential.


Figure 38. Applications of the AHS and Smartway


One direction that future efforts can take concerns the application of our research results in various ways (see Figure 38). Applications of the various systems that have been developed, such as sensors, lane markers, road-to-vehicle communication systems, and network systems are shown as follows. One such application concerns road traffic control (see Figure 39). Because lane markers function normally even when covered by snow, the application of lane markers, road surface sensors, and beacons for safer and more efficient snow plowing is possible. Another application concerns pedestrian services that recently have been attracting attention (see Figure 40).With the use of pedestrian-lane markers for the disabled, services aimed at promoting greater efficiency and comfort for pedestrians are becoming possible. Applications in this area will be studied in earnest.


Figure 39. Examples of Applications relating to Traffic Control



Figure 40. Applications relating to Pedestrian Services



Figure 41. Integration, Coordination, Cooperation, and Competition

Last, new relations in various areas relating to actualizing Cruise Assist Systems will be described briefly. New relations among the industry, academia, and governmental sectors-relations that transcend areas and industries such as telecommunications, electronics, and vehicles-will become necessary. Internationally, coordination will be necessary, chiefly among Japan, Europe, and the United States. We believe that building new relation in integration, coordination, and competition amid cooperation will become vitally important in making Cruise Assist Systems a reality.