Evolving AHS

Two Processes to Achieve Fully Automated Driving

The ultimate goal of AHS is a fully automated driving system, which would include platooning. There are two processes, A and B, that can be followed to achieve this. (See Fig. 1)
Process A emphasizes the idea of making the system available on as many roads as possible, rather than raising the control level of vehicle operations. And since its functional improvements can be made in stages, it is called an "evolutional process."
Process B will first apply a fully advanced system on given segments of the road system and use this as a model to gradually expand to other parts of the road system. Since this will require technological innovations, it is called an "innovative process."
AHS is an area of ITS in which R&D is being aggressively conducted by Japan, the U.S. and Europe. As was introduced on page 2 of this ITS-Review, a large-scale AHS demonstration dubbed "DEMO '97" was held in San Diego, U.S.
The demonstration itself was a great success, but it also revealed that there was still much to be discussed in terms of the purpose of AHS, its concept, work-sharing between vehicles and the infrastructure, and the pros and cons of dedicated lanes. Also in terms of its definition, as for some AHS denotes a fully automated driving, while for others it means a wide range of driving assistance features which even in-corporate collision prevention systems.
In this respect, the theme " AHS evolution" of the AHS Research Association's exhibit drew a great deal of interest as a development strategy. We would like to examine what AHS is in the light of our definition.


"DEMO'97"
An exhibit by the Ministry of Construction and the AHS Research Association
The "ica" display which represented the "AHS evolution" attracted many visitors

Fig. 1

Evolutional Process

If we consider safety to be the primary purpose of AHS, process A, in which functional developments can be made in stages and in various ways, without necessarily adhering to the principle of automated driving, would be effective and easy to deploy on all roads.
In process A, or the evolutional process, AHS can be classified into three subsystems according to specific functions for assisting driving.(See Fig. 2)
AHS-i (Information) is a system which supports some of the information gathering tasks. AHS-c (Control) is a system whereby the system not only supports information gathering, but some of the driving operations as well. And AHS-a (Automated cruise) is a system whereby the system does 100% of the information gathering and the driving operations, and even takes on the responsibility for safe driving.
To realize AHS-a , we must overcome a number of important hurdles, not just in terms of technology, but also in relation to the responsibilities it will bear for vehicle operations.

Fig. 2


Evolving AHS

AHS-iand AHS-cwill progress together. There are many levels of the driving support provided by these two systems, and there is continuous progress to be made in their evolution. Meanwhile, the functions of AHS-a are considered to be very different. A 99% automated AHS-c, although it may seem similar, is completely different from a 100% automated AHS-a, because the latter bears the whole responsibility for vehicle operations while the former does not.
The functional development of "išcša" will not progress simultaneously on all roads and vehicles. Those functions that require advanced infrastructures will at first only be used on given segments of the road system, and the services they provide will only be available to cars with compatible systems. Therefore, it is reasonable to foresee that AHS will evolve in stages in a segmented manner.
From these analyses, our conclusion is that AHS should be considered an evolutional process and that its functions should be developed in the išcša sequence.
Further, AHS development will also require international compatibility. International cooperation is crucial for efficient technological development and the realization of true interoperability from country to country.

Fig. 3


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