Communications: electrical – Traffic control indicator – Intersection normally under local controller
Reexamination Certificate
1999-03-03
2001-11-06
Trieu, Van T (Department: 2632)
Communications: electrical
Traffic control indicator
Intersection normally under local controller
C340S905000, C340S911000
Reexamination Certificate
active
06313757
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for traffic-dependent controlling of means for controlling traffic.
Traffic-dependent traffic controlling takes place today for example via traffic signal installations, alternating traffic signs, changeable parking space information signs or radio announcements. The traffic-dependent data is obtained via traffic detectors such as induction loops, radar detectors, or infrared detectors.
For example, given traffic signal installations as means for controlling traffic, the phase sequences or signal sequences thereof are determined by predetermined signal programs. The signal programs can thereby be varied according to the selected control method. Thus, in traffic-dependent control methods, e.g. the time duration of the individual phases, the sequence of the individual phases and the number of different phases (given need-related requests) in the signal program are changed. In time-of-day-dependent control methods, different signal programs, and thus different phase sequences, are switched at fixedly predetermined times of day (e.g. in peak traffic hours).
For the selection of the signal program or, respectively, for the selection of the phase duration, the sequence of phases or the number of phases, traffic-related characteristic quantities are evaluated that are determined using the traffic detectors. In the case of a signal program with fixed times, the characteristic quantities are converted off-line during the design processing. In the case of a signal program adaptation or signal program formation, the characteristic quantities are processed continuously, with the possibility of a controlling alternating between traffic flow and signal controlling. The momentary signal programs are thereby calculated on-line and evaluated according to a predetermined control logic, on the basis of respectively updated characteristic quantities. With the aid of traffic detectors, occupation values are detected in the spatial surroundings of the traffic signal installations, from which values characteristic quantities of the traffic flow are derived. Characteristic quantities include for example the wait time of the vehicles at the traffic signal installation, the length of the traffic queue at the traffic signal installation, the traffic heaviness, i.e. vehicles per cross-section, travel speed, signaling (request) by pedestrians, cyclists and/or vehicles, degree of occupation, traffic density, degree of capacity utilization and the load quotient. Given a traffic-dependent signal program selection, the prepared characteristic quantities of the traffic flow are combined in the control logic for the selection of the signal programs with conditional equations and threshold values.
From the reference “Richtlinien für Lichtsignalanlagen” ((RiLSA)—Lichtzeichenanlagen für den Stra&bgr;enverkehr—ed. 1992, published by the Forschungsgesellschaft für Stra&bgr;en- und Verkehrswesen, Arbeitsgruppe Verkehrsführung und Verkehrssicherheit, pp. 46 to 47, as well as Appendix D, pp. 90 to 110), it is known how control logics are represented using flow diagrams. The phases and phase sequences of the traffic signal installation that are useful for the traffic-dependent controlling are thereby shown in a phase sequence plan. The exchange between the phases is defined precisely and is shown in comprehensible fashion in the phase transition. A flow diagram contains the logical and chronological conditions for the duration of the phases and for the switching of the phase transitions, and thus completely represents the sequence of the traffic-dependent controlling. Logical conditions thereby hold for the combination of the characteristic quantities of the traffic flow, and chronological conditions predetermine the chronological context of the program sequences, such as for example minimal and maximal clearance times of a signal group given free circulation time. Only a single flow diagram is thereby to be represented for all signal programs. This single flow diagram becomes increasingly difficult to understand as the complexity of the control logic increases, and a translation of the conditions prescribed in the flow diagram into a traffic-oriented description that a control apparatus of a traffic signal installation can interpret becomes increasingly difficult.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for traffic-dependent controlling of means for controlling traffic, which are constructed so as to be able to be adapted to new traffic conditions with a low expense, and which permit simple conversion into a traffic-oriented specification.
In a common database data file there are stored the conditional equations, as well as actions that are to be executed upon a transition, located within a predetermined context, of a momentary state into an updated state better adapted to the momentary traffic flow, and rules that combine the conditional equations and the actions with one another. By means of this common storing in a predetermined database format, there results both an easily surveyable representation and also a common format for various changes between states.
In a preferred construction of the method, several database data files are combined with one another in order flexibly to handle complex sequences.
According to another embodiment, it is advantageously provided that fixed control hierarchies are constructed by means of predetermined processing sequences of various database data files.
The construction according to a further embodiment is particularly flexible, according to which the control hierarchies can be modified, in that within the database data files reference is made to database data files that do not follow directly in the processing sequence.
The method can advantageously be adapted to traffic conditions changed in this way, which can be taken into account only by means of a adaptation and/or selection of the control program located outside the predetermined context. The adaptation takes place in that the conditional equations, the rules and/or the actions of the database data files are modified and stored.
The method according to another embodiment can be adapted particularly well to the traffic conditions in that within the actions calculations are carried out whose results are taken into account in subsequent database data files of a processing sequence.
For traffic signal installations as means for controlling traffic, the momentary signal sequence (momentary signal program) as a momentary state is advantageously replaced by a further signal sequence (further signal program) as an updated state.
For traffic management systems as means for controlling traffic, the momentary control strategy as a momentary state is advantageously replaced by a further control strategy as an updated state.
The structure common to all database data files permits an implementation of the determination, described in the database data file, of the current control program by means of an algorithm that is common for all database data files.
A combination direction allocated to the actions is provided that, after the execution of the action, refers to a further database data file, in order advantageously to obtain, by means of a combination of database data files, an apparatus that is to be used flexibly for various traffic sequences.
In a further advantageous construction, in the database data files a combination direction to further database data files is contained, independent of the executed actions, whereby a fixed processing hierarchy of the database data files among themselves is achieved.
By means of the assembling of conditional equations by means of logical combinations of individual conditions and the logical combination thereof, complex control conditions can be combined in an easily surveyable, flexible manner.
For traffic signal installations as means for controlling traffic, the momentary signal sequence as a momentary state is advantageously replaced by a further si
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
Trieu Van T
LandOfFree
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