Systems and methods for controlling road traffic in a traffic light controlled intersection

Abstract

According to one aspect, the present description relates to a system for controlling road traffic, the system comprising an intersection controller (110) configured to transmit electrical signals to optical units (21A, 22A, 23A) of traffic lights at the intersection, the electrical signals resulting from control signals, a transmitter (120) configured to transmit, to connected vehicles, messages configured to inform of an assumed state of at least one optical unit, and a safety module (130). The safety module comprises a receiver (135) configured to receive, via wireless link, each message transmitted by the transmitter (120); a measurement unit configured to determine, simultaneously on receiving the message, an actual state of the at least one optical unit; and a processing unit configured to generate an inconsistency signal in the event of a difference between the assumed state and the actual state of the at least one optical unit.

Description

[0001] Traffic control systems and processes at a signalized intersection

[0002] Technical field of the invention

[0003] The invention relates to systems and methods for controlling road traffic in a signalized intersection and applies in particular to traffic control in the presence of connected vehicles.

[0004] State of the art

[0005] Connected vehicles, particularly autonomous driverless vehicles, need to know the status of traffic lights to determine whether they can proceed through a signalized intersection. This information is transmitted in a known manner by traffic light controllers via a secure wireless link. This link notably uses Vehicle-to-Infrastructure (V2I) technology, where V2I is an abbreviation for "Vehicle-to-Infrastructure." The V2I wireless link may include, for example, Dedicated Short Range Communication (DSRC), which is part of the IEEE 802.11 WLAN family of standards and is known in the United States as Wireless Access in Vehicular Environments (WAVE) and in Europe as ITS-G5.The V2I wireless link can also be based on the mobile telephone network such as "cellular V2X" also known as C-V2X.

[0006] Regardless of the wireless communication technique used, the aim is to ensure that the information transmitted to connected vehicles is not erroneous.

[0007] US patent 11,521,486 [Ref. 1] describes in general terms traffic control systems and methods. Fig. 1 reproduces, as an example, a diagram of a traffic control system as described in [Ref. 1].

[0008] In such a traffic control system, a traffic controller 84, also called an intersection controller, is connected to a data aggregator 82, for example, by an electrical connection 87 such as, for example, a copper wire, an aluminum wire, or a fiber optic cable. The intersection controller 84 is also connected to a roadside unit 70 (or "RSU") by means of an electrical connection 72, and the RSU 70 is connected to the data aggregator 82 by means of an electrical connection 74, for example, a metallic connection or an optical connection. The RSU 70 has an antenna 60 configured to transmit a signal in the cloud 64 to a receiving antenna 66, which is connected to the data aggregator 82.Here, the "cloud" 64 can include a system configured to communicate with a central control facility, automobiles, buses, drones, other traffic light controllers, other data aggregators, etc. In operation, the intersection controller 84 transmits a dedicated Global Positioning System (GPS) signal for Digital Signal Crossing Response (DSRC) to the RSU 70, which in turn transmits a signal to the cloud 64, which transmits a signal to the receiver 66, which receiver 66 transmits the signal to the data aggregator 82. The RSU 70 also transmits the signal to the aggregator 82 in a wired feedback configuration via the electrical interconnect 74. The data aggregator 82 compares the wired feedback signal 74 with the wireless signal transmitted from the RSU 70 to the cloud.If there is a discrepancy between the wired signal 74 received by the data aggregator 82 and the wireless signal received by the data aggregator 82, the data aggregator 82 generates a comparison signal indicating the discrepancy or error. This comparison signal can serve as a fault indicator or error signal and can be transmitted to the intersection controller 84 to indicate that an error detection or event mismatch has occurred. The intersection controller 84 can then transmit a signal to the cloud 64 indicating that the intersection should be placed in "flash mode," where all traffic lights display a flashing signal to ensure intersection safety. Such a traffic control system is particularly advantageous in the event of malicious signal spoofing.

[0009] EP 3564922A1 [Ref. 2] also describes a system and method for detecting errors or mismatches of events in a traffic control system for a signalized intersection. However, the system described does not apply to an intersection where connected vehicles are circulating.

[0010] One objective of this description is to propose a road traffic control system that further improves the safety of the intersection, particularly an intersection where connected vehicles circulate.

[0011] Summary of the invention

[0012] In this description, the term "include" has the same meaning as "include" or "contain," and is inclusive or open-ended, not excluding other elements not described or depicted. Furthermore, in this description, the terms "approximately" or "substantially" are synonymous with (meaning the same as) a margin of error of 10% or more, for example, 5%, of the respective value.

[0013] According to a first aspect, the present description relates to a road traffic control system for at least one first intersection comprising a set of lights, the control system comprising: at least one first intersection controller for the control of the lights of said first intersection, each light comprising a plurality of optical units each configured to emit an optical signal of a different color, the first intersection controller being configured to transmit electrical signals to said optical units by means of electrical control lines for the control of the optical signals, said electrical signals resulting from first control signals;a transmitter configured to transmit to one or more connected vehicles moving in the first intersection, via wireless link, at least the first messages with a given periodicity, each first message being configured to inform said connected vehicle(s) of a supposed state of at least one optical unit of at least one light, the supposed state being determined by said first control signals; and at least one first safety module comprising: a receiver configured to receive, via wireless link, each first message transmitted by said transmitter; a measuring unit configured to determine simultaneously upon receipt of each first message configured to inform of a supposed state of at least one optical unit of at least one light, an actual state of said at least one optical unit, by means of a measurement of a current signal and / or a voltage signal on the electrical control line of said at least one optical unit;a processing unit configured to generate an inconsistency signal in case of a difference between the assumed state and the actual state of said at least one optical unit.;

[0014] Thus, in a safety module of a road traffic control system, according to the first aspect, the receiver receives a message identical to that received by the connected vehicle(s). The message is configured to indicate the assumed state of at least one optical unit of at least one traffic light. To this end, the message is determined based on the control signals that generate the electrical signals transmitted to said at least one optical unit for controlling the optical signals. Furthermore, the measuring unit is configured to simultaneously determine, upon receiving this message, the actual state of said at least one optical unit. Simultaneous determination means that the latency between measuring the actual state of said at least one optical unit and receiving the message indicating the assumed state is less than 500 ms, advantageously less than 300 ms, and advantageously less than 100 ms.

[0015] In practice, in exemplary embodiments, the initial control signals are defined according to a sequence that specifies the times at which the electrical signals are transmitted to the optical units and the transmission durations of these signals, based on the desired duration of the corresponding optical signal transmission. The first messages are transmitted to the connected vehicles and the receiver of the safety module, in exemplary embodiments, with a predetermined periodicity. For example, the first messages are transmitted at time intervals ranging from approximately 100 ms to approximately 500 ms. In exemplary embodiments, the latency between measuring the actual state of at least one optical unit and receiving the message reporting the assumed state is less than the time interval between the transmission of two messages.

[0016] The applicant has shown that the safety module according to the first aspect ensures that the status information of one or more traffic lights transmitted to connected vehicles—that is, the optical signal emitted by the optical unit(s) of said traffic light(s) (e.g., "red light," "green light")—is rigorously identical to the visual information delivered by said traffic light(s). Thus, the safety module according to the first aspect, as in the prior art described in [Ref. 1], ensures the integrity of a transmitted message, but also identifies any inconsistency between the information from said traffic light(s) transmitted to connected vehicles and the visual information corresponding to the actual state of said traffic light(s). An inconsistency can occur, in particular, in the event of excessive latency (e.g.,greater than approximately 500 ms) between the transmission of information to connected vehicles about the state of the lights and the transmission of electrical signals to control the state of the lights.

[0017] In a road traffic control system according to the first aspect, the transmitter is, for example, an electronic communication card for wireless communication connected to an antenna. In exemplary embodiments, the first messages transmitted by the transmitter via wireless link are SPaT messages (Signal Phase and Timing) indicating the assumed state of at least one optical unit. An SPaT message is defined by the ETSI TS 103 301, ISO / TS 19091, and SAE J2735 standards. In exemplary embodiments, each first message is configured to inform the connected vehicle(s) of the assumed state of each optical unit of a plurality of optical units of at least one traffic light.The measurement unit is then configured to simultaneously determine, by means of a measurement of a current signal and / or a voltage signal on the electrical control line of each optical unit of said plurality of optical units, a real state of each optical unit and the processing unit is configured to generate said inconsistency signal in case of difference between the assumed state and the real state of at least one optical unit of said plurality of optical units.

[0018] According to one or more embodiments, the processing unit of the safety module is configured to transmit the inconsistency signal to the first intersection controller in order to switch the first intersection to a safe state and / or to stop the transmission of the first messages by the transmitter. A "safe state" of the intersection is, for example, a state in which the lights are flashing yellow or a state in which the lights are off. By stopping the transmission of the first messages by the transmitter, the connected vehicles enter a so-called "degraded mode" in which they no longer receive status information from the optical units.

[0019] According to one or more embodiment examples, the security module receiver includes an electronic communication board for wireless link connected to an antenna.

[0020] According to one or more embodiment examples, said first safety module is external to the first intersection controller, that is to say that the entire receiver, measuring unit and processing unit are arranged in a box external to a box in which the first intersection controller is arranged.

[0021] According to one or more embodiment examples, the first safety module is integrated, or at least partially integrated, into the first intersection controller, that is to say that all or part of the components forming the first safety module are arranged in the housing in which the first intersection controller is arranged.

[0022] For example, in some embodiments, the measuring unit configured to determine the actual state of the optical unit(s) is a component of the first junction controller. Generally, the transmitter is configured to receive the first control signals for determining the assumed state of at least one optical unit via a wired connection, for example, through electrical or optical connections.

[0023] According to one or more exemplary embodiments, the first junction controller is configured to transmit, via a wired connection, the first control signals to the transmitter for determining the assumed state of at least one optical unit. The wired connections are, for example, electrical or optical connections.

[0024] In some embodiments, the transmitter may include an electronic board integrated into the intersection controller, i.e., housed in the same enclosure as the intersection controller, said enclosure being located near the first intersection. The transmitter may share a common power supply with the intersection controller.

[0025] In other embodiments, the transmitter can be an external component of the intersection controller, dedicated to wireless communication with connected vehicles. In these examples, the transmitter is located outside the intersection controller housing. For example, it is mounted on the intersection itself. According to one or more embodiments, the first intersection controller is configured to generate at least some of the first control signals.

[0026] Thus, in some implementation examples, all the initial control signals are generated by the first junction controller. For example, the control signals are generated according to a pre-established timing schedule that defines the sequence of control signals. This sequence defines when the electrical signals are transmitted to the optical units and their durations.

[0027] According to one or more exemplary embodiments, the road traffic control system further includes a centralized traffic management unit, and at least some of the initial control signals are generated by this centralized traffic management unit. As before, the control signals can be generated according to a pre-established timing schedule defining the sequence and duration of the control signals.

[0028] The initial control signals generated by the centralized traffic management unit are then transmitted via wired connection to the first junction controller for the control of the optical signals from the optical units. In some embodiments, the wired connections are made using electrical or optical connections.

[0029] In some embodiments, only some of the initial control signals are generated by the central traffic management system, and the first intersection controller is configured to generate the remaining initial control signals based on the initial control signals received by the central traffic management system. For example, the central traffic management system is configured to transmit the control signal for the green optical unit of the traffic light to the intersection controller. The control signals for the other optical units can then be generated by the intersection controller.

[0030] In implementation examples, the first set of control signals is generated by the centralized traffic management unit and transmitted via wired link to the first intersection controller.

[0031] In some embodiments, said centralized traffic management unit is configured to transmit said transmitter, via wired link, said first control signals for determining the supposed state of said at least one optical unit.

[0032] According to one or more embodiment examples, the first safety module is configured to transmit said inconsistency signal to said first intersection controller and said first intersection controller is configured to transmit said inconsistency signal to said centralized traffic management unit, said centralized traffic management unit being configured to in turn transmit an alert signal to the first intersection controller in order to switch the intersection to a safe state and / or to stop the transmission of messages by the sender.

[0033] In some embodiment examples, the centralized traffic management unit is configured to generate second control signals which are transmitted via wired link to a second junction controller at a second junction.

[0034] According to one or more embodiments, the transmitter is configured to also transmit, via wireless link, second messages at a given interval. Each second message is configured to inform one or more connected vehicles of the assumed state of at least one optical unit of at least one traffic light at the second intersection, the assumed state being determined by said second control signals. In some embodiments, the transmitter receives control signals from the central traffic management system for the transmission of each first and second message. In some embodiments, the first and second messages each incorporate geolocation data for the traffic lights, i.e., they contain information relating to their GPS position.

[0035] In exemplary embodiments, the road traffic control system includes said second intersection controller for the control of lights of said second intersection and a second safety module configured to receive every second message by wireless link, simultaneously determine, by means of a measurement of a current signal and / or a voltage signal on the electrical control line of at least one optical unit of a light of the second intersection, an actual state of said at least one optical unit and generate an inconsistency signal in case of difference between the assumed state and the actual state of said at least one optical unit.

[0036] According to one or more exemplary embodiments, the centralized traffic management unit is configured to generate said first control signals and transmit them by wire link to the first junction controller, and is configured to generate second control signals and transmit them by wire link to the second junction controller of the second junction; the transmitter receives the first and second control signals from the centralized traffic management unit for the transmission of the first and second messages.

[0037] According to one or more embodiment examples, the system according to the first aspect further comprises a centralized traffic management unit and said first control signals are generated by said first intersection controller and transmitted by wired link to said centralized traffic management unit.

[0038] In some embodiments, the centralized intersection management unit is configured to transmit to said transmitter, via wired link, said first control signals for determining the supposed state of said at least one optical unit.

[0039] In examples of embodiments: said centralized traffic management unit is configured to receive further, via wired link, at least second control signals generated by at least one second intersection controller of a second intersection; the transmitter is configured to transmit further, via wireless link, second messages with a given periodicity, each second message being configured to inform one or more connected vehicles of a supposed state of at least one optical unit of at least one light of the second intersection, the supposed state being determined by said second control signals; the centralized intersection management unit is configured to transmit further, to said transmitter, via wired link, said second control signals for the determination of the supposed state of said at least one optical unit.

[0040] According to one or more embodiments, the first intersection controller is configured to generate the first control signals, and the second intersection controller at the second intersection is configured to generate second control signals. The central traffic management unit is configured to receive, via wired connection, the first control signals generated by the first intersection controller and is configured to receive, via wired connection, the second control signals generated by the second intersection controller. The transmitter then receives the first and second control signals from the central intersection management unit to transmit the first and second messages.

[0041] According to a second aspect, the present description relates to a method of controlling road traffic at at least one first intersection, implemented by a road traffic control system according to the first aspect.

[0042] More specifically, said first intersection comprising a set of lights, each light comprising a plurality of optical units each configured to emit an optical signal of a different color, the method comprises: the transmission, by a first intersection controller, of electrical signals to said optical units by means of electrical control lines for the control of optical signals, said electrical signals resulting from first control signals; the transmission to one or more connected vehicles moving in the first intersection, by wireless link, by means of a transmitter, of first messages with a given periodicity, each first message being configured to inform said connected vehicle(s) of a supposed state of at least one optical unit of at least one light, the supposed state being determined by said first control signals; the reception of each first message by a first safety module;Simultaneously with the said reception of the said first message, the determination, by the said first safety module and by means of a measurement of a current signal and / or a voltage signal on the electrical control line of the said at least one optical unit, of a real state of the said at least one optical unit; the generation, by the said first safety module, of an inconsistency signal in case of a difference between the supposed state and the real state of at least one optical unit.

[0043] Brief description of the figures

[0044] Other features and advantages of the invention will become apparent from the following description, illustrated by the following figures:

[0045] Fig. 1 (already described) represents a diagram of a known state-of-the-art traffic control system;

[0046] Fig. 2 is a diagram illustrating a first example of a road traffic control system according to the present description;

[0047] Fig. 3 is a diagram illustrating a second example of a road traffic control system according to the present description;

[0048] Fig. 4 is a diagram illustrating in more detail elements of an example of a road traffic control system according to this description;

[0049] Fig. 5 is a diagram illustrating in more detail an example of measuring the actual state of an optical unit using a safety module as described herein;

[0050] Fig. 6A is a diagram illustrating a third example of a road traffic control system according to the present description;

[0051] Fig. 6B is a diagram illustrating a fourth example of a road traffic control system according to this description.

[0052] Detailed description

[0053] In the figures, the elements are not drawn to scale for better visibility. Fig. 2 is a diagram illustrating a first example of a traffic control system 100 according to this description. In the example in Fig. 2, the system 100 is configured for traffic control at an intersection 10 comprising a set of traffic lights. In Fig. 2, four traffic lights 20A, 20B, 20C, 20D are shown, but of course, there may be fewer or more; moreover, the set of lights may include lights for motor vehicles, bicycles, pedestrians, etc. Each traffic light comprises a plurality of optical units (21A, 22A, 23A), each configured to emit a different colored optical signal, for example, red, green, yellow. Thus, in Fig.2. Light 20A comprises a plurality of three optical units 21A, 22A, 23A; light 20B comprises a plurality of three optical units 21B, 22B, 23B; light 20C comprises a plurality of three optical units 21c, 22c, 23c; light 20D comprises a plurality of three optical units 21D, 22D, 23D. Of course, each light can comprise a greater or lesser number of optical units.

[0054] As illustrated in Fig. 2, the road traffic control system 100 includes a junction controller 110 for controlling the traffic lights at junction 10. The junction controller 110 is configured to transmit electrical signals to the optical units via control lines referenced 30A, 30B, 30C, and 30D, respectively, for controlling the optical signals. These electrical signals are derived from control signals. For example, the control signals are generated by the junction controller 10. The control signals are generated according to a pre-established timing schedule that defines the sequence of control signals. This sequence defines when the electrical signals are transmitted to the optical units and their durations, typically a few tens of seconds.

[0055] The road traffic control system 100 further includes a transmitter 120 configured to transmit to one or more connected vehicles 50 moving in the intersection 10, by wireless link, messages with a given periodicity, each message being configured to inform said connected vehicle(s) 50 of a supposed state of at least one optical unit of at least one light, the supposed state being determined by said control signals.

[0056] The message is, for example, a SPaT message (acronym for the Anglo-Saxon abbreviation "Signal Phase and Timing"). Each message can include information relating to a supposed state of one or more optical units of one or more lights.

[0057] The transmitter 120 is configured for wireless transmission, for example, short-range transmission (or DSRC, for "Dedicated Short Range Communication"), which is part of the IEEE 802.11 WLAN family of standards and is known in the United States as "Wireless Access in Vehicular Environments" (WAVE) and in Europe as ITS-G5. The V2I wireless link can also be based on the mobile phone network, such as "cellular V2X," also known as C-V2X. As illustrated in Fig. 2, the transmitter may include an electronic board integrated into the intersection controller, i.e., housed in the same enclosure as the intersection controller. This enclosure is generally located near the first intersection, i.e., at a distance of less than 100 meters. In some embodiments, the transmitter may share a common power supply with the intersection controller.

[0058] In this example, the intersection controller transmits the control signals to the transmitter via a wired connection. Wired connections include, for example, electrical or optical connections.

[0059] In general, wired connections, such as electrical or optical connections, will be represented in the figures as solid lines, and wireless connections as dashed lines. The road traffic control system 100 also includes a safety module 130 configured to generate an inconsistency signal in the event of a difference between the assumed state and an actual state of at least one optical unit, as will be described in more detail later.

[0060] Figure 3 is a diagram illustrating a second example of a road traffic control system as described herein. The road traffic control system 200 described in Figure 3 is substantially similar to the road traffic control system 100 described in Figure 2, and the components are not detailed again.

[0061] Unlike the 100 traffic control system, in the example of the 200 traffic control system described in Fig. 3, the transmitter 120 is an external component of the intersection controller, dedicated to wireless communication with connected vehicles, such as a roadside unit (RSU). The roadside unit is equipped with wireless communication technology, such as dedicated short-range communication (DSRC) or C-V2X communication. The roadside unit is located outside the housing that contains the intersection controller. It can, for example, be mounted on a traffic light, signpost, or other intersection infrastructure.

[0062] As before, the intersection controller 110 is configured to transmit the initial control signals to the transmitter 120 via a wired connection. Wired connections include, for example, electrical or optical connections. Fig. 4 is a diagram illustrating in more detail a safety module 130 of a road traffic control system as described herein and its operation with the intersection controller 110 and the transmitter 120.

[0063] In the example shown in Fig. 4, only two traffic lights, 20A and 20B, are illustrated. The intersection controller 110 includes, for example, a power relay 112 connected to a power supply 105. The intersection controller 110 also includes, in this example, a processor 116, or CPU (Central Processing Unit), in which the control signals are programmed according to a pre-established time schedule, and a switching board 114 configured to supply the control lines 30A and 30B to the optical units of the traffic lights 20A and 20B, respectively, based on the control signals received from the processor 116. Thus, for example, in the example shown in Fig. 4, each control line 30A and 30B includes a plurality of connecting wires, for example, four connecting wires in this example, to supply each optical unit of a traffic light. In the example in Fig.4, we have thus illustrated the connecting wires 31A, 32A, 33A, 34A to connect respectively the optical units 21A, 22A, 23A (Fig. 2), the last connecting wire 34A being the common potential.

[0064] In some embodiments, the switching card 114 of the controller 110 can send the processor 116 a real state of the optical units. In case of an inconsistency between the real state of an optical unit and the assumed state corresponding to the control signal, the processor 116 can transmit a signal to the power relay 112, for example, to cut off the power supply and turn off the traffic lights at the intersection.

[0065] The security module 130 includes a receiver 135 configured to receive, via wireless link, the message transmitted by the transmitter 120. The receiver includes, for example, an electronic communication card for wireless link connected to an antenna.

[0066] The security module also includes a measuring unit 133 and a processing unit 137.

[0067] The measuring unit 133, an example of which is described in more detail in Fig. 5, is configured to determine simultaneously upon receipt of the message, a real state of the optical unit(s), by means of a measurement of a current signal and / or a voltage signal on the electrical control line of said at least one optical unit.

[0068] The processing unit 137 is configured to generate an inconsistency signal in case of a difference between the assumed state and the actual state of said at least one optical unit.

[0069] For example, as illustrated in Fig. 4, the processing unit 137 is configured to transmit the inconsistency signal to the intersection controller 110 in order to switch the intersection to a safe state. A "safe state" of the intersection is, for example, a state in which the lights are flashing yellow or a state in which the lights are off. More specifically, in embodiments such as that illustrated in Fig. 4, the inconsistency signal can be transmitted directly to the power relay 112 to cut off the power supply and turn off the intersection lights.

[0070] In other embodiments, the processing unit 137 can be configured to transmit the said inconsistency signal to the junction controller 110 in order to stop the transmission of messages by the transmitter 120. The inconsistency signal can then be transmitted to the processor 116.

[0071] Thus, in a safety module according to the first aspect, the receiver receives a message identical to that received by the connected vehicle(s). The message is configured to indicate the assumed state of at least one optical unit of at least one traffic light. To this end, the message is determined based on the control signals that generate the electrical signals transmitted to said at least one optical unit for controlling the optical signals. Furthermore, the measuring unit is configured to simultaneously determine, upon receiving this message, the actual state of said at least one optical unit. Simultaneous determination means that the latency between measuring the actual state of said at least one optical unit and receiving the message indicating the assumed state is less than 500 ms, advantageously less than 300 ms, and advantageously less than 100 ms.Advantageously, in exemplary embodiments, the latency between measuring the actual state of at least one optical unit and receiving the message reporting the assumed state is less than the time interval between the transmission of two messages. Messages can indeed be transmitted to the connected vehicles and the receiver of the safety module, in exemplary embodiments, with a predetermined periodicity. For example, messages are transmitted at time intervals ranging from approximately 100 ms to approximately 500 ms.

[0072] The applicant has shown that the safety module according to the first aspect makes it possible to ensure that the status information of one or more lights transmitted to connected vehicles, i.e. the optical signal emitted by the optical unit(s) of said light(s) (e.g. "red light", "green light"), is rigorously identical to the visual information delivered by said light(s).

[0073] Indeed, the safety module identifies any inconsistency between the information from the traffic lights transmitted to connected vehicles and the visual information corresponding to the actual state of the lights. An inconsistency can occur, in particular, in the event of excessive latency (e.g., greater than approximately 500 ms) between the transmission of information to connected vehicles about the status of the traffic lights and the transmission of electrical signals to control the status of the lights. An inconsistency can also occur in the event of an intrusion into wireless communications (e.g., a cyberattack). When using a roadside unit to transmit messages (Fig. 3), an inconsistency can also occur in the event of signal degradation between the intersection controller 110 and the roadside unit 120, or in the event of an intrusion.

[0074] Fig. 5 is a diagram illustrating in more detail an example of measuring the actual state of an optical unit using a safety module as described herein.

[0075] As illustrated in Fig. 5, the measuring unit 133 in this example is configured to measure, firstly, the current intensity on each connecting wire 31A, 32A, and 33A for the electrical connection of the optical units 21A, 22A, and 23A of the 20A light. This measurement is represented by the ammeter A. The measuring unit 133 in this example is also configured to measure the voltage between each connecting wire 31A, 32A, and 33A and the common potential (connecting wire 34A). This measurement is represented by the voltmeter V. A combination of current and voltage measurements allows for a precise determination of the actual state of the 20A optical unit. Of course, this measurement method is not exhaustive.Note that in the examples illustrated in the figures, the safety module 130 is represented as being external to the intersection controller 110, that is to say that the entire receiver, measuring unit and processing unit are arranged in a box outside the box in which the intersection controller is arranged.

[0076] However, other embodiments are possible. In particular, the safety module 130 can be integrated, or at least partially integrated, into the intersection controller 110; that is, all or part of the components forming the safety module are arranged within the housing containing the intersection controller. For example, the measuring unit 133 can be a measuring unit already included in the intersection controller. Fig. 6A is a diagram illustrating a third example of a road traffic control system 300 according to this description, configured to control road traffic at a first intersection 10A and at least one second intersection (not shown). The first intersection 10A is, for example, similar to intersection 10 in Fig. 2. It is controlled by an intersection controller 110A.A safety module 130A, as described previously, generates an inconsistency signal if there is a difference between the assumed state of at least one optical unit transmitted to a connected vehicle 50A moving through the intersection 10A and the actual state of said at least one optical unit. In the example shown in Fig. 6A, the road traffic control system 300 further includes a centralized traffic management unit 150, at least some of the initial control signals being generated by the centralized traffic management unit 150 and transmitted via wired connection to said first intersection controller 110A.

[0077] As illustrated in Fig. 6A, the centralized traffic management unit 150 is further configured to generate second control signals which are transmitted via wired link to a second junction controller 110B of the second junction.

[0078] In some embodiments, only some of the first and second control signals are generated by the central traffic control unit 150. The first intersection controller 110A is configured to generate the remaining first control signals based on the first control signals received by the central traffic control unit 150, and the intersection controller 110B is configured to generate the remaining second control signals based on the second control signals received by the central traffic control unit 150. For example, the central traffic control unit is configured to transmit the control signal for the green optical unit of the traffic light to the intersection controller. The control signals for the other optical units can then be generated by the intersection controller.Transmitter 120 is configured in this example to also transmit, wirelessly, second messages to connected vehicles moving in the second intersection. As shown in Fig. 6A, transmitter 120 receives the first and second control signals from the central traffic management unit for the transmission of these messages. Also shown in Fig. 6A, the first and second control signals are transmitted by the central traffic management unit 150 to transmitter 120 via a wired connection (solid line).

[0079] In some implementation examples, the first and second messages each incorporate geolocation data for the traffic lights, meaning they contain information about their GPS position. Thus, connected vehicles moving through the first intersection (10A) will only need to consider messages related to the traffic lights at that intersection, and connected vehicles moving through the second intersection will only need to consider messages related to the traffic lights at that intersection.

[0080] Transmitter 120 is advantageously a long-range wireless communication module. It is configured, for example, for transmitting messages using long-range cellular technology, such as 4G or 5G. As before, the safety module 130A identifies any inconsistency between the traffic light status information transmitted to connected vehicles and the corresponding visual information reflecting the actual status of the traffic light(s). An inconsistency can occur, in particular, due to latency between the transmission of traffic light status information to connected vehicles via transmitter 120 and the transmission of electrical signals to control the traffic light status. An inconsistency can also occur in the event of an intrusion into wireless communications (e.g., a cyberattack) or in the event of signal degradation or intrusion between the transmitter of the central traffic management unit 120 and the intersection controller 110A.

[0081] Fig. 6B is a diagram illustrating a fourth example of a road traffic control system 400 according to this description, configured to control road traffic from a first junction 10A and at least a second junction (not shown).

[0082] The road traffic control system 400 is substantially similar to the road traffic control system 300 illustrated in Fig. 6A.

[0083] In this example, however, the first junction controller 110A is configured to generate the first control signals, and the second junction controller 110B (not shown) is configured to generate the second control signals. The central traffic management unit 150 is configured to receive, via a wired connection, the first control signals generated by the first junction controller and the second control signals generated by the second junction controller. The transmitter 120 then receives the first and second control signals from the central junction management unit 150 for the transmission of the first and second messages. As illustrated in Fig. 6B, the first and second control signals are transmitted by the central traffic management unit 150 to the transmitter 120 via a wired connection (solid line).

[0084] As before, the 130A safety module identifies any inconsistency between the information from the traffic lights transmitted to the connected vehicles 50A moving through the first intersection and the visual information corresponding to the actual state of the traffic lights. An inconsistency can occur, in particular, in the event of latency between the transmission of information on the status of the traffic lights to the connected vehicles via the transmitter 120 and the transmission of the electrical signals to control the status of the traffic lights. An inconsistency can also occur in the event of an intrusion into wireless communications (e.g., cyberattack) or in the event of signal degradation or intrusion between the transmitter of the centralized traffic management unit 120 and the intersection controller 110A. In the examples in Fig. 6A and Fig.6B, the first safety module 130A can be configured to transmit to the first junction controller 110A said inconsistency signal if an inconsistency signal is generated, and the first junction controller can be configured to transmit the inconsistency signal to the centralized traffic management unit 150, said centralized traffic management unit being configured to in turn transmit an alert signal to the first junction controller, for example for switching the junction to a safe state.

[0085] Although described through a number of embodiment examples, the safety module, the system and the method of road traffic control according to this description include various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these various variants, modifications and improvements form part of the scope of the invention as defined by the following claims.

[0086] References

[0087] Ref. 1: US 2007 / 0195990

[0088] Ref. 2: EP 3564922A1

Claims

DEMANDS 1. A road traffic control system (100) for at least one first intersection (10) comprising a set of lights (20A, 20B, 20C, 20D), the system comprising: at least one first intersection controller (110, 110A) for the control of the lights of said first intersection, each light (20A) comprising a plurality of optical units (21A, 22A, 23A) each configured to emit an optical signal of a different color, the first intersection controller being configured to transmit electrical signals to said optical units by means of electrical control lines (30A) for the control of the optical signals, said electrical signals resulting from first control signals;a transmitter (120) configured to transmit to one or more connected vehicles (50) moving in the first intersection, by wireless link, first messages with a given periodicity, each first message being configured to inform said connected vehicle(s) (50) of a supposed state of at least one optical unit of at least one light, the supposed state being determined by said first control signals; and at least one first safety module (130) comprising: a receiver (135) configured to receive, by wireless link, each first message transmitted by said transmitter (120);a measuring unit (133) configured to determine simultaneously upon receipt of each first message configured to report a supposed state of at least one optical unit of at least one light, an actual state of said at least one optical unit, by means of a measurement of a current signal and / or a voltage signal on the electrical control line of said at least one optical unit; a processing unit (137) configured to generate an inconsistency signal in case of a difference between the supposed state and the actual state of said at least one optical unit.

2. A system according to claim 1, wherein: each first message is configured to inform said connected vehicle(s) (50) of a supposed state of each optical unit of a plurality of optical units of at least one traffic light, and the measuring unit (133) is configured to simultaneously determine, by means of a measurement of a current signal and / or a voltage signal on the electrical control line of each optical unit of said plurality of optical units, an actual state of each optical unit; the processing unit (137) is configured to generate said inconsistency signal in case of difference between the supposed state and the actual state of at least one optical unit of said plurality of optical units.

3. System according to any one of the preceding claims, wherein the processing unit (137) is configured to transmit said inconsistency signal to said intersection controller in order to switch the intersection into a safe state and / or to stop the transmission of messages by the sender.

4. System according to any one of the preceding claims, wherein the first intersection controller (110) is configured to generate at least a portion of said first control signals.

5. System according to any one of the preceding claims, wherein the first intersection controller (110) is configured to transmit said transmitter (120), by wired connection, said first control signals for determining the supposed state of said at least one optical unit.

6. System according to any one of claims 1 to 4, further comprising a centralized traffic management unit (150) and in which at least a part of the first control signals are generated by the centralized traffic management unit (150) and transmitted by wire link to said first intersection controller.

7. System according to claim 6, wherein the first intersection controller (110) is configured to transmit said transmitter (120), by wired link, said first control signals for determining the supposed state of said at least one optical unit.

8. System according to claim 6, wherein said centralized traffic management unit is configured to transmit said transmitter (120), via wired link, said first control signals for determining the supposed state of said at least one optical unit.

9. System according to any one of claims 6 to 8, wherein said first safety module (130) is configured to transmit said inconsistency signal to said first intersection controller and said first intersection controller is configured to transmit said inconsistency signal to said centralized traffic management unit (150), said centralized traffic management unit being configured to in turn transmit an alert signal to the first intersection controller in order to switch the intersection to a safe state and / or to stop the transmission of messages by the sender.

10. System according to any one of claims 6 to 9, wherein the centralized traffic management unit (150) is configured to generate second control signals which are transmitted by wire link to a second junction controller (110B) of a second junction.

11. System according to claim 10, wherein the transmitter (120) is configured to further transmit, via wireless link, second messages with a given periodicity, each second message being configured to inform one or more connected vehicles of a supposed state of at least one optical unit of at least one light of the second intersection, the supposed state being determined by said second control signals.

12. System according to any one of claims 1 to 4, further comprising a centralized traffic management unit (150) and wherein said first control signals are generated by said first junction controller (110) and transmitted by wired link to said centralized traffic management unit (150).

13. System according to claim 12, wherein the centralized intersection management unit is configured to transmit to said transmitter (120), by wired link, said first control signals for determining the supposed state of said at least one optical unit.

14. System according to any one of claims 12 or 13 wherein: said centralized traffic management unit is configured to further receive, via wired connection, at least second control signals generated by at least one second intersection controller of a second intersection; the transmitter (120) is configured to further transmit, via wireless connection, second messages with a given periodicity, each second message being configured to inform one or more connected vehicles of a supposed state of at least one optical unit of at least one light of the second intersection, the supposed state being determined by said second control signals; the centralized intersection management unit is configured to further transmit, to said transmitter (120), via wired connection, said second control signals for the determination of the supposed state of said at least one optical unit.

15. Method for controlling road traffic at at least one first intersection (10), said first intersection comprising a set of traffic lights (20A, 20B, 20C, 20D), each traffic light (20A) comprising a plurality of optical units (21A, 22A, 23A) each configured to emit an optical signal of a different color, the method comprising: the transmission, by a first intersection controller (110, 110A), of electrical signals to said optical units by means of electrical control lines (30A, 30B, 30c, 30D) for the control of the optical signals, said electrical signals resulting from first control signals; the transmission to one or more connected vehicles (50) moving in the first intersection, by wireless link, by means of a transmitter (120), of the first messages with a given periodicity, each first message being configured to inform said connected vehicle(s) (50) of a supposed state of at least one optical unit of at least one light, the supposed state being determined by said first control signals; the reception of each first message by a first safety module (130);Simultaneously with the said reception of the said first message, the determination, by the said first safety module and by means of a measurement of a current signal and / or a voltage signal on the electrical control line of the said at least one optical unit, of an actual state of the said at least one optical unit; the generation, by the said first safety module, of an inconsistency signal in case of a difference between the supposed state and the actual state of the said at least one optical unit.

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