JP7304733B2 - signal controller - Google Patents

Description

The present invention relates to a signal control device with an internal clock.

A traffic control system is known that transmits and receives traffic data between a plurality of traffic control devices in order to control traffic equipment such as traffic signals. For example, the traffic control system includes a central device installed in a traffic control center, a signal control device that controls signal lights, and terminal devices such as vehicle detectors and optical beacons that acquire traffic data.

The central unit judges the presence or absence of vehicles based on the traffic data acquired by the terminal unit, determines signal control parameters, and transmits them to the signal control unit. The signal control device executes tier control of the signal lights based on the received signal control parameters. In a general signal control device, the tier control of signal lamps is not synchronized with the time. A signal control device that is not synchronized with time has a function of transmitting the time of the central device to the signal control device and correcting it using a communication line. A signal control device that performs time-synchronized control uses a communication line to access a time server installed in a traffic control center at regular intervals, and records the time stored in the internal clock (hereinafter also referred to as internal time). ) is modified.

On the other hand, there is known a stand-alone signal control device having a function of acquiring time information based on radio waves received by a GPS (Global Positioning System) antenna and correcting the internal time based on the time information. (See Patent Document 1, for example).

Japanese Patent Application Laid-Open No. 2003-296879

A stand-alone type signal control device detects a synchronization signal transmitted together with time information from a receiver that receives a GPS signal, and corrects the internal time. Therefore, if the detection accuracy of the synchronization signal is low, the error with the time information becomes large. In this case, there is a problem that the stepping timing of the next tier and the cycle start timing of the next cycle are shifted. The traffic signal device connected to the central unit also corrects the internal clock using a communication line, but since the internal clock is not synchronized with the stepping timing, it has the same problem as the stand-alone type signal control device.

Especially in recent years, the development of a driving support system (ITS: Intelligent Transport System) that uses probe data to provide traffic parameters useful for safe driving support and eco-driving support has been promoted. In this system, information on the color of traffic signals installed on the route is transmitted from the roadside antenna to the vehicle-mounted device, making it possible to provide drivers with appropriate speed and information according to traffic conditions and driving situations. However, if there is a discrepancy between the stepping timing and the cycle start timing of the next tier, the light color information sent to the on-board unit will differ from the actual light color information, and the ever-changing light color information will be adjusted to the appropriate timing. It becomes difficult to stably provide

Therefore, it is necessary to increase the sampling frequency of the synchronizing signal in order to improve the detection accuracy of the synchronizing signal. On the other hand, if a series of procedures for detecting a synchronizing signal is used to correct the internal time, there is a problem that the load on the system becomes extremely high.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a signal control device capable of reducing the load of time adjustment processing while increasing the accuracy of adjusting the internal time.

A signal control device according to one aspect of the present invention includes an internal clock, a signal generation section, an acquisition section, and a time management section.
The internal clock keeps internal time.
The signal generator generates a control signal for controlling a signal lamp based on the internal time.
The acquisition unit acquires time information and its synchronization signal.
When the time information is acquired, the time management unit performs time detection processing for detecting a reference time serving as a starting point of the time information based on the synchronization signal; A time correction process for correcting the time is executed by a different task.

The signal control device is configured to execute the process of detecting the synchronization signal and the process of correcting the internal time as different tasks. As a result, it is possible to reduce the load of the time adjustment process while increasing the accuracy of the internal time adjustment, compared to the case where the synchronization signal detection process and the internal time adjustment process are processed in one task.

Typically, the time management unit detects the reference time by sampling the synchronization signal at a first period in units of milliseconds, and detects the reference time at a second period longer than the first period. Configured to correct the internal time.

The first period may be 1 millisecond and the second period may be 10 milliseconds.

The signal control device may further include a communication terminal that receives radio waves containing information related to current time and transmits the time information to the acquisition unit.

According to the signal control device of the present invention, it is possible to reduce the load of time adjustment processing while increasing the accuracy of adjusting the internal time.

1 is a schematic configuration diagram of a traffic control system; FIG. It is a schematic diagram of the road intersection to which the said traffic control system is applied. 1 is a block diagram showing the configuration of a signal control device according to one embodiment of the present invention; FIG. FIG. 4 is a schematic diagram showing the relationship between time information and a synchronizing signal; FIG. 4 is an explanatory diagram showing an example of a method of detecting a reference time; It is a flowchart which shows an example of the processing procedure performed in the time detection part of the said signal control apparatus. 4 is a flow chart showing an example of a processing procedure executed by a time correction unit of the signal control device; It is a schematic diagram which shows the modification of a structure of the said time detection part. FIG. 9 is an explanatory diagram of the action of the time detection unit in FIG. 8;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Traffic control system]
FIG. 1 is a schematic configuration diagram of a traffic control system 100 according to one embodiment of the present invention, and FIG. 2 is a schematic diagram of a road intersection to which the traffic control system 100 is applied. In this embodiment, a traffic control system having an ITS function will be described as an example.

A traffic control system 100 of this embodiment includes a signal control device 10 , a roadside antenna 20 , and a traffic control center 50 .

As shown in FIG. 2, the signal control device 10 includes vehicle lamps 1V and 2V installed on roads R1 and R2 extending in the east-west direction (horizontal direction in the figure) and the north-south direction (vertical direction in the figure). To control a plurality of signal lamps including pedestrian lamps 1P and 2P installed at a road crosswalk.

The signal control device 10 uses a commercial power supply as a power source, and controls the light emission (blue, yellow, red) of each signal lamp with a preset lighting time (number of seconds) and cycle. The signal control device 10 is typically installed in a control box (not shown) attached to a pole of the traffic light S, and electrically connected to each of the lamps 1V, 2V, 1P, and 2P by wire. Hereinafter, the lamp devices 1V, 2V, 1P, and 2P are also collectively referred to as the signal lamp device 1, unless otherwise described individually.

The signal control device 10 is configured to communicate with the traffic control center 50 and the roadside antenna 20 .

The roadside antenna 20 is configured to be able to communicate with a vehicle V traveling on roads (or routes) R1 and R2 on which the traffic signal S is installed, and can transmit to the vehicle V light color information regarding the vehicle lamps 1V and 2V. configured as possible. Although not shown in the vehicle V, in addition to an on-vehicle device that can receive the light color information transmitted from the roadside antenna 20, information related to the vehicle lamps 1V and 2V is provided to the driver based on the light color information. Presenting devices (displays, speakers, etc.) are installed.

The light color information is information related to the light color of a traffic signal located in front of the vehicle V in the direction of travel, and typically includes time information at the time of transmission, the light color of the traffic signal when the vehicle V passes, and the following information. Includes remaining time (seconds remaining) to stairs. As a result, it becomes possible to provide driving assistance information such as signal passage assistance and red light deceleration assistance to the traveling vehicle V. FIG. Further, when the vehicle V is an automatically driven vehicle, it is possible to allow the vehicle itself to autonomously determine braking control using the light color information.

The roadside antenna 20 is not limited to being installed independently of the signal control device 10 and may be installed inside the signal control device 10 . That is, the signal control device 10 may have a transmission function of transmitting the lamp color information by itself.

[Signal control device]
Next, details of the signal control device 10 will be described. FIG. 3 is a block diagram showing the configuration of the signal control device 10. As shown in FIG.

The signal control device 10 includes a main control unit 11 , a transmission section 12 and a lamp switch 13 .

The main control unit 11 controls the operation of the signal lamp device 1 . The transmission unit 12 is a communication module capable of wireless or wired communication with the roadside antenna 20 and the control center 50 . The transmission unit 12 acquires control setting information for controlling the signal lamp device 1 from the control center 50 . The lamp switch 13 has a switching circuit that controls lighting or extinguishing of the signal lamp 1 based on instructions from the main control unit 11 .

The main control unit 11 has a control section 31 , an acquisition section 32 , a timer 33 , a memory 34 and a backup clock (hardware clock) 35 .

The control section 31 is a computer including a CPU (Central Processing Unit), and controls the operation of the main control unit 11 in an integrated manner. The control unit 31 has an internal clock (software clock) 311 , a signal generation unit 312 , a time management unit 313 and a timer management unit 316 .

The internal clock 311 keeps internal time at least in units of milliseconds based on the output from the timer 33 . The signal generator 312 generates a control signal for controlling the signal lamp 1 (lamp switch 13) based on the internal time. The time management unit 313 calibrates the internal clock 311 and the backup clock 35 based on the time information acquired by the acquisition unit 32, as will be described later. The timer management unit 316 manages operation timings of various processes executed in the time management unit 313, which will be described later, based on the output of the timer 33. FIG.

The acquisition unit 32 is configured by a receiving circuit that acquires time information regarding the current time from the communication terminal 40 . The communication terminal 40 is a terminal device including an antenna capable of receiving radio waves (GPS signals) transmitted from the GPS satellites 60 . The communication terminal 40 incorporates a time correction unit that generates time information from received radio waves and outputs the time information to the acquisition unit 32 together with a synchronization signal for detecting the starting point of the time information.

The time adjustment unit may include, for example, a radio clock. An interface such as RS422, which has the electrical characteristics of a balanced digital interface circuit, is used for transmission of time information from the time correction unit to the acquisition unit 32 in order to deal with external noise.

Note that the time information and the synchronization signal may be configured to be generated by the acquisition unit 32 based on the GPS signal transmitted from the communication terminal 40 . Moreover, the communication terminal 40 may be configured as a device independent of the signal control device 10 or may be built in the signal control device 10 .

The memory 34 is composed of a non-volatile semiconductor memory or the like that stores programs for various processes executed by the control unit 31 . The memory 34 stores control setting information of each signal lamp device 1 acquired through the transmission unit 12, time information acquired through the acquisition unit 32, light color output history, and the like. The control setting information typically refers to the signal constants of the signal lamp device 1 . Traffic light constants include ladders, cycles, splits, offsets, timetables, sensitive seconds, etc.

The timer 33 incorporates a crystal oscillator, a counter circuit that counts the number of times the crystal oscillator oscillates, and outputs a clock necessary for the clock function of the internal clock 311 . The hardware clock 35 is a backup clock and incorporates a crystal oscillator, a counter circuit, an auxiliary battery, and the like. The hardware clock 35 is not limited to being built in the signal processing device 10, and may be externally attached to the signal processing device 10 as an external device.

[Time management part]
Next, details of the time management unit 313 will be described.

The time management unit 313 has a time detection unit 314 and a time correction unit 315, and executes detection processing of the synchronization signal and correction processing of the internal time as different tasks.

(Time detection processing)
When the acquisition unit 32 receives the time information from the communication terminal 40, the time detection unit 314 detects the reference time, which is the starting point of the time information, based on the synchronization signal transmitted together with the time information. In this embodiment, the time detection unit 314 detects the reference time by sampling the synchronization signal at a predetermined frequency.

FIG. 4 is a schematic diagram showing the relationship between time information and a synchronizing signal. As shown in FIG. 4, the time information T1 is a serial signal representing the current time and is transmitted every second. The synchronization signal T2 is a pulse wave (pulse signal) that rises in synchronization with the second second, and its duty ratio is, for example, 20%. The time detection unit 314 detects the rising time of the synchronizing signal T2 and stores the detected time in the memory 34 as the reference time that is the starting point of the time information T1.

FIG. 5 is an explanatory diagram showing an example of a method of detecting the reference time. FIG. 6 is a flowchart showing an example of a reference time detection processing procedure executed by the time detection unit 314 .

The time detector 314 determines whether or not it is time to adjust the time, and if it is time to adjust the time, sets the time adjustment reception permission flag to 1 (ON) (steps 101 and 102).

The time adjustment execution timing can be arbitrarily set. For example, when a time adjustment instruction is received from the control center 50 .

When the modified time reception permission flag becomes 1, the time detection unit 314 determines whether or not the acquisition unit 32 has received the time information T1 from the communication terminal 40, and if received, the time included in the time information T1. It is stored in the memory 34 as the correction time (steps 103, 104). Subsequently, the time detection unit 314 sets the synchronization signal sampling permission flag to 1 (ON), and executes sampling processing of the synchronization signal T2 (step 105).

As shown in FIG. 5, the synchronization signal is sampled at a predetermined sampling period (first period) from the time when the time information T1 is received until the synchronization signal T2 becomes significant (H level). Sample T2. In this embodiment, the synchronization signal T2 is sampled at operation timings of 1 millisecond intervals, and the synchronization signal is detected at the time when the synchronization signal T2 is determined to be significant (time t5 in the example of FIG. 5). ON" determination is executed (Yes in step 106).

In addition, as a method of detecting the sync signal, by adopting a technology that determines "ON" only when the significant level of the sync signal is detected a predetermined number of times in a row, erroneous detection due to noise superimposed on the sync signal is prevented. be able to. However, in this method, the larger the predetermined number of times, the larger the detection error of the synchronizing signal. On the other hand, in this embodiment, by acquiring the time information and the synchronization signal via an interface such as RS422 having the electrical characteristics of a balanced digital interface circuit, the noise superimposed on the synchronization signal at the interface is reduced. As a result, even when the synchronization signal is detected and determined only once, the synchronization signal can be stably detected without erroneous detection.

When it is determined that the synchronization signal is "ON", the time detection unit 314 turns on the time adjustment request flag, and performs time adjustment processing so that the time adjustment processing in the time adjustment unit 315, which will be described later, starts 10 milliseconds later. Reset the operating criteria timer (step 107).

After that, the time detection unit 314 sets the synchronization signal sampling permission flag and the corrected time reception permission flag to 0 (OFF), and ends the time detection processing (steps 108 and 109). After that, when the timing for implementing time adjustment arrives, the above-described processing is executed again.

(Time correction processing)
Time correction unit 315 executes processing for correcting the internal time of internal clock 311 . FIG. 7 is a flow chart showing an example of an internal time adjustment processing procedure executed by time adjustment unit 315 .

The time adjustment process executed by the time adjustment unit 315 is a task different from the above-described time detection process, and is executed at preset operation timing regardless of whether the time adjustment process is executed or not. In the present embodiment, the time correction unit 315 performs the following time at an operation timing (second cycle, 10 milliseconds) longer than the sampling cycle (first cycle, 1 millisecond) of the synchronization signal T2 in the time detection unit 314. Take corrective action.

The time adjustment unit 315 determines whether or not the operation reference timer reaches the operation timing (step 201). When the operation reference timer reaches the operation timing, the time adjustment unit 315 determines whether or not the time adjustment request flag is ON (step 202). The time adjustment request flag is ON if detection of the synchronization signal T2 in the time detection process described above is completed (step 107), and if detection is not completed (No in step 202), the internal time is set to 10 milliseconds. Add seconds and terminate the process. At this time, the millisecond unit of the internal time is maintained as it is.

On the other hand, if the time adjustment request flag is ON (Yes at step 202), time adjustment unit 315 calibrates internal clock 311 based on the adjustment time stored in memory 34 at step 104 above. The time adjustment unit 315 reads out the adjusted time from the memory 34 and adjusts the internal time to the adjusted time by adding 10 milliseconds, which is the operation timing of the operation reference timer (step 204). As a result, the clock time of the internal clock 311 is corrected in units of milliseconds. The time adjustment unit 315 further adjusts the time of the backup clock 35 to the same time as the internal time (step 205).

After correcting the times of the internal clock 311 and the backup clock 35, the time correction unit 315 saves the time correction history in the memory 34 (step 206). Note that this process is not limited to being performed during the time adjustment process, and may be performed at different operation timings in another task. By this processing, the time information of the control setting information of each signal lamp device 1 stored in the memory 34 is updated.

(Effect)
As described above, the signal control device 10 of the present embodiment is configured to execute the process of detecting the synchronization signal and the process of correcting the internal time as different tasks. As a result, it is possible to reduce the load of the time adjustment process while increasing the accuracy of the internal time adjustment, compared to the case where the synchronization signal detection process and the internal time adjustment process are processed in one task.

That is, in this embodiment, the synchronization signal detection process is executed in units of 1 millisecond, and the internal time correction process is executed in units of 10 milliseconds. The shorter the detection operation period of the synchronization signal, the more accurately the time can be detected, and the detection error can be suppressed to 1 millisecond or less.

On the other hand, if the internal time is corrected at the same timing as the time detection operation, the processing load of the system will be significantly increased, and there is a risk that other processing of the signal control device 10 will be affected. On the other hand, in this embodiment, the time detection operation and the internal time correction operation are divided into different tasks, and the internal time adjustment operation timing is set longer than the time detection operation timing, thereby adjusting the internal time. While improving the accuracy, the processing load of the system is reduced.

In particular, according to this embodiment, since the operation timing of time detection can be limited to a limited detection period from the time information is received until the significant level of the synchronization signal is detected (see FIG. 5), the system load can be reduced. You can contribute more.

According to the signal control device 10 of the present embodiment, the error of the internal time from the current time can be suppressed to 1 millisecond or less, so the lighting timing of each signal lamp device 1 can be controlled with high precision. As a result, it is possible to suppress the occurrence of deviations in the stepping timing of the next stage and the cycle start timing. In addition, since the lighting and extinguishing timings of the traffic lights can be synchronized with high accuracy with other adjacent traffic lights, it is possible to effectively prevent the occurrence of traffic jams due to missynchronization. In addition, since the time accuracy of the light color output history stored in the memory 34 is improved, it becomes easy to grasp when and what light color was output even when referring to it later.

Furthermore, since the error of the internal time can be reduced, the accuracy of the time parameter of the light color information transmitted to the vehicle V via the roadside antenna 20 is improved, and a highly reliable driving support system can be ensured. As a result, it is possible to provide the driver with appropriate speed and information according to traffic conditions and driving scenes. In addition, highly accurate braking control is possible for self-driving vehicles.

(Modification)
Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and can be modified in various ways.

For example, in the above embodiments, the synchronization signal detection operation timing is 1 millisecond, but it is not limited to this, and may be several milliseconds or sub-milliseconds. Similarly, the internal time correction operation timing is not limited to 10 milliseconds, and may be several tens of milliseconds. In other words, the timing of time detection and time correction can be appropriately set according to the load and capacity of the system.

In the above embodiments, the time detection unit 314 is configured to detect the synchronization signal by sampling the synchronization signal, but it is configured to detect the synchronization signal by interrupt processing using hardware. may In this case, as schematically shown in FIGS. 8 and 9, the time detection unit 314 includes an interrupt controller, permits interrupt processing when receiving the time information T1, and detects the rising edge of the synchronization signal T2 by hardware. The operation reference timer for the time adjustment process may be reset at the time (step 107). Even with such a configuration, the synchronization signal can be detected with an error of 1 millisecond or less.

Furthermore, in the above embodiments, time synchronization using GPS signals has been described as an example, but the present invention is not limited to this. can also be modified.

DESCRIPTION OF SYMBOLS 1... Signal lamp 10... Signal control apparatus 11... Main control unit 31... Control part 32... Acquisition part 33... Timer 34... Memory 35... Backup clock 40... Communication terminal 311... Internal clock 312... Signal generation part 313... Time management part 314... Time detection unit 315... Time correction unit 316... Timer management unit

Claims (3)

an internal clock for measuring internal time;
a signal generator that generates a control signal for controlling the signal lamp based on the internal clock;
an acquisition unit that acquires time information and its synchronization signal;
a time detection process for detecting a reference time, which is the starting point of the time information based on the synchronization signal when the time information is acquired , by sampling the synchronization signal at a first period in units of milliseconds ; a time management unit that executes a time adjustment process for adjusting the internal time based on the time information and the reference time in a second cycle longer than the first cycle, as a different task ;
The time management unit samples the synchronization signal at the first period from when the time information is acquired until the reference time is detected.
Signal control device. The signal control device according to claim 1,
the first period is 1 millisecond;
The signal controller, wherein the second period is 10 milliseconds. The signal control device according to claim 1 or 2 ,
A signal control apparatus, further comprising: a communication terminal that receives radio waves containing information related to current time and transmits the time information to the acquisition unit.

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