Signal control device, signal control method, and signal control program

Abstract

To suppress a time change of a lamp color state while suppressing a difference between a GPS time and a time of an internal clock.SOLUTION: A signal control device comprises a GPS signal reception unit, an internal clock, a clock signal generation unit, a lamp color control unit and an internal time management unit. The GPS signal reception unit receives a GPS signal and outputs a PPS signal. The internal clock generates an internal time. The clock signal generation unit generates a first clock signal which consists of a pulse group of a shorter cycle than a cycle of the PPS signal and becomes a reference of control of a lamp color state. The lamp color control unit uses the time of the internal clock and the first clock signal to control the lamp color state of a traffic light. The internal time management unit corrects a difference between rise timing of the PPS signal and a specific time of the internal clock. In such a case, the internal time management unit estimates second rise timing subsequence to the first rise timing of the PPS signal from the first rise timing and makes the specific time of the internal clock coincident with timing of a pulse of the first clock signal closest to the second rise timing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to the technology of time synchronization of signal control devices.

Background Art

[0002] The signal control device stores signal control information. The signal control information describes the display ladder steps, and the display ladder steps indicate the procedure for switching the state of the traffic signal colors of the traffic lights installed at intersections.

[0003] The signal control device includes an internal clock (RTC (Real Time Clock)) and a reference clock transmitter that generates a reference clock. Based on the time output by the internal clock, the signal control device synchronizes with the reference clock and switches each step of the display ladder steps. Thereby, the signal control device switches the state of the traffic signal colors (green signal, yellow signal, red signal, etc.) of the traffic lights installed at intersections and holds each traffic signal color time for a predetermined time length set in advance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Currently, the signal control device is required to synchronize the time of the internal clock with the GPS time.

[0006] However, in the conventional signal control device, the time of the internal clock and the GPS time are not synchronized. Here, if synchronized with the GPS time without considering the reference clock, the time of the traffic signal state and the like will change.

[0007] An object of the present invention is to provide a technique capable of suppressing a time change in a lamp color state while suppressing a difference between a GPS time and an internal clock time.

Means for Solving the Problems

[0008] The signal control device of the present invention is configured as shown below in order to achieve the above object.

[0009] The signal control device includes a GPS signal receiving unit, an internal clock, a clock signal generating unit, a lamp color control unit, and an internal time management unit.

[0010] The GPS signal receiving unit receives a GPS signal and outputs a PPS signal. The internal clock generates an internal time. The clock signal generating unit generates a first clock signal composed of a pulse train having a period shorter than the period of the PPS signal, which serves as a reference for controlling the lamp color state. The lamp color control unit controls the lamp color state of the signal device using the time of the internal clock and the first clock signal. The internal time management unit corrects the difference between the rising timing of the PPS signal and a specific time of the internal clock. At this time, the internal time management unit estimates a second rising timing after the first rising timing from the first rising timing of the PPS signal, and matches the specific time of the internal clock with the timing of the pulse of the first clock signal closest to the second rising timing.

[0011] According to this configuration, while synchronizing with the first clock signal serving as a reference for lamp color control, the difference between the time of the internal clock and the rising timing of the PPS signal is reduced.

[0012] Further, the signal control device has the following configuration. The signal control device includes a step management unit that generates a step pulse for changing the lamp color state. The clock signal generating unit generates a second clock signal having a period shorter than the first clock signal.

[0013] The step management unit detects the difference between the timing of the pulse of the first clock signal and the timing of the step pulse using the second clock signal. If the time difference between the timing of the pulse of the first clock signal and the timing of the step pulse is greater than the permission threshold, the step management unit adjusts the timing of the step pulse to the timing of the second clock signal within the permission threshold based on the timing of the pulse of the first clock signal.

[0014] According to this configuration, the synchronization error between the step pulse and the first clock signal is adjusted to be small.

[0015] Also, the signal control device has the following configuration. The GPS signal receiving unit performs filter processing to extract the PPS signal from the GPS signal. The internal clock management unit estimates the second rising timing from the rising timing of the filtered PPS signal.

[0016] According to this configuration, the second rising timing is estimated with higher accuracy.

[0017] Also, the signal control device has the following configuration. The internal time management unit calculates the rewrite time of a specific time in reverse and sets the rewrite start timing of the specific time. The internal time management unit starts rewriting the specific time from the rewrite start timing.

[0018] According to this configuration, the update (correction) of the internal time is executed more reliably.

Advantages of the Invention

[0019] According to this invention, while suppressing the difference between the GPS time and the time of the internal clock, the time change of the lamp color state can be suppressed.

Brief Description of the Drawings

[0020]

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DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described. In the following description, time and timing indicate a certain point in time, and time indicates the length between two different points in time.

[0022] <1. Application Example> FIG. 1 is a functional block diagram of the signal control device according to this example. FIG. 2 is a diagram showing an example of a timing chart of each signal of the signal control device according to this example.

[0023] The clock signal generation unit 29 of the signal control device 10 generates a first clock signal S100 with a period of 100 msec and a second clock signal S10 with a period of 10 msec.

[0024] The GPS signal reception unit 22 of the signal control device 10 receives a GPS signal. The GPS signal reception unit 22 detects the rising timing (first rising timing) of the PPS signal of the GPS signal by a task using the second clock signal.

[0025] The RTC management unit 23 estimates the second rising timing of the PPS signal from the first rising timing of the PPS signal. The second rising timing is a timing later than the first rising timing. The RTC is a real-time clock and is an internal clock that is independently generated and timed by the signal control device 10.

[0026] The RTC management unit 23 detects the pulse timing (synchronization timing) of the first clock signal S100 closest to the second rising timing. The RTC management unit 23 causes the specific time tsc of the RTC to coincide with the synchronization timing.

[0027] With this configuration and processing, the signal control device 10 can suppress the deviation of the reference for controlling the lamp color and can reduce the difference between the specific time tsc of the RTC and the rising timing of the PPS signal.

[0028] <2. Configuration example> As shown in FIG. 1, the signal control device 10 includes a control unit 20, an RTC 30, and a lamp color signal output unit 40. The control unit 20 includes a lamp color control unit 21, a GPS signal reception unit 22, an RTC management unit 23, and a clock signal generation unit 29. The signal control device 10 is connected to a plurality of traffic lights 91-94 (traffic light 91, traffic light 92, traffic light 93, traffic light 94). Note that the plurality of traffic lights 91-94 are installed, for example, at an intersection of a main road and a secondary road. And, for example, traffic lights 91 and 92 are traffic lights for the main road, and traffic lights 93 and 94 are traffic lights for the secondary road.

[0029] The control unit 20 includes a storage unit (not shown). The storage unit stores signal control information. As is well known, the signal control information includes a step ladder and signal control parameters. The step ladder is a step indicating the order of the blue, yellow, and red lamp colors of the traffic light. The signal control parameter is a parameter that determines the time of each step ladder. The signal control parameter is set according to the time zone.

[0030] The clock signal generation unit 29 generates a first clock signal S100 with a period of 100 msec and a second clock signal S10 with a period of 10 msec. Note that the period of the first clock signal is shorter than the period of the PPS signal, and the period of the second clock signal may be shorter than the period of the first clock signal. However, as the signal control device 10, usually, the period of the first clock signal is 100 msec, and the period of the second clock signal is 10 msec. The first clock signal S100 and the second clock signal S10 are synchronized. That is, the rising timing of the pulse of the first clock signal S100 and the rising timing of the pulse of the second clock signal S10 coincide with each other.

[0031] The RTC 30 generates an RTC (internal time).

[0032] The light color control unit 21 reads signal control information from the storage unit, and based on the first clock signal S100 and referring to the internal time, determines the light color control information. More specifically, the light color control unit 21 determines signal control parameters by referring to the internal time. While timing based on the first clock signal S100, the light color control unit 21 determines the light color control information for the plurality of signal lights 91 - 94 according to the step steps. The light color control unit 21 outputs the determined light color control information to the light color signal output unit 40.

[0033] Also, the light color control unit 21 generates step pulses and outputs them to the plurality of signal lights 91 - 94. The step pulse is a pulse signal that gives the switching timing of the step steps. The step pulse is generated and output in synchronization with the second clock signal.

[0034] The GPS signal reception unit 22 receives a GPS signal received by an antenna (not shown). The GPS signal reception unit 22 extracts a PPS signal from the GPS signal using well-known filter processing.

[0035] The RTC management unit 23 manages the RTC (internal time) and controls it so that the difference between the PPS signal and a specific time of the RTC (internal time) becomes small.

[0036] Based on the traffic signal color control information and the stepping pulses, the traffic signal color output unit 40 generates traffic signal color signals for a plurality of traffic signals 91-94 and outputs them to the plurality of traffic signals 91-94. The plurality of traffic signals 91-94 perform predetermined traffic signal colors according to the traffic signal color signals.

[0037] Thereby, the plurality of traffic signals 91-94 can execute traffic signal colors of each color in synchronization with the first clock signal. Also, the plurality of traffic signals 91-94 can execute traffic signal colors according to the time.

[0038] <3. Operation Example> In addition to the above-described traffic signal color control, the signal control device 10 executes a process of synchronizing the following RTC with the PPS signal of GPS. Note that the synchronization process in this embodiment is not limited to making the RTC completely coincide with the PPS signal, but means correcting the RTC and the PPS signal so that the time difference becomes small based on the first clock signal.

[0039] FIG. 3 is a flowchart showing an example of the synchronization process to the PPS signal of GPS. FIG. 4 is a flowchart showing a specific example of the setting process of the reset timing of the RTC. FIG. 5 is a flowchart showing a specific example of the reset process of the RTC.

[0040] The GPS signal receiving unit 22 receives a GPS signal, extracts a PPS signal, and outputs it to the RTC management unit 23.

[0041] As shown in FIG. 3, the RTC management unit 23 detects the rising timing (the first rising timing) of the PPS signal by a process (10 ms task) using the second clock signal as the reference timing (S11).

[0042] The RTC management unit 23 sets the reset timing of the RTC synchronized with the first clock signal (the reference signal of the 100 ms task) using the first rising timing of the PPS signal (S12).

[0043] More specifically, as shown in FIGS. 2 and 4, the RTC management unit 23 estimates the next rising timing (second rising timing) of the PPS signal from the first rising timing of the PPS signal (S121). At this time, the first rising timing is detected by filter processing. Therefore, the detected first rising timing is delayed by a delay time τf from the first rising timing of the actual PPS signal, as shown in FIG. 2.

[0044] Therefore, the RTC management unit 23 estimates the second rising timing in consideration of this delay time τf. For example, the period of the rising timing of the PPS signal is 1 second. Therefore, the RTC management unit 23 estimates the time Tde = 1 - τf after the detection time of the first rising timing as the second rising timing.

[0045] The RTC management unit 23 detects the pulse timing of the first clock signal (reference signal of the 100 ms task) closest to the second rising timing (more precisely, the rising timing of the pulse of the first clock signal). The RTC management unit 23 sets this detected pulse timing as the reset timing of the RTC (S122).

[0046] As shown in FIG. 3, the RTC management unit 23 resets the RTC in units of 1 second in synchronization with the set reset timing (S13).

[0047] More specifically, as shown in FIGS. 2 and 5, the RTC management unit 23 sets the start timing of rewriting the RTC (S131) using the pulse timing of the second clock signal (the reference signal for the 10 ms task) (more precisely, the rising timing of the pulse of the second clock signal). For example, it takes about 16 ms to rewrite the RTC. Therefore, the RTC management unit 23 sets a time Tp that is sufficiently longer than the rewriting time (for example, two pulses of the second clock signal). The RTC management unit 23 sets the pulse timing Tp before the pulse timing of the second clock signal at the same timing as the second rising timing, for example, the pulse timing two pulses before the pulse timing of the second clock signal at the same timing as the second rising timing, as the start timing of rewriting the RTC. Thereby, it is possible to prevent the rewriting of the RTC from being too late, and the RTC can be reset more reliably.

[0048] The RTC management unit 23 detects the pulse timing tr (the pulse timing of the second clock signal) at which the rewriting of the RTC starts (S132), and performs the rewriting process of the RTC (S133).

[0049] The RTC management unit 23 performs zero adjustment of the RTC (S134) at the pulse timing (reset timing) of the first clock signal that is closest to the second rising timing of the PPS signal detected in S122. The zero adjustment of the RTC is a process of truncating the RTC to less than 0.1 seconds.

[0050] By performing such processing, the RTC management unit 23 can reduce the time difference between the PPS signal and the RTC without operating the first clock signal. For example, as shown in FIG. 2, the time difference Δt before performing this processing can be reduced to a time difference Δtc (<Δt). Thereby, the RTC management unit 23 can substantially synchronize the PPS signal and the RTC.

[0051] Therefore, the signal control device 10 can substantially synchronize the PPS signal and the RTC while maintaining the cycle of the lamp color control.

[0052] <4. Modified Example> Next, a modified example of the signal control device will be described. This modified example is different from the above example in that the signal control device 10A adjusts the stepping pulse.

[0053] FIG. 6 is a functional block diagram of the signal control device according to the modified example. FIG. 7 is a diagram showing an example of the timing chart of each signal of the signal control device according to the modified example. FIG. 8 is a flowchart showing an example of the adjustment of the stepping pulse.

[0054] As shown in FIG. 6, the signal control device 10A includes a control unit 20A. The control unit 20A is different from the control unit 20 of the above example in that it further includes a stepping management unit 24. Other configurations of the control unit 20A are the same as those of the control unit 20, and the description of the same parts will be omitted.

[0055] The stepping management unit 24 detects the pulse timing of the first clock signal (the start timing of the 100 ms task) (S21).

[0056] The stepping management unit 24 detects the timing of the stepping pulse using the second clock signal (10 ms task) (S22).

[0057] The stepping management unit 24 calculates the difference between the timing of the stepping pulse and the pulse timing of the first clock signal that is closest to the timing of this stepping pulse. If the timing difference is greater than the threshold value (for example, 50 ms) (S23: YES), the stepping management unit 24 uses the second clock signal (10 ms task) to adjust the timing of the stepping pulse so that the difference from the pulse timing of the first clock signal becomes equal to or less than the threshold value (for example, 50 ms) (S24). For example, in the case of FIG. 7, the stepping management unit 24 adjusts the timing of the stepping pulse to synchronize with any of the plurality of pulse timings t00 - t04 within the period Pstp. Note that if the timing difference is equal to or less than the threshold value (for example, 50 ms) (S23: NO), the stepping management unit 24 does not adjust the stepping pulse and maintains it as it is.

[0058] By performing such processing, the signal control device 10A can monitor and adjust so that the difference between the step pulse and the pulse timing of the first clock signal is within a desired range.

[0059] Furthermore, the correspondence relationship between the configuration according to the present invention and the configuration according to the above-described embodiment can be described as follows in the appended note. <Appended Note> A GPS signal receiving unit (22) that receives a GPS signal and outputs a PPS signal, An internal clock (RTC30), A clock signal generation unit (29) that generates a first clock signal composed of a pulse group having a period shorter than the period of the PPS signal and serving as a reference for controlling the lamp color state, A lamp color control unit (21) that controls the lamp color state using the time of the internal clock and the first clock signal, A signal control device (10) comprising: An internal time management unit (RTC management unit 23) that corrects the difference between the rising timing of the PPS signal and a specific time of the internal clock, The internal time management unit (RTC management unit 23) Estimates a second rising timing after the first rising timing from the first rising timing of the PPS signal, Matches the specific time of the internal clock with the timing of the pulse of the first clock signal closest to the second rising timing, Signal control device (10).

Explanation of Reference Numerals

[0060] 10, 10A: Signal control device 20, 20A: Control unit 30: RTC 40: Lamp color signal output unit 21: Lamp color control unit 22: GPS signal receiving unit 23: RTC management unit 24: Step management unit 29: Clock signal generation unit 91 - 94: Signal lights

Claims

1. A GPS signal receiving unit that receives a GPS signal and outputs a PPS signal, An internal clock, A clock signal generation unit that generates a first clock signal composed of a pulse group having a period shorter than the period of the PPS signal and serves as a reference for controlling the lighting color state, A lighting color control unit that controls the lighting color state using the time of the internal clock and the first clock signal, A signal control device comprising: An internal time management unit that corrects the difference between the rising timing of the PPS signal and a specific time of the internal clock, The internal time management unit, Estimates a second rising timing after the first rising timing from the first rising timing of the PPS signal, Matches the specific time of the internal clock with the timing of the pulse of the first clock signal closest to the second rising timing. Signal control device.

2. A step management unit that generates a step pulse for changing the lighting color state, The clock signal generation unit, Generates a second clock signal having a period shorter than the first clock signal, The step management unit, Detects the difference between the timing of the pulse of the first clock signal and the timing of the step pulse using the second clock signal, If the time difference between the timing of the pulse of the first clock signal and the timing of the step pulse is greater than a permission threshold, adjusts the timing of the step pulse to the timing of the second clock signal within the permission threshold based on the timing of the pulse of the first clock signal. The signal control device according to claim 1.

3. The GPS signal receiving unit, Performs a filter process to extract the PPS signal from the GPS signal, The internal time management unit, Estimating the second rising timing from the rising timing of the filtered PPS signal. The signal control device according to claim 1 or claim 2.

4. The internal time management unit Calculating backward the rewriting time of the specific time to set the rewriting start timing of the specific time, Starting the rewriting of the specific time from the rewriting start timing. The signal control device according to any one of claims 1 to 3.

5. A signal control device A GPS signal receiving step of receiving a GPS signal and outputting a PPS signal; An internal time generating step of generating an internal time; A clock signal generating step of generating a first clock signal composed of a pulse group having a period shorter than the period of the PPS signal and serving as a reference for controlling the lamp color state; A lamp color state control step of controlling the lamp color state using the time of the internal clock and the first clock signal; A signal control method for executing The signal control device has an internal time management step of correcting the difference between the rising timing of the PPS signal and a specific time of the internal clock, The internal time management step A step of estimating a second rising timing after the first rising timing from the first rising timing of the PPS signal; A step of matching the specific time of the internal clock with the timing of the pulse of the first clock signal closest to the second rising timing, Signal control method.

6. A GPS signal receiving step of receiving a GPS signal and outputting a PPS signal; An internal time generating step of generating an internal time; A clock signal generation step that generates a first clock signal composed of a pulse group having a period shorter than the period of the PPS signal and serves as a reference for controlling the lamp color state; A lamp color state control step that controls the lamp color state using the time of the internal clock and the first clock signal; A signal control program for causing a computer to execute: An internal time management step for correcting the difference between the rising timing of the PPS signal and a specific time of the internal clock; The internal time management step includes: A step of estimating a second rising timing after the first rising timing from the first rising timing of the PPS signal; A step of matching the specific time of the internal clock with the timing of the pulse of the first clock signal closest to the second rising timing; Including A signal control program.

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