Train radio system

Abstract

This invention provides a train radio system that can efficiently switch between ground radio equipment compared to conventional technology. [Solution] In a train radio system in which an onboard device 1 having a radio communication unit 15 of a train T and at least one of a plurality of ground radio devices 20 arranged along the running path R of the train T communicate wirelessly, the onboard device 1 predicts the position of the train T at the next communication timing based on the position and speed of the train T using a train position prediction unit 13, and sets a ground radio device 20 that can ensure a longer communication time from among the ground radio devices 20 having a communication area that covers the position of the train T predicted by the train position prediction unit 13 as the next connection destination (communication partner) using a radio connection destination setting unit 14, and performs radio communication with the ground radio device 20 set as the next connection destination (communication partner) using a radio communication unit 15.

Description

Technical Field

[0001] The present invention relates to a train radio system.

Background Art

[0002] An example of a conventional train radio system is described in Patent Document 1. The train radio system described in Patent Document 1 includes an on-vehicle device having a radio communication unit and a plurality of ground radio devices (radio base stations) arranged in a radio train control section and communicating with the radio communication unit of the on-vehicle device. When the position of the antenna exceeds the handover point, the radio communication unit of the on-vehicle device performs handover to switch the ground radio device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing handover when the position of the antenna exceeds the handover point, the radio communication unit of the on-vehicle device usually starts the switching preparation for switching the ground radio device to the next ground radio device when the position of the antenna reaches a predetermined position in front of the handover point. Here, considering the case where the train is running at high speed, it is necessary to ensure a sufficient distance between the predetermined position and the handover point. However, if this is done, the time from the completion of the switching preparation to the handover may become unnecessarily long for a train running at low speed. On the other hand, for a train running at a higher speed, a situation may occur where the switching preparation for immediately switching to a new ground radio device after the handover has been performed must be started. Therefore, it cannot be said that the switching of the ground radio device has been efficiently performed in the prior art.

[0005] The present invention aims to provide a train radio system that can efficiently switch between ground radio devices compared to the prior art. [Means for solving the problem]

[0006] According to one aspect of the present invention, a novel train radio system is provided. The provided train radio system is configured to communicate wirelessly between an onboard device having a train radio communication unit and at least one of a plurality of ground radio devices arranged along the train's track. The onboard device predicts the position of the train at the next communication timing based on the train's position and speed, and sets the ground radio device that can ensure a longer communication time from among the ground radio devices having a communication area that covers the predicted position as the next communication partner. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a train radio system that can switch ground radio devices more efficiently than the conventional technology. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically illustrates a train radio system according to an embodiment of the system. [Figure 2] This is a diagram showing the general configuration of the train. [Figure 3] This is a block diagram showing an example of the functional configuration of onboard equipment for a train. [Figure 4] This is a flowchart illustrating an example of the operation (processing) of an on-board device. [Figure 5] This diagram illustrates the operation (processing) of the wireless connection destination setting unit of the on-board device. [Figure 6] This diagram illustrates the operation (processing) of the wireless connection destination setting unit of the on-board device. [Figure 7] This diagram illustrates the operation (processing) of the wireless connection destination setting unit of the on-board device. [Figure 8] This diagram illustrates the operation (processing) of the wireless connection destination setting unit of the on-board device. [Figure 9] This diagram illustrates the operation (processing) of the wireless connection destination setting unit of the on-board device. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the attached drawings.

[0010] Figure 1 is a schematic diagram showing a train radio system according to an embodiment of the present invention. The train radio system according to the embodiment includes a train T traveling along a track R in the direction of the arrow, and a plurality of ground radio devices 20 arranged at intervals from each other along the track R of the train T. The train T is equipped with an onboard device 1, which has a wireless communication unit 15 as described later. In addition, each of the plurality of ground radio devices 20 has a communication area 21 on which wireless communication is possible. Although not particularly limited, in this embodiment, each of the plurality of ground radio devices 20 is connected by wire or wireless to a central control device (not shown) that comprehensively manages all trains traveling along the track R.

[0011] In the train radio system according to this embodiment, the onboard device 1 of train T communicates wirelessly with at least one of the multiple ground radio devices 20. This allows predetermined information, particularly information for controlling train T, to be transmitted and received between the onboard device 1 of train T and the central control device. Wireless communication between the onboard device 1 of train T and at least one of the multiple ground radio devices 20, in other words, communication between the onboard device 1 of train T and the central control device, is performed at a predetermined communication cycle. While not particularly limited, the predetermined communication cycle may be, for example, 0.5 seconds. Furthermore, the onboard device 1 of train T is configured to perform a so-called handover (handoff), which involves switching the ground radio device 20 to which it communicates as needed as train T moves, in order to continuously communicate with itself (onboard device 1) and the central control device.

[0012] Figure 2 shows a schematic configuration of train T. Referring to Figure 2, in this embodiment, in addition to the onboard equipment 1, train T is also equipped with a speed generator 3, onboard equipment 5, drive unit 7, and braking unit 9.

[0013] The speed generator 3 is attached to the axle of train T. The speed generator 3 outputs a signal corresponding to the rotation speed of the train T's axle. The output signal of the speed generator 3 is used to determine the speed and distance traveled by train T. The output signal of the speed generator 3 is input to the onboard equipment 1 via a cable or the like.

[0014] The onboard unit 5 is mounted on the underside of the train T, preferably on the front underside of the train T. When the onboard unit 5 passes over the ground beacon G installed on the track R, it receives information (ground beacon information) transmitted from the ground beacon G. The ground beacon information received by the onboard unit 5 is sent to the onboard device 1 via a cable or the like. The ground beacon information transmitted from the ground beacon G (hereinafter simply referred to as "ground beacon information of ground beacon G") may include the ground beacon ID, which is the identification information of the ground beacon G, and various information corresponding to the location where the ground beacon G is installed. Note that the ground beacon G is omitted in Figure 1, and only one ground beacon G is shown in Figure 2, but in reality, multiple ground beacons G are installed along the track R.

[0015] The drive unit 7 includes an electric motor and an internal combustion engine (diesel engine), which are the power source for train T. Control commands output from the onboard equipment 1 are input to the drive unit 7 via cables, etc. The drive unit 7 controls the driving force applied to the axles of train T according to the input control commands.

[0016] The braking system 9 includes a service brake and an emergency brake. The service brake is the brake normally used to decelerate and / or stop the train T. The emergency brake is the brake used when it is necessary to bring the train T to an emergency stop. Control commands output from the onboard equipment 1 are input to the braking system 9 via cables, etc. The braking system 9 controls the braking force of the service brake applied to the axles or wheels of the train T, or activates the emergency brake, according to the input control commands.

[0017] FIG. 3 is a diagram showing a functional configuration example of the on-vehicle device 1. Referring to FIG. 3, in the present embodiment, the on-vehicle device 1 includes an on-vehicle database (on-vehicle DB) 11, a running status detection unit 12, a train position prediction unit 13, a wireless connection destination setting unit 14, a wireless communication unit 15, and a running control unit 16.

[0018] The on-vehicle DB 11 stores train-related information, travel route-related information, ground wireless device-related information, etc. The train-related information includes the length of the train T, the characteristics of the drive device 7, and / or the characteristics of the braking device 9. The travel route-related information includes the maximum speed in each section of the travel route R and the positions of each ground element G (for example, the positions associated with the ground element IDs). The ground wireless device-related information includes the positions of each ground wireless device 20 and the communication areas 21 of each ground wireless device 20.

[0019] The running status detection unit 12 is configured to detect the running status of the train T based on the output signal of the speed generator 3, the ground element information of the ground element G received by the on-vehicle element 5, and the information stored in the on-vehicle DB 11. Specifically, the running status detection unit 12 calculates and detects the speed of the train T based on the output signal of the speed generator 3. Further, the running status detection unit 12 calculates and detects the position of the train T based on the position of the ground element G obtained most recently and the travel distance of the train T from the ground element G calculated based on the output signal of the speed generator 3. The detection results of the running status detection unit 12 are provided to the train position prediction unit 13, the wireless communication unit 15, and the running control unit 16.

[0020] The train position prediction unit 13 is configured to predict the position of the train T at the next communication timing in the predetermined communication cycle based on the detection results of the running status detection unit 12. Specifically, the train position prediction unit 13 predicts the position that the train T will reach at the next communication timing based on the position and speed of the train T detected by the running status detection unit 12 and the time (≤ the predetermined communication cycle) until the next communication timing. The prediction results of the train position prediction unit 13 are provided to the wireless connection destination setting unit 14.

[0021] The wireless connection destination setting unit 14 sets the next ground wireless device 20 to connect to based on the information stored in the onboard DB 11 and the prediction results of the train position prediction unit 13. Specifically, the wireless connection destination setting unit 14 sets the ground wireless device 20 that has a communication area 21 covering the position of train T predicted by the train position prediction unit 13 (the position of train T at the next communication timing) as the next ground wireless device 20 to connect to. In other words, the wireless connection destination setting unit 14 sets the ground wireless device 20 that has a communication area 21 covering the position of train T predicted by the train position prediction unit 13 as the next connection destination (communication partner). The setting result by the wireless connection destination setting unit 14 is provided to the wireless communication unit 15.

[0022] In this embodiment, the wireless connection destination setting unit 14 searches the onboard DB 11 based on the position of train T predicted by the train position prediction unit 13 and acquires all ground wireless devices 20 having a communication area 21 that covers the position of train T predicted by the train position prediction unit 13 as connection destination candidates. If there is only one such ground wireless device 20 (i.e., a connection destination candidate), the wireless connection destination setting unit 14 sets that ground wireless device 20 as the next connection destination (communication partner).

[0023] On the other hand, if there are multiple such ground radio devices 20 (i.e., candidate connection destinations), the wireless connection destination setting unit 14 sets the ground radio device 20 that is furthest forward from the perspective of the train T as the next connection destination (communication partner). The reason for this is that the ground radio device 20 that is furthest forward from the perspective of the train T can usually communicate to a position further forward than other ground radio devices 20 that are closer, thus ensuring a longer communication time (communication distance) after (wireless) connection, and also reducing the number of times the ground radio devices 20 need to be switched.

[0024] Therefore, in other words, if there are multiple ground radio devices 20 having a communication area 21 that covers the position of train T predicted by the train position prediction unit 13, the wireless connection destination setting unit 14 can also set the ground radio device 20 that can ensure a longer communication time (communication distance) after (wireless) connection as the next connection destination (communication partner).

[0025] The wireless communication unit 15 has a wireless antenna 15a for communicating with various ground wireless devices 20. When the wireless connection destination setting unit 14 sets the next connection destination (communication partner), the wireless communication unit 15 is configured to establish a wireless connection with the ground wireless device 20 of the next connection destination (communication partner) by the next communication timing. The wireless communication unit 15 is configured to transmit the position and speed of train T detected by the running condition detection unit 12 via the wireless antenna 15a to the ground wireless device 20 with which the wireless connection has been established, and to receive the stopping limit position of train T from the ground wireless device 20 with which the wireless connection has been established via the wireless antenna 15a. The stopping limit position is the position (limit position) by which train T must stop, and is created by the central control device considering the running conditions of other trains running on the running track R. The stopping limit position received by the wireless communication unit 15 is provided to the running control unit 16.

[0026] The running control unit 16 outputs a control command to the drive unit 7 to accelerate or maintain a constant speed of the train T, and stops outputting the control command to allow the train T to coast. The running control unit 16 also outputs a control command to the braking unit 9 to decelerate or stop the train T. In particular, in this embodiment, the running control unit 16 is configured to generate a speed check pattern based on the stopping limit position received by the wireless communication unit 15, and to output a control command to the braking unit 9 to decelerate or stop the train T when the speed of the train T exceeds the corresponding speed on the speed check pattern.

[0027] Next, the operation (processing) of the on-board device 1 related to wireless communication with the ground radio equipment 20 will be described. Figure 4 is a flowchart showing an example of the operation (processing) of the on-board device 1.

[0028] In step S1, the train status detection unit 12 of the onboard device 1 detects the train status (position and speed of train T).

[0029] In step S2, the train position prediction unit 13 of the onboard device 1 predicts the position of train T at the next communication timing in the predetermined communication cycle, based on the running conditions of train T detected by the running conditions detection unit 12. For example, when the position of train T is P, the speed of train T is V, and the time until the next communication timing is t, the train position prediction unit 13 predicts the position of train T at the next communication timing (after time t) using the formula "P + V × t".

[0030] In step S3, the wireless connection destination setting unit 14 of the onboard device 1 searches the onboard DB 11 based on the predicted location of train T, and acquires all ground wireless devices 20 having a communication area 21 that covers the predicted location of train T as candidate ground wireless devices 20 for connection at the next communication timing.

[0031] In step S4, the wireless connection destination setting unit 14 of the on-board device 1 determines whether there are multiple candidate ground wireless devices 20 for connection. If there is only one candidate ground wireless device 20 for connection, the process proceeds to step S5; if there are multiple candidate ground wireless devices 20 for connection, the process proceeds to step S6.

[0032] In step S5, the wireless connection destination setting unit 14 of the on-board device 1 sets one of the candidate ground wireless devices 20 as the next connection destination (i.e., communication partner).

[0033] In step S6, the wireless connection destination setting unit 14 of the onboard device 1 sets the ground wireless device 20 located furthest forward from the perspective of the train T as the next connection destination (i.e., communication partner) from among the multiple candidate ground wireless devices 20 for connection destinations. As mentioned above, the ground wireless device 20 located furthest forward from the perspective of the train T is also the ground wireless device 20 that can ensure a longer communication time (communication distance) after (wireless) connection.

[0034] In step S7, the wireless communication unit 15 of the on-board device 1 establishes a wireless connection with the ground wireless device 20, which is set as the next connection destination (communication partner). Then, when the communication timing in the predetermined communication cycle arrives, the wireless communication unit 15 of the on-board device 1 communicates wirelessly with the ground wireless device 20 with which the wireless connection has been established.

[0035] Figures 5 to 9 are diagrams illustrating the operation (processing) of the wireless connection destination setting unit 14 of the onboard device 1. Here, the first ground radio device 20A, the second ground radio device 20B, and the third ground radio device 20C are set in this order in the direction of travel of the train T, and each has a first communication area 21A, a second communication area 21B, and a third communication area 21C, respectively. The first communication area 21A and the second communication area 21B overlap (first overlapping area 22), and the second communication area 21B and the third communication area 21C overlap (second overlapping area 23). The train T is traveling within the first communication area 21A of the first ground radio device 20A, which is before the first overlapping area 22, and the onboard device 1 of the train T has established wireless communication with the first ground radio device 20A, which is hatched.

[0036] Figure 5 shows the case where train T is moving slowly. In this case, as shown by the dashed line in Figure 5, the position of train T at the next communication timing, as predicted by the train position prediction unit 13 of the onboard device 1, remains within the first communication area 21A of the first ground radio device 20A, which is before the first overlapping area 22. Therefore, only the first ground radio device 20A is acquired as a connection destination candidate, and the wireless connection destination setting unit 14 of the onboard device 1 sets the first ground radio device 20A as the next connection destination (communication partner). Consequently, the wireless communication unit 15 of the onboard device 1 continues wireless communication with the first ground radio device 20A at the next communication timing. In other words, there is no switching of the ground radio device that becomes the communication partner of the onboard device 1.

[0037] Figure 6 shows the case where the speed of train T is faster than in Figure 5. In this case, as shown by the dashed line in Figure 6, the position of train T at the next communication timing predicted by the train position prediction unit 13 of the onboard device 1 will be within the first overlapping area 22 of the first communication area 21A of the first ground radio device 20A and the second communication area 21B of the second ground radio device 20B. Therefore, the first ground radio device 20A and the second ground radio device 20B are acquired as connection destination candidates, and the wireless connection destination setting unit 14 of the onboard device 1 sets the second ground radio device 20B, which is the furthest forward from the perspective of train T, as the next connection destination (communication partner). In other words, the wireless connection destination setting unit 14 of the onboard device 1 sets the second ground radio device 20B, which will provide a longer communication time (communication distance) than the first ground radio device 20A when connected, as the next connection destination (communication partner). Therefore, the wireless communication unit 15 of the on-board device 1 establishes a wireless connection with the second ground wireless device 20B instead of the first ground wireless device 20A, and performs wireless communication with the hatched second ground wireless device 20B at the next communication timing. In other words, the ground wireless device with which the on-board device 1 communicates is switched from the first ground wireless device 20A to the second ground wireless device 20B.

[0038] Figure 7 shows the case where the speed of train T is faster than in Figure 6. In this case, as shown by the dashed line in Figure 7, the position of train T at the next communication timing predicted by the train position prediction unit 13 of the onboard device 1 will be within the second communication area 21B of the second ground radio device 20B, which is beyond the first overlapping area 22. Therefore, only the second ground radio device 20B is acquired as a connection destination candidate, and the wireless connection destination setting unit 14 of the onboard device 1 sets the second ground radio device 20B as the next connection destination (communication partner). Consequently, the wireless communication unit 15 of the onboard device 1 establishes a wireless connection with the second ground radio device 20B instead of the first ground radio device 20A, and performs wireless communication with the hatched second ground radio device 20B at the next communication timing. In other words, as in the case of Figure 6, the ground radio device that becomes the communication partner of the onboard device 1 is switched from the first ground radio device 20A to the second ground radio device 20B.

[0039] Figure 8 shows the case where the speed of train T is faster than in Figure 7. In this case, as shown by the dashed line in Figure 8, the position of train T at the next communication timing predicted by the train position prediction unit 13 of the onboard device 1 will be within the second overlapping area 23 of the second communication area 21B of the second ground radio device 20B and the third communication area 21C of the third ground radio device 20C. Therefore, the second ground radio device 20B and the third ground radio device 20C are acquired as connection destination candidates, and the wireless connection destination setting unit 14 of the onboard device 1 sets the third ground radio device 20C, which is the furthest forward from the perspective of train T, as the next connection destination (communication partner). In other words, the wireless connection destination setting unit 14 of the onboard device 1 sets the third ground radio device 20C, which will provide a longer communication time (communication distance) than the second ground radio device 20B if connected, as the next connection destination (communication partner). Therefore, the wireless communication unit 15 of the on-board device 1 establishes a wireless connection with the third ground wireless device 20C instead of the first ground wireless device 20A, and performs wireless communication with the hatched third ground wireless device 20C at the next communication timing. In other words, the ground wireless device with which the on-board device 1 communicates is switched from the first ground wireless device 20A to the third ground wireless device 20C.

[0040] Figure 9 shows the case where the speed of train T is faster than in Figure 8. In this case, as shown by the dashed line in Figure 9, the position of train T at the next communication timing predicted by the train position prediction unit 13 of the onboard device 1 will be within the third communication area 21C of the third ground radio device 20C, which is beyond the second overlapping area 23. Therefore, only the third ground radio device 20C is acquired as a connection destination candidate, and the wireless connection destination setting unit 14 of the onboard device 1 sets the third ground radio device 20C as the next connection destination (communication partner). Accordingly, the wireless communication unit 15 of the onboard device 1 establishes a wireless connection with the third ground radio device 20C instead of the first ground radio device 20A, and performs wireless communication with the hatched third ground radio device 20C at the next communication timing. In other words, as in the case of Figure 8, the ground radio device that becomes the communication partner of the onboard device 1 is switched from the first ground radio device 20A to the third ground radio device 20C.

[0041] As described above, in the train radio system according to the embodiment, the onboard device 1 having a radio communication unit 15 on the train T and at least one of a plurality of ground radio devices 20 arranged at intervals from each other along the running path R of the train T communicate wirelessly at a predetermined communication cycle. The onboard device 1 of the train T predicts the position of the train T at the next communication timing in the predetermined communication cycle based on the position and speed of the train T, and is configured to set as the next communication partner a ground radio device 20 from among the ground radio devices 20 having a communication area 21 that covers the predicted position, which can ensure a longer communication time (communication distance) after wireless connection.

[0042] Specifically, the onboard equipment 1 of train T is configured such that if there is one ground radio device 20 having a communication area 21 covering the predicted location, it sets that ground radio device 20 as the next communication partner, and if there are multiple ground radio devices 20 having a communication area 21 covering the predicted location, it sets the ground radio device 20 that is furthest forward from the perspective of train T as the next communication partner.

[0043] Therefore, the next communication partner, the ground radio equipment 20, is appropriately set according to the running status of train T, preventing gaps in radio communication and enabling efficient switching of the ground radio equipment 20. For example, the time from preparation for switching to the ground radio equipment 20 to the actual switching of the ground radio equipment 20 is not unnecessarily prolonged, thus avoiding unnecessary occupation of radio resources. Furthermore, situations where preparation for switching to a new ground radio equipment 20 must be started immediately after switching ground radio equipment 20 are avoided, thereby suppressing an increase in the number of times the ground radio equipment 20 is switched.

[0044] In the above-described embodiment, the running status detection unit 12 of the onboard device 1 detects the position and speed of train T as the running status of train T, and the train position prediction unit 13 of the onboard device 1 predicts the position of train T at the next communication timing based on the position and speed of train T detected by the running status detection unit 12 and the time until the next communication timing. However, it is not limited to this. In addition to the position and speed of train T, the running status detection unit 12 may further detect the acceleration and / or deceleration of train T as the running status of train T. The running status detection unit 12 may detect the acceleration (deceleration) of train T based on the output signal of an acceleration (deceleration) sensor provided on train T, or it may detect the acceleration (deceleration) of train T by determining the change in the speed of train T per unit time.

[0045] In this case, the train position prediction unit 13 may be configured to predict the position of train T at the next communication timing based on the position, speed, and acceleration of train T detected by the running condition detection unit 12, and the time until the next communication timing. For example, when the position of train T is P, the speed of train T is V, the acceleration (deceleration) of train T is a, and the time until the next communication timing is t, the train position prediction unit 13 uses the formula "P + V × t + a × t 2 The position of train T (after time t) at the next communication timing can be predicted by " / 2".

[0046] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and can be appropriately modified and changed based on the technical concept of the present invention. [Explanation of symbols]

[0047] 1...On-board equipment, 3...Speed ​​generator, 5...On-board transceiver, 7...Drive system, 9...Braking system, 11...On-board DB, 12...Training status detection unit, 13...Train position prediction unit, 14...Wireless connection destination setting unit, 15...Wireless communication unit, 20...Ground wireless device, 20A...First ground wireless device, 20B...Second ground wireless device, 20C...Third ground wireless device, 21...Communication area, 21A...First communication area, 21B...Second communication area, 21C...Third communication area, 22...First overlapping area, 23...Second overlapping area, G...Ground transceiver, R...Track, T...Train

Claims

1. A train radio system in which an onboard device having a train radio communication unit and at least one of a plurality of ground radio devices arranged along the train's track communicate via radio, The onboard device predicts the position of the train at the next communication timing based on the train's position and speed, and sets a ground radio device that has a communication area covering the predicted position and can ensure a longer communication time as the next communication partner. Train radio system.

2. The train radio system according to claim 1, wherein the onboard device sets the ground radio device located furthest forward from the train as the next communication partner among ground radio devices having a communication area that covers the predicted position.

3. The train radio system according to claim 1, wherein the onboard device further takes into account the acceleration or deceleration of the train to predict the position of the train at the next communication timing.

4. The on-board device has a database that stores information related to the ground radio devices, including the location of each of the plurality of ground radio devices and the communication area of ​​each of them. The on-board device searches the database based on the predicted location, acquires all ground radio devices having a communication area covering the predicted location, and sets the next communication partner. A train radio system according to any one of claims 1 to 3.

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