FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ON-BOARD CONTROL DEVICE AND ACCELERATION SENSOR DIAGNOSIS
METHOD;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION
ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE
ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO
1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

2
DESCRIPTION
Field
[0001] The present disclosure relates to an on-board
5 control device to be installed in a train including an
acceleration sensor, and an acceleration sensor diagnosis
method.
Background
10 [0002] In recent train control systems such as a
communications based train control (CBTC) or a digital
automatic train control (ATC), an on-board control device
installed in a train calculates a train position using a
tachometer, a pick-up coil, or the like and calculates a
15 brake pattern used to control train intervals based on the
calculated train position. Therefore, it is important to
accurately manage the train position by the on-board
control device. However, when the on-board control device
calculates the train position, a train speed, or the like
20 using the tachometer, the pick-up coil, or the like, an
error of the train position increases if slipping or
sliding of wheels of the train occurs.
[0003] For such a problem, by installing an acceleration
sensor, the train can detect slipping or sliding by
25 comparing an acceleration detected by the acceleration
sensor and an acceleration calculated from a signal of the
tachometer and correct the train position, the train speed,
or the like in a case where slipping or sliding is detected.
In order to accurately detect slipping or sliding and
30 correct the train position, the train speed, or the like,
the train needs to periodically confirm soundness of the
acceleration sensor. Patent Literature 1 discloses a
technique for diagnosing an acceleration sensor by a

3
vehicle control system.
Citation List
Patent Literature
5 [0004] Patent Literature 1: Japanese Patent Application
Laid-open No. 2016-137731
Summary
Technical Problem
10 [0005] However, according to the related art described
above, the vehicle control system includes a vibration
source that vibrates the acceleration sensor in order to
diagnose the soundness of the acceleration sensor.
Therefore, there has been a problem in that a device
15 configuration of the vehicle control system becomes
complicated.
[0006] The present disclosure has been made in view of
the above, and an object is to obtain an on-board control
device that can periodically diagnose soundness of an
20 acceleration sensor with a simple configuration.
Solution to Problem
[0007] To solve the above problem and achieve an object,
the present disclosure is directed to an on-board control
25 device to be installed in a train. The on-board control
device includes: a communication unit to be communicable
with a tachometer that outputs pulses corresponding to the
number of revolutions of wheels of the train, a pick-up
coil that receives a telegraph that includes identification
30 information of a ground coil from the ground coil, an
acceleration sensor a detection axis of which is provided
along a traveling direction of the train, and a master
controller; a storage unit to store information regarding a

4
gradient value at each position on a train line where the
train travels; and a control unit to specify a train
position of the train by using information acquired from
the pick-up coil and the tachometer, determine a traveling
5 state of the train from information acquired from the
master controller, and, when the train coasts or is stopped,
diagnose soundness of the acceleration sensor based on a
comparison result obtained by comparing a first
acceleration of the train output from the acceleration
10 sensor with a second acceleration in a traveling direction
of the train calculated by using a gravity acceleration and
a gradient value at the train position.
Advantageous Effects of Invention
15 [0008] According to the present disclosure, an effect
can be obtained that an on-board control device can
periodically diagnose soundness of an acceleration sensor
with a simple configuration.
20 Brief Description of Drawings
[0009] FIG. 1 is a diagram illustrating a configuration
example of a train control system according to a first
embodiment.
FIG. 2 is a diagram illustrating an installation
25 example of an acceleration sensor included in a train
according to the first embodiment.
FIG. 3 is a block diagram illustrating a configuration
example of an on-board control device according to the
first embodiment.
30 FIG. 4 is a diagram illustrating an example of
information stored in a storage unit of the on-board
control device according to the first embodiment.
FIG. 5 is a flowchart illustrating an operation of the

5
on-board control device according to the first embodiment.
FIG. 6 is a flowchart illustrating an operation for
determining whether or not the acceleration sensor is
normal by the on-board control device according to the
5 first embodiment.
FIG. 7 is a flowchart illustrating an operation for
detecting slipping or sliding using a tachometer and the
acceleration sensor in a case where the acceleration sensor
is normal and executing correction processing, by the on10 board control device according to the first embodiment.
FIG. 8 is a flowchart illustrating an operation of the
on-board control device for detecting slipping or sliding
using the tachometer and executing the correction
processing when the acceleration sensor is anomalous,
15 according to the first embodiment.
FIG. 9 is a diagram illustrating an example when
processing circuitry included in the on-board control
device according to the first embodiment includes a
processor and a memory.
20 FIG. 10 is a diagram illustrating an example when the
processing circuitry included in the on-board control
device according to the first embodiment includes dedicated
hardware.
FIG. 11 is a diagram illustrating a configuration
25 example of a train control system according to a second
embodiment.
FIG. 12 is a diagram illustrating an installation
example of a biaxial acceleration sensor included in a
train according to the second embodiment.
30 FIG. 13 is a flowchart illustrating an operation of an
on-board control device according to the second embodiment.
FIG. 14 is a flowchart illustrating an operation for
determining whether or not the biaxial acceleration sensor

6
is normal by the on-board control device according to the
second embodiment.
FIG. 15 is a diagram illustrating a configuration
example of the biaxial acceleration sensor included in the
5 train according to the second embodiment.
Description of Embodiments
[0010] Hereinafter, an on-board control device and an
acceleration sensor diagnosis method according to
10 embodiments of the present disclosure will be described in
detail with reference to the drawings.
[0011] First Embodiment.
FIG. 1 is a diagram illustrating a configuration
example of a train control system 100 according to a first
15 embodiment. The train control system 100 includes a train
10, a ground coil 11, a ground wireless device 12, and a
ground device 13. The train 10 includes an acceleration
sensor 1, an on-board control device 2, a pick-up coil 3, a
master controller 4, a tachometer 5, an on-board wireless
20 device 6, an on-board antenna 7, a brake device 8, and a
propulsion control device 9.
[0012] The acceleration sensor 1 is installed such that
a first detection axis that is a detection axis is provided
along a traveling direction of the train 10. FIG. 2 is a
25 diagram illustrating an installation example of the
acceleration sensor 1 included in the train 10 according to
the first embodiment. It is assumed that the train 10 is
oriented toward a direction indicated by an arrow 80 and
travels. To simplify the description, in FIG. 2, only the
30 train 10 and the acceleration sensor 1 installed in the
train 10 are schematically illustrated. Furthermore, in
FIG. 2, the traveling direction of the train 10 is
represented by an x axis. The acceleration sensor 1

7
detects a first acceleration, which is an acceleration in
the traveling direction of the train 10, and outputs the
first acceleration to the on-board control device 2. Note
that, in FIG. 2, a gradient value at a train position of
5 the train 10 to be described later and a gravity
acceleration g applied to the train 10 are illustrated.
[0013] The pick-up coil 3 receives a telegraph including
an identifier (ID) that is identification information of
the ground coil 11 from the ground coil 11 installed on the
10 ground, and outputs the ID of the ground coil 11 to the onboard control device 2.
[0014] The master controller 4 is provided around an
operator’s seat (not illustrated) of the train 10 and
accepts an operation by an operator. In FIG. 1, an example
15 is illustrated in which the train 10 includes the master
controllers 4 in a first car and a rear car. The master
controller 4 outputs information regarding an operation
state of a powering notch, a brake notch, or the like
received from the operator, to the on-board control device
20 2. The information regarding the operation state of the
powering notch, the brake notch, or the like output from
the master controller 4 to the on-board control device 2 is
information indicating a traveling state of the train 10,
for example, information indicating whether the train 10 is
25 in an acceleration state, a deceleration state, or a
coasting state.
[0015] The tachometer 5 generates pulses corresponding
to the number of revolutions of a wheel of the train 10 and
outputs the generated pulses to the on-board control device
30 2.
[0016] The on-board wireless device 6 performs wireless
communication with the ground wireless device 12. The onboard wireless device 6 transmits data such as positional

8
information on the train 10 that is calculated by the onboard control device 2 and acquired from the on-board
control device 2 to the ground wireless device 12 through
wireless communication via the on-board antenna 7.
5 Furthermore, the on-board wireless device 6 receives
control information such as information on stop limit of
the train 10 calculated by the ground device 13 from the
ground wireless device 12 through wireless communication
via the on-board antenna 7.
10 [0017] The brake device 8 executes processing for
deceleration, processing for stop, or the like of the train
10, based on a brake command from the on-board control
device 2.
[0018] The propulsion control device 9 drives an
15 electric motor that rotates the wheels based on a driving
command from the on-board control device 2 and executes
acceleration processing of the train 10.
[0019] The on-board control device 2 is installed in the
train 10 and controls traveling and stop of the train 10 at
20 the time of the operation of the train 10. The on-board
control device 2 periodically calculates the train position
of the train 10. Specifically, the on-board control device
2 calculates a train speed, a traveling distance, or the
like of the train 10 from the number of pulses acquired
25 from the tachometer 5 and a diameter of the wheel of the
train 10 and further calculates the train position of the
train 10 using the telegraph acquired from the pick-up coil
3, that is, positional information on the ground coil 11.
The on-board control device 2 transmits the calculated
30 positional information to the ground wireless device 12 via
the on-board wireless device 6 and the on-board antenna 7.
Furthermore, the on-board control device 2 receives the
information on stop limit of the train 10 calculated by the

9
ground device 13 from the ground wireless device 12 via the
on-board antenna 7 and the on-board wireless device 6. The
on-board control device 2 generates a stop deceleration
pattern using the information on stop limit or the like and
5 controls traveling of the train 10 using the generated stop
deceleration pattern. Specifically, when the train speed
of the train 10 exceeds the stop deceleration pattern, the
on-board control device 2 outputs the brake command to the
brake device 8. Furthermore, the on-board control device 2
10 periodically diagnoses soundness of the acceleration sensor
1. An operation for periodically diagnosing the soundness
of the acceleration sensor 1 by the on-board control device
2 will be described later.
[0020] In the train control system 100, a ground system
15 including devices provided on the ground includes the
ground coil 11, the ground wireless device 12, and the
ground device 13.
[0021] The ground coil 11 transmits a telegraph
including the ID that is the identification information of
20 the ground coil 11. Note that, although only one ground
coil 11 is illustrated in the example in FIG. 1, the
plurality of ground coils 11 is actually provided at
specified intervals on a train line where the train 10
travels.
25 [0022] The ground wireless device 12 performs wireless
communication with the train 10, specifically, the on-board
wireless device 6 via the on-board antenna 7. The ground
wireless device 12 receives the data such as the positional
information on the train 10 calculated by the train 10
30 through wireless communication. Furthermore, the ground
wireless device 12 transmits the control information such
as the information on stop limit of the train 10 calculated
by the ground device 13 to the train 10 through wireless

10
communication.
[0023] The ground device 13 is connected to the ground
wireless device 12, receives the positional information on
the train 10 from the on-board control device 2 of the
5 train 10 via the on-board wireless device 6, the on-board
antenna 7, and the ground wireless device 12 and manages
the positional information on the train 10 that travels in
a jurisdiction area. Note that one train 10 is illustrated
in the example in FIG. 1. However, the ground device 13
10 can manage pieces of positional information on the
plurality of trains 10. When the plurality of trains 10 is
traveling in the jurisdiction area, the ground device 13
calculates stop limits for the plurality of trains 10,
based on the pieces of positional information on the
15 plurality of trains 10, in order to manage intervals for
the plurality of trains 10. The ground device 13 transmits
the information on stop limit indicating the stop limit of
the train 10 obtained by calculation to the on-board
control device 2 of the train 10, via the ground wireless
20 device 12, the on-board antenna 7, and the on-board
wireless device 6. Furthermore, the ground device 13
generates the control information such as deceleration
information based on the positional information on the
plurality of trains 10 and transmits the control
25 information to the on-board control device 2 of the train
10 via the ground wireless device 12, the on-board antenna
7, and the on-board wireless device 6.
[0024] In the example in FIG. 1, an example in which the
train control system 100 is applied to a wireless train
30 control system is illustrated. However, the train control
system 100 is not limited to this. The train control
system 100 can be applied to a system that includes a
digital ATC device in which the ground device 13 detects

11
the train positions of the plurality of trains 10 using a
track circuit and transmits a position of a preceding train
to the on-board control device 2 via the track circuit.
[0025] Subsequently, the operation for periodically
5 diagnosing the soundness of the acceleration sensor 1 by
the on-board control device 2 and the configuration of the
on-board control device 2 will be described in detail. FIG.
3 is a block diagram illustrating a configuration example
of the on-board control device 2 according to the first
10 embodiment. The on-board control device 2 includes a
communication unit 21, a storage unit 22, and a control
unit 23.
[0026] The communication unit 21 communicates with the
acceleration sensor 1, the pick-up coil 3, the master
15 controller 4, the tachometer 5, the on-board wireless
device 6, the brake device 8, and the propulsion control
device 9.
[0027] The storage unit 22 stores information regarding
a gradient value at each position on the train line where
20 the train 10 travels, and information in which the ID of
the ground coil 11 and the installation position of the
ground coil 11 are associated. FIG. 4 is a diagram
illustrating an example of information stored in the
storage unit 22 of the on-board control device 2 according
25 to the first embodiment. FIG. 4 illustrates an example in
which the storage unit 22 stores pieces of the information
described above in a form of a database. The storage unit
22 stores a specific gradient value, a gradient start
position according to the gradient value, and a gradient
30 end position according to the gradient value, as the
information regarding the gradient value at each position
on the train line where the train 10 travels. Furthermore,
the storage unit 22 stores information regarding the ID and

12
the installation position of each ground coil 11 as the
information in which the ID of the ground coil 11 and the
installation position of the ground coil 11 are associated.
[0028] The control unit 23 specifies the train position
5 of the train 10 using the information acquired from the
pick-up coil 3 and the information acquired from the
tachometer 5. Specifically, the control unit 23 specifies
the train position of the train 10 using the ID of the
ground coil 11 received from the ground coil 11 via the
10 pick-up coil 3 and the communication unit 21, and the
installation position of the ground coil 11 corresponding
to the ID of the ground coil 11 stored in the storage unit
22. The control unit 23 calculates a traveling distance
from the ground coil 11 based on the number of pulses
15 corresponding to the number of revolutions of the wheel
obtained from the tachometer 5, and updates the train
position of the train 10 as needed. The control unit 23
determines a traveling state of the train 10 from the
information acquired from the master controller 4.
20 Specifically, the control unit 23 determines whether the
train 10 is accelerating, decelerating, coasting, or
stopped. The control unit 23 compares a first acceleration
that is an acceleration of the train 10 output from the
acceleration sensor 1 with a second acceleration, which is
25 an acceleration in the traveling direction of the train 10
calculated using the gravity acceleration g and the
gradient value at the train position of the train 10, when
the train 10 is coasting or stopped. The second
acceleration is a component of the gravity acceleration g
30 in the train traveling direction. The control unit 23
diagnoses the soundness of the acceleration sensor 1, based
on a comparison result.
[0029] In general, when the train 10 accelerates or

13
decelerates under a special situation in which a surface of
the railway track where the train 10 is traveling is wet,
wheel slipping or sliding may occur. When slipping or
sliding of the wheel of the train 10 occurs, the number of
5 pulses generated by the tachometer 5 does not match an
actual train speed, traveling distance, or the like of the
train 10. Therefore, the on-board control device 2
executes processing for determining whether or not slipping
or sliding of the wheel of the train 10 has occurred, and
10 correcting the train position of the train 10 if slipping
or sliding has occurred. Here, in the train 10, the
acceleration sensor 1 is not affected by slipping, sliding,
or the like of the wheel. Therefore, if the acceleration
sensor 1 is in a sound state, it is preferable that the on15 board control device 2 detects idling or sliding of the
wheel using the acceleration output from the acceleration
sensor 1 that is not affected by slipping, sliding, or the
like of the wheel, and performs correction when slipping or
sliding has occurred. Therefore, the on-board control
20 device 2 periodically diagnoses the soundness of the
acceleration sensor 1.
[0030] FIG. 5 is a flowchart illustrating an operation
of the on-board control device 2 according to the first
embodiment. As described above, in the on-board control
25 device 2, communication with other components is performed
by the communication unit 21, and all the other operations
are performed by the control unit 23. Therefore, for
simplicity, the description is made with the on-board
control device 2 being the subject. The on-board control
30 device 2 determines whether or not the acceleration sensor
1 is normal (step S101). An operation for determining
whether or not the acceleration sensor 1 is normal by the
on-board control device 2 will be described in detail. FIG.

14
6 is a flowchart illustrating the operation for determining
whether or not the acceleration sensor 1 is normal by the
on-board control device 2 according to the first embodiment.
The flowchart illustrated in FIG. 6 indicates details of
5 the operation in step S101 in the flowchart illustrated in
FIG. 5.
[0031] The on-board control device 2 acquires the ID of
the ground coil 11 via the pick-up coil 3 (step S201). The
on-board control device 2 specifies a position
10 corresponding to the ID of the ground coil 11, based on the
information in which the ID of the ground coil 11 and the
installation position of the ground coil 11 are associated
and stored in the storage unit 22 (step S202). The onboard control device 2 acquires pulses corresponding to the
15 number of revolutions of the wheel of the train 10 from the
tachometer 5, calculates the traveling distance from the
ground coil 11, and updates a train position x of the train
10 as needed (step S203). The on-board control device 2
specifies a gradient value Gx at the train position x of
20 the train 10 (step S204). As described above, the storage
unit 22 stores a gradient value at each position on the
train line where the train 10 travels, that is, the
gradient value Gx corresponding to the train position x of
the train 10. An expression method of the gradient value
25 Gx, that is, a unit is %, ‰, or the like. Here, in order
to simplify a coefficient, as illustrated in FIG. 2, it is
assumed that the gradient value Gx=H/L from a distance L of
traveling in the horizontal direction and a height H that
has changed at the time of traveling by the distance L. In
30 general, since an upper limit of the gradient of the train
line of railroads is assumed as about 50‰, this is because
it can be assumed that sinθ≈tanθ=H/L with such a small
angle θ. The on-board control device 2 acquires

15
information regarding the traveling state of the train 10
from the master controller 4 (step S205).
[0032] When the train 10 is coasting (step S206: Yes) or
when the train 10 is not coasting (step S206: No) but is
5 stopped (step S207: Yes), the on-board control device 2
determines whether or not the first acceleration detected
by the acceleration sensor 1 matches the second
acceleration that is the component of the gravity
acceleration g (step S208) in the traveling direction of
10 train. If the train 10 is coasting (step S206: Yes) or
stopped (step S207: Yes), an acceleration other than the
acceleration caused by the gravity acceleration g is not
generated; accordingly, the first acceleration output from
the acceleration sensor 1 has the same value as that of the
15 second acceleration, that is, “g×sinθ≈g×Gx”, the component
of the gravity acceleration g in the train traveling
direction. The on-board control device 2 may calculate a
difference between the first acceleration (α_Sen_x) and the
second acceleration (g×Gx), in consideration of a
20 measurement error or the like of the acceleration sensor 1
and determine that the accelerations match when an absolute
value of the difference falls within a first threshold
THRE1. The first threshold THRE1 is a threshold that is
specified in advance in consideration of the measurement
25 error or the like of the acceleration sensor 1, and is, for
example, stored in the storage unit 22. Note that, the onboard control device 2 can detect whether the train 10 is
in an acceleration state, a deceleration state, or a
coasting state because the on-board control device 2
30 acquires the information regarding the traveling state from
the master controller 4. Furthermore, the on-board control
device 2 can detect whether the train 10 is stopped because
the on-board control device 2 has acquired the pulses

16
corresponding to the number of revolutions of the wheel
from the tachometer 5.
[0033] When the first acceleration and the second
acceleration do not match (step S208: No), the on-board
5 control device 2 determines that the acceleration sensor 1
is anomalous (step S209). When the first acceleration and
the second acceleration match (step S208: Yes), the onboard control device 2 determines that the acceleration
sensor 1 is normal (step S210). Note that, when the train
10 10 is not coasting (step S206: No) and the train 10 is not
stopped (step S207: No), the on-board control device 2
assumes that the acceleration sensor 1 is normal without
diagnosing the soundness of the acceleration sensor 1 at
this operation (step S211) and determines that the
15 acceleration sensor 1 is normal (step S210).
[0034] The description returns to the flowchart in FIG.
5. When the acceleration sensor 1 is normal (step S101:
Yes), the on-board control device 2 performs detection for
slipping or sliding using the tachometer 5 and the
20 acceleration sensor 1, and executes the correction
processing if slipping or sliding is detected (step S102).
FIG. 7 is a flowchart illustrating an operation, by the onboard control device 2 according to the first embodiment,
for detecting slipping or sliding using the tachometer 5
25 and the acceleration sensor 1 when the acceleration sensor
1 is normal and executing the correction processing. The
on-board control device 2 calculates a third acceleration
(α_TM) from the pulse output from the tachometer 5. The
on-board control device 2 compares the calculated third
30 acceleration (α_TM) with the first acceleration (α_Sen_x)
detected by the acceleration sensor 1. Specifically, the
on-board control device 2 calculates a difference between
the third acceleration (α_TM) and the first acceleration

17
(α_Sen_x).
[0035] When the difference between the third
acceleration (α_TM) and the first acceleration (α_Sen_x) is
larger than a first slipping threshold SLIP1 used to detect
5 slipping (step S301: Yes), the on-board control device 2
determines that slipping of the wheel of the train 10 has
occurred and executes the correction processing (step S302).
Specifically, while the slipping state continues, the onboard control device 2 calculates the train speed and the
10 train position of the train 10 using the first acceleration
(α_Sen_x) output from the acceleration sensor 1.
[0036] When the difference between the third
acceleration (α_TM) and the first acceleration (α_Sen_x) is
equal to or less than the first slipping threshold SLIP1
15 (step S301: No) and is smaller than a first sliding
threshold SLIDE1 used to detect sliding (step S303: Yes),
the on-board control device 2 determines that sliding of
the wheel of the train 10 has occurred and executes the
correction processing (step S304). Specifically, while the
20 sliding state continues, the on-board control device 2
calculates the train speed and the train position of the
train 10 using the first acceleration (α_Sen_x) output from
the acceleration sensor 1.
[0037] When the difference between the third
25 acceleration (α_TM) and the first acceleration (α_Sen_x) is
equal to or more than the first sliding threshold SLIDE1
(step S303: No), the on-board control device 2 determines
that neither sliding nor slipping of the wheel of the train
10 has occurred and determines that the correction
30 processing is unnecessary (step S305). In this way, the
on-board control device 2 determines whether slipping has
occurred or not based on a comparison result obtained by
comparing the calculated difference with the first slipping

18
threshold used to detect slipping, and determines whether
or not sliding has occurred based on a comparison result
obtained by comparing the calculated difference with the
first sliding threshold used to detect sliding.
5 [0038] The description returns to the flowchart in FIG.
5. When the acceleration sensor 1 is anomalous (step S101:
No), the on-board control device 2 detects slipping or
sliding using the tachometer 5 and executes the correction
processing when slipping or sliding is detected (step S103).
10 FIG. 8 is a flowchart illustrating an operation of the onboard control device 2 for detecting slipping or sliding
using the tachometer 5 and executing the correction
processing when the acceleration sensor 1 is anomalous,
according to the first embodiment. The on-board control
15 device 2 calculates a fourth acceleration of the train 10
from an increment of the pulses per unit time of the
tachometer 5. Specifically, the on-board control device 2
calculates the fourth acceleration of the train 10 using
the number of pulses per unit time T0 of the tachometer 5,
20 for example, using the number of pulses P1 per unit time T0
between t1 seconds to t2 seconds and the number of pulses
P1+N1 increased by N1 pulses in the next unit time T0
between t2 seconds to t3 seconds.
[0039] When the fourth acceleration is larger than a
25 second slipping threshold SLIP2 used to detect slipping
(step S401: Yes), the on-board control device 2 determines
that slipping of the wheel of the train 10 has occurred and
executes the correction processing (step S402).
Specifically, when the on-board control device 2 detects
30 slipping and calculates the train position of the train 10
based on the pulse of the speed generator 5, a calculated
head position of the of the train 10 is ahead of an actual
head position of the train 10, and a margin for control is

19
secured. Therefore, a pulse signal of the tachometer 5 is
used as it is. On the other hand, a calculated rear
position of the train 10 is ahead of an actual rear
position of the train 10, which results in calculating a
5 position for stop limit of the subsequent train with less
margin for control. Therefore, for example, the on-board
control device 2 performs correction so as to secure the
margin for control with a method for calculating the train
position of the train 10 on the assumption that the train
10 10 has traveled at a constant speed from a time m1 seconds
before the time when slipping is detected, for example.
[0040] When the fourth acceleration is equal to or less
than the second slipping threshold SLIP2 (step S401: No)
and is smaller than a second sliding threshold SLIDE2 used
15 to detect sliding (step S403: Yes), the on-board control
device 2 determines that sliding of the wheel of the train
10 has occurred and executes the correction processing
(step S404). Specifically, when the on-board control
device 2 detects sliding and calculates the train position
20 of the train 10 based on the pulse signal of the speed
generator 5, the calculated head position of the train 10
is behind the actual head position of the train 10, which
reduces margin for control because the on-board control
device 2 determines a timing to output the brake command
25 based on a decision that separation from the brake pattern
is larger than actual separation. Therefore, the on-board
control device 2 performs correction for securing the
margin for control with a method for calculating the train
position of the train 10 or the like on the assumption with
30 that the train has traveled at a constant speed from a time
m2 seconds before the time when sliding is detected, for
example. On the other hand, the calculated rear position
of the train 10 is behind the actual rear position of the

20
train 10, the stop limit position of the subsequent train
is calculated with margin for control secured. Therefore,
the on-board control device 2 uses the pulse signal of the
tachometer 5 as it is.
5 [0041] When the fourth acceleration is equal to or more
than the second sliding threshold SLIDE2 (step S403: No),
the on-board control device 2 determines that neither
slipping nor sliding of the wheel of the train 10 has
occurred, and determines that the correction is unnecessary
10 (step S405). As above, the on-board control device 2
determines whether or not slipping occurs based on a
comparison result obtained by comparing the fourth
acceleration with the threshold used to detect slipping,
and determines whether or not sliding occurs based on a
15 comparison result obtained by comparing the fourth
acceleration with the threshold used to detect sliding.
[0042] When the acceleration sensor 1 is anomalous (step
S101: No), the on-board control device 2 does not use the
signal of the acceleration sensor 1, detects slipping or
20 sliding with only the pulse signal of the tachometer 5, and
performs correction if slipping or sliding is detected. In
this case, a true train position, train speed, acceleration,
or the like of the train 10 under slipping or sliding is
unknown. Therefore, in order to secure the margin for
25 control, the on-board control device 2 needs to execute
excessive correction for speed and position using, for
example, a physical limit value, a performance limit value,
or the like such as a train maximum acceleration, a train
maximum deceleration, and a maximum gradient. Therefore,
30 in the train control system 100, train intervals of the
plurality of trains 10 may excessively increase.
[0043] On the other hand, when the acceleration sensor 1
is normal (step S101: Yes), the on-board control device 2

21
can detect slipping or sliding of the wheel of the train 10
using the signal of the acceleration sensor 1 that is not
affected even when the wheel of the train 10 slips or
slides, and perform correction if slipping or sliding has
5 been detected. As a result, the train intervals of the
trains 10 do not become excessive, which results in
stabilizing transportation density in the train control
system 100.
[0044] Subsequently, a hardware configuration of the on10 board control device 2 will be described. In the on-board
control device 2, the communication unit 21 is an interface
such as a communication device. The storage unit 22 is a
memory. The control unit 23 is implemented by processing
circuitry. The processing circuitry may be a processor and
15 a memory that executes programs stored in the memory or may
be dedicated hardware.
[0045] FIG. 9 is a diagram illustrating an example where
processing circuitry 90 included in the on-board control
device 2 according to the first embodiment includes a
20 processor 91 and a memory 92. When the processing
circuitry 90 includes the processor 91 and the memory 92,
each function of the processing circuitry 90 of the onboard control device 2 is implemented by software, firmware,
or a combination of software and firmware. The software or
25 the firmware is described as a program and is stored in the
memory 92. The processing circuitry 90 implements each
function by reading and executing the program stored in the
memory 92 by the processor 91. That is, the processing
circuitry 90 includes the memory 92 that stores the program
30 that results in executing the processing of the on-board
control device 2. Furthermore, it can be said that these
programs are programs for causing a computer to execute a
procedure and a method of the on-board control device 2.

22
[0046] Here, the processor 91 may be a central
processing unit (CPU), a processing device, an arithmetic
device, a microprocessor, a microcomputer, a digital signal
processor (DSP), or the like. Furthermore, the memory 92
5 is, for example, a non-volatile or volatile semiconductor
memory such as a random access memory (RAM), a read only
memory (ROM), a flash memory, an erasable programmable ROM
(EPROM), and an Electrically EPROM (EEPROM) (registered
trademark), a magnetic disk, a flexible disk, an optical
10 disk, a compact disk, a mini disk, or a digital versatile
disc (DVD).
[0047] FIG. 10 is a diagram illustrating an example when
processing circuitry 93 included in the on-board control
device 2 according to the first embodiment includes
15 dedicated hardware. When the processing circuitry 93
includes the dedicated hardware, the processing circuitry
93 illustrated in FIG. 10 is, for example, a single circuit,
a composite circuit, a programmed processor, a parallelprogrammed processor, an application specific integrated
20 circuit (ASIC), a field-programmable gate array (FPGA), or
a combination thereof. Each function of the on-board
control device 2 may be implemented by the processing
circuitry 93 for each function, and the functions may be
collectively implemented by the processing circuitry 93.
25 [0048] Note that some of the functions of the on-board
control device 2 may be implemented by dedicated hardware,
and some of the functions may be implemented by software or
firmware. In this way, the processing circuitry can
implement each function described above by the dedicated
30 hardware, software, firmware, or the combination thereof.
[0049] As described above, according to the present
embodiment, the on-board control device 2 installed in the
train 10 diagnoses the soundness of the acceleration sensor

23
1 based on the comparison result obtained by comparing the
first acceleration detected by the acceleration sensor 1
and the second acceleration that is the component of the
gravity acceleration g in the traveling direction of train,
5 when the train 10 is coasting or stopped. Thus, the onboard control device 2 can periodically diagnose the
soundness of the acceleration sensor 1 with a simple
configuration, without using a vibration source that
vibrates the acceleration sensor 1 while the train 10 is
10 traveling. When the acceleration sensor 1 is normal, the
on-board control device 2 can improve accuracy in detecting
slipping or sliding and can prevent or reduce excessive
correction on slipping or sliding even when slipping or
sliding has occurred.
15 [0050] Second Embodiment.
In a second embodiment, a case will be described where
a train includes a biaxial acceleration sensor.
[0051] FIG. 11 is a diagram illustrating a configuration
example of a train control system 100a according to the
20 second embodiment. In the train control system 100a, the
train 10 in the train control system 100 according to the
first embodiment illustrated in FIG. 1 is replaced with a
train 10a. In the train 10a, the acceleration sensor 1 and
the on-board control device 2 in the train 10 according to
25 the first embodiment illustrated in FIG. 1 are replaced
with a biaxial acceleration sensor 1a and an on-board
control device 2a, respectively.
[0052] The biaxial acceleration sensor 1a is an
acceleration sensor that includes a first detection axis
30 and a second detection axis. The biaxial acceleration
sensor 1a is installed such that the first detection axis
is provided along a traveling direction of the train 10a,
and the second detection axis is provided to be

24
perpendicular to the first detection axis and along a
vertical direction with respect to a floor surface of the
train 10a. FIG. 12 is a diagram illustrating an
installation example of the biaxial acceleration sensor 1a
5 included in the train 10a according to the second
embodiment. It is assumed that the train 10a is oriented
to the direction indicated by the arrow 80 and travels. To
simplify the description, in FIG. 12, only the train 10a
and the biaxial acceleration sensor 1a installed in the
10 train 10a are schematically illustrated. Furthermore, in
FIG. 12, the traveling direction of the train 10a is
represented by an x axis, and the vertical direction with
respect to the floor surface of the train 10a is
represented by a z axis. The biaxial acceleration sensor
15 1a detects a first acceleration that is an acceleration in
the traveling direction of the train 10a, detects a fifth
acceleration that is an acceleration in the vertical
direction with respect to the floor surface of the train
10a, and outputs the accelerations to the on-board control
20 device 2a.
[0053] When the biaxial acceleration sensor 1a is
disposed in the train 10a in this way, an output component
in the z-axis direction of the biaxial acceleration sensor
1a, that is, the fifth acceleration should match a value
25 that is uniquely determined based on only a gradient value
at a position of the train 10a, regardless of the
acceleration of the train 10a, if the biaxial acceleration
sensor 1a is normal. As illustrated in FIG. 12, when the
gradient value Gx=H/L (angle θ) is satisfied, an output
30 component in the z-axis direction of the gravity
acceleration g, that is, a sixth acceleration is g×cosθ=g×√
(1-sin2θ)≈g×√ (1-Gx2).
[0054] A configuration of the on-board control device 2a

25
is similar to the configuration of the on-board control
device 2 according to the first embodiment illustrated in
FIG. 3. The on-board control device 2a performs an
operation similar to that of the on-board control device 2
5 according to the first embodiment. However, an operation
for determining whether or not the biaxial acceleration
sensor 1a is normal is different. FIG. 13 is a flowchart
illustrating the operation of the on-board control device
2a according to the second embodiment. The on-board
10 control device 2a determines whether or not the biaxial
acceleration sensor 1a is normal (step S121). Note that,
operations in steps S102 and S103 in FIG. 13 are the same
as the operations in steps S102 and S103 in the flowchart
according to the first embodiment illustrated in FIG. 5.
15 The operation for determining whether or not the biaxial
acceleration sensor 1a is normal by the on-board control
device 2a will be described in detail. FIG. 14 is a
flowchart illustrating the operation for determining
whether or not the biaxial acceleration sensor 1a is normal
20 by the on-board control device 2a according to the second
embodiment. The flowchart illustrated in FIG. 14 indicates
details of the operation in step S121 in the flowchart
illustrated in FIG. 13. In the flowchart illustrated in
FIG. 14, operations in step S201 to step S204 are the same
25 as the operations in step S201 to step S204 in the
flowchart according to the first embodiment illustrated in
FIG. 6.
[0055] The on-board control device 2a determines whether
or not the fifth acceleration (α_Sen_z) regarding the
30 second detection axis output from the biaxial acceleration
sensor 1a, matches the sixth acceleration (g×√ (1-Gx2)) in
the vertical direction with respect to the floor surface of
the train 10 that is calculated using the gravity

26
acceleration g and the gradient value Gx at the train
position (step S221). The on-board control device 2a may
calculate a difference between the fifth acceleration
(α_Sen_z) and the sixth acceleration (g×√ (1-Gx2)) in
5 consideration of a measurement error or the like of the
biaxial acceleration sensor 1a, and determine that the
accelerations match when an absolute value of the
difference is within a second threshold THRE2. The second
threshold is specified in advance in consideration of the
10 measurement error or the like of the biaxial acceleration
sensor 1a, and is, for example, stored in a storage unit 22.
The on-board control device 2a performs the determination
in step S221, regardless of a traveling state of the train
10a. If the fifth acceleration and the sixth acceleration
15 match (step S221: Yes), the on-board control device 2a
determines that a detection unit and a common unit of the
second detection axis are normal by the biaxial
acceleration sensor 1a (step S222).
[0056] FIG. 15 is a diagram illustrating a configuration
20 example of the biaxial acceleration sensor 1a included in
the train 10a according to the second embodiment. The
biaxial acceleration sensor 1a includes detection units 30
and 40 and a common unit 50. The detection unit 30 is a
detection unit of the first detection axis that includes an
25 x-axis acceleration sensor unit 31, an analog to digital
(A/D) converter 32, and a filter unit 33. The detection
unit 40 is a detection unit of the second detection axis
that includes a z-axis acceleration sensor unit 41, an A/D
converter 42, and a filter unit 43. The common unit 50
30 includes a power supply unit 51, a control logic unit 52, a
first in first out (FIFO) 53, a serial input/output (I/O)
unit 54, and a transmission cable 55. The common unit 50
is used by the detection units 30 and 40 in common. The

27
acceleration sensor 1 according to the first embodiment can
diagnose a failure only when the train 10 is stopped or
coasting. However, the biaxial acceleration sensor 1a of
the on-board control device 2a can constantly diagnose a
5 failure of the detection unit 40 that is the detection unit
of the second detection axis and the common unit 50 in step
S222. In this way, the on-board control device 2a can
diagnose the soundness of the detection unit 40 and the
common unit 50 included in the biaxial acceleration sensor
10 1a, regardless of the traveling state of the train 10a,
based on the comparison result obtained by comparing the
fifth acceleration regarding the second detection axis
output from the biaxial acceleration sensor 1a with the
sixth acceleration in the vertical direction with respect
15 to the floor surface of the train 10a that is calculated
using the gravity acceleration g and the gradient value at
the train position.
[0057] Operations in subsequent steps S205 to S208 are
the same as the operations in steps S205 to S208 in the
20 flowchart according to the first embodiment illustrated in
FIG. 6. If the fifth acceleration and the sixth
acceleration do not match (step S221: No), the on-board
control device 2a determines that the biaxial acceleration
sensor 1a is anomalous (step S223). If the first
25 acceleration and the second acceleration do not match (step
S208: No), the on-board control device 2a determines that
the biaxial acceleration sensor 1a is anomalous (step S223).
If the first acceleration and the second acceleration match
(step S208: Yes), the on-board control device 2a determines
30 that the biaxial acceleration sensor 1a is normal (step
S224). Note that, when the train 10a is not coasting (step
S206: No) and the train 10a is not stopped (step S207: No),
the on-board control device 2a does not diagnose soundness

28
of the biaxial acceleration sensor 1a at the current
operation and assumes that the biaxial acceleration sensor
1a is normal (step S225).
[0058] As described above, according to the present
5 embodiment, the on-board control device 2a installed in the
train 10a can determine whether or not the detection unit
40 of the second detection axis and the common unit 50 of
the biaxial acceleration sensor 1a are normal without using
a vibration source that vibrates the biaxial acceleration
10 sensor 1a and regardless of the traveling state of the
train 10a.
[0059] The configurations illustrated in the above
embodiments indicate examples and can be combined with
other known techniques. Furthermore, the embodiments can
15 be combined with each other, and some configurations can be
partially omitted or changed without departing from the
scope.
Reference Signs List
20 [0060] 1 acceleration sensor; 1a biaxial acceleration
sensor; 2, 2a on-board control device; 3 pick-up coil; 4
master controller; 5 tachometer; 6 on-board wireless
device; 7 on-board antenna; 8 brake device; 9 propulsion
control device; 10, 10a train; 11 ground coil; 12 ground
25 wireless device; 13 ground device; 21 communication unit;
22 storage unit; 23 control unit; 30, 40 detection unit;
31 x-axis acceleration sensor unit; 32, 42 A/D converter;
33, 43 filter unit; 41 z-axis acceleration sensor unit;
50 common unit; 51 power supply unit; 52 control logic
30 unit; 53 FIFO; 54 serial I/O unit; 55 transmission cable;
100, 100a train control system.
We Claim:
[Claim 1] An on-board control device to be installed in a
5 train, comprising:
a communication unit to be communicable with a
tachometer that outputs pulses corresponding to the number
of revolutions of wheels of the train, a pick-up coil that
receives a telegraph that includes identification
10 information of a ground coil from the ground coil, an
acceleration sensor a detection axis of which is provided
along a traveling direction of the train, and a master
controller;
a storage unit to store information regarding a
15 gradient value at each position on a train line where the
train travels; and
a control unit to specify a train position of the
train by using information acquired from the pick-up coil
and the tachometer, determine a traveling state of the
20 train from information acquired from the master controller,
and, when the train coasts or is stopped, diagnose
soundness of the acceleration sensor based on a comparison
result obtained by comparing a first acceleration of the
train output from the acceleration sensor with a second
25 acceleration in the traveling direction of the train
calculated by using a gravity acceleration and a gradient
value at the train position.
[Claim 2] The on-board control device according to claim 1,
30 wherein
when the acceleration sensor is normal, the control
unit calculates a difference between a third acceleration
of the train calculated from the pulses output from the

30
tachometer and the first acceleration, determines whether
slipping occurs based on a comparison result obtained by
comparing the difference with a threshold used to detect
the slipping, and determines whether sliding occurs based
5 on a comparison result obtained by comparing the difference
with a threshold used to detect the sliding.
[Claim 3] The on-board control device according to claim 1,
wherein
10 when the acceleration sensor is anomalous, the control
unit calculates a fourth acceleration of the train from an
increment of the pulses per unit time of the tachometer,
determines whether slipping occurs based on a comparison
result obtained by comparing the fourth acceleration with a
15 threshold used to detect the slipping, and determines
whether sliding occurs based on a comparison result
obtained by comparing the fourth acceleration with a
threshold used to detect the sliding.
20 [Claim 4] The on-board control device according to any one
of claims 1 to 3, wherein
the acceleration sensor includes a first detection
axis that is the detection axis and a second detection axis
that is perpendicular to the first detection axis and is
25 provided along a vertical direction with respect to a floor
surface of the train, and
the control unit diagnoses soundness of a common unit
of the first detection axis and the second detection axis
included in the acceleration sensor, regardless of a
30 traveling state of the train, based on a comparison result
obtained by comparing a fifth acceleration regarding the
second detection axis output from the acceleration sensor
with a sixth acceleration in the vertical direction with

respect to the floor surface of the train, the sixth
acceleration being calculated using the gravity
acceleration and the gradient value at the train position.
5 [Claim 5] An acceleration sensor diagnosis method of an onboard control device to be installed in a train,
the on-board control device including
a communication unit to be communicable with a
tachometer that outputs pulses corresponding to the number
10 of revolutions of a wheel of the train, a pick-up coil that
receives a telegraph that includes identification
information of a ground coil from the ground coil, an
acceleration sensor a detection axis of which is provided
along a traveling direction of the train, and a master
15 controller,
a storage unit to store information regarding a
gradient value at each position on a train line where the
train travels, and
a control unit,
20 the method comprising:
a first step of specifying a train position of the
train by using information acquired from the pick-up coil
and the tachometer by the control unit;
a second step of determining a traveling state of the
25 train from information acquired from the master controller
by the control unit; and
a third step of diagnosing, when the train coasts or
is stopped, soundness of the acceleration sensor, based on
a comparison result obtained by comparing a first
30 acceleration of the train output from the acceleration
sensor with a second acceleration in the traveling
direction of the train calculated using a gravity
acceleration and a gradient value at the train position, by

32
the control unit.
[Claim 6] The acceleration sensor diagnosis method
according to claim 5, wherein
5 in the third step, when the acceleration sensor is
normal, the control unit calculates a difference between a
third acceleration of the train calculated from the pulses
output from the tachometer and the first acceleration,
determines whether slipping occurs based on a comparison
10 result obtained by comparing the difference with a
threshold used to detect the slipping, and determines
whether sliding occurs based on a comparison result
obtained by comparing the difference with a threshold used
to detect the sliding.
15
[Claim 7] The acceleration sensor diagnosis method
according to claim 5, wherein
in the third step, when the acceleration sensor is
anomalous, the control unit calculates a fourth
20 acceleration of the train from an increment of the pulses
per unit time of the tachometer, determines whether
slipping occurs based on a comparison result obtained by
comparing the fourth acceleration with a threshold used to
detect the slipping, and determines whether sliding occurs
25 based on a comparison result obtained by comparing the
fourth acceleration with a threshold used to detect the
sliding.
[Claim 8] The acceleration sensor diagnosis method
30 according to any one of claims 5 to 7, wherein
the acceleration sensor includes a first detection
axis that is the detection axis and a second detection axis
that is perpendicular to the first detection axis and is

33
provided along a vertical direction with respect to a floor
surface of the train, and
in the third step, the control unit diagnoses
soundness of a common unit that is common for the first
5 detection axis and the second detection axis included in
the acceleration sensor, regardless of a traveling state of
the train, based on a comparison result obtained by
comparing a fifth acceleration regarding the second
detection axis output from the acceleration sensor with a
10 sixth acceleration in the vertical direction with respect
to the floor surface of the train, the sixth acceleration
being calculated using the gravity acceleration and the
gradient value at the train position.