RAIL VEHICLE WHEEL SENSOR PROVIDED WITH SECURE COMMUNICATION AND CONFIGURATION

Abstract

According to the invention a rail vehicle wheel sensor assembly (ZCK) is provided that comprises a rail vehicle wheel detection system (UWK) and a two-wire interface in the form of a current loop, by means of which the wheel detection system (UWK) is connected to an external device (SO). The wheel sensor assembly (ZCK) is characterised in that it comprises a wheel detection configuration system (UKDK) connected to the wheel detection system (UWK), an authorisation and configuration system (UA) capable of storing at least one secret (SK), used for secure communication with the external device (SO) and for forwarding configuration commands to the wheel detection configuration system (UKDK) connected thereto, a communication converter system (UM) used for the signal conversion, a wheel sensor supply voltage conversion system (UKU), a voltage summation and voltage-to-sensor-output-current conversion system (UKUI), an output signal permission system (UZSW) and a power supply system (UZ).

According to the invention a rail vehicle wheel detection device (DWK) comprising two or more such wheel sensor assemblies is further provided.

Claims

1. A rail vehicle wheel sensor assembly (ZCK) comprising: a rail vehicle wheel detection system (UWK) and a two-wire interface in the form of a current loop, by means of which the wheel detection system (UWK) is connected to an external device (SO); a wheel detection configuration system (UKDK) connected to the wheel detection system (UWK), used to configure the wheel detection system (UWK) and comprising at least one analog or digital circuit, and the output state of which changes the mode of operation of the wheel detection system (UWK) by changing its operating parameters; a communication converter system (UM); a wheel sensor supply voltage conversion system (UKU) for forwarding signals from the external device (SO); a power supply system) UZ) used to supply power to at least one system within the wheel sensor assembly (ZCK); characterised in that the wheel sensor assembly (ZCK) further comprises: an authorisation and configuration system (UA) capable of storing at least one secret (SK), used for secure communication with the external device (SO) and for forwarding configuration commands to the wheel detection configuration system (UKDK) connected thereto, wherein the authorisation and configuration system (UA) comprises a logic circuit (UL), a non-volatile memory circuit (NVM) and a cryptographic circuit (UKR), wherein the logic circuit (UL) is connected to the non-volatile memory circuit (NVM) and to the cryptographic circuit (UKR), the cryptographic circuit (UKR) being capable of storing at least one secret (SK) in the form of a secret cryptographic key, without the possibility of reading the secret from the outside, wherein the logic circuit (UL) being destined to encode and decode transmitted information and to verify the authorization of the external device (SO) to configure the wheel detection system (UWK), is configured to use the crypto graphic keys stored in the cryptographic circuit (UKR). a communication converter system (UM) used for the signal conversion between the authorisation and configuration system (UA) and the wheel sensor interface; a wheel sensor supply voltage conversion system (UKU) connected to the input of the authorisation and configuration system (UA) via the communication converter system (UM) in order to forward signals from the external device (SO); a voltage summation and voltage-to-sensor-output-current conversion system (UKUI) used for summing voltages at the two inputs thereof and for producing an output signal of the wheel sensor assembly (ZCK) in the form of a current signal; an output signal permission system (UZSW) acting as an intermediary in connecting an output signal (X) of the wheel detection system (UWK) and output signals (6) of the authorisation and configuration system (UA) to the inputs of the voltage summation and voltage-to-sensor-output-current conversion system (UKUI); and a power supply system (UZ) used to supply power to at least one system within the wheel sensor assembly (ZCK).

2. (canceled)

3. The wheel sensor assembly (ZCK) according to claim 1, characterised in that: the logic circuit (UL) is configured to store, in a non-volatile memory circuit (NVM), information on the successfully performed authorisation verification process during an attempt to access the wheel detection configuration system (UKDK), as well as on the unsuccessfully performed authorisation verification process during an attempt to access the wheel detection configuration system (UKDK), wherein the logic circuit is configured to add an identifier that unambiguously determines the order of the stored information.

4. The wheel sensor assembly (ZCK) according to claim 1, characterised in that: the output signal permission system (UZSW) comprises: a first key circuit (KI) controlled by the authorisation and configuration system (UA) by means of a first key circuit control signal (6), such that, depending on the state of the first key circuit control signal (6), either the output (9) of the wheel detection system (UWK) providing its output signal (X) indicating the presence of a wheel, or a determined voltage value (Usygl) is delivered to the first input of the voltage summation and voltage-to-sensor-output-current conversion system (UKUI), where the determined voltage value (Usygl) is below the level of the internal wheel presence output signal (X) while a wheel is present over the wheel detection system (UWK), a second key circuit (K2) controlled by a communication permission system (UZK) by means of a second key circuit control signal (12), such that, depending on the state of the second key circuit control signal (12), either the output of the authorisation and configuration system (UA) for sending signals to the external device (SO), or a determined voltage value (Usyg2) is delivered to the second input of the voltage summation and voltage-to-sensor-output-current conversion system (UKUI), where the determined voltage value (Usyg2) is 0, wherein the communication permission system (UZK) controls the second key circuit (K2) in such a way it continuously monitors the frequency band of a signal (X2) at the output of the first key circuit (KI) and in case the frequency band of the signal (X2) exceeds a predetermined level (Fg), said signal (Usyg2) is delivered to the output of the second key circuit (K2).

5. The wheel sensor assembly (ZCK) according to claim 1-3 and 4, characterised in that: it comprises a sensor and sensor environment monitoring system (UMCO), to which at least one internal signal of the wheel sensor assembly (ZCK) and at least one sensor for monitoring environmental operating conditions of the wheel sensor assembly (ZCK) are connected, and which is connected by means of a digital connection to, preferably integrated into, the authorisation and configuration system (UA).

6. The wheel sensor assembly (ZCK) according to claim 5, characterised in that at least one internal signal of the wheel detection system (UWK) is in particular provided to the sensor and sensor environment monitoring system (UMCO), and said at least one sensor is used in particular for monitoring environmental operating conditions of the wheel detection system (UWK).

7. The wheel sensor assembly (ZCK) according to claim 5 or 6, characterised in that sensors for measuring vibrations (CW) and/or temperature (CT) and/or humidity (CH) are used as said at least one sensor.

8. The wheel sensor assembly (ZCK) according to claim 1, characterised in that the wheel detection system (UWK) comprises a generator circuit (G) comprising a resonant circuit with an arrangement of coils, the output of which is connected to an amplifier circuit (W), wherein the operating parameters changed by the wheel detection configuration system (UKDK) are operating parameters of the generator circuit (G) and/or of the amplifier circuit (W).

9. The wheel sensor assembly (ZCK) according to claim 8 characterised in that: the arrangement of coils belonging the generator circuit (G) is formed by at least two coils connected in an opposing manner in order to eliminate interferences.

10. The wheel sensor assembly (ZCK) according to claim 8 or 9 characterised in that: it comprises a wheel sensor test system (UT) that is connected by means of a digital connection to the authorisation and configuration system (UA), preferably integrated into it, wherein a wheel simulation system (USK) in the form of a test coil (CTST) situated near the arrangement of coils belonging to the generator circuit (G) is connected to the wheel sensor test system (UT), wherein when a current flows through the test coil (CTST), it causes a reaction of the generator circuit (G) similar to that for a wheel passing over the wheel sensor.

11. The wheel sensor assembly (ZCK) according to any of claims 5-10, characterised in that the authorisation and configuration system (UA), the sensor and sensor environment monitoring system (UMCO), the wheel sensor test system (UT) and the wheel detection configuration system (UKDK) are integrated into one common system.

12. The wheel sensor assembly (ZCK) according to any of the preceding claims, characterised in that: the wheel sensor assembly (ZCK) has modular design, wherein: the wheel detection system (UWK) and the wheel detection configuration system (UKDK) form a wheel detection module (MDK), the authorisation and configuration system (UA) and the communication converter system (UM) form a secure communication and wheel sensor configuration module (MBCK), the output signal permission system (UZSW), the power supply system (UZ), the wheel sensor supply voltage conversion system (UKU) and the voltage summation and voltage-to-sensor-output-current conversion system (UKUI) form a wheel sensor interface module (MKZ).

13. A railway vehicle wheel detection device (DWK) comprising two or more wheel sensor assemblies (ZCK1, ZKC2) as defined in claim 1, wherein said two or more wheel sensor assemblies (ZCK1, ZKC2) are arrangeable one after another along a rail and connectable in parallel to the same external device (SO) by means of separate current loops.

14. The railway vehicle wheel detection device (DWK) according to claim 13, wherein it comprises a common housing in which the two or more wheel sensor assemblies (ZCK1, ZKC2) are contained.

Description

[0041] The invention is explained in more detail in embodiments and in the drawing, wherein:

[0042] FIG. 1 illustrates a schematic block diagram of a wheel sensor assembly;

[0043] FIG. 2 illustrates a schematic block diagram of a secure communication and wheel sensor configuration module;

[0044] FIG. 3 is a schematic block diagram of an output signal permission system,

[0045] FIG. 4 is a schematic block diagram of the wheel sensor assembly with attached wheel sensor and sensor environment monitoring system,

[0046] FIG. 5 is a schematic block diagram of the wheel sensor assembly with attached wheel sensor test system;

[0047] FIG. 6 is a schematic block diagram of a wheel detection device comprising two wheel sensor assemblies.

EXAMPLE 1

[0048] A wheel sensor assembly ZCK presented in FIG. 1 is connected to an external device SO by means of a two-wire interface in the form of a current loop. The wheel sensor assembly ZCK comprises a wheel detection module MDK, a secure communication and wheel sensor configuration module MBCK and a wheel sensor interface module MKZ.

[0049] The wheel detection module MDK comprises a generator circuit G comprising a resonant circuit with an arrangement of coils connected in an opposing manner in order to eliminate interferences, the output of which is connected 1 to the input of an amplifier circuit W having adjustable amplification characteristics. A wheel detection configuration system UKDK provides, by means of signal 2, a suitable working point of the generator circuit G by changing its operating frequency or by changing the resonant frequency of the resonant circuit. The wheel detection configuration system UKDK also provides, by means of signal 3, an amplification characteristics shape of the amplifier circuit W.

[0050] The wheel detection configuration system UKDK is controlled by signal 4 developed by an authorisation and configuration system UA based on the commands received from the external device SO.

[0051] A secure communication and wheel sensor configuration module MBCK comprises the authorisation and configuration system UA, capable of storing at least one secret SK, used for secure communication with the external device SO and for forwarding configuration commands to the wheel detection configuration system UKDK connected thereto as well as a communication converter system UM used for the signal conversion between the authorisation and configuration system UA and the sensor interface module MKZ.

[0052] The authorisation and configuration system UA, forming part of the secure communication and wheel sensor configuration module MBCK, comprises, as shown in FIG. 2, a logic circuit UL connected to a non-volatile memory circuit NVM and to a cryptographic circuit UKR capable of storing at least one secret SK in the form of a secret cryptographic key, without the possibility of reading the secret from the outside, wherein the logic circuit UL uses the cryptographic keys stored in the cryptographic circuit UKR to encode and decode transmitted information and to verify the authorisation of the external device to configure the sensor. Based on a symmetric key and/or a digital certificate stored in the cryptographic circuit (UKR) in the production process of the sensor, temporary keys are generated which allow to carry out authentication and authorisation operations based on known algorithms during the communication with the external device SO, and to encrypt the transferred information.

[0053] The authentication process is performed in accordance with the needs of a given application and the expected security level. A message authentication code is normally used, whose parameters can be configured by selecting from the known methods such as MD5, SHA-1 or those belonging to the group of SHA-2. In special cases the authorisation process may also be performed with the use of a digital signature preferably using ECC certificates (Elliptic curve cryptography) or, in special cases, RSA certificates.

[0054] The encryption of the transferred information is also performed in accordance with the needs of a given application and the expected security level. AES-128 encryption is normally used which in special cases may be replaced by a more complex algorithm, e.g. AES-256.

[0055] The configuration commands are transferred to the wheel sensor assembly ZCK with the use of changes in the sensor supply voltage. A voltage signal supplied at the power input of the sensor, after being processed in the wheel sensor interface module MKZ by the supply voltage conversion system UKU, is forwarded to the authorisation and configuration system UA by means of the communication converter system UM converting the voltage signal 8 to a digital signal 5. The communication converter system UM also provides conversion of the output digital signal 5 of the authorisation and configuration system UA to an analog form 7 which is converted to an output current signal in the wheel sensor interface module MKZ.

[0056] Due to the cybersecurity requirements, the configuration commands comprise information on the expected configuration and sender and on the sender's authorisation to configure the sensor, which information are encoded with the use of the cryptographic key known to the authorisation system and being stored as a hidden secret SK in the cryptographic circuit UKR in such a way it is possible to unequivocally decode transferred information and to identify the sender. The authorisation and configuration system UA performs the analysis of the configuration command with the use of the logical circuit UL and, in case the analysis result of the configuration command confirms sender's authorisation to configure the wheel sensor, the configuration signals 4 are transferred to the wheel detection configuration system UKDK which cause a configuration change of the wheel detection module MDK. Information associated with the operation of the authorisation and configuration system UA are stored in the non-volatile memory circuit NVM forming part of the authorisation and configuration system UA, allowing the past events to be retrieved, wherein to the successive entries an identifier is added that unambiguously determines the order of the stored information. In particular, in case the analysis result does not confirm sender's authorisation to configure the wheel sensor, information about occurring such a situation is stored in the non-volatile memory circuit NVM.

[0057] Referring again to FIG. 1, the sensor interface module MKZ comprises a power supply system UZ used for supplying power to the wheel detection module MDK and the secure communication and wheel sensor configuration module MBCK, a wheel sensor supply voltage conversion system UKU connected to the input of the authorisation and configuration system UA by means of the communication converter system UM in order to forward signals from the external system, a voltage summation and voltage-to-sensor-output-current conversion system UKUI used for summing voltages at the two inputs thereof and for producing an output signal of the assembly of the wheel sensor systems in the form of a current signal, and an output signal permission system UZSW acting as an intermediary in connecting an output signal of the amplifier circuit W and the output signals of the authorisation system UA to the inputs of the voltage summation and voltage-to-sensor-output-current conversion system UKUI.

[0058] As shown in FIG. 3, the output signal permission system UZSW forming part of the sensor interface module MKZ comprises: [0059] a first key circuit K1 controlled by the authorisation and configuration system UA by means of a first key circuit control signal 6, such that, depending on the state of the first key circuit K1 control signal, either the output of the amplifier circuit W of the wheel detection module MDK providing the internal wheel presence signal 9, or a determined voltage value having Usyg1 level is delivered to the first input of the voltage summation and voltage-to-sensor-output-current conversion system UKUI, where Usyg1 is below the level of the internal wheel presence signal 9 while a wheel is present over the wheel sensor. Such functionality enables to disconnect the output of the amplifier W from the input of the voltage summation and voltage-to-sensor-output-current conversion system UKUI, when there is a need of transferring information by the authorisation and configuration system UA in compliance with the safety rules. [0060] a second key circuit K2 controlled by a communication permission system UZK by means of a second key circuit K2 control signal 12, such that, depending on the state of the second key circuit control signal 12, either the output of the authorisation and configuration system UA for sending signals 7 to the external device SO, or a determined voltage value having Usyg2 level, where Usyg2=0, is delivered to the second input of the voltage summation and voltage-to-sensor-output-current conversion system UKUI, wherein the communication permission system UZK controls the second key circuit in such a way it continuously monitors the frequency band of a signal X2 at the output of the first key circuit, and in case the frequency band of the signal X2 exceeds a predetermined level Fg corresponding to the minimum frequency used by the communication converter system UM, the signal Usyg2 is delivered to the output of the second key circuit K2. Monitoring of the frequency band of the signal X2 is implemented by evaluating the rate of change of the signal X2 and, in case the rate of the recorded change approaches the level corresponding to the frequency Fg at the output of the communication permission system UZK, a signal is generated that determines the position of the second key circuit K2, such that the signal Usyg2 is supplied at the output 11 for a time period not less than 100 ms. Such functionality ensures that there is no interference of the signals of the wheel detection module MDK caused by the signals from the secure communication and wheel sensor configuration module MBCK, what could happen during the passage of a high-speed train.

EXAMPLE 2

[0061] A sensor and sensor environment monitoring system UMCO shown in FIG. 4 is connected to the system described in example 1, preferably integrated into it, to which internal signals of the wheel detection module MDK, such as frequency of the generator G, input and output signals in the amplifier circuit W in the present example, of the sensor interface module MKZ, such as sensor supply voltage or sensor output current in the present example, are supplied and sensors for measuring vibrations CW, humidity CH and temperature CT are connected that are used for monitoring environmental operating conditions of the wheel sensor.

[0062] The sensor and sensor environment monitoring system UMCO acquires and evaluates in a quasi-continuous manner signals associated with the operation of the wheel sensor assembly ZCK and with the environmental conditions such as vibration, temperature and humidity in the sensor environment, and then forwards them by means of a digital connection to the authorisation and configuration system UA, wherein both systems UMCO and UA are preferably integrated with each other. In particular, monitoring of the environmental conditions may relate the wheel detection system UWK.

[0063] The information are then transferred to the external device SO using the secure communication ensured by the secure communication and wheel sensor configuration module MBCK.

EXAMPLE 3

[0064] As shown in FIG. 5A, a wheel sensor test system UT is connected to the system described in example 1, to which a wheel simulation system USK in the form of a test coil CTST situated near the arrangement of coils belonging to the generator circuit G is connected, wherein when a current flows through the test coil CTST, it causes a reaction of the generator circuit G similar to that for a wheel passing over the wheel sensor.

[0065] The wheel sensor test system UT checks the correct operation of the wheel sensor systems by causing a current to flow through the test coil CTST in a controlled manner and by observing the responses of the systems in the form of changes in the output signal of the amplifier W and/or in the output current of the wheel sensor. The test procedure is started automatically, at defined intervals or on request from the external device SO via the authorisation and configuration system UA. Information on the check result are transferred from the wheel sensor test system UT to the external device SO using the secure communication ensured by the secure communication and wheel sensor configuration module MBCK.

EXAMPLE 4

[0066] The systems described in examples 1, 2 and 3 are simultaneously used. As a result, an advanced wheel sensor assembly is achieved, equipped with the internal secure configuration systems, the internal test system and the internal sensor and sensor environment monitoring system with the provision of secure communication with the external device SO.

EXAMPLE 5

[0067] Aa schematic block diagram of a wheel detection device DWK is illustrated in FIG. 6 that comprises two wheel sensor assemblies ZCK1 and ZCK2 in a common housing, connected in parallel to the external device SO by means of separate current loops. The wheel sensor assemblies ZCK1 and ZCK2 are constructed as described in any of the previous examples and are arranged one after another along a rail on which railway vehicle wheels run. Signals delivered by the wheel sensor assemblies ZCK1 and ZCK2 to the external device SO using the secure configuration methods as described are processed by the external device SO or by a further system e.g. for detecting the travel direction or speed of a rail vehicle.

[0068] Although the above examples describe specific implementation variants of the invention, the invention is not limited to those variants but only by the claims. A person skilled in the art will easily notice possible changes, modifications and adaptations that can be made without departing from the scope of the invention defined by claims. In particular, without departing from the scope of the invention, the individual systems being parts of the wheel sensor assembly can be integrated with each other in various combinations, e.g. one integrated system can simultaneously perform several functions specific to several systems. Similarly, depending on requirements, individual systems can be grouped into modules, so that individual modules comprise one or more systems. Moreover, individual systems, whether they are integrated into common systems or grouped into modules, can be spatially distributed, e.g., such that the individual systems and/or modules are spatially separated from each other with connections provided between them.

LIST OF REFERENCE NUMERALS

[0069] CH sensor for measuring humidity [0070] CT sensor for measuring temperature [0071] CTST test coil [0072] CW sensor for measuring vibrations [0073] DWK wheel detection device [0074] G generator circuit [0075] MBKC secure communication and wheel sensor configuration module [0076] MDK wheel detection module [0077] MKZ wheel sensor interface module [0078] NVM non-volatile memory circuit [0079] SK secret [0080] SO external device [0081] UA authorisation and configuration system [0082] UKDK wheel detection configuration system [0083] UKR cryptographic circuit [0084] UKU wheel sensor supply voltage conversion system [0085] UKUI voltage summation and voltage-to-sensor-output-current conversion system [0086] UL logic circuit [0087] UM communication converter system [0088] UMCO sensor and sensor environment monitoring system [0089] USK wheel simulation system [0090] UT wheel sensor test system [0091] UWK wheel detection system [0092] UZ power supply system [0093] UZSW output signal permission system [0094] W amplifier circuit [0095] ZCK wheel sensor assembly