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.

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 (K 2 ) 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 (K 2 ) in such a way it continuously monitors the frequency band of a signal (X 2 ) at the output of the first key circuit (KI) and in case the frequency band of the signal (X 2 ) exceeds a predetermined level (Fg), said signal (Usyg2) is delivered to the output of the second key circuit (K 2 ).   
     
     
         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 (ZCK 1 , ZKC 2 ) as defined in  claim 1 , wherein said two or more wheel sensor assemblies (ZCK 1 , ZKC 2 ) 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 (ZCK 1 , ZKC 2 ) are contained.