Function safety cloud platform for rail transit real-time control system and control method

Abstract

The invention relates to a functional security cloud platform and a control method for a rail transit real-time control system, the cloud platform follows a fault-security principle during design and meets the requirements of EN50129 functional security SIL4 level, and the cloud platform comprises a communication gateway used for providing a unified access entrance; the safe real-time virtualization system is used for virtual management, clock self-inspection and interrupt distribution; the security middleware runs in a virtual machine distributed by the security real-time virtualization system and is used for security clock verification, CPU memory self-check result verification, security communication, security voting, cycle control and application management; and the cloud management platform is matched with a virtual machine management module in the secure real-time virtualization system to jointly realize management of virtualization resources. Compared with the prior art, the method has the advantages of high safety, high reliability, high availability, high maintainability, high performance and the like.

Description

Technical Field

[0001] The present invention relates to a rail transit signal system, and in particular to a functional safety cloud platform and a control method for a rail transit real-time control system. Background Art

[0002] As an important part of public transportation, rail transit has the advantages of high efficiency, large capacity, fast and convenient, safe and comfortable, and low energy consumption. It is of great significance to reduce resource and environmental pressure and alleviate traffic congestion. The signal system is the core system to ensure the safety of rail transit, provide information services, and improve transportation efficiency. The safety computer platform is a fault-oriented safety bottom-level platform. It is a general platform serving the signal system of the rail transit industry and a core component of the rail transit signal system.

[0003] The traditional signal system has the following problems: 1) It uses fully independently developed boards and subsystems distributed at various sites, which has poor flexibility, low equipment resource utilization, relatively closed subsystems, and long communication links between subsystems, which increases the response time of the entire system. 2) Once the construction is completed and put into operation, it is difficult to add new interfaces or new equipment to expand the current system, and upgrading and transformation are difficult and scalability is poor. Cloud technology has strong scalability and flexibility, so that computing resources are no longer restricted by time and space, and provides the foundation and driving force for the digitalization, integration and intelligence of rail transit systems. With the rapid development of urban rail transit and the deepening of digital transformation, the application of cloud technology in the field of rail transit is becoming more and more extensive. At present, in the urban rail transit system, non-functional safety systems (such as integrated monitoring systems / AFC / PIS / PA, etc.) in the external service system, office system, and operation system have been put on the cloud, and SIL4 signal systems (such as ZC / DSU / interlocking) have not been put on the cloud. First, the current urban rail cloud cannot meet the real-time deterministic requirements of the signal system, and second, it cannot provide the safety evidence required by the SIL4 system.

[0004] After searching, Chinese patent publication number CN110027596A discloses a rail transit train operation control system based on cloud computing. The system includes: cloud computing devices and local train control devices connected through redundant communication networks; cloud computing devices provide real-time computing and storage services to all local train control devices, and provide redundant multiple real-time computing and storage services to a single local train control device for a single calculation application related to train operation control in a virtual isolation or physical isolation manner, and calculate and generate multiple redundant calculation results and send them to the local train control device; the local train control device completes its own security input, security data comparison, train control security calculation control and security output processing process, and obtains secure calculation results for multiple calculation results through security comparison. However, the existing patent only proposes a solution to the overall system architecture and functional safety, and does not involve the specific implementation of the functional safety and information security assurance strategy of the relevant cloud computing devices, and the functional safety and information security of the cloud are subject to the local devices, and the specific security assurance scheme for the heterogeneous cloud computing architecture is not involved. Therefore, how to further improve the security of the cloud platform for rail transit systems has become a technical problem that needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a functional safety cloud platform and control method for rail transit real-time control systems.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to a first aspect of the present invention, a functional safety cloud platform for rail transit real-time control systems is provided. The cloud platform is designed in accordance with the fail-safe principle and complies with the requirements of EN50129 functional safety SIL4 level. The cloud platform includes:

[0008] Communication gateway, used to provide a unified access portal;

[0009] Secure real-time virtualization system for virtual management, clock self-checking and interrupt distribution;

[0010] The security middleware runs in the virtual machine allocated by the secure real-time virtualization system and is used for security clock verification, CPU memory self-test result verification, secure communication, secure voting, cycle control, and application management;

[0011] The cloud management platform works with the virtual machine management module in the secure real-time virtualization system to jointly manage virtualized resources.

[0012] As a preferred technical solution, the cloud platform also includes:

[0013] Basic hardware equipment used to host a secure real-time virtualization system;

[0014] The secure clock card with PCIe interface provides all virtual machines with the control signals they need for periodic operation.

[0015] As a preferred technical solution, the real-time virtualization system manages basic hardware devices and abstracts them into multiple independent virtual machines to achieve secure isolation of resources between virtual machines.

[0016] As a preferred technical solution, the secure clock board of the PCIe interface adopts redundant clocks of two independent crystal oscillators.

[0017] As a preferred technical solution, the secure real-time virtualization system adopts a hardware self-test process that complies with EN50129, including instruction self-test, register self-test, memory self-test, and memory management unit self-test of all CPU cores.

[0018] As a preferred technical solution, the secure real-time virtualization system adopts a time-dividable real-time scheduling process that complies with ARINC 653 requirements.

[0019] As a preferred technical solution, the secure real-time virtualization system adopts a precise time synchronization protocol processing process based on 1588v2.

[0020] As a preferred technical solution, the security middleware supports applications forming a 2X2oo2 system.

[0021] As a preferred technical solution, the security middleware includes a security protocol module, an application management module and a security voting module.

[0022] According to a second aspect of the present invention, a control method for the functional safety cloud platform for rail transit real-time control system is provided, the control method comprising:

[0023] Step S1, the communication gateway collects input from the external system;

[0024] Step S2, the communication gateway forwards the input of the external system to the 2oo2 application virtual machine;

[0025] Step S3, the security protocol module of the security middleware processes the input data and forwards it to the application virtual machine;

[0026] Step S4, the application management module of the security middleware triggers the application task, and the 2oo2 application virtual machines perform operations on their respective channels;

[0027] Step S5, the 2oo2 application virtual machines transmit the calculation results to the security middleware respectively;

[0028] Step S6, the security voting module of the security middleware performs a 2-out-of-2 consistency comparison on the application data;

[0029] Step S7, if the security voting module of the security middleware passes the vote, the data is merged and the merged data is sent to the communication gateway; otherwise, the application management module is notified to maintain the security state of the application;

[0030] Step S8: the communication gateway sends the information to the external system.

[0031] According to a third aspect of the present invention, there is provided an electronic device, comprising a memory and a processor, wherein a computer program is stored in the memory, and the method described above is implemented when the processor executes the program.

[0032] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein the program implements the method described when executed by a processor.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1) The present invention follows the fail-safe principle, complies with the requirements of EN50129 functional safety SIL4 level, and has the characteristics of high safety, high reliability, high availability, high maintainability and high performance;

[0035] 2) The present invention combines TYPE-1 microkernel-based secure virtualization with a cloud management platform to form a cloud platform that can support real-time control systems, making the platform both real-time and cloud-like. The secure platform utilizes the isolation function of secure virtualization technology, and different applications are deployed in different virtual machines, avoiding interference between different applications and improving system security;

[0036] 3) In order to solve the real-time deterministic requirements of information clouds similar to KVM, the present invention combines the preemptive priority scheduling algorithm, introduces the time-sharing scheduling idea that meets the requirements of ARINC 653, and implements a deterministic scheduling algorithm, thereby improving the determinism of virtualization layer scheduling and ensuring the real-time requirements of application operation. In addition, even if the number of virtual machines is greater than the number of implemented CPU cores, the real-time determinism of the application is guaranteed, so that the number of supported applications is not limited by the number of CPU cores;

[0037] 4) In terms of security, the present invention adds the hardware self-check function that complies with EN50129 (including instruction self-check, register self-check, memory self-check, memory management unit self-check, etc. of all CPU cores) to the virtualization layer, thereby increasing the security of the virtualization layer, and integrating the self-check function into the virtualization scheduling process, thereby making the design of security functions in the virtual machine simpler and more versatile;

[0038] 5) The present invention introduces the 1588V2 precise time synchronization protocol, which makes the time synchronization accuracy of each server in the cluster higher, which is more conducive to the alignment of tasks between 2x2oo2 virtual machines and the reliability of 2oo2 tasks;

[0039] 6) The present invention designs a secure clock board with a PCIe interface, which can be installed on a commercial server to provide a secure periodic control signal for a security control system running on a secure cloud, thereby ensuring the safe operation of the entire system and simplifying the design of the cloud platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the structure of the real-time security cloud platform system of the present invention;

[0041] Figure 2 This is a schematic diagram of the 2x2-take-2 security product architecture based on the real-time security cloud platform of the present invention;

[0042] Figure 3 A schematic diagram of the time-sharing scheduling of self-checking and virtual machines by the virtualization software of the present invention;

[0043] Figure 4 This is a schematic diagram of a secure clock card for a PCIe interface of the present invention;

[0044] Figure 5 A flow chart of checking and distributing interrupt signals for a secure clock of a PCIe interface of the present invention;

[0045] Figure 6 This is a flow chart of the main system of the present invention entering the main cycle and then adding a system to initialize and enter the main cycle;

[0046] Figure 7 This is a workflow diagram of the 2x2oo2 application of the present invention. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] The present invention provides a functional safety cloud platform for rail transit real-time control systems. The safety computing platform consists of a cloud management platform, a gateway unit, a safety middleware, a safety real-time virtualization, basic hardware equipment (such as a general server), and a safety clock board with a PCIe interface.

[0049] 1) The cloud management platform cooperates with the virtual machine management module in the secure real-time virtualization system to jointly manage virtualized resources, including but not limited to the creation, start, stop, and destruction of virtual machines, and manages images and services, and is responsible for the monitoring, diagnosis, and maintenance functions of the entire system.

[0050] 2) The communication gateway provides a unified access portal and flow control for the entire system.

[0051] 3) The security middleware includes a real-time operating system, security clock verification, CPU memory self-test result verification, security communication, security voting, support for application composition 2X2oo2 system (identified as master-MPU1, master-MPU2, standby-MPU1, standby-MPU2), as well as cycle control, application management, etc. It runs in a virtual machine allocated by the secure real-time virtualization software;

[0052] 4) Secure real-time virtualization system, including virtual management, clock self-test and interrupt distribution, hardware self-test function in accordance with EN50129 (including instruction self-test, register self-test, memory self-test, memory management unit self-test, etc. of all CPU cores), and management of basic hardware resources, including CPU, memory, network, storage and other resources. Physical hardware resources (such as CPU, memory, I / O devices, etc.) are abstracted into multiple independent virtual environments. Each virtual environment is called a virtual machine instance (VM). It can achieve secure isolation of resources between virtual machines without interfering with each other, ensuring the independence of upper-level software during runtime, thereby realizing flexible scheduling and efficient utilization of resources.

[0053] 5) The secure clock card of the PCIe interface provides all virtual machines with the control signals required for periodic operation. It uses a redundant clock with two independent crystal oscillators. The working clock generates an application time timer for determining the time for software use. The working clock generates a clock interrupt every 2ms; the check clock verifies the correctness of the application time. The check clock is within a timing interrupt of a working clock, and the check clock counts the working clock through the clock interrupt; and the count is latched in a 16-bit latch, which is a constant in the absence of offset.

[0054] In the following description, a two-out-of-two secure computing platform based on cloud computing will be used as an example. Figure 1 , 2 As shown, the control steps of the present invention are as follows:

[0055] 1) The communication gateway collects input from external systems;

[0056] 2) The communication gateway forwards the external system input to the 2oo2 application virtual machine;

[0057] 3) The security protocol module of the application virtual machine security middleware processes the data and forwards it to the application;

[0058] 4) The security middleware application management module triggers the application task, and the 2oo2 application virtual machines perform operations on their respective channels;

[0059] 5) The 2oo2 application virtual machines pass the calculation results to the security middleware respectively;

[0060] 6) The security voting module of the security middleware performs a 2-out-of-2 consistency comparison on the application data;

[0061] 7) If the security voting module of the security middleware passes the vote, the algorithm is used to merge the data and send the data to the communication gateway; otherwise, the application management module is notified to maintain the security state;

[0062] 8) The communication gateway sends the information to the external system.

[0063] The layered structure of the present invention is as follows Figure 1 , Figure 2 As shown, Figure 3 It shows the time-sharing scheduling self-check and virtual machine status of virtualization software in single CPU single virtual machine and single CPU multiple virtual machines. Figure 4 The PCIe interface security clock card schematic is shown. Figure 5 The security clock verification and interrupt signal distribution process of the PCIe interface are explained. Figure 6 This is the flow chart of the main system entering the main cycle and then joining a system to initialize and enter the main cycle. Figure 7 It is a workflow diagram of the 2x2oo2 application of the present invention.

[0064] The hardware system uses the Inspur Yingzheng CS5280F3 server based on the ARMv8 architecture 64-core Feiteng CPU. It is an SMP (Symmetric Multi-Processing) architecture. Compared with AMP (Asymmetric Multi-Processing), all CPUs in the SMP architecture are equal, without master-slave or primary-secondary distinction. They can all independently execute tasks and access system resources; self-developed secure real-time virtualization software can ensure real-time and secure isolation between different virtual machines. If the secure cloud platform supports the application composition of 2X2oo2, at least 4 servers should be used. The cloud management platform is developed based on openstack, and the gateway unit directly deploys the Linux operating system.

[0065] like Figure 4 and Figure 5 As shown in the figure, the checksum and interrupt signal distribution flow chart of the secure clock of the PCIe interface is described in detail as follows:

[0066] 1) When the system starts, the virtualization software clears the initial value of the security clock and resets the corresponding value to zero; clears the interrupt of the security clock;

[0067] 2) When a clock interrupt occurs, the virtualization software calls the interrupt program to read the clock count value of the latch;

[0068] 3) The virtualization software determines whether the count value is within the tolerance range, if not, proceeds to step 7);

[0069] 4) The virtualization software performs VCP encoding on the value to obtain the encoded checksum;

[0070] 5) The virtualization software distributes the checksum and 2ms interrupt signal to each virtual machine

[0071] 6) The virtualization software shuts down all virtual machines on the machine and enters standby mode;

[0072] Figure 6 It is the process of initializing the master-slave system into the master cycle, which is described in detail as follows:

[0073] 1) After the hardware is started, the virtualization software precise clock synchronization module synchronizes the current time with the 1588v2 time synchronization server;

[0074] 2) Each virtual machine of 2X2oo2 has a precise time T1, and then each virtual machine maintains its own local time;

[0075] 3) The 2X2oo2 virtual machine master-MPU2 and standby-MPU1 / MPU2 send heartbeat messages to the master-MPU1;

[0076] 4) If the master system has not entered the main cycle, the master-MPU1 only replies to the master-MPU2 with a message that it has entered the main cycle. The message carries the time T2, which is the expected time to enter the main cycle.

[0077] 5) After time T2, Master-MPU1 and Master-MPU2 enter the master cycle after receiving the 2ms interrupt of the safety clock;

[0078] 6) After the main system enters the main cycle, if it receives the heartbeat message of the backup-MPU1 and backup-MPU2, it replies with the message of entering the main cycle. The message carries the time T3, where T3 is the expected time to enter the main cycle, T3 = T2 + main cycle length;

[0079] 7) After time T3, after receiving the 2ms interrupt of the safety clock, standby-MPU1 and standby-MPU2 enter the main cycle;

[0080] Figure 7The overall workflow of the present invention is described in detail as follows:

[0081] 1) Power on the system and load the virtualization software;

[0082] 2) The virtualization software precise clock synchronization module synchronizes the current time with the 1588v2 time synchronization server;

[0083] 3) The virtualization software loads the application virtual machine according to the cloud management command;

[0084] 4) The 2x2oo2 application virtual machines perform master-slave negotiation; if it is the master system, proceed to step 5.1; if it is the slave system, proceed to step 5;

[0085] 5) The virtual machines of the main system 2oo2 negotiate to enter the main cycle time, and then enter the main cycle after the corresponding time is reached;

[0086] 6) The virtual machines of the slave system 2oo2 and the virtual machines of the master system 2oo2 enter the main cycle time, and after the corresponding time, they enter the main cycle;

[0087] 7) During the main cycle operation, the 2x2oo2 application virtual machine performs master-slave judgment. If it is a master system, it switches to 8.1; if it is a slave system, it switches to 9.1;

[0088] 8.1) The virtual machine of the master system 2oo2 sends clock synchronization information to the slave system 2oo2 unit;

[0089] 8.2) The 2oo2 virtual machine of the main system processes security data and triggers application logic to process security data;

[0090] 8.3) The virtual machine of the main system 2oo2 obtains data from the application for security voting; if it passes, continue, otherwise go to 10;

[0091] 8.4) The main system 2oo2 virtual machine will output the data obtained from the application;

[0092] 8.5) The virtual machine of the master system 2oo2 sends its own status data to the virtual machine of the slave system 2oo2;

[0093] 8.6) The main system 2oo2 virtual machine returns to 7) and enters the next cycle;

[0094] 9.1) The virtual machines of the slave system 2oo2 perform clock synchronization with the virtual machines of the master system 2oo2;

[0095] 9.2) Obtain the secure real-time library status data from the 2oo2 virtual machine. If OK, refresh the local information synchronously;

[0096] 9.3) The virtual machine of the slave system 2oo2 reads the synchronization data sent by the virtual machine of the master system 2oo2, and triggers the application logic to process the security data;

[0097] 9.4) The 2oo2 virtual machine obtains data from the application for security voting; if it passes, it returns to 7) and enters the next cycle;

[0098] Otherwise go to 10);

[0099] 10) The safety 2oo2 unit enters the safety state and remains in the safe state.

[0100] In addition, an embodiment of the present invention also provides an electronic device including a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or computer program instructions loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM, and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0101] Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks.

[0102] The processing unit performs the various methods and processes described above, such as the method of the present invention. For example, in some embodiments, the method of the present invention can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the method of the present invention described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform the method of the present invention by any other appropriate means (e.g., by means of firmware).

[0103] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0104] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0105] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0106] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A functional safety cloud platform for rail transit real-time control systems, characterized in that: The cloud platform is designed to follow the fail-safe principle and meet the requirements of EN50129 functional safety SIL4 level. The cloud platform includes: Communication gateway, used to provide a unified access portal; Secure real-time virtualization system for virtual management, clock self-checking and interrupt distribution; The security middleware runs in the virtual machine allocated by the secure real-time virtualization system and is used for security clock verification, CPU memory self-test result verification, security communication, security voting, cycle control, and application management; The cloud management platform works with the virtual machine management module in the secure real-time virtualization system to jointly manage virtualized resources.

2. According to claim 1, a functional safety cloud platform for rail transit real-time control system is characterized in that: The cloud platform also includes: Basic hardware equipment used to host a secure real-time virtualization system; The secure clock card with PCIe interface provides all virtual machines with the control signals they need for periodic operation.

3. According to claim 2, a functional safety cloud platform for rail transit real-time control system is characterized in that: The real-time virtualization system manages basic hardware devices and abstracts them into multiple independent virtual machines to achieve secure isolation of resources between virtual machines.

4. According to claim 2, a functional safety cloud platform for rail transit real-time control system is characterized in that: The PCIe interface security clock board adopts redundant clocks of two independent crystal oscillators.

5. According to claim 1, a functional safety cloud platform for rail transit real-time control system is characterized in that: The secure real-time virtualization system adopts a hardware self-test process that complies with EN50129, including instruction self-test, register self-test, memory self-test, and memory management unit self-test of all CPU cores.

6. According to claim 1, a functional safety cloud platform for rail transit real-time control system is characterized in that: The secure real-time virtualization system adopts a time-dividable real-time scheduling process that complies with ARINC 653 requirements.

7. According to claim 1, a functional safety cloud platform for rail transit real-time control system is characterized in that: The secure real-time virtualization system adopts a precise time synchronization protocol processing process based on 1588v2.

8. According to claim 1, a functional safety cloud platform for rail transit real-time control system is characterized in that: The security middleware supports applications to form a 2X2oo2 system.

9. A functional safety cloud platform for rail transit real-time control systems according to claim 8, characterized in that: The security middleware includes a security protocol module, an application management module and a security voting module.

10. A control method for a functional safety cloud platform for a rail transit real-time control system according to claim 9, characterized in that: The control method includes: Step S1, the communication gateway collects input from the external system; Step S2, the communication gateway forwards the input of the external system to the 2oo2 application virtual machine; Step S3, the security protocol module of the security middleware processes the input data and forwards it to the application virtual machine; Step S4, the application management module of the security middleware triggers the application task, and the 2oo2 application virtual machines perform operations on their respective channels; Step S5, the 2oo2 application virtual machines transmit the calculation results to the security middleware respectively; Step S6, the security voting module of the security middleware performs a 2-out-of-2 consistency comparison on the application data; Step S7, if the security voting module of the security middleware passes the vote, the data is merged and the merged data is sent to the communication gateway; otherwise, the application management module is notified to maintain the security state of the application; Step S8: the communication gateway sends the information to the external system.

11. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the program, the method according to claim 10 is implemented.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to claim 10 is implemented.

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