CN101936110B - Intelligent door control system for rail train doors - Google Patents

Abstract

An intelligent gate control system for rail train doors. Between the train top bus and the train door system, a gate control system network composed of a field bus is set. The gate control system network is provided with a gateway module, a node module, a CAN bus, and a gateway module. Connect with the train top-level bus, receive the control signal transmitted by the train top-level bus and convert it into a CAN bus signal for the node module to identify, and the node module transmits the CAN bus signal to the motor drive module in the train door system through CAN communication. The motor drive module drives the action of the train door; a gateway module corresponds to a group of node modules and the same number of motor drive modules and train doors as the number of node modules. There is also an independent monitoring and diagnosis module in the door control system network. Through monitoring and diagnosis The maintenance interface reserved on the module is used to run the maintenance and repair software to overhaul the door control system.

Description

Rail train door intelligent door control system

technical field

The invention relates to a control system for opening and closing rail train doors, in particular to an intelligent door control system for rail train doors on urban rail trains, and belongs to the technical fields of automatic control and network communication. the

Background technique

The rail train door controller is mainly used for the control of the doors of rail trains such as subways and light rails: it receives signals such as door opening and closing transmitted on the bus in the top-level control system of the train, and combines some sensor signals in the train doors such as travel switches, position sensors and Signals such as safety light curtains are used to realize operations such as opening and closing of train doors. Due to the short distance between the station and the station of the urban rail train operation line, the number of doors in a single car is large, and the frequent opening and closing of the train doors may easily lead to damage to the electrical components of the door control system and the mechanical parts of the door system, thereby causing The door failures of operating trains occur frequently. After these failures occur, the door will be cut off, and when the failure is serious, the train will be disconnected, passengers will be cleared or rescued. The problems in the control part of the car door (referred to as the door controller) are mainly reflected in the following aspects: 1) the reliability does not meet the corresponding requirements, the mean time between failures of the existing door controller is small, and some Component failure rates are unusually high. 2) The anti-interference ability is weak. The communication between some existing gate controllers and trains uses serial ports such as RS232 and RS485, which are greatly affected by common-mode interference in the environment. 3) The circuit of the existing door controller is integrated in the physical layer structure, which makes the maintenance of the door controller difficult and the operability of the upgrade is poor. The components of the door controller system are coupled with each other. If there is a fault, the whole system will not work normally, and due to the serious coupling, it will take a long time for maintenance and repair. 4) The intelligence is poor, and corresponding measures cannot be adopted according to the level of the fault after a fault occurs, and the fault cannot be eliminated independently. Once a fault occurs, the door controller stops working, and simply sends an alarm through sound and indicator lights. 5) Poor reconfigurability and universality. Existing rail train door controller products are only suitable for a certain type or type of train of a certain manufacturer, and do not have good reconfigurability and universality. fitness. the

Contents of the invention

Aiming at the deficiencies of the existing rail train door controllers, the present invention adopts the idea of modular design to propose a rail train door intelligent door control system with high reliability, strong anti-interference ability, easy upgrade and maintenance, and independent fault diagnosis function . the

In order to achieve the above object, the present invention adopts the following technical solutions: an intelligent door control system for rail train doors, which drives the motor to realize the opening and closing of the train doors by receiving the door opening and closing control signals transmitted on the bus in the top-level control system of the train. The feature is: between the train top-level bus and the train door system, a gate control system network composed of a field bus is set. The gate control system network is provided with a gateway module, a node module and a CAN bus. The control signal transmitted by the top-level bus of the train is converted into a CAN bus signal recognized by the node module. The node module transmits the CAN bus signal to the motor drive module in the train door system through CAN communication. The motor drive module drives the train door. Action: one gateway module corresponds to a group of node modules and the same number of motor drive modules and train doors as the number of node modules; the gateway module and the node module are both composed of microcontrollers as the main body. the

Also be provided with the monitoring and diagnosing module that adopts double micro-controller structure in the described door control system network, this module is also connected with gateway module and node module by CAN bus; The control signal and the door state information transmitted by each node module are stored in the memory, and the corresponding fault diagnosis algorithm is set in the monitoring and diagnosis module. When the door control system fails, the module makes a fault diagnosis. And the diagnosis results are sent to the train bus through the gateway module and then transmitted to the train front control system; when the train is in the maintenance state, through the maintenance interface reserved on the monitoring diagnosis module, the maintenance and repair software is run to overhaul the door control system;

On the one hand, the node module sends the signal converted by the gateway module and various sensor signals in the door system to the motor drive module to control the movement of the door; on the other hand, it sends corresponding instructions to the motor drive module, Query the current, speed, temperature and other signals of the motor in real time, monitor the status information of the nodes, and transmit the monitored status information to the monitoring and diagnosis module. the

The gateway module, node module and motor drive module are all independently designed, and each module circuit board is reserved with a standard interface. the

Advantages and remarkable effects of the present invention:

1) The present invention adopts the idea of modular design in the design, divides the door control system into several large modules, and designs circuit boards separately for each module, and each module exists independently at the physical layer, and each module circuit board The reserved standard interface can prepare for subsequent module connection combination. the

2) Increase the intelligence of the door control system by adding a monitoring and diagnosis module. In the fault diagnosis algorithm, an offline and online two-layer diagnostic algorithm is designed to classify the corresponding faults, and independently eliminate some simple faults, and some Important components build failure prediction models. The monitoring and diagnosis module is equipped with a corresponding maintenance interface. When the door control system fails, it can be diagnosed and maintained through the maintenance interface. The door control system uses a differential bus signal with strong anti-interference ability, which can well remove Some common mode interference. the

3) In view of the inconsistency of the communication protocols used in the top layer of rail trains, the gateway module is designed separately. This module adopts the replaceable design principle, and the door control system can adapt to different bus protocols by simply replacing the module or reconfiguring the software resources. track train. the

4) The present invention adopts a field bus control scheme, and equips each car door with a node module for directly controlling the motor driver on the car door. The node module, the gateway module and the monitoring and diagnosis module form the door control system network through the field bus, which can realize the simultaneous control of multiple car doors by one door control system. The number is not limited, as long as it does not exceed the maximum number of nodes of the field bus, it has good universality, and this performance enables the present invention to be used on rail trains of different models. the

The present invention can be used in urban rail transit trains with many doors. The doors of a carriage are grouped into one group, and a door control system network is established for each group of doors to facilitate door control; For a small number of medium and long-distance rail cars, the doors of several carriages can be incorporated into a gate control system network, or a gate control system network can be configured for the doors of a train formation, so it has good versatility. the

Description of drawings

Fig. 1 is a schematic diagram of the principle of the present invention;

Fig. 2 is the overall structural block diagram of hardware system of the present invention;

Figure 3 is a structural block diagram of the monitoring and diagnosis module and its peripheral circuits;

Fig. 4 is the program flow diagram of the monitoring and diagnosis module MC9S12XS128 chip operation when the train is in working condition;

Fig. 5 is the program flow diagram of monitoring and diagnosis module S3C2440A chip operation when the train is in working condition;

Fig. 6 is the operating interface of the monitoring and diagnosis module maintenance and repair software when the train is in the maintenance state;

Fig. 7 is a flowchart of the offline and online two-layer fault diagnosis algorithm of the monitoring and diagnosis module. the

Detailed ways

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. the

With reference to Fig. 1, the present invention adopts the idea of modular design, and the door control system of design is mainly made up of gateway module, node module and car door system (comprising motor drive module and car door), and gateway module and node module directly form the door control system through CAN bus Network, the gateway module is used to bridge the train bus and gate control system network. Since the CAN bus adopts non-destructive bus arbitration technology, supports multi-master and multi-slave structure, and uses short-frame data structure, the transmission is stable and reliable, and it has a high communication rate in short-distance transmission (up to 1Mbps within 40m), and has The error detection mechanism can automatically monitor whether the node is disconnected from the bus, and will automatically shut down the permanently failed node. The system of the present invention is provided with a gateway module, a node module and a motor drive module to realize the basic functions of the rail train door controller - door opening, door closing, emergency unlocking and door removal functions. These functions are also the most important functions of the rail train. However, in order to better ensure the reliability of the basic functions of the door control system, following the principle of simplicity and reliability, some backup functions, such as fault monitoring and diagnosis, maintenance and other functions, are implemented in the monitoring and diagnosis module. The realization of these functions requires some relatively Complicated components, so the reliability of this module is lower than other modules. The independent design principle is adopted in the design, and this module can be used independently as a module without restricting other modules. After this module breaks down, because the CAN bus can automatically carry out error monitoring, if this module occurs permanent failure directly closes this node, does not affect the realization of the basic function of door control system after closing this node, so the reliability of the present invention is higher high. the

The function of the monitoring and diagnosis module is divided into two situations: 1) When the train is in working state, it mainly receives the control signal transmitted by the gateway module and the status information transmitted by each node module, and stores the above information data in the memory; and designs in this module Corresponding fault diagnosis algorithm, when the door control system fails, the module can make a fault diagnosis, and the diagnosis result is sent to the train bus through the gateway module and then transmitted to the train front control system. 2) When the train is in the maintenance state, the door control system can be overhauled through the maintenance interface reserved on the module. At present, the maintenance tool used in the present invention is a liquid crystal display with touch function, and the display is connected to the maintenance interface. On the interface, by running the maintenance and repair software in this module, some simple inspection and maintenance can be performed on the door control system. the

The gateway module is connected to the train bus, receives the control signals transmitted by the train bus, and converts them into CAN bus signals that can be recognized by the gate control system nodes. This module mainly acts as a bridge for mutual conversion between different communication protocols, and will accept The control signal transmitted to the train bus is transmitted to the monitoring and diagnosis module and the signal data is saved. the

On the one hand, the node module sends the signal converted by the gateway module and the signals of various sensors (travel, position, light curtain) in the door system to the motor drive module to send corresponding control signals, and the motor drive module controls the movement of the door; The motor drive module sends corresponding commands to query the motor current, speed, driver temperature and other signals in real time, monitors the status information of the gate control node, and transmits the monitored status information to the monitoring and diagnosis module. the

The motor driver module is the executive component that controls each door control node—the motor, which drives the door movement. The CAN bus is used for communication between the door control system node and the motor driver. The main reason is that the CAN bus uses differential signals to resist common mode interference. Strong, high stability. the

The reconfigurability of the present invention is embodied in the following two points: 1) the door controller does not limit the specific number of doors of each carriage. Since the gate controller CAN bus is used as the basis for the connection between the internal gate control nodes, the CAN bus is a field bus that supports multiple masters and multiple slaves, and each gate control system node can be directly connected to the CAN bus, so It is required that the number of doors in each car does not exceed the maximum number of nodes supported by the CAN bus (the actual number of doors in each car is much smaller than this value), and there is no limit to the number of doors in each car. At present, different track trains are produced The number of doors of a single carriage of the train produced by the manufacturer is generally 6, 8 and 10, so the present invention can better adapt to the production differences of different manufacturers. 2) The current train bus standard is not unified. The coexistence of multiple buses requires that the gate control system network can be bridged with different train buses, so as to realize the control of the gate control system by the upper computer such as the vehicle control unit through the train bus. The gate controller designed by the invention can adapt to different train buses by replacing the gateway module or reconfiguring the corresponding software and hardware resources to the module. the

By using a modular design method, the structural level of the hardware can be clearly expressed, thereby reducing the difficulty of development. By dividing the modules reasonably, the reliability and stability of the system are improved, and it also provides conditions for the upgradeability of the hardware part. When the system fails, the modular design helps to improve the speed and accuracy of fault diagnosis, and the faulty module can be directly replaced during maintenance, making maintenance simple and improving the efficiency of maintenance work. the

Fig. 2 is a structural block diagram of a specific hardware system of the present invention. In the design of the present invention, a networked and modular design method is used. The following mainly introduces the specific implementation scheme of each control module of the present invention and the selected control chip. the

The motherboard of the monitoring and diagnosis module adopts a dual-microcontroller structure. The specific microcontrollers selected are Samsung S3C2440A for data analysis and processing of ARM cores and Freescale MC9S12XS128 for processing communication protocol S12X cores. The S3C2440A micro-controller The controller runs Windows CE operating system, which is mainly used for data collection and analysis, running fault diagnosis algorithm, and providing maintenance interface with LCD screen with touch function. MC9S12XS128 microcontroller is designed to realize the high real-time performance of the system, without operating system, it is used for preprocessing of various control signals and communication data. The communication between the monitoring and diagnosis module and the door control system network is completed by the MC9S12XS128 processor. The MC9S12XS128 with the bus frequency set at 40MHz can not only handle the work related to the communication protocol, but also have enough remaining system resources for processing and independently sending some basic Door control signal without the intervention of S3C2440A microcontroller which focuses on data analysis and processing. This is very necessary. If the work of the communication part, including the processing of the communication protocol, is completed by the ARM core microcontroller, at the same time, the monitoring and diagnosis module must process the data of all door control system nodes. When the number of nodes in the control system network is large, the few remaining system resources of the S3C2440A microcontroller may not be sufficient to meet the operating requirements of the communication protocol, thereby affecting the real-time performance of the system, and even causing the gating running under the Windows CE operating system System applications become completely unresponsive. the

The node module uses Freescale MC9S12DG128 microcontroller with S12 core to receive various sensor signals in the door system, realize motor control, and communicate with the door control system network. The gate control system network established by using the CAN bus connects the gate control system gateway, the gate control system nodes and the system monitoring and diagnosis, and is used to transmit the door control signal and the state parameters of the car door. The door control system node needs to be connected to the door control system network, that is, it needs to have CAN bus communication function. As a door controller, the node should also be able to control the operation of the door motor and the work of other external devices, such as indicator lights and buzzers. The present invention is to use CAN bus communication mode with strong anti-interference ability in controlling the car door motor, so two CAN controllers need to be used in this module, the Freescale MC9S12DG128 microcontroller that the present invention selects, its built-in MSCAN module includes Two CAN controllers and a large number of general-purpose I/O ports are very suitable for the requirements of the present invention on the door control system node. The door control system node needs to accurately detect the actual position of the car door and the situation of obstacles on the door movement path. Here, two diffuse reflection photoelectric switches are used for position detection at both ends of the door. The through-beam photoelectric switch is used to detect obstacles between the doors. the

The gateway module is used to bridge the train bus and the door control system network. The gate control system network uses the CAN bus, and the train bus is not unified at present. Siemens and Bombardier mostly use MVB to produce rail trains, and French Alstom and Faiveley use WORLDFIP. All the data in the door control system that needs to be transmitted to the train bus is forwarded through the gateway module, and the gateway module receives the door control signal on the train bus and forwards it to other node devices in the system through the door control system network. The gateway module adopts an easy-to-replace design, adapting to the application environment of different types of train buses. Using FPGA as the main control chip of the module, in order to adapt to different train buses, it is only necessary to program different configuration programs for the FPGA chip. the

Illustrate in conjunction with Fig. 3 the concrete realization and effect of some peripheral circuits used in the monitoring and diagnosis module parts in the present invention, it mainly consists of processor unit 1, processor unit 2, SD card, liquid crystal screen with touch function, JTAG emulator, BDM emulator, CAN transceiver. the

The microprocessor chip of processor unit 1 selects Samsung's high-performance, low-power consumption ARM920T system 32-bit S3C2440A. The SD card uses Kingston's SD card with a storage capacity of 1GB. The reset circuit selects MAX811 chip. Use the manual reset input of the MAX811. In the UART-RS232 circuit, the UARTO interface module of the S3C2440A chip is converted to RS232 level by the MAX3232 chip. the

The microprocessor chip of the processor unit 2 selects Freescale's MC9S12XS128. The CAN controller module in the MC9S12XS128 chip needs to be connected to a CAN transceiver before it can be connected to the CAN physical bus. Here we choose PCA82C250, which is mainly designed for high-speed CAN communication (up to 1Mbps) and meets the "ISO11898" standard. The interference to the CAN transceiver needs to be isolated from the CAN controller, and the 6N137 high-speed optocoupler is used for isolation. In the isolation, the B0505-1W chip power isolation module of Jinshengyang Company is used, and the CAN bus transceiver circuit signal and system are realized after cooperating with the optocoupler. The circuit is completely isolated during fault diagnosis. the

The two microcontrollers, S3C2440A and MC9S12XS128, each perform their own responsibilities. The division of labor clearly completes the door control task, laying the foundation for the high real-time performance of the system. Therefore, the efficient and stable communication between the two microcontrollers is the key to the ultimate goal of high performance. . Here, the built-in asynchronous serial communication modules of the two microcontrollers are fully utilized, which is more suitable for short-distance, single-task transmission processes. In the hardware connection, in theory, the communication between them can be realized by cross-connecting the receiving and receiving leads of the asynchronous serial communication modules of the two microcontrollers, but since the communication level voltage of the S3C2440A is 3.3V, and the The communication level is 5.0V, and a level shifter needs to be connected in actual operation. Here, 74LVC4245 is selected as the bus level shifter. the

The function of system monitoring and diagnosis is divided into two situations: 1) When the train is in working state, it mainly receives the status information transmitted by each node module, on the one hand, stores the above information data in the SD card memory, and on the other hand, displays the status information on the LCD screen. Node status information. The corresponding fault diagnosis algorithm is designed in this module. When the door control system fails, the module can make a fault diagnosis, and the diagnosis result is sent to the train bus through the gateway module and then transmitted to the train front control system. 2) When the train is in the maintenance state, the door control system can be overhauled through the maintenance interface reserved on the module. At present, the maintenance tool used in the present invention is a liquid crystal display with touch function, and the display is connected to the maintenance interface. On the interface, run the maintenance and repair software in this module, and then some simple inspection and maintenance can be performed on the door control system. the

According to the chip and the connection mode selected in the first embodiment, the functional process realized by the above-mentioned system monitoring and diagnosis module is discussed in two cases. the

First, when the train is in working condition, the program flow chart of the MC9S12XS128 chip in this module is shown in Figure 4, and the method of interrupt programming is mainly used to ensure real-time performance. Include the following steps:

Step 1: The processor core completes initialization tasks, including internal memory and register initialization, I/O port initialization, MSCAN module initialization and SCI1 module initialization. the

Step 2 After the processor completes the initialization, the foreground program enters a circular waiting state, and the program keeps resetting the watchdog. the

When entering the cycle waiting, the processor should respond to the MSCAN module interrupt and the SCI1 module interrupt, and the interrupt priority of the MSCAN module is higher than the SCI1 module interrupt priority. the

The interrupt of MSCAN is to accept the interrupt and accept the node status information transmitted in the CAN network (including the status of the two travel switches of the gating node, the status of the through-beam photoelectric switch, the current of the motor, the speed of the motor and the temperature of the motor driver) , MC9S12XS128 forwards the received node status information to S3C2440A through the SCI1 port. the

The interrupt of SCI1 is also an interrupt, which accepts the fault diagnosis result information sent by S3C2440A through its own UART1 module. MC9S12XS128 sends the fault diagnosis results received to each node of the CAN network through the MSCAN port. the

The program flowchart of the operation of the S3C2440A chip in this module is shown in Figure 5, including the following steps:

Step 1: The processor core completes the initialization work, including internal memory and register initialization, I/O port initialization, UART1 module initialization, and LCD screen initialization.

Step 2 sets some global variables to save some data needed in fault diagnosis, and these global variable data are updated at any time. the

Step 3: Run the fault diagnosis algorithm to obtain the fault diagnosis result, and update the state information of the gate control node in the LCD screen according to the diagnosis result. the

Step 4: Transmit the fault diagnosis result to the MC9S12XS128 chip through the UART1 module, wait for the response time (diagnosis does not need to be performed in real time, only need to be performed at intervals), and enter the next diagnosis. the

Among them, the UART 1 interrupt is the receiving interrupt, which mainly accepts the node status information sent by the MC9S12XS128 chip, adds the time information of the data according to the real-time clock module in the S3C2440A, and stores the information in the SD card. the

Second, when the train is in the maintenance state, the maintenance and repair function can be realized by running the maintenance and repair software on the S3C2440A. The specific implementation is as follows:

Figure 6 is the running interface of the maintenance and repair software. By clicking some buttons in the interface, the status of the relevant gate nodes can be observed. Among them, the "#0~#9" buttons represent the 10 gate control nodes that need to be detected, and the "open, close, stop ” means to open, close and stop the door node. Each node adds a corresponding node status display box to display the node status, and it displays "static" during initialization. Let’s use a simple example to illustrate the maintenance process: For example, click the “#0~#9” button and then click the “Open” button to control 10 door control nodes to open the door. When the monitoring and diagnosis module is running correctly, perform the above operations Finally, if a door does not perform the corresponding action, it means that the node is faulty, and the node can be checked in detail to find out the root cause of the fault. Through the simple inspection and maintenance function provided by this module, it is convenient to find out some faults, which brings certain convenience to the maintenance personnel. the

Fig. 7 is a flowchart of the two-layer fault diagnosis algorithm used in the present invention. The fault diagnosis system of the present invention is mainly designed for the electrical part of the door system, including the diagnosis of the motor. Design a two-layer fault diagnosis system according to actual requirements:

The first layer adopts an online fault diagnosis system, which mainly monitors various parameters of the door control system in real time, and performs simple fault diagnosis in the main control system module according to the current stage monitoring data to analyze the cause of possible faults, and adopts fault tree analysis According to the method, the diagnosed faults are classified according to the severity, and some simple faults are directly taken corresponding measures to eliminate the faults. For the faults that cannot be solved by self-diagnosis, the fault signal is sent out through the indicator to remind the maintenance personnel. the

The second layer adopts an offline fault diagnosis system. This system mainly records the data of various parameters after the door control system has been running for a period of time in the memory (select a storage device such as SD card that will not lose data when power is turned off). The door control system provides The interface for communicating with the host computer (such as a serial port) transmits the stored data to a host computer with strong computing power such as a PC or a workstation, and designs a more accurate and reliable fault diagnosis program in the host computer to prevent the failure of the door control system. Do precise positioning. At the same time, relevant prediction models can be introduced to further predict some faults that may occur later in the door control system. the

Finally, briefly explain the composition of the power supply system in the present invention. Each component in the present invention accepts the 110VDC power supply of the train system, and needs to use two voltage power supplies of +5V and +3.3V. First, use VICOR's DC/DC converter specially used on rail trains, the specific model is V110A12C400BF, to convert the 110VDC power supply on the train to 12VDC. Then choose the fixed output version of LM2596. The LM2596 switching voltage regulator is a step-down power management monolithic integrated circuit that can output a drive current of 3A. It also has good linearity and load regulation characteristics, and the input voltage can be as high as 40V. 12 VDC can get 5.0V power supply voltage through LM2596S-5.0; 12 VDC can get 3.3V power supply voltage through LM2596S-3.3V. the

Although the above has described the embodiment of the present invention in conjunction with accompanying drawing, those skilled in the art can make various deformation and modification in the scope of described claim, as what the present invention specifically uses is CAN bus, for adopting some similar scene The bus implements the door control system or the door control system node according to the idea of the present invention to receive the sensor signals used in the door system, and transmits the corresponding control commands to the motor drive module through communication. For the motor control method, PWM, analog, etc. can also be used. The present invention selects communication mode in realizing, as using other modes also can become rail train gate controller of the present invention. the

Claims (2)

1. A rail train door intelligent door control system, by receiving the door-opening and door-closing control signals transmitted on the bus in the top-level control system of the train, the drive motor realizes the opening and closing of the train door. Between the systems, a gate control system network composed of a field bus is set. The gate control system network is provided with a gateway module, a node module and a CAN bus. It is converted into a CAN bus signal recognized by the node module, and the node module transmits the CAN bus signal to the motor drive module in the train door system through CAN communication, and the motor drive module drives the action of the train door; a gateway module corresponds to a group of node modules And the same number of motor drive modules and train doors as the number of node modules; the gateway module and the node module are all composed of microcontrollers; Said gate control system network is also provided with a monitoring and diagnosing module that adopts a double micro-controller structure, and this module is also connected with the gateway module and the node module through the CAN bus; when the train is in working condition, the monitoring and diagnosing module receives Control signals and door status information transmitted by each node module and store the above information data in the memory. When the door control system fails, the module makes a fault diagnosis and sends the diagnosis result to the train bus through the gateway module and then to the In the front desk control system of the train; when the train is in the maintenance state, through the maintenance interface reserved on the monitoring and diagnosis module, the maintenance and repair software is run to overhaul the door control system; On the one hand, the node module transmits the signal converted by the gateway module and various sensor signals in the door system to the motor drive module, and sends corresponding control signals to the motor drive module, and the motor drive module controls the movement of the door; on the other hand, it sends the motor drive module The module sends corresponding instructions to query the current, speed and driver temperature signals of the motor in real time, and transmits the monitored status information to the monitoring and diagnosis module. 2. The intelligent door control system for rail train doors according to claim 1, characterized in that: the gateway module, the node module and the motor drive module are all independently designed, and each module circuit board is reserved with a standard interface.

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