Exploring the application of digital twin technology in the field of artillery equipment protection

This paper addresses the problem that artillery condition assessment work is still stuck in the way of regular maintenance and after-the-fact repair, which makes it difficult to achieve accurate equipment protection, etc. Taking a typical artillery loading system as the research object, this paper uses simulation and experimentation to carry out research on loading system condition assessment by constructing a digital twin system framework for artillery equipment condition assessment, studying the construction of twins, data transmission between physical entities and twins and other key technologies, and providing a reference method for achieving accurate artillery maintenance and protection.


Introduction
In the background of actual combat training, artillery equipment using the load conditions are harsh, equipment to carry out the task of higher requirements, maintenance and security tasks are increasingly heavy, the difficulty of maintenance and security also increased accordingly.Once the artillery equipment failure, usually affects the daily training of the troops, wartime directly affects the force combat ability to play and even the completion of the entire combat mission [1].
The emergence of digital twin technology has provided a new technical approach to solving the problem of artillery equipment security.The digital twin makes comprehensive use of perception, computing, modelling and other information technologies to describe, diagnose, predict and make decisions about physical entities in virtual space, realising the interactive mapping of physical space and virtual space.Digital twin technology uses the state parameter updates of physical entities and the simulation operation data of digital twins to accurately map the whole life cycle process of equipment, which has a promising application in the fields of product design, production and health management.

Overall design of a digital twin technology-based condition assessment of artillery loading systems
Different from the traditional equipment state assessment method, the digital twin-based artillery ammunition loading system state assessment method, by building a digital twin of the equipment, to achieve accurate mapping of the equipment operating state in virtual space, where the key link is the construction of the digital twin model, the virtual-real interaction of state data, the physical fusion of information in the state assessment process and other technical research.

Digital twins model
Digital twins inside.The digital twin is a mapping for the physical world, a virtual space constructed by the integrated use of perception, computing, modelling and other information technologies.The

Functional requirement analysis
A certain type of artillery ammunition loading system is a complex electro-mechanical-hydraulic coupling system, and its operating state is mainly characterised by specific kinematic and kinetic parameters.The traditional dynamics simulation model is an ideal model based on design drawings and carries out dynamics simulation, which mainly reflects the initial operating state of the equipment.However, due to the complex structure of the equipment and the harsh working environment, it is difficult for the dynamics simulation model based on design drawings to accurately and timely reflect the operating state of the equipment in the service process.The digital twin model of the loading system designed in this paper focuses on the construction of the digital twin, the interaction between real and imaginary state data, and the acquisition and transmission of information in the process of state evaluation, making full use of the advantages of digital twin technology to achieve accurate and timely monitoring of the operating state of the loading system, and thus providing a new technical means to achieve equipment failure prediction and maintenance decisions at a later stage.To meet the above objectives, the digital twin model of the loading system constructed in this paper is mainly equipped with functions such as data acquisition and transmission, virtual and real data interaction, operational status monitoring, fault mechanism evolution and status evaluation feedback.The specific functions are described as follows [5][6].
First, data acquisition and transmission.Taking into account the structural composition, working principle, service environment and testing conditions of a certain type of artillery ammunition loading system, it should have the function of acquiring and storing the equipment state parameters, and can transmit the original data obtained into the digital twin after pre-processing, and later provide data support for driving the simulation of the digital twin of the artillery loading system.
Second, virtual and real data interaction.Data interaction between physical space and virtual space is the key to digital twin technology.By formulating the communication protocol between test data and the digital twin, the two-way data interaction between the physical entity and the digital twin is realised.
Third, operational state monitoring.The state data is collected and transmitted from the physical entity to drive the system for dynamics simulation and monitor the operational state of the equipment in virtual space in real time.At the same time, according to the changes of real-time state parameters, combined with the given threshold, the equipment operating state monitoring and early warning.
Fourth, fault mechanism evolution.According to the changes of state parameters under different working conditions, set the operating parameters of the digital twin, simulate the operating condition of the loading system, and obtain the fault evolution law of the equipment off heavy parts, which can be fed back to the physical entity and used for the later equipment maintenance guarantee.
Fifth, state evaluation feedback.According to the simulation operation results of the digital twin, combined with the historical state data of the physical space equipment, accurately assess the actual operation state of the loading system and give advice on the maintenance and guarantee of the equipment.

System framework design
Based on the analysis of the connotation and basic components of the digital twin model, combined with the analysis of the functional requirements of the condition assessment of the artillery loading system, this paper puts forward the system framework of the digital twin model for the condition assessment of the artillery loading system, which consists of three major parts, one is the construction of the digital twin based on the coupled modelling of multi-physical fields, the second is the acquisition and transmission of condition data based on physical entities, and the third is the condition monitoring and assessment based on the digital twin and evaluation.This is shown in Figure 3.

Digital twin creation for artillery loading systems
A digital twin is a mapping of a physical entity in virtual space, and the creation of an accurate digital twin is the basis of digital twin technology.In this paper, the digital twin of an artillery ammunition loading system is constructed using a certain type of artillery ammunition loading system as a physical entity, and the analysis platforms of dynamics simulation, finite element numerical analysis and fatigue life simulation are integrated to provide a research vehicle for the later development of digital twinbased loading system condition assessment.

Artillery ammunition loading system
A certain type of artillery ammunition loading system pedestal mainly contains a simulated pedestal, simulated fire, coordinated arm type ammunition pusher, tailstock type ammunition magazine, hydraulic system and other components, as shown in Figure 4:

Loading system digital twin realisation
The artillery loading system is a complex electromechanical device and the construction of its digital twin requires a multi-physical scale description, digitising the physical equipment and expressing it as a digital model that can be recognised by a computer.The operational state of the loading system is

MEIE-2023
Journal of Physics: Conference Series 2591 (2023) 012059 mainly characterised by specific kinematic and dynamic parameters.Therefore, a digital twin of the artillery ammunition loading system is constructed using ADAMS dynamics simulation software.The purpose of the artillery loading system is to deliver the projectile from the storage cylinder into the chamber accurately and smoothly through a series of mechanical actions.Therefore, by studying the values and trends of the key displacement, velocity, force, attitude and other state parameters of the projectile or other mechanisms during the loading process, the operational status of the loading system can be assessed.
A high fidelity virtual digital twin has been established, a drive function has been reserved as an interface to update the solid state parameters, and a dynamics simulation has been carried out with ideal working conditions as a basis for data transfer.

Method of acquiring and transmitting state parameters of the digital twin model of artillery loading system
When using the virtual prototype model to assess the state of the artillery loading system, the initial conditions entered in the digital twin can hardly be consistent with the actual situation, which eventually leads to inaccurate assessment results.Therefore, considering the structural composition, working principle, service environment and testing conditions of the equipment, the real-time state parameters of the physical entity of the loading system are collected and transmitted to the digital twin as the initial working conditions and boundary conditions of the simulation operation through multi-sensor fusion technology and data transmission and storage technology, as the basis for the equipment state assessment.

Loading system state parameters selection
Failure mode analysis.The various operational phases of the loading system do not operate in isolation, but in interdependence and mutual influence.The final result of each mechanical action is the initial condition for the next action.Therefore, a minor failure in the first action in the timing sequence does not necessarily affect the current action, but may be amplified by more steps and lead to the subsequent delivery action not being completed.Based on the simulation analysis of the loading system, the dynamics and key state parameters of the gun loading system under normal operation are clarified.Combining the collected failure history data and expert experience, the causes affecting the abnormalities of the above state parameters are analysed, and the failure modes and causes of failure are collated for each action phase of the mechanism.
Condition parameter selection.The failure modes and causes of failure of the loading system were analysed and summarised, and research was conducted to determine the parameter indicators that could directly characterise or indirectly reason about the health status of the equipment.The measured equipment real-time state parameters are used as the driving force and boundary conditions for the simulation, so that the operating state of the virtual twin is highly consistent with the physical entity.After high fidelity simulation calculations, other state parameters are monitored in the digital twin model, while the more easily measured transverse displacement of the cartridge and the thrust force on the projectile during the pushing action are measured as a supplement to the joint analysis to obtain credible state assessment results.

Loading system state parameters acquisition
Based on the results of the dynamics simulation and the actual operation of the mechanism, suitable sensors were selected for parameter acquisition, and a parameter testing scheme for this test was developed, the relevant process is shown in Figure 5.

Loading system status parameter transmission method
State parameter transmission scheme.After the state parameters of the loading system are obtained, data transmission is carried out based on IOT technology, and the synchronisation and processing of the measured data and the ADAMS software simulation system is realised, as shown in the figure.The state parameter transmission and processing system mainly consists of 4G/5G data remote transmission equipment, simulation system and host platform.
The wireless transmission device remotely transmits the collected data to the simulation system via the 4G/5G communication network using TCP communication protocol; the data receiving software in the simulation system receives the data transmitted via the wireless communication module via TCP listening and uses it for simulation calculation, the transmission process is shown in Figure 6.The use of an IoT cloud platform for data communication has many advantages over explicit data transmission.Firstly, data is not lost, based on the MQTT communication protocol, data is published to the IoT platform in the form of 'releases' and devices that 'subscribe' to the topic can access changes to the data in time to respond; secondly, it is extremely easy to build Data management applications, due to the long operation of the device brings a huge amount of basic data, the use of IoT cloud platform, you can achieve permanent preservation of data, and through a variety of graphical components, with low code to achieve complex data visualization and analysis functions, and even on the platform can seamlessly verify artificial intelligence and big data algorithms.
Software program design.The software that accompanies the hardware design is complex and consists of four parts.Software 1, the data interaction software based on Adams Command Server is developed on the host computer where the analysis software ADAMS is installed.The software is based on the TCP protocol and receives data from the wireless transmission device, parses it and sends it to The key link in the digital twin platform for state assessment of artillery loading systems is to realize the data interaction between the virtual and real spaces, i.e. the association of the virtual twin constructed based on ADAMS dynamics simulation with the state parameters in the physical space.In this paper, based on an in-depth study and analysis of the underlying communication principles of the ADAMS software, we propose the use of TCP commands to communicate with ADAMS in order to achieve virtual control.

Conclusions
This paper addresses the current problems that artillery condition assessment still remains in the form of regular maintenance and after-the-fact repair, which makes it difficult to achieve accurate equipment protection, introduces digital twin technology into the field of equipment condition assessment, takes the artillery loading system as the research object, carries out a digital twin system framework for artillery equipment condition assessment, studies the construction of twin bodies, data transmission between physical entities and twin bodies and other key technologies, and carries out The study of the state assessment of the loading system.At the same time, by analysing the potential and value of the application of digital twin technology on equipment, the cultivation and application of this technology is proposed, which is of great reference significance for improving the level of equipment protection.

Figure 1 .
Figure 1.Digital twin technology.Basic composition of digital twin.The Beihang digital twin technology research team has proposed a five-dimensional model of the digital twin.The five-dimensional model of the digital twin is a generic model that can be applied to different research objects in various fields[4].The five-dimensional model of the digital twin includes the connections between physical entities, virtual entities, services, twin data and other components, as shown in Figure2.

Figure 3 .
Figure 3. Digital twin system for artillery loading system status assessment.

Figure 4 .
Figure 4. Schematic diagram of the platform structure of a certain type of artillery ammunition loading system.

Figure 6 .
Figure 6.State parameter transmission and processing procedure.Data transmission is based on 4G/5G communication networks, i.e. the collected front-end physical quantities are digitised and then transmitted remotely to the receiving end via dedicated data transmission hardware.To achieve this design objective, a cloud-based IoT platform based on the MQTT communication protocol is used for data communication.The use of an IoT cloud platform for data communication has many advantages over explicit data transmission.Firstly, data is not lost, based on the MQTT communication protocol, data is published to the IoT platform in the form of 'releases' and devices that 'subscribe' to the topic can access changes to the data in time to respond; secondly, it is extremely easy to build Data management applications, due to the long operation of the device brings a huge amount of basic data, the use of IoT cloud platform, you can achieve permanent preservation of data, and through a variety of graphical components, with low code to achieve complex data visualization and analysis functions, and even on the platform can seamlessly verify artificial intelligence and big data algorithms.Software program design.The software that accompanies the hardware design is complex and consists of four parts.Software 1, the data interaction software based on Adams Command Server is developed on the host computer where the analysis software ADAMS is installed.The software is based on the TCP protocol and receives data from the wireless transmission device, parses it and sends it to software for simulation.Software 2, the IoT communication software, is responsible for communicating with the cloud-based IoT platform, exchanging data based on the MQTT protocol and forwarding data from the device side to the data interaction software in a timely manner using a subscription/publishing model.Software 3, IoT communication software, is responsible for receiving data reported by the data collection software, parsing it into JSON data format, reporting it to the cloud IoT platform, using JavaScript/Python for development, and exchanging data with the cloud IoT platform based on the MQTT protocol.Software 4, the cloud IoT service platform data service software, cloud software requires data traceability, permanent preservation, visual display and other functions.Data transfer technology based on ADAMS digital twin and object space.