Semi-physical Simulation Platform Research Articles

A Multi-Target Consensus-Based Auction Algorithm for Distributed Target Assignment in Cooperative Beyond-Visual-Range Air Combat

With recent advances in airborne weapons, air combat tends to occur in the form of beyond-visual-range (BVR) combat and multi-aircraft cooperation. Target assignment is critical in multi-aircraft BVR air combat decision-making. Most previous research on target assignment for multi-aircraft cooperative BVR air combat has focused on centralized algorithms, which can be time-consuming and unreliable. This paper proposes an efficient distributed target assignment algorithm called the multi-target consensus-based auction algorithm (MTCBAA). First, by analyzing the main geometric aspects of BVR air combat, a target assignment model for cooperative BVR air combat was established. Next, based on a consensus-based auction algorithm (CBAA), the MTCBAA was developed to solve the target assignment problem by introducing a cooperative decision-making variable. Although the MTCBAA is based on a greedy mechanism, it can guarantee at least 50% global optimization performance, which was proven through a demonstration of the minimum optimization performance of a centralized target assignment algorithm, since the centralized algorithm is equivalent to the MTCBAA. Finally, experiments were conducted, including an experiment that illustrates the operation of the proposed algorithm, Monte Carlo comparisons with a centralized target assignment method based on the immune algorithm, and deployment experiments on a semi-physical simulation platform. Compared with the heuristic target assignment algorithm, the proposed algorithm significantly improved the target assignment efficiency. The practicality of the proposed algorithm was further verified through a distributed semi-physical simulation experiment.

Design and Implementation of Semi-Physical Platform for Label Based Frame Switching in Integrated Satellite Terrestrial Networks

With the explosion of traffic demand in recent years, the integration of satellite optical networks and terrestrial networks (ISTN) creates a promising networking solution for future low-latency, high-rate, and high-capacity communications. Owing to the high cost of deploying and maintaining a satellite optical network, it is critical to carefully design and plan the network to ensure the performance of the network. Thus, a semi-physical simulation platform based on software-defined networks (SDNs) is developed to simulate a satellite optical network and evaluate the performance of the proposed label-based advanced orbiting system (AOS) frame switching method that adheres to the Consultative Committee for Space Data Systems’ recommended standard (CCSDS). The semi-physical simulation platform has two major innovations: (1) adapting and integrating network protocols between the CCSDS and open system interconnect (OSI) reference models, particularly at the data link layer, and (2) the foundation for an SDN-based satellite optical network. In the control plane, real-time VxWorks Simulators serve as controllers to establish and manage various network protocols and the link manager protocol (LMP). Here, network protocols include open shortest path first (OSPF) for routing managing and controlling messages, constraint shortest path first–traffic engineering (CSPF-TE), and constraint-label distribution protocol (CR-LDP) for routing data services. LMP is used to assign and reserve satellite optical link resources. The performance of the architecture and protocols is evaluated via a semi-physical simulation platform.

Hardware-in-the-loop simulation of inverter power supply controller based on StarSim and DSP

Aiming at the contradiction between the requirements for rapid development and verification of inverter power supply controller products and the actual construction of real inverter power supply circuit topology, this paper proposes to build a semi-physical simulation platform based on StarSim and DSP. This paper takes the single-phase full-bridge inverter power supply as an example, use Shanghai ModelingTech company’s StarSim real-time simulator as the hardware platform, establish the circuit model in Matlab/Simulink and select NI PXIe-7846R board to run circuit extensions, and use TMS320F28335 as controller of the phase inverter power supply, based on StarSim HIL host computer program to load the model, configure the IO, and test and verify. The experimental results show that the semi-physical test platform has high accuracy and feasibility, shortens the development cycle of the controller, and greatly reduces the development cost of the controller.

Fault Tolerance Method of Low-Resolution Hall Sensor in Permanent Magnet Synchronous Machine

The estimation of the motor rotor positions with high-precision based on low-resolution Hall sensors becomes an important trend to realize the vector control in low-cost permanent magnet synchronous machine (PMSM) based control systems. Most existing studies focus on the methods to improving the estimating precision of rotor positions, while the estimating precision of failed Hall sensors and the corresponding control strategies for fault tolerance is rarely explored. This paper proposes a method that can online estimate the position of a PMSM rotor with fault detection and fault tolerance. Such a method is able to achieve both stable and precise estimations on rotor position even when one or two Hall sensors fail. Meanwhile, it can meet the needs of vector control under variable speed and load on the PMSM. Finally, a dSPACE-based semi-physical simulation platform is established, which is used to validate the effectiveness of the proposed method with multiple experiments.

Internal model control for rocket launcher position servo system based on improved wavelet neural network

This paper proposes an improved wavelet neural network-internal model controller (WNN-IMC) for the rocket launcher position servo system. Due to complex nonlinearities and uncertainties of external disturbances in the rocket launcher position servo system, it is vitally challenging to establish its accurate model by the mechanical modeling technique. A wavelet neural network (WNN) identification method is proposed to determine the system mathematical model through test datum, which optimized by the hybrid algorithm of differential evolution (DE) and particle swarm optimization (PSO). Then, the proposed method is applied to identify the semi-physical simulation platform of the rocket launcher velocity servo system. The results demonstrate that the validity of the DEPSO-WNN method is better than that of the WNN and PSO-WNN methods. Finally, compared with the WNN-IMC controller and the ADRC controller, the effectiveness of the improved WNN-IMC controller is verified by the semi-physical simulation experiments.

Online SoC Estimation of Lithium-Ion Batteries Using a New Sigma Points Kalman Filter

The accurate state of charge (SoC) online estimation for lithium-ion batteries is a primary concern for predicting the remaining range in electric vehicles. The Sigma points Kalman Filter is an emerging SoC filtering technology. Firstly, the charge and discharge tests of the battery were carried out using the interval static method to obtain the accurate calibration of the SoC-OCV (open circuit voltage) relationship curve. Secondly, the recursive least squares method (RLS) was combined with the dynamic stress test (DST) to identify the parameters of the second-order equivalent circuit model (ECM) and establish a non-linear state-space model of the lithium-ion battery. Thirdly, based on proportional correction sampling and symmetric sampling Sigma points, an SoC estimation method combining unscented transformation and Stirling interpolation center difference was designed. Finally, a semi-physical simulation platform was built. The Federal Urban Driving Schedule and US06 Highway Driving Schedule operating conditions were used to verify the effectiveness of the proposed estimation method in the presence of initial SoC errors and compare with the EKF (extended Kalman filter), UKF (unscented Kalman filter) and CDKF (central difference Kalman filter) algorithms. The results showed that the new algorithm could ensure an SoC error within 2% under the two working conditions and quickly converge to the reference value when the initial SoC value was inaccurate, effectively improving the initial error correction ability.

Compound Fault Diagnosis of Stator Interturn Short Circuit and Air Gap Eccentricity Based on Random Forest and XGBoost

Taking the traction motor of CRH2 high-speed train as the research object, this paper proposes a diagnosis method based on random forest and XGBoost for the compound fault resulting from stator interturn short circuit and air gap eccentricity. First, the U-phase and V-phase currents are used as fault diagnosis signal and then the Savitzky–Golay filtering method is used for the noise deduction from the signal. Second, the wavelet packet decomposition is used to extract the composite fault features and then the high-dimensional features are optimized by the principal component analysis (PCA) method. Finally, the random forest and XGBoost are combined to detect composite faults. Using the experimental data of CRH2 semiphysical simulation platform, the diagnosis of different fault modes is completed, and the high diagnosis accuracy is achieved, which verifies the validity of this method.

Research on Anti-Skid Control Strategy for Four-Wheel Independent Drive Electric Vehicle

Four-wheel independent drive electric vehicles have become the latest development trend of electric vehicles due to their simple structure and high control accuracy. Aiming at the sliding problem of four-wheel independent driving electric vehicles in the driving process, a driving anti-skid control strategy is designed. The strategy includes two contents: (1) a road recognition module that tracks the best slip rate in real time; (2) a slip rate control module that uses fuzzy PID control. Then, based on Carsim and MATLAB/Simulink, the vehicle dynamics model, tire model and driving anti-skid control model are established. A simulation of the driving anti-skid control algorithm is carried out to verify the feasibility of the control strategy. Finally, based on the built-up dSPACE semi-physical experimental simulation platform, the verification was carried out, and the test and simulation results were compared to verify the effective feasibility of the driving anti-skid control strategy.

Research on Semi-Physical Simulation Testing of Inter-Satellite Laser Interference in the China Taiji Space Gravitational Wave Detection Program

To guarantee a smooth in-orbit space gravitational wave detection for the Taiji mission, a semi-physical simulation test of inter-satellite laser interference is carried out. The semi-physical simulation test consists of three aspects: the establishment of the inter-satellite laser link, interferometry of the inter-satellite ranging, and simulation of the space environment. With the designed specifications for the semi-physical simulation platform, the test results for the inter-satellite laser interference can be obtained. Based on the semi-physical simulation test, the risks of inter-satellite laser interference technology can be mitigated, laying a solid foundation for the successful detection of in-orbit gravitational waves.

Energy management and emission control for range extended electric vehicles

Range extended electric vehicles (REEVs), transition vehicles between combustion engine vehicles and electric vehicles, have been widely used due to their advantages of low fuel consumption and low emissions. By optimizing power management and after-treatment system control strategies, it is possible to achieve lower fuel consumption and emissions. This study proposes an integrated control method based on optimization strategies for the auxiliary power unit (APU) on/off system and energy management optimization for extended hybrid electric vehicles. The Elitist Nondominated Sorting Genetic Algorithm (NSGA-II) optimization method is used to determine the control parameters. In addition, considering the frequent start and stop characteristics of the APU caused by the optimization strategy, closed-loop control of the urea injection is established to solve the ammonia leakage problem. Due to their high computational efficiency, the proposed energy management and urea injection algorithms can be easily implemented in real time. The actual operating emissions of engines under the different strategies are tested on a semi-physical simulation platform, focusing on the analysis and comparison of NOx emissions. The conclusion has certain reference significance for vehicle production.

Research on moon surface positioning and navigation method based on stellar vector measurement

In response to the needs of positioning and navigation in lunar exploration projects such as manned landing on the moon, and the initial positioning of the lunar lander, this paper proposes a lunar positioning and navigation method based on stellar vector measurement and inclination information fusion, and demonstrates the correctness of the algorithm. A semi-physical simulation platform was built and the experimental method verified that the accuracy reached the positioning accuracy index of 30 arc seconds. Lunar surface positioning is different from ground positioning and cannot be positioned by satellites. This method solves the problems of low timeliness and low accuracy of ground measurement and control methods, greatly improving the timeliness and accuracy of lunar surface positioning, and has positive significance for lunar exploration projects.

Aerodynamic-Parameter Identification and Attitude Control of Quad-Rotor Model with CIFER and Adaptive LADRC

Current research on quadrotor modeling mainly focuses on theoretical analysis methods and experimental methods, which have problems such as weak adaptability to the environment, high test costs, and long durations. Additionally, the PID controller, which is currently widely used in quadrotors, requires improvement in anti-interference. Therefore, the aforementioned research has considerable practical significance for the modeling and controller design of quadrotors with strong coupling and nonlinear characteristics. In the present research, an aerodynamic-parameter estimation method and an adaptive attitude control method based on the linear active disturbance rejection controller (LADRC) are designed separately. First, the motion model, dynamics model, and control allocation model of the quad-rotor are established according to the aerodynamic theory and Newton–Euler equations. Next, a more accurate attitude model of the quad-rotor is obtained by using a tool called CIFER to identify the aerodynamic parameters with large uncertainties in the frequency domain. Then, an adaptive attitude decoupling controller based on the LADRC is designed to solve the problem of the poor anti-interference ability of the quad-rotor and adjust the key control parameter b0 automatically according to the change in the moment of inertia in real time. Finally, the proposed approach is verified on a semi-physical simulation platform, and it increases the tracking speed and accuracy of the controller, as well as the anti-disturbance performance and robustness of the control system. This paper proposes an effective aerodynamic-parameter identification method using CIFER and an adaptive attitude decoupling controller with a sufficient anti-interference ability.

Presynchronous Grid-Connection Strategy of Virtual Synchronous Generator Based on Virtual Impedance

The virtual synchronous generator (VSG) technology of inverter is widely used to provide the inertia and damping support for power system. However, an additional measurement device PLL (phase-locked loop) is required in the virtual synchronous generator grid connection to track the voltage phase, amplitude, and frequency, which restricts the flexible output of the distributed power generation system. To tackle this challenge, a method for grid-connected control of virtual synchronous generator based on virtual impedance is proposed. It is assumed that there is a virtual power exchange between the synchronous machine and the power grid when the virtual synchronous generator is off-grid, the virtual impedance is developed to calculate the virtual current, and when the virtual current is zero, the output voltage of the VSG can be synchronized with the voltage of the power grid, thereby seamlessly switching between off-grid and grid-connected VSG. A semiphysical simulation platform is built based on RT-LAB; simulation and experimental results show that the proposed grid synchronization control strategy of the VSG can achieve seamless transform between different VSG modes, which is simpler than the conventional synchronization control, while having a good active and reactive power tracing performance.

Model Error Analysis of Load Simulator System

The load simulator is the main semi-physical simulation equipment to detect the performance of the steering gear. Linear models or black box models are often used in load simulator modeling, but the modeling error needs to be further analyzed due to its prominent nonlinear and strong coupling characteristics. In this paper, the semi-physical simulation platform of the electric load simulator was built, and a linear model and a system identification model based on Artificial Neural Network (ANN) were established respectively. The error characteristics of the above models were further analyzed by statistical distribution and power spectral density. The research results can provide support for the controller design and the selection of state estimation method.

Speed-adaptive dynamic surface attitude control for a satellite with moving masses under input constraints

This paper investigates an attitude control technique for a low Earth orbit nanosatellite with moving masses based on the active use of aerodynamic forces. A speed-adaptive dynamic surface control scheme is designed to comprehensively solve the practical problems of aerodynamic model error, the dynamic effect of movement, stroke limitation, and slow convergence. Multiple constraints are imposed on the inputs to reduce the fast-varying dynamic effect of the masses to be negligible. Other slow-varying disturbances are precisely estimated by a nonlinear observer. In particular, to resolve the contradiction between the overshoot and the attitude convergence speed, a novel adaptive law is designed based on the smooth hyperbolic tangent function to adjust the convergence parameter within the given boundary. Moreover, considering the actual physical limitation, hard constraints are imposed on two actuators. Finally, by using the Lyapunov approach, it is proven that, despite uncertain dynamics, unknown disturbances and input constraints, the attitude error can be adjusted to be arbitrarily small by choosing the proper parameters. A semi-physical simulation platform is built to verify the feasibility of the moving mass actuator and the effectiveness and robustness of the proposed control scheme.

A scalable unsignalized intersection system for automated vehicles and semi-physical implementation

With the rapid development of automated vehicle (AV) technologies, unsignalized intersection scenario has attracted a lot of research attentions in the field of intelligent transportation system (ITS). In this paper, to improve the real-time unsignalized intersection coordination performance and guarantee the reliability of vehicle scheduling, a distributed and scalable scheduling algorithm (DSA) for unsignalized intersection system is proposed. First, to make the vehicle passing the intersection practical, we present a collision-free traffic scenario which is based on the improvement of the existing unsignalized scheduling approach. Specifically, the turning directions of automated vehicles would not be restricted so that AV can turn in a practical arc curve trajectory. Second, a distributed consistency protocol (DCP) based on the edge computing of roadside units is proposed to ensure the real-time scheduling messages transfer. Finally, to verify the proposed unsignalized intersection system, a semi-physical simulation platform (SPSP) is established on a sand table model. Both the software simulation results and the sand table measured data of the SPSP have verified the effectiveness of the algorithm, which is believe to further promote the practical engineering applications of automated vehicles.

Enhancing the Resilience of Low Earth Orbit Remote Sensing Satellite Networks

The Low Earth orbit Remote Sensing (LRS) satellite network is envisioned as an essential component of bolstering space information applications, thus extending conventional ground information applications to the on-board space information applications. However, it inevitably faces grave challenges imposed by the dynamics of the satellite network's topology, by the intermittence of Inter-Satellite communication Links (ISLs) as well as by the mobility-induced satellite-access switching of mobile terminals. Hence, this is a very different networking landscape from that of the terrestrial Internet. Against these challenging problems, we propose a resilient networking architecture for LRS Satellite Networks (LRS-SNs), with special emphasis on their dynamic routing, resilient transmission and their intrinsic mobility. Specifically, path-quality aided and lifetime-aware dynamic routing is proposed for enhancing the routing against dynamic topology changes. Hop-by-hop data transmission is relied upon for providing transmission resilience against ISL intermittence. Furthermore, data caching is invoked for providing resilience against intermittent communications imposed by dynamic satellite access switching. We employ a semi-physical simulation platform for evaluating the achievable performance of the proposed resilient network architecture.

Gyro-less angular velocity estimation and intermittent attitude control of spacecraft using coarse-sensors based on geometric analysis

Gyro-less angular velocity estimation is significant for the attitude control of spacecraft when the gyro is unavailable. The paper considered that the angular velocity remains almost constant in a short free-motion period, indicating that these endpoints of celestial body directions are on parallel planes. On this basis, we developed a novel angular velocity estimation method by optimizing these parallel planes with an iterative algorithm. Moreover, we proposed an alternative intermittent attitude control method, including a free-motion period for angular velocity calculation and a control period for attitude stabilization, respectively. Wherein, the length of the free-motion period is adjusted according to the magnitude of angular velocity to improve the calculation accuracy. Besides, we introduced a control law and analyzed the system stability using the Lyapunov method. For validation, we developed some simulation cases by constructing a semi-physical simulation platform and analyzed the effects of observation noise, the moment of inertia, and angular velocity. The simulation results show that the angular velocity estimation method has better accuracy and faster convergence than the Kalman method when considering observation noise. That is, the proposed intermittent attitude control method is feasible for the attitude stabilization.

DC‐link capacitor voltage balance strategy of independent double three‐phase common bus five‐level NPC/H‐bridge inverter based on finite control set

This study aims at the DC-link capacitor voltage imbalance problem of independent double three-phase common bus five-level neutral point-clamped/H-bridge inverter, which is applied to an electromagnetic launch system under instant high-power and high-current conditions. First, the traditional method of voltage balance strategy based on redundant vectors is described, and the key factors leading to the DC-link capacitor voltage fluctuation is analysed in detail. Second, the objective function is constructed to predict the variation trend of DC-link capacitance voltage difference. Third, an optimised voltage balance strategy is proposed. At first, the optimised strategy calculates the variation trends of the voltage difference for all three-phase switch vector combinations. Then, the results make up a voltage balance finite control set. At last, compare the results in the set to select the vector combination corresponding to the minimum variation for output. Finally, tested by the semi-physical real-time simulation platform, and the proposed optimised voltage balance strategy is verified effective for improving DC-link capacitor voltage imbalance and inhibiting the voltage difference fluctuation.

A Semi-Physical Platform for Guidance and Formations of Fixed-Wing Unmanned Aerial Vehicles.

Unmanned Aerial Vehicles (UAVs) have multi-domain applications, fixed-wing UAVs being a widely used class. Despite the ongoing research on the topics of guidance and formation control of fixed-wing UAVs, little progress is known on implementation of semi-physical validation platforms (software-in-the-loop or hardware-in-the-loop) for such complex autonomous systems. A semi-physical simulation platform should capture not only the physical aspects of UAV dynamics, but also the cybernetics aspects such as the autopilot and the communication layers connecting the different components. Such a cyber-physical integration would allow validation of guidance and formation control algorithms in the presence of uncertainties, unmodelled dynamics, low-level control loops, communication protocols and unreliable communication: These aspects are often neglected in the design of guidance and formation control laws for fixed-wing UAVs. This paper describes the development of a semi-physical platform for multi-fixed wing UAVs where all the aforementioned points are carefully integrated. The environment adopts Raspberry Pi’s programmed in C++, which can be interfaced to standard autopilots (PX4) as a companion computer. Simulations are done in a distributed setting with a server program designed for the purpose of routing data between nodes, handling the user inputs and configurations of the UAVs. Gazebo-ROS is used as a 3D visualization tool.