Semi-physical Simulation System Research Articles

A Review of the Research on Electro-hydraulic Load Simulator and Characteristics with Improvement Methods

Abstract: The electro-hydraulic load simulator is a semi-physical simulation system. It is used to simulate different loads on the bearing capacity object (steering gear system) under working conditions and further test the dynamic and static characteristics of the bearing capacity object. Therefore, it is widely used in important applications such as the simulation of various loads and the development of high-performance steering gear systems. By analyzing and discussing the electro-hydraulic load simulator equipment and its improvement methods, some useful conclusions have been drawn to predict the development of the electro-hydraulic load simulator and its key technologies. The current status of research on electro-hydraulic load simulator prototypes is discussed in depth. The electro-hydraulic load simulators are classified according to the loading system applying force (torque). The improvement methods of the electro-hydraulic load simulator, including the method of suppressing the extraneous force, the compensation method of nonlinear factors, and the method of establishing the mathematical model, are analyzed and summarized. By summarizing the literature and patents on electro-hydraulic load simulation technology, the principle, and characteristics of different equipment and improvement methods are analyzed and compared, and future development of electro-hydraulic load simulation equipment and technology is discussed. The research on the characteristics of the prototype, the hardware means and control strategy to suppress the extraneous force, the compensation of nonlinear factors, and the methods of establishing the mathematical model are beneficial to improve the loading accuracy of the electro-hydraulic load simulator.

Sensorless Control Strategy for Interior Permanent Magnet Synchronous Motors in the Full-Speed Section

Along with the advancement of modern control technology, electric vehicles have gradually become the leading force in the development of the automobile industry. Interior permanent magnet synchronous motors (IPMSMs) have gradually become a mainstream electric vehicle drive component due to their high power density and excellent controllability. This type of motor can form a high-precision closed-loop control system with position sensors, which improves the overall performance. However, the operating conditions are complicated, and position sensor failure can easily occur, which reduces the stability of the motor system. For the fault-tolerant control problem of position sensor failure, pulse high-frequency voltage injection and an improved sliding mode observer (SMO) are employed to achieve the sensorless control of both the low-speed and medium-high-speed sections of the electric motor. Combining the advantages of high-frequency voltage injection in the low-speed section with a high accuracy of position estimation and the advantages of improved SMO in the high-speed section with low computational volume, the composite sensorless control strategy is proposed for IPMSM in the full-speed section. Secondly, an improved SMO using a segmented composite function as the control function is proposed to improve the robustness of the system. It is proposed to address the issue of the smooth transition between the low-speed section and the medium- and high-speed section by using linear weighting. Finally, in order to validate the accuracy of the sensorless control technology, a rapid control prototype of IPMSMs based on Speedgoat is constructed by using a semi-physical simulation system. The efficacy of the control algorithms in the low-speed section, high-speed section and transition interval is verified.

Fault tolerant attitude control of under-actuated spacecraft: Theory and experiment

This paper investigates fault tolerant attitude control theory and experiment for under-actuated spacecraft with one reaction wheel completely broken and two others suffering actuator faults of partial loss of effectiveness or bias. A non-smooth robust adaptive fault tolerant control law is proposed under the zero-momentum and input saturation conditions. It shows that the available reaction wheels need to produce sufficient control torque for the fault tolerance. Such a new control method is implemented in a semi-physical simulation system of an air-bearing platform. Experimental results show the effectiveness of the proposed method in spacecraft practical engineering.

Integrity Detection and Supplementary Experimental Design of Semi-Physical Simulation Data on Aircraft Landing Points

For the semi-physical simulation test process of the coordinates of aircraft landing points, the concept of a completeness test for landing point simulation data is proposed, and a completeness test criterion based on field test data and expert estimation information is established. An integrity detection method for semi-physical simulation data, including data dimensionality reduction, data expansion, and regularization, drawing the envelope of the confidence region and establishing the completeness test criterion steps, is proposed. For landing points that do not satisfy the requirements of completeness, a surrogate model of the semi-physical simulation system was constructed based on a backpropagation neural network method, and the test conditions for data of this point were supplemented. Finally, application verification was carried out. Through the field and semi-physical simulation test research of a 534A aircraft, it was verified that the method can well realize the inspection of the completeness of the semi-physical simulation test data and the design of supplementary test conditions. It lays a good foundation for the fusion of subsequent semi-physical simulations and field test data.

Second-order sliding-mode on SO(3) and fault-tolerant spacecraft attitude control

As one of attitude representation methods for a rigid body, the rotation matrices defined on the special orthogonal matrix group SO(3) can give the unique, global and nonsingular solution. For the attitude control systems evolving on Lie group SO(3)×R3, a second-order sliding surface is constructed and proved to be a Lie subgroup, along which the reduced-order dynamics is almost globally asymptotically stable at the equilibrium state. Based on the new sliding-mode surface, a fault-tolerant controller is designed to deal with the actuator faults and external disturbances in attitude control systems. The new method is numerically simulated and further implemented in a semi-physical simulation system of an air-bearing platform to verify its effectiveness in spacecraft practical engineering.

Research on high‐efficiency optimization algorithm applied to near‐field effect error correction

In order to achieve a more efficient and accurate correction of near-field error in the semiphysical radio frequency simulation system, the precise control parameters of the three antenna elements need to be obtained. This article is based on the method of moments electromagnetic simulation, and propose corresponding improvement ideas for the problems of limited optimization accuracy and low calculation efficiency in the near-field error correction process. From the aspects of high-precision intelligent inversion algorithm and high-efficiency electromagnetic forward modeling, systematic optimization design and verification were carried out. The results prove that the control parameter filtering scheme based on PSO-GA hybrid method has better optimization efficiency and accuracy than single genetic algorithm or differential evolution algorithm, which can provide more ideal initial amplitude and phase parameters for the subsequent selection of electromagnetic simulation and forward verification. In order to solve the problem of time-consuming in the electromagnetic simulation, the multivariate vector forward model based on GA-BP network and PSO-SVM network are established, which can achieve high-precision positioning of synthetic vector target points. The neural network method has been proved to be feasible on the basis of the current sample size. The paper selects hybrid algorithms to improve the shortcomings of single algorithm and uses algorithms to optimize neural networks, thereby obtaining better optimization results and reducing the time-consuming of electromagnetic simulations, which can realize efficient correction of near-field error.

Application and Performance Evaluation of Resource Pool Architecture in Satellite Edge Computing

Satellites will play a vital role in the future of the global Internet of Things (IoT); however, the resource shortage is the biggest limiting factor in the regional task of massiveequipment in the IoT for satellite service. Compared with the traditional isolated mode of satellite resources, the current research aims to realize resource sharing through satellite cooperation in satellite edge computing, to solve the problems of limited resources and low service quality of a single satellite. We propose a satellite resource pool architecture-oriented regional task in satellite edge computing. Different from fixed servers in ground systems, the satellite orbital motion brings challenges to the construction of the satellite resource pool. After the capacity planning of the satellite resource pool for regional tasks is given, an algorithm based on search matching is proposed to solve the dynamic satellite selection problem. A ground semi-physical simulation system is built to perform experiments and evaluate the performance of three modes of satellite resource sharing: isolated mode, cooperative mode, and pooled mode. The results show that the pooled mode, compared with the isolated mode, improves the task success rate by 19.52%, and at the same time increases network resources and energy consumption in the same scenario. Compared with the cooperation mode, the performance of task success rate and resource utilization rate is close to that of the pooled mode, but it has more advantages in response time and load balancing of satellite resources. This shows that in the IoT, the resource pool is of great benefit as it improves the task response time and improves the load balance of satellite resources without degrading the performance, which makes sense in task-demanding scenarios.

Underwater Submarine Path Planning Based on Artificial Potential Field Ant Colony Algorithm and Velocity Obstacle Method.

Navigating safely in complex marine environments is a challenge for submarines because proper path planning underwater is difficult. This paper decomposes the submarine path planning problem into global path planning and local dynamic obstacle avoidance. Firstly, an artificial potential field ant colony algorithm (APF-ACO) based on an improved artificial potential field algorithm and improved ant colony algorithm is proposed to solve the problem of submarine underwater global path planning. Compared with the Optimized ACO algorithm proposed based on a similar background, the APF-ACO algorithm has a faster convergence speed and better path planning results. Using an inflection point optimization algorithm greatly reduces the number and length of inflection points in the path. Using the Clothoid curve fitting algorithm to optimize the path results, a smoother and more stable path result is obtained. In addition, this paper uses a three-dimensional dynamic obstacle avoidance algorithm based on the velocity obstacle method. The experimental results show that the algorithm can help submarines to identify threatening dynamic obstacles and avoid collisions effectively. Finally, we experimented with the algorithm in the submarine underwater semi-physical simulation system, and the experimental results verified the effectiveness of the algorithm.

Research on multi-fault diagnosis method and test platform of main transmission Machinery of wind Turbine based on electrical signal

An optimised design was carried out based on the original semi-physical simulation system for the main drive chain of a wind turbine. The input of upper computer simulating wind condition, the safety control of electrical signal and vibration signal acquisition module, relay and AC contactor and dual motor control were added. Simultaneously, the simulation schemes of some common faults on the main drive of wind turbines were also designed in order to perform the experimental simulation of the single fault and multi fault. The primary purpose of simulation is to use practical approaches(such as FFT,EMD)to analyze the changes of the fault signals based on the collected electrical signals, and to determine whether there is a fault through comparison and theoretical analysis. In addition, it aimed for verifying the feasibility of electrical signals under multi-fault conditions, and discussing advantages of electrical signals over vibration signals.

Power dynamic allocation strategy for urban rail hybrid energy storage system based on iterative learning control

In urban rail transit, hybrid energy storage system (HESS) is often designed to achieve “peak shaving and valley filling” and smooth out DC traction network power fluctuation. In this paper, a variable gain K iterative learning control (K-ILC) is proposed to balance the DC regulated voltage characteristics and the optimal lifetime of the battery storage system in the HESS. Firstly, according to the traction power demand obtained from the train running speed demand, a moving average filters algorithm (MAF) is used to assign the high-frequency power command to the onboard ultracapacitors and the low-frequency power command to the batteries and traction network, respectively. Then, in order to prolong the battery life, a variable gain ratio is introduced in the traditional PD open-loop iterative learning control by designing the power allocation switching rules and the optimal change trajectory of battery life. This will provide the control of the battery charging and discharging current so as to prevent overcharge and overdischarge. To verify the effectiveness of the proposed strategy, experiments are performed both in MATLAB/Simulink and in the RT-LAB semi-Physical real-time simulation system. The experimental results show that the proposed control strategy effectively stabilizes the bus voltage and extends the battery lifetime.

Design of a Semi-physical Simulation and Testing system for Space Robot Operating platform

In view of the importance and complexity of the control and execution tasks of the space robot, the development of a real test environment has the risks of high cost and long cycle. Therefore, a semi-physical simulation and testing system is designed for the space robot operating platform. The system is composed of a robotic arm console, a central control system, a fusion system, a position tracking system, etc., to realize the verification of the hardware electrical interface, software algorithm logic and task operation process of the robotic operating platform. Through the realization of 3D animation demonstration of the robot operation, motion tracking and other simulations, the semi-physical simulation and testing system has a higher visualization and a stronger sense of experience, and can simulate the complex operating conditions of the system on orbit. At present, the simulation and testing system has been successfully applied to the ground test of the space robot operating platform, and its reliability and simulation verification effect are better.

Ground semi-physical simulation experiment study of one-dimensional drag-free control

Drag-free control is one of the key technologies for the verification of Taiji-1 satellite. In the direction of sensitive axis, the drag-free controller receives the measurement signal from the high-precision gravitational reference sensor on the satellite, and instructs the micro-thruster system to counteract the disturbance force acting on the sensitive axis, so that the microgravity level in the sensing axis direction of the satellite can reach the order of 10[Formula: see text] m/s2 in the measurement band. In order to fully verify the drag-free control system, a ground one-dimensional drag-free semi-physical simulation system is built to simulate the performance of various payloads in the drag-free control loop, and to verify the performance and technical targets that the drag-free control system can achieve in the ground control loop. Through the small angle approximation, the equivalent relationship between the rotation of the experimental model and the translational motion of the experimental satellite in the direction of drag-free is demonstrated. In the condition of neglecting the stiffness and damping of the suspended pendulum, the parameters of the suspended pendulum are designed according to the principle of equal acceleration, and their effectiveness is verified by numerical simulation. According to the operation mode of on orbit drag-free control, the ground drag-free experimental scheme and drag-free controller are designed, and the experimental research and verification are carried out. The results show that the controller can effectively control the displacement and acceleration of the experimental model, and also can effectively suppress the disturbance of certain amplitude and frequency.

X-ray pulsar navigation based on two-stage estimation of Doppler frequency and phase delay

In X-ray pulsar-based navigation (XPNAV), the appearance of Doppler effects caused by the dynamic motion of the spacecraft would severely degrade the navigation accuracy. In this paper, we develop a new XPNAV method based on a two-stage estimation method of Doppler frequency and phase delay to overcome the Doppler effects. Based on the pre-established phase model of the pulsar at the SSB and the predicted states of the spacecraft, the real-time phase model at the spacecraft is modeled with respect to the initial position and velocity errors of the spacecraft. It turns out that within an observation interval, a constant Doppler frequency can be estimated to overcome the effect of the initial velocity error, and then the phase delay caused by the initial position error can be estimated by using the computationally efficient methods based on epoch folding. Under this frame, the H-test for uniformity, which needs no prior knowledge of the light curve, is used to estimate the Doppler frequency and the fast maximum likelihood method is used to estimate the phase delay. The dynamic model and measurement model of the proposed navigation method are also given. Photon-level simulation results obtained by using the ground-based semi-physical simulation system for X-ray pulsar signals show a significant improvement over the traditional XPNAV method.

Individual Pitch Control of Wind Turbines Based on SVM Load Estimation and LIDAR Measurement

With the development of wind turbines to the large scale with high rated powers, how to reduce fatigue loads is the key factor for modern wind turbine control. Aiming at reducing the wind turbine structural fatigue loads, an individual pitch control (IPC) method based on SVM estimation of blade root loads was proposed in this paper. The blade root loads were dynamically estimated by a SVM model according to light detection and ranging (LIDAR) wind speed data. Two approximate decoupling systems for yaw moments and pitch moments were then obtained through Coleman transform. Meanwhile, two individual pitch controllers were designed to reduce the loads and a wind speed feedforward controller was adopted to improve the pitch control performance. The proposed method was verified by a FAST, LIDAR and RT-LAB semi-physical real-time combined simulation system. On this basis, a master control unit was developed and the overall unit was further verified by a CRRC wind turbine master control and pitch joint test platform. Compared with collective pitch control (CPC) and the IPC based on azimuth, the proposed method is effective on reducing fatigue loads and vibration.

Information Fusion Based on Complementary Filter for SINS/CNS/GPS Integrated Navigation System of Aerospace Plane.

In order to solve the problems of heavy computational load and poor real time of the information fusion method based on the federated Kalman filter (FKF), a novel information fusion method based on the complementary filter is proposed for strapdown inertial navigation (SINS)/celestial navigation system (CNS)/global positioning system (GPS) integrated navigation system of an aerospace plane. The complementary filters are designed to achieve the estimations of attitude, velocity, and position in the SINS/CNS/GPS integrated navigation system, respectively. The simulation results show that the proposed information fusion method can effectively realize SINS/CNS/GPS information fusion. Compared with FKF, the method based on complementary filter (CF) has the advantages of simplicity, small calculation, good real-time performance, good stability, no need for initial alignment, fast convergence, etc. Furthermore, the computational efficiency of CF is increased by 94.81%. Finally, the superiority of the proposed CF-based method is verified by both the semi-physical simulation and real-time system experiment.

Construction and Test Method of A Semi-physical Simulation System for Laser Driving Guidance Weapon

Construction and Test Method of A Semi-physical Simulation System for Laser Driving Guidance Weapon

Robust Model-Predictive Control for Inductively Coupled Plasma Generation With a Semiphysical Simulation

In this article, a novel robust tuning approach based on model-predictive control (MPC) for an inductively coupled plasma (ICP) generation process is presented. Several key aspects related to this methodology are the modeling of the ICP generation process, the robust joint tuning (RJT) algorithm, and the semiphysical simulation of the MPC algorithm. The ICP generation process model is built by a system identification method based on steady and dynamic responses, followed by a general model-predictive controller. Then, an automatic RJT algorithm is developed for the model-predictive controller to quickly obtain the optimal weighting parameters. The proposed RJT algorithm can minimize the ICP generation control system's maximum total variations in the output with a specific dynamic performance requirement and model uncertainty, providing a tradeoff between the dynamic performance and robustness. Finally, a semiphysical simulation system based on dSPACE and a field-programmable gate array is designed to illustrate the effectiveness of the model-predictive controller for the ICP generation control process and the RJT algorithm. Experimental results indicate the validity and good performance of the proposed model-predictive controller and the RJT algorithm.

High‐precision target echo generation technology based on one‐dimensional linear array radar

The high-precision target echo generation in the field of radar systems is particularly important for large-scale, comprehensive testing of radars. Conventional echo generation techniques often use planar array air feed to simulate echoes. However, it is complicated and expensive to achieve the echo generation with traditional planar array. Therefore, this study proposes a high-precision target generation technique based on one-dimensional linear arrays. The simulation system achieves the target radial high-precision simulation through DRFM technology; the target azimuth high-precision simulation is achieved through differential GPS technology; and the target elevation high-precision simulation is realised through vertical one-dimensional linear array antenna switching. The semi-physical simulation system presented here has the advantages of simple control, low cost, low link loss, easy maintenance, and high simulation target accuracy. Finally, the system was tested in the field to verify the theoretical concept of the article.

A Fuzzy Control Strategy of Burn-Through Point Based on the Feature Extraction of Time-Series Trend for Iron Ore Sintering Process

Sinter ore is the main raw material for ironmaking, and burn-through point (BTP) is one of the significant factors to measure the stability of the sintering process. In this article, through the feature extraction of time-series trend, a fuzzy control strategy is presented for the BTP. First, the Hurst exponent of the time series for the BTP is calculated by resorting to the rescaled range analysis method, by which the trend feature is analyzed. Then, by using the Mann–Kendall test, both global and local trend feature variable of the time series for the BTP are extracted and regarded as the inputs of the fuzzy controller. Next, a fuzzy controller for the BTP is designed to produce the control quantity of the strand velocity. Finally, based on a semiphysical simulation system and the raw data collected from an iron and steel plant, an experiment is carried out to demonstrate the effectiveness of the proposed control strategy.

Design and Performance Evaluation of a Simple Semi-Physical Human-Vehicle Collaborative Driving Simulation System

Human-vehicle collaborative driving (HVCD) has a novel concept of an intermediate stage from the development of a normal smart vehicle to self-driving vehicle, requires the vehicle’s decision-making authority equivalent to the human driver’s operation. As the self-driving vehicle cannot achieve full-condition driving without human driver yet and still have a long time to go, the collaborative driving can exploit both machine and human specialties, which requires human and vehicle intelligence to control the vehicle simultaneously and work together. However, there were a few studies focusing on the HVCD that experimental environment and evaluation methods are rarely discussed, even under the simulation conditions, which limits the development of collaborative driving. To bridge the significant gaps, this paper designed simple semi-physical simulation system architecture for the HVCD. First, the simple designed system can achieve basic functions, including human control input as the normal driver, vehicle intelligence with local and global sensor data process and decision fusion. The presented system can use and process this multi-source information to achieve the HVCD in the simulated environment. Second, the evaluation method based on vehicle driving safety, stability, and rapidity is proposed and discussed, which matters most for system performance test and feasibility verification. In addition, experiments with different decision fusion conditions were presented and the experimental results show that the proposed simple semi-physical HVCD simulation system can work smoothly and reflect the practical scenario. Furthermore, the performance of different fusion weights experiments shows the advantages of both human driver and vehicle intelligence, which provides a reference for the HVCD related research improvement.