Hardware-in-the-loop Simulation System Research Articles

Development of Model-Based PEM Water Electrolysis HILS (Hardware-in-the-Loop Simulation) System for State Evaluation and Fault Detection

Hydrogen is attracting attention as a good energy-storage medium for renewable energy. Among hydrogen production technologies using renewable energy, water electrolysis is drawing attention as a key technology for green hydrogen production using renewable energy. In particular, polymeric electrolyte membrane water electrolysis systems have several advantages compared to other types of water electrolysis technologies, such as small size and mass, high efficiency, low operating temperature, and low power consumption. However, until now, proton-exchange membrane (PEM) water electrolysis systems have not been reliable. In this study, system failure diagnosis techniques were presented among the various methods for improving reliability. We developed PEM water electrolysis stack models and system models to predict the performance of the system and analyze the dynamic properties using MATLAB/Simulink® 2018a, which have been validated under various conditions. The developed dynamic characteristic simulation model applies hardware-in-the-loop simulation (HILS) technology to configure experimental devices to interact in real-time. The developed PEMWE HILS system accepts signals that control the system, operates the experimental setup and simulation model in real-time, and diagnoses the system’s failure based on the results.

Research on flight control system hardware in the loop simulation system based on NI hardware platform for Unmanned Aerial Vehicle

HIL(Hardware in the loop) simulation of UAV(Unmanned Aerial Vehicle) plays an important role in flight control sysrtem development and algorithm verification. Taking the open source flight control system Pixhawk as the research object, this paper establishes a HIL system based on NI(National Instrument) hardware platform. The dynamic model and kinematic model are modeled through Simulink, the online management of simulation model is realized through Veristand, and the online display of model parameters and fault injection are realized through Labview. The simulation system can test the functional performance, reliability and safety of flight control system. The simulation results show that the simulation platform works reliably and has good real-time performance. It can effectively and reliably carry out the HIL of flight control system for UAV.

A Passivity-Based Velocity Control Method of Hardware-in-the-Loop Simulation for Space Robotic Operations

The hardware-in-the-loop (HIL) simulation is an important approach to test space robotic operations, rendering virtual free-floating dynamics on robotic facilities. However, this approach suffers from velocity divergence due to intrinsic time delay in the control loop. This paper proposes a passivity-based control strategy to handle the simulation divergence. A HIL simulation system with an industrial robot is modelled and its divergence problems are analyzed through numerical simulations. Then, through representing the HIL simulation system in a passivity network of view, the passivity observer (PO) of the dynamic system is established. The PO includes the effect of a real contact damping on energy flow of the passivity network during a contact process. Thus, a passivity controller is defined. Moreover, a real-time estimation method for contact damping is presented. Finally, collision experiments against a virtual wall and real collision experiments are both implemented. The experimental results show that the simulation divergence due to the time delay can be prevented by the proposed control strategy, and that the velocity characteristics with high fidelity are rendered on the HIL simulation system.

Hardware-in-the-Loop Simulation for Compound Catenary Systems

This study proposes a new pantograph testing method for railway pantograph/overhead contact lines (OCL) systems, based on hardware-in-the-loop simulation (HILS) consisting of a physical pantograph and a numerical compound OCL model. A servo-hydraulic actuator fixed to a frame structure is used to realize vertical displacement of the contact wire model. In order to compensate for phase lag of the servo-hydraulic actuator and stabilize the HILS system, the dynamically substructured system (DSS) method is used. This HILS enables the investigation of dynamic interactions between the contact wire of the OCL and the pantograph head, due to dropper-passing of the pantograph. In order to validate the proposed method, HILS testing is carried out at the Railway Technical Research Institute. The contact force between the actuator and the pantograph head is measured using a loadcell. Results from this experimental investigation are compared with those generated by a numerical simulation of the emulated system, i.e. the system to be represented by the HILS experimentation.

Analysis of Rotor Position Detection Performance According to the Frequency of Square Waveform Voltage in the Harmonic Injection Sensorless Method through HILS

In this paper, the rotor position estimation performance of the sensorless scheme for permanent magnet synchronous motors (PMSMs) implemented through the injection of high-frequency square-wave voltage according to the frequency of the square-wave voltage is presented through HILS (Hardware In the Loop Simulation) experiments. An inverter using an IGBT device usually has a switching frequency of around 15 kHz. On the other hand, GaN devices that can be switched on and off at frequencies higher than 100 kHz have been recently developed, and research is being actively conducted to apply GaNs to a variable speed system. The purpose of this study is to conduct HILS experiments to analysis the rotor position estimation ability of the sensorless technique in cases where a high switching frequency was applied, such as GaN devices, with that of a system having a usual switching frequency, such as IGBT. In the HILS system used in this study, an inverter and motor model implemented with Simulink are located in a real-time simulator. A sensorless motor control method was implemented with an FPGA control board, which includes a PWM interrupt service routine of 100 kHz frequency and a harmonic injection and position detection algorithm. The HILS experiments show rotor position detection errors according to the various frequency of the harmonic voltage injected for estimating the rotor position with a PWM frequency of 100 kHz cases. According to the experimental results, good position estimation was possible not only when the harmonic of 10 kHz corresponding to 1/10 of the PWM frequency was injected, but also when the harmonic of 1 kHz corresponding to 1/100 of the PWM frequency was injected. The experiments suggest that position estimation errors decrease as the frequency of the harmonic voltage increases, and, based on the foregoing, it is thought that the application of a GaN device capable of realizing a high switching frequency in a variable speed drive system can be another advantage.

Smith predictor compensation and fuzzy incremental control for delay of space docking hardware-in-the-loop simulation system

Hardware-in-the-loop (HIL) simulation for space manipulator docking is an important means to simulate real space docking on the ground. The HIL simulation system in this paper utilizes the contact force measured by force sensor to calculate the dynamics of the mechanisms, and the docking process is simulated by the parallel robot. The measurement delay of force sensor and dynamic response delay of the parallel robot are inevitable, which not only affect the accuracy of simulation but also lead to the instability of the HIL simulation system. The traditional first-order phase compensation is the most commonly used force sensor compensator; but when the force changes with a high frequency, its compensation effect becomes bad, which will lead to the divergence of the HIL simulation system. Most control methods of the parallel robot are based on the model of the parallel robot, but the forces of the parallel robot are complex during the docking process, and the system parameters, motion frequency, and dynamic response characteristics are time-varying; thus, it is difficult to design the controller based on the model. In this paper, the Smith predictor compensation (SPC) method and fuzzy incremental control (FIC) method are utilized to decrease the delays of the force sensor and parallel robot, respectively. The effectiveness of the Smith predictor compensation and fuzzy incremental control method in reducing the delay of the HIL system and in improving the stability of the system is verified by simulation and experiment; compared with the traditional first-order phase compensation and proportional-integral-differential control methods, the advantages of the proposed methods are illustrated. The research in this paper provides an important technical means for accurately simulating the real docking process.

배전지능화 단말장치의 모의시험을 위한 가상 배전계통 HILS 시스템 개발

This paper proposes a virtual distribution HILS(Hardware-In-the-Loop Simulation) system for testing of FRTU(Feeder Remote Terminal Unit) for distribution automation systems. Recently, the distribution automation systems have been complicated because of the reliability improvement of the power system, new power distribution facilities, and upgrading the operating system. However, real-time digital simulators are difficult to build systems due to expensive facilities and cannot implement actual distribution automation systems. Therefore, in this paper, the HILS system is developed by using FRTU, interface devices based on DSP(Digital Signal Processor), Labview monitoring through the TCP/IP communication, and real-time power system analysis simulator. The proposed HILS system is verified through the results of systematic analysis of distribution automation systems, real-time simulation, and functional verification by using the feeder remote terminal unit.

Design and Implementation of a Hardware-in-the-Loop Simulation System for a Tilt Trirotor UAV

The tilt trirotor unmanned aerial vehicle (UAV) is a novel aircraft that has broad application prospects in transportation. However, the development progress of the aircraft is slow due to the complicated control system and the high cost of the flight experiment. This work attempts to overcome the problem by developing a hardware-in-the-loop (HIL) simulation system based on a heavily developed and commercially available flight simulator X-Plane. First, the tilt trirotor UAV configuration and dynamic model are presented, and the parameters are obtained by conducting identification experiments. Second, taking the configuration of the aircraft into account, a control scheme composed of the mode transition strategy, hierarchical controller, and control allocation is proposed. Third, a full-scale flight model of the prototype is designed in X-Plane, and an interface program is completed for connecting the autopilot and X-Plane. Then, the HIL simulation system that consists of the autopilot, ground control station, and X-Plane is developed. Finally, the results of the HIL simulation and flight experiments are presented and compared. The results show that the HIL simulation system can be an efficient tool for verifying the performance of the proposed control scheme for the tilt trirotor UAV. The work contributes to narrowing the gap between theory and practice and provides an alternative verification method for the tilt trirotor UAV.

Design and achievement of hardware-in-the-loop simulation system for strapdown semi-active laser seeker

According to the work characteristics of semi-active laser-guided weapon system, at first, the optical characteristics of the laser received by seeker were analyzed; and mathematical model of the optical signal power received by seeker was established. Secondly, a hardware-in-the-loop simulation(HILS) system was designed for strapdown seeker. In order to simulate energy and laser spot’s continuous variations, a high-precision continuous dynamic laser energy attenuation system and a digital micromirror device(DMD) spot projection system were designed respectively. In the end, the HILS system was used to evaluate the performances of strapdown seeker and the seeker was tested for response coherence among the four quadrants, field of view(FOV), linear field of view, minimum received optical power, and angle measurement accuracy.

Hardware-in-the-Loop Testing of Automatic Lift Dropping System for Heavy Trucks

This paper focuses on a novel hardware-in-the-loop (HIL) system designed for developing the automatic operation of the axle lifting and dropping system for heavy trucks for compliance with the European Union Mass and Dimensions Policy and for evaluating the developed system for different axle loading, road slippage, truck speed, handbrake position and driver input combinations. Such a system is expected to be advantageous over manual operation in fuel consumption, tire wear, road surface damage and ease of taking off on slippery surfaces. An auto lift/drop algorithm in the form of a State Transition Diagram (STM) was developed to meet these requirements and has been implemented in the developed HIL simulation system that contains mechanical, pneumatic, electrical and control elements and a TruckMaker simulation model. In the HIL simulator, the electronic control unit (ECU) operated as if it is working in the real truck. Comprehensive scenarios can be generated and executed in this HIL simulation environment to test the algorithm and the set-up itself before the more expensive and time consuming experimental verification with a real truck. This approach allowed the lift axle automation algorithm and hardware to be tested fully in a safe lab environment where the algorithm could be improved and optimized Results of the HIL simulation verified the advantages of such an automated lift axle lifting and dropping system over manually operated axle dropping systems. The developed system was successfully implemented later in a truck and was used in series production trucks.

A Novel Integrated Simulation and Testing Platform for Self-Driving Cars With Hardware in the Loop

Effective simulation and testing environment is a vital part in the research of self-driving vehicles. It is capable of testing self-driving software and hardware quickly in a variety of virtual environments at low cost. However, as for the current mainstream simulation platforms, a considerable gap exists between the constructed virtual environment and the actual self-driving platform, which decreases the efficiency of development and makes it difficult to complete the migration from the virtual scenario to the real environment. Therefore, in this paper, we proposed a novel hardware-in-the-loop (HiL) simulation system. It takes the real hardware electronic control unit (ECU) of the self-driving vehicle as a part of the simulation platform, which improves the efficiency of development and testing, and also, the verified algorithms can be implemented into self-driving cars faster than ever before. The proposed HiL simulation system mainly consists of four parts: the vehicle kinematic model simulation, the multi-sensor simulation, the environment simulation, and the ECU hardware. Simulation experiments on applying the HiL system are used to verify the validity of self-driving algorithms in virtual scenes, including perception, planning, decision making, and control. Furthermore, algorithms that are tested in the simulation environment can be rapidly deployed into the real self-driving vehicles. In this paper, we also presented the verification processes of various algorithms, such as planning and control. These algorithms are implemented in the HiL system, and the experimental results show the validity of our proposed platform.

Real-Time Interface Model Investigation for MCFC-MGT HILS Hybrid Power System

The research on the control strategy and dynamic characteristics of the Molten Carbonate Fuel Cell-Micro Gas Turbine (MCFC-MGT) hybrid power system has received much attention. The use of the Hardware-In-the-Loop Simulation (HILS) method to study the MCFC-MGT hybrid power system, where the MCFC is the model subsystem and the MGT is the physical subsystem, is an effective means to save development cost and time. The difficulty with developing the MCFC-MGT HILS system is the transfer of the mass, energy, and momentum between the physical subsystem and the model subsystem. Hence, a new Simulation–Stimulation (Sim–Stim) interface model of the MCFC-MGT HILS hybrid power system to achieve a consistent mass, energy, and momentum with the prototype system of the MCFC-MGT hybrid power system is proposed. In order to validate the Sim–Stim interface model before application in an actual system, both a real-time model of the MCFC-MGT hybrid power system and the MCFC-MGT HILS hybrid power system based on the Sim–Stim interface model were developed in the Advanced PROcess Simulation (APROS) platform. The step-up and step-down of the current density, which were strict for the Sim–Stim interface model, were studied in these two models. The results demonstrated that the Sim–Stim interface model developed for the MCFC-MGT HILS hybrid power system is rapid and reasonable.

Design and implementation of a real-time hardware-in-the-loop testing platform for a dual-rotor tail-sitter unmanned aerial vehicle

Tail-sitter vertical take-off and landing (VTOL) vehicle is a promising airframe among all the unmanned aerial vehicles (UAV), although challenges regarding the control strategies remain for civil applications, such as high susceptibility to wind disturbance while hovering. A real-time hardware-in-the-loop (HIL) simulation method for a tail-sitter UAV, an efficient tool for developing the control system, is presented in this paper. A nonlinear six-degrees-of-freedom dynamic model that covers the full angle-of-attack range is derived using the component breakdown approach. The environmental model is further introduced in the real-time simulation application to provide prevailing and gust wind conditions. A commonly used open-source flight controller was embedded in the proposed HIL framework. This HIL testbed can help researchers minimise the time spent debugging the controller program and moving from the simulation control system to the practical control one. The HIL simulation system was validated with the typical complete flight scenarios of a tail-sitter, including hovering, forward transition, cruise, and back transition. The results demonstrate that the HIL system can be an efficient tool for verifying the performance of hardware and software designs of the control system at the development stage for tail-sitter UAVs.

Modeling method of a ladar scene projector based on physically based rendering technology.

The ladar scene projector is a key device in the hardware-in-the-loop (HWIL) simulation system. Ladar scene modeling is a fundamental work of developing a ladar scene projector. A modeling method based on physically based rendering technology and OpenGL is proposed in this paper. This modeling method can quickly generate delay, amplitude, and pulse width data for all return signals in a large-array-scale ladar scene. A 100×100-array-sized ladar scene model with a distance range of 0-3 km is simulated. The average data generation time is only 5.31 ms. Distance resolution is 1.5 m, and the peak-valley error is less than 0.15 m. This method achieves efficient modeling and fast hardware update rates, which greatly improves the real-time performance of the ladar scene projector. It has strong practicality and can be directly applied in the HWIL simulation system.

Development of Mobile Ground Control System and GPS Base Auto Tracking Antenna

Flight test of both rocket and high speed Unmanned Aerial Vehicle (UAV), which is currently developed by LAPAN, can not be separated from the need for a monitoring system of all the attitude of the vehicles. Utilizing and combining some of the available equipment components into a ground control system (GCS) equipped with GPS based auto tracking antenna, makes it easy in previous flight test activities that only do tracking antenna manually. This ground control system is equipped with automatic tracking antenna that always leads to the vehicle, so that the data attitude of flying the vehicle will be maximally monitored and analyzed directly with ease. This system has been tested on a laboratory scale related to testing using hardware in the loop simulation system

Hardware-in-the-Loop Simulation on Fault Current Limiting Operation of RE-123 Coated Conductors Under the Influence of Spatial Inhomogeneity

We have investigated transient behavior of RE-123 coated conductors in fault current limiting operation based on experimental hardware-in-the-loop simulation (HILS). Fault current limiting function of superconducting electric power application is attractive to maximize the potential of power system; such a function can be realized by the transition to the resistive state of superconducting wire. However, the phenomena is relatively complicated: nonlinear current transport properties varying with time-dependent temperature rise. Furthermore, from practical point of view, the influence of spatially homogeneity of cooling and local critical current properties in RE-123 coated conductors must be clarified for reliable operation. To demonstrate this, we developed HILS system using real-time digital simulator. Fault current limiting operation was successfully demonstrated for dc electric railway system. This method enabled us to evaluate the real-time responses of RE-123 coated conductors such as nonlinear properties and thermal behaviors under a power grid network. In particular, we applied RE-123 coated conductors with spatially inhomogeneous cooling and local critical currents to the experiment to understand the influences of them on the fault current limiting and recovery functions. Furthermore, such transient phenomena were successfully described by an electrically and thermally coupled analysis taking into account of temperature dependent nonlinear transport properties of the RE-123 coated conductors based on the percolation transition model. The method and findings will become crucial for effective and reliable designs of superconducting fault current limiters.

Hybrid Smith predictor and phase lead based divergence compensation for hardware-in-the-loop contact simulation with measurement delay

On the ground the hardware-in-the-loop (HIL) simulation is a good approach to test the contact dynamics of spacecraft docking process in space. Unfortunately, due to the time delay in the system the HIL contact simulation becomes divergent. However, the traditional first-order phase lead compensation approach still result in a small divergence for the pure time delay. The serial Smith predictor and phase lead compensation approach proposed by the authors recently will lead to an over-compensation and an obvious convergence. In this study, a hybrid Smith predictor and phase lead compensation approach is proposed. The hybrid Smith predictor and phase lead compensation can achieve a higher simulation fidelity with a little convergence. The phase angle of the compensator is analyzed and the stability condition of the HIL simulation system is given. The effectiveness of the proposed compensation approach is tested by simulations on an undamped elastic contact process.

Development of Hardware-in-the-Loop Simulation Based on Gazebo and Pixhawk for Unmanned Aerial Vehicles

Hardware-in-the-loop simulation (HILS) is well known as an effective approach in the design of unmanned aerial vehicles (UAV) systems, enabling engineers to test the control algorithm on a hardware board with a UAV model on the software. Performance of HILS is determined by performances of the control algorithm, the developed model, and the signal transfer between the hardware and software. The result of HILS is degraded if any signal could not be transferred to the correct destination. Therefore, this paper aims to develop a middleware software to secure communications in HILS system for testing the operation of a quad-rotor UAV. In our HILS, the Gazebo software is used to generate a nonlinear six-degrees-of-freedom (6DOF) model, sensor model, and 3D visualization for the quad-rotor UAV. Meanwhile, the flight control algorithm is designed and implemented on the Pixhawk hardware. New middleware software, referred to as the control application software (CAS), is proposed to ensure the connection and data transfer between Gazebo and Pixhawk using the multithread structure in Qt Creator. The CAS provides a graphical user interface (GUI), allowing the user to monitor the status of packet transfer, and perform the flight control commands and the real-time tuning parameters for the quad-rotor UAV. Numerical implementations have been performed to prove the effectiveness of the middleware software CAS suggested in this paper.

A rotor-aerodynamics-based wind estimation method using a quadrotor

Attempts to estimate horizontal wind by the quadrotor are reviewed. Wind estimations are realized by utilizing the quadrotor’s thrust change, which is caused by the wind’s effect on the rotors. The basis of the wind estimation method is the aerodynamic formula for the rotor’s thrust, which is verified and calibrated by experiments. A hardware-in-the-loop simulation (HILS) system was built as a testbed; its dynamic model and control structure are demonstrated. Verification experiments on the HILS system proved that the wind estimation method was effective.

A Force and Displacement Compensation Method Toward Divergence and Accuracy of Hardware-in-the-Loop Simulation System for Manipulator Docking

The hardware-in-the-loop (HIL) simulation system for manipulator docking is an important means to simulate the flexible manipulator on-orbit docking dynamics process. However, the delay of the HIL simulation system leads to the accuracy loss and divergence problems of the system; in this paper, a force and displacement compensation method was proposed toward these problems of the manipulator docking HIL simulation system for single-mass, multi-stiffness, and multi-damping contact. First, time delays including the contact force delay and the force measurement delay were considered. The real-time on-line identification method was applied in the time-varying HIL simulation system, and the contact force delay was compensated by the identification parameters and the discrete force compensation model. The force measurement delay was compensated by a phase lead based force compensation model. The dynamic response model of the motion simulator was not required in the force compensation. In addition, the displacement phase lead compensation model was used to reduce the displacement phase delay of the motion simulator, which improved the reproduction accuracy of the HIL simulation system. Based on the simulation and experimental results, it is shown that the proposed method can effectively and satisfactorily prevent the divergence and improve the accuracy of the reproduction.