Hardware-in-the-loop Environment Research Articles

Single-Phase Shift Modulation of DAB Converter in Typhoon HIL Simulation

Solid-state transformer (SST) could be a solution for a future distribution system, in which many renewable energy sources (RES) are integrated. The SST consists of a single-phase dual-active bridge (DAB) converter, which is scale-down the dc voltage level. The control objective of the DAB converter used in the SST is to control its output voltage. This control strategy consists of a proportional-integral (PI) controller and a single-phase shift (SPS) modulation. Numerous literatures have mentioned about the SPS modulation for the DAB converter. However, they do not provide procedures in implementing the SPS modulation in the real controller. This paper aims to develop the SPS modulation in the real controller of the STM32F446RE microcontroller. The proposed SPS modulation is based on a master-slave timer feature, which is available in the STM32 microcontroller. The development process and testing of the complete control strategy of the DAB converter were carried out in the hardware-in-the-loop (HIL) simulation using Typhoon HIL. This scheme speeds up the development of process and reduces the costs. The experiment in the HIL environment shows that proposed control strategy of the DAB converter consisting of the PI controller and the SPS modulation is successfully implemented in the real microcontroller of the STM32F446RE. The proposed control strategy of the DAB converter is capable of bidirectional power flow, which is useful for integrating distributed generators in the load side. Moreover, this control strategy can reject the disturbance caused by loads.

Multi-Dimensional Bisection Method in HIL Environment: Stability and Chatter Prediction in Turning

In turning operations, the harmful small-amplitude but high-frequency chatter vibrations are identified in hardware-in-the-loop (HIL) experimental environment by means of the application of a multi-dimensional bisection method. The dummy workpiece clamped to the real main spindle is excited by contactless electromagnetic actuators and the response of the workpiece is detected by laser-based sensors. According to the present and the stored previous positions of the rotating workpiece, the desired cutting force characteristic along with the surface regeneration effect can be emulated by means of a high-performance real target computer. While the conventional experimental results in the HIL environment identify the stability limits of the cutting operation accurately only in a high-resolution grid of the technological parameters, the embedded bisection method reduces significantly both the size of the required grid and the time duration of the measurement by path following the boundaries of the linear loss of stability. Based on this technique, the experimental stability boundary of the emulated turning process is presented in a wide range of spindle speeds.

Laboratory Implementation of a Wide-area Damping Controller using a Dynamic Hardware Emulator

The ongoing decarbonisation of the electric power system brings new challenges in terms of system dynamics and stability, as the substitution of generation units with rotating masses towards generation units based on power electronics entails a substantial loss of inertia. To meet the new challenges and maintain the reliability of the electrical grid, innovative solutions are required. Therefore, this paper presents a two-step approach to test and validate controller structures for damping inter-area oscillations. First, the controller was developed and tested in a control hardware in the loop environment. Then, the controller was transferred to a dynamic hardware emulator (scaled version of the Kundur's two area transmission network in the laboratory consisting of physical hardware) for final performance validation. It is shown that with a conventional power system stabilizer (PSS) and a proportional wide-area damping controller (WADC), the damping of inter-area oscillations is improved in an emulated power system. In addition, with the setup created, different types of controllers and other challenges related to wide-area damping control can be investigated in the future.

Visual servoing for coordinated precise attitude control in the TOM small satellite formation

Formations of multiple satellites observe target areas on the Earth’s surface from different perspectives, enabling construction of 3D surface maps by photogrammetric methods. The main objective of TOM (Telematics Earth Observation Mission) is to monitor ash clouds during Volcanic Eruptions with a satellite formation consisting of three CubeSats. TOM is Bavaria’s contribution to the multi-national Telematics International Mission (TIM), composed of 7 satellites by partners from 4 continents. To achieve sufficient overlap of the images for the usage of photogrammetric methods, very precise and coordinated attitude control of the satellites is necessary. This paper presents a vision-based attitude control approach using image data to calculate the control input, also referred to as visual servoing. Thus, the cameras and data processing capacity onboard the CubeSats will be used for both image acquisition and attitude determination, eliminating the need for additional precise attitude sensors like star trackers. To perform visual servoing, highly distinctive features are identified and tracked in the images. The control input for reaction wheels is calculated from the movement of the features between consecutive images. To ensure that the images captured by the different satellites overlap sufficiently for photogrammetric processing, the satellites track the same target area based on feature data exchange directly between the satellites. Simulations of realistic scenarios based on the TOM project show the applicability of the presented attitude control approach. In a first step, a software-based Earth observation simulator generates the acquired images, demonstrating feasibility to compute and track features in satellite images to compute the AOCS (Attitude and Orbit Control System) input. In the second step, hardware-in-the-loop (HiL) simulations allow to realistically characterize the performance of this approach. This HiL environment utilizes two high-precision/high-dynamics turntables as 3-axis attitude simulators, where the satellites with their cameras are mounted, while the observation target is mounted on a mobile robot to simulate the relative orbit motion.

Photovoltaic Energy Conversion System Integrated Into Unbalanced Distribution Electrical Networks Through Hardware in the Loop

In this article, a real-time, hardware in the loop (HIL) and experimental photovoltaic energy conversion system (PVECS) integrated into unbalanced distribution electrical networks is presented. Commonly, the three-phase voltages are not balanced, because the input–output of single-phase loads in low and medium voltage networks. In this context, the photovoltaic (PV) systems integration under the dq0-Frame control operation scheme, tend to generate current deformations. In contrast, a new control technique for PVECS interconnection is validated in a HIL scheme, even in the presence of unbalanced voltage. This new technique is considered simple and easy to implement, since it consists of a single PI control loop, guaranteeing reliable operation under unbalances voltage events. Thus, preserving favorable characteristics, such as: 1) always balanced currents; 2) low harmonic distortion; 3) unit power factor; and 4) Compliance with the rules of the network code. The PVECS effectiveness is assessed by complete mathematical model, the simulation results are evaluated using MATLAB-Simulink (MATLAB r2018, Mathworks, Natick, MA, USA), and the experimental results are validated with a small-scale prototype operating in a HIL environment and the real-time simulator Opal-RT Technologies (Montreal, QC, Canada); integrating a power capacity of 15 kW in distribution networks.

Model-Based Design Approach for Validation of Vehicle Longitudinal Control Algorithm

In this paper, model-based testing strategies are described for the validation of an Adaptive Cruise Control (ACC) algorithm developed for a 2019 Chevrolet Blazer as part of the EcoCAR Mobility Challenge. A team of undergraduate and graduate students developed testing procedures to assess model fidelity, and to identify and resolve issues with the algorithm before deployment to a student-modified production vehicle. The algorithm validation is conducted via three progressive levels of validation environments: Model-In-the Loop (MIL), Hardware-In-the-Loop (HIL), and Driver-In-the-Loop (DIL). When the ACC algorithm is evaluated using system requirements in the testing sequence, the MIL environment performs the tests at least 87% faster than the HIL environment. The MIL environment can also utilize parallel computing, which leverages multi-core CPUs to conduct multiple simulations simultaneously. Although comparisons between MIL and HIL results revealed good agreements, slight differences in system dynamics highlights a need for future Vehicle-In-the-Loop (VIL) testing. By showing how the concepts can be applied to the validation of an autonomous feature in a vehicle with detailed test scenarios and evaluation metrics, the paper will serve as a good reference for the students and engineers interested in this field.

Hardware-In-the-Loop Simulation of Time-Delayed Anti-Swing Controller for Quadrotor with Suspended Load

Quadrotor flying vehicles with suspended loads have a lot of applications, such as mine detection and transferring loads for delivery, or through places where ground vehicles cannot reach. In these applications, the payload will be suspended underneath the vehicle and it is subjected to large oscillations due to external disturbances or the acceleration of the vehicle itself. These oscillations add additional forces and moments to the quadrotor, and this deteriorates its performance and stability. In this paper, we developed a hardware-in-the-loop (HIL) simulation platform for a quadrotor with a suspended load system using Gazebo. The developed platform can be used to understand the dynamics of the system and design control systems to suppress the oscillation of the suspended load. An anti-swing controller that is based on time-delayed feedback of the load swing angles is implemented in the designed HIL environment to show the usefulness of the newly developed system and the effectiveness of the anti-swing controller.

Attenuation of DC-Link Pulsation of a Four-Wire Inverter during Phase Unbalanced Current Operation

This paper proposes a control algorithm for a hybrid power electronic AC/DC converter for prosumer applications operating under deep phase current asymmetry. The proposed system allows independent control of active and reactive power for each phase of the power converter without current pulsation on the DC link connected to an energy store. The system and its algorithm are based on a three-phase converter in four-wire topology (AC/DC 3p-4w) with two dual-active bridge (DC/DC) converters, interfaced with a supercapacitor and an energy storage. The control algorithm tests were carried out in a Hardware in the Loop environment. Obtained results indicate that operation with deep unbalances and powers of opposite signs in individual phases leads to current oscillations in the DC link. This phenomenon significantly limits energy storage utilization due to safety and durability reasons. The proposed algorithm significantly reduces the level of pulsation in the DC link which increases safety and reduces strain on lithium-ion storage technology, enabling their application in four-wire converter applications.

A robust lateral tracking control strategy for autonomous driving vehicles

A robust steering torque control strategy for lateral tracking functionality of autonomous driving vehicles that perform active steering, active accelerating and active braking is researched in this paper. The main target of this research is to track references of lateral position and heading angle, which are provided by upstream motion planning module, via torque that robotic arm applies to steering hand wheel. Firstly, a system with tracking errors is generated and analyzed. To keep control system’s robustness against time varying parameters, such as speed, center of mass, etc., gain-scheduling approach is utilized to obtain proper feedback gain. To achieve performance robustness, methods of linear matrix inequalities are used in design to maintain a performance function. Control performance is validated in Hardware in the loop environment built by ETAS labcar and Matlab/Simulink for a lane changing scenario and two typical parking scenarios. Results show that the proposed control strategy can regulate vehicle to follow target trajectory precisely even when speed varies. In lane changing scenario, steady state error is close to zero and maximum lateral position error is about ±30 cm. In parking scenarios, tracking error of lateral position is about ±3 cm, and of heading angle is about ±0.1 rad at end points. In addition, in comparison with linear quadratic regulator (LQR) and model predictive control (MPC), the proposed control outperformances in the three test scenarios.

Multi‐frequency averaging (MFA) model of a generic electric vehicle powertrain suitable under variable frequency of averaging developed for remote operability

Geographically distributed hardware-in-the-loop (HIL) testing has the potential to allow hybrid vehicle powertrain components (battery, motor drive, and engine) to be developed at geographically remote locations but tested concurrently and coupled. Inter-location internet communication links can allow non-ideal behaviour observed in a physical component in one location (e.g. an electrical drive) to be imposed on another physical component elsewhere (e.g. an ICE), and vice-versa. A key challenge is how to represent the behaviour of a remote, physical component under testing in a local HIL environment. Internet communications are too slow and unreliable to transmit waveforms in real-time and so one solution is to use a local ‘slave’ model whose behaviour and parameters are tuned based on observations at the remote location. This study proposes a multi-frequency averaging (MFA) slave model of an electric motor drive system for use in this application; it addresses a weakness in previously published work by extending the MFA model to variable frequency operation. The model was benchmarked against experimental operation (and its equivalent simulation model) in open-loop and closed-loop space vector pulse-width modulation control strategy, fixed and variable frequency operation. Results show significant reconciliation of model and experiment.

The airplane trim system – new functionalities

PurposeA standard automatic flight control system – autopilot – will become required equipment of the future aircraft, operating in the common sky. For a specific group of aircraft, they are too expensive and too energy-consuming solutions. This paper aims to present the concept of an automatic flight control system that overcomes those limitations.Design/methodology/approachThe proposed automatic flight control system uses the trim tabs in all prime flight controlling surfaces: elevator, ailerons and rudder, for stabilizing and controlling the steady flights of an aircraft.FindingsThe results of an aeroplane flight controlled with the use of trim tabs simulation tests and remarks have been presented and discussed. The simulation was conducted in real-time hardware in the loop environment. The stabilization of the flight was achieved in performed test scenarios.Originality/valueThe possibility to control an aircraft with coordinated deflections of the trimming surfaces is a beneficial alternate to those currently used and can be recommended for use in the next-generation aircraft.

Hardware-In-The-Loop and Software-In-The-Loop Testing of the MOVE-II CubeSat

This article reports the ongoing work on an environment for hardware-in-the-loop (HIL) and software-in-the-loop (SIL) tests of CubeSats and the benefits gained from using such an environment for low-cost satellite development. The satellite tested for these reported efforts was the MOVE-II CubeSat, developed at the Technical University of Munich since April 2015. The HIL environment has supported the development and verification of MOVE-II’s flight software and continues to aid the MOVE-II mission after its launch on 3 December 2018. The HIL environment allows the satellite to interact with a simulated space environment in real-time during on-ground tests. Simulated models are used to replace the satellite’s sensors and actuators, providing the interaction between the satellite and the HIL simulation. This approach allows for high hardware coverage and requires relatively low development effort and equipment cost compared to other simulation approaches. One key distinction from other simulation environments is the inclusion of the electrical domain of the satellite, which enables accurate power budget verification. The presented results include the verification of MOVE-II’s attitude determination and control algorithms, the verification of the power budget, and the training of the operator team with realistic simulated failures prior to launch. This report additionally presents how the simulation environment was used to analyze issues detected after launch and to verify the performance of new software developed to address the in-flight anomalies prior to software deployment.

CNN-Based Fault Localization Method Using Memory-Updated Patterns for Integration Test in an HiL Environment

Automotive electronic components are tested via hardware-in-the-loop (HiL) testing at the unit and integration test stages, according to ISO 26262. It is difficult to obtain debugging information from the HiL test because the simulator runs a black-box test automatically, depending on the scenario in the test script. At this time, debugging information can be obtained in HiL tests, using memory-updated information, without the source code or the debugging tool. However, this method does not know when the fault occurred, and it is difficult to select the starting point of debugging if the execution flow of the software is not known. In this paper, we propose a fault-localization method using a pattern in which each memory address is updated in the HiL test. Via a sequential pattern-mining algorithm in the memory-updated information of the transferred unit tests, memory-updated patterns are extracted, and the system learns using a convolutional neural network. Applying the learned pattern in the memory-updated information of the integration test can determine the fault point from the normal pattern. The point of departure from the normal pattern is highlighted as a fault-occurrence time, and updated addresses are presented as fault candidates. We applied the proposed method to an HiL test of an OSEK/VDX-based electronic control unit. Through fault-injection testing, we could find the cause of faults by checking the average memory address of 3.28%, and we could present the point of fault occurrence with an average accuracy of 80%.

On stability of emulated turning processes in HIL environment

Hardware-in-the-loop (HIL) experimental setup is presented to investigate the stability of turning processes. A dummy workpiece is fixed to a main spindle, which is excited in the radial direction by electromagnetic contactless actuators. The actuators emulate contact force characteristics including surface regeneration effect between the cutting tool and the workpiece with 100 kHz sampling frequency. The cutting force is calculated by a high performance real time target that uses the measured present and previous values of the relative displacements of the dummy workpiece. The loss of linear stability is monitored for various real spindle speeds and virtual chip widths. Measured lobe diagrams are compared with the results of theoretical stability analysis.

Fault Localization by Comparing Memory Updates between Unit and Integration Testing of Automotive Software in an Hardware-in-the-Loop Environment

During the inspection stage, an integration test is performed on electronic automobile parts that have passed a unit test. The faults found during this test are reported to the developer, who subsequently modifies the source code. If the tester provides the developer with memory usage information (such as functional symbol or interface signal), which works differently from normal operation in failed Hardware-in-the-Loop (HiL) testing (even when the tester has no source code), that information will be useful for debugging. In this paper, we propose a fault localization method for automotive software in an HiL environment by comparing the analysis results of updated memory between units and integration tests. Analyzing the memory usage of a normally operates unit test, makes it possible to obtain memory-updated information necessary for the operation of that particular function. By comparing this information to the memory usage when a fault occurs during an integration test, erroneously operated symbols and stored values are presented as potential root causes of the fault. We applied the proposed method to HiL testing for an OSEK/VDX-based electronic control unit (ECU). As a result of testing using fault injection, we confirmed that the fault causes can be found by checking the localized memory symbols with an average of 5.77%. In addition, when applying this methodology to a failure that occurred during a body control module (BCM) (which provides seat belt warnings) test, we could identify a suspicious symbol and find the cause of the test failure with only 8.54% of localized memory symbols.

A testing framework for predictive driving features with an electronic Horizon

This paper proposes a novel approach for automated functional testing of map-based fusion algorithms in complex vehicle networks. The hybrid data representation of detailed digital maps and physical automotive sensors provides an extended view of the ego-vehicle environment and thereby facilitates improved inferences and more competent decision-making. It has therefore been instrumental in the ongoing development of predictive driving features, e.g. fuel-efficient driving, traffic sign recognition and highway-pilot. The presented approach utilises a closed-loop Hardware-in-the-Loop (HiL) co-simulation framework to evaluate the performance of the decision level fusion algorithms. The method contains both the structural design and resource-efficient integration into the HiL test bench in the example of traffic sign recognition. In reality, discrepancy between visual and map data is omnipresent due to map errors, old map data or optical detection failure. Through fault injection, defined inconsistencies can be produced within the HiL simulation environment. Amongst others, the fault injection covers the placement and value of traffic signs. These failures can be used for robustness testing of the fusion algorithms. Subsequently, a method for correlation analysis between field observations and synthetic simulation is realised to extend the requirements-based test coverage adaptively and systematically by modular and parameterised scenario specifications. In summary, the results show that the extended HiL environment is capable of generating electronic Horizon data which can easily be adapted or extended.

Simulation model of a gear synchronisation unit for application in a real-time HiL environment

ABSTRACTGear shifting simulations using the multibody system approach and the finite-element method are standard in the development of transmissions. However, the corresponding models are typically large due to the complex geometries and numerous contacts, which causes long calculation times. The present work sets itself apart from these detailed shifting simulations by proposing a much simpler but powerful synchronisation model which can be computed in real-time while it is still more realistic than a pure rigid multibody model. Therefore, the model is even used as part of a Hardware-in-the-Loop (HiL) test rig. The proposed real-time capable synchronization model combines the rigid multibody system approach with a multiscale simulation approach. The multibody system approach is suitable for the description of the large motions. The multiscale simulation approach is using also the finite-element method suitable for the analysis of the contact processes. An efficient contact search for the claws of a car transmission synchronisation unit is described in detail which shortens the required calculation time of the model considerably. To further shorten the calculation time, the use of a complex pre-synchronisation model with a nonlinear contour is presented. The model has to provide realistic results with the time-step size of the HiL test rig. To reach this specification, a particularly adapted multirate method for the synchronisation model is shown. Measured results of test rigs of the real-time capable synchronisation model are verified on plausibility. The simulation model is then also used in the HiL test rig for a transmission control unit.

Development of High-Reliability EV and HEV IM Propulsion Drive With Ultra-Low Latency HIL Environment

This paper proposes an improved and robust method of minimizing the error in propulsion-drive line-currents that are reconstructed from a single dc-link current measurement. The proposed algorithm extends and then shortens the relevant phase pulse-widths in order to provide optimal sampling of the dc-link currents in two consecutive pulsewidth modulation (PWM) periods. The proposed PWM pattern control enables an improved sampling method which cancels offset jitter-like waveform errors present in all three reconstructed line-currents, which is due to a specific combination of nonsimultaneously sampled dc-link current and line-current PWM ripple. The improvement in induction motor drive accuracy using a single current-sensor and no shaft sensor (as proposed in this paper), over that of conventional methods, is shown. Thanks to an ultra-low latency hardware-in-the loop (HIL) emulator, the proposed algorithm, its implementation on a DSP processor, code optimization and “laboratory” testing were all merged into one development step. In order to perform final tests of the proposed current-reconstruction algorithm and to verify the usefulness of the developed HIL platform by means of comparison, experimental results obtained on a real hardware setup are provided.

Model-based testing of embedded systems in hardware in the loop environment

The evolution of software testing technologies has significantly reduced software testing execution times, but the test design and generation are still often implemented with slow manual-oriented methods. Model-based testing (MBT) offers automation to test design and generation, and different MBT solutions are familiar from research, but more effort needs to be done to adopt MBT for industrial use. Hardware in the loop (HIL) is a simulation and testing technique used in the development and testing of embedded systems. HIL is a challenging application field for MBT due to complex and non-deterministic nature of some embedded systems. To tackle this problem, the authors present a novel prototype platform in which online and offline MBT is applied to HIL environment. MBT in general has been introduced for HIL in scientific literature before, but the application of online MBT in HIL is a novel approach. The whole novel MBT in HIL prototype platform along with the used MBT tool, platform architecture and MBT process are presented accompanied by experimental results and analysis of two case studies with an example embedded system under test.

Real-time multi-rate HIL simulation platform for evaluation of a jet engine fuel controller

A new Hardware-In-the-Loop (HIL) platform is developed for testing of a turbojet engine fuel control system using a multi-rate simulation platform. The HIL equipment consists of an industrial PC and a commercial I/O board for jet engine simulation as the controlled process and an Electronic Control Unit (ECU) as the fuel controller. The controlled process consisting of actuator, physical process and sensors is fully simulated in HIL simulation. However, the high resolution signals of some components in the HIL simulation cause the real-time simulation to become difficult due to the need of small time-steps. As a result, the disparity between the jet engine model sampling rate and these high resolution signals requires a multi-rate simulation. In this study, a multi step size simulation is developed using multiple processors. These processors are designed to synchronize the status of the engine model with the control system as well as to convert the raw data of the I/O boards to actual input and output signals in real-time. These features make the HIL equipment more effective and flexible. The HIL environment is proved to be an efficient tool to develop various control functions and to validate the software and hardware of the engine fuel control system.