Automotive Test Research Articles

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE WINDSHIELD DEICING ANALYSIS OF A COMMERCIAL VEHICLE

In this study, the windshield deicing analysis of a light commercial vehicle was numerically and experimentally investigated in a transient manner. In the numerical study, the more realistic three-dimensional (3D) Computational Fluid Dynamics (CFD) models with three different inlet vent configurations include steady and unsteady calculations were developed by using an enthalpy-porosity technique that the liquid form of a cell was defined as a liquid fraction. The experimental study was also performed in a standard test room and the comparative results were presented and discussed. The temperature values were suddenly increased especially close to the inlet vents. The deicing process was started nearly at ten minutes for both numerical and experimental studies and the liquid fraction values increased rapidly after fifteen minutes which the temperature value of the air inlet vents were about 30°C. The highest temperature values on the windshield were 33°C and 80% of the A-zone defrosted in 20 minutes and 95% of the B-zone defrosted in 40 minutes from the beginning of the test period which were compatible with the international automotive test standards. The defrosted regions obtained from the numerical 2 and experimental studies were quite similar during all stages of the deicing process. The homogeneous and the largest defrosted zone was achieved for Case-1 which had defroster inlet vents with equal surface area and space between these inlet vents. The presented method and numerical results can be used as a reference study for further similar studies include improving the defrosting performance of light commercial vehicles.

Lifecycle Management of Automotive Safety-Critical Over the Air Updates: A Systems Approach

With the increasing importance of Over The Air (OTA) updates in the automotive field, maintaining safety standards becomes more challenging as frequent incremental changes of embedded software are regularly integrated into a wide range of vehicle variants. This necessitates new processes and methodologies with a holistic view on the backend, where the updates are developed and released, and the frontend (vehicle), to which the updates are deployed. In this paper, we introduce an approach, including a process and a methodology, for continuous contract-based design, validation and deployment of modular updates for variant-rich automotive systems. The approach considers the vehicle as part of its connected environment enclosing a backend and concentrates on safety-critical applications. In addition, we present the UPDateable Automotive Test dEmonstratoR (UPDATER), which is a mock-up for modern Electric/Electronic architectures including a backend and a frontend part. It serves as a prototype for developing, deploying and monitoring automotive OTA updates. In a case study based on UPDATER, we apply the approach to three exemplary updates of a variable Advanced Driver Assistance System (ADAS). We show how the updates development and management may be achieved in an efficient and agile way.

Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear.

Wear and surface microgeometry aspects of fiber-reinforced hybrid composite dry friction clutch facings are revealed in a novel way: after different, real life automotive tests during their lifetime. This study examines and reveals the tribological response of friction material surfaces to real life application conditions with two different facing diameters and in two directions. Along the increasing activation energy scale, wear values increased according to two different trends, sorting tests into two main groups, namely ‘clutch killer’ and ‘moderate’. Wear results also highlighted the influence of mileage and test conditions, with clutch killer tests also creating considerable wear-more than 0.1 mm-at inner diameters: 1% higher wear was generated by 90% higher mileage; another 1% increment could be caused by insufficient cooling time or test bench-specific conditions. Surface roughness values trends varied accordingly with exceptions revealing effects of facing size, friction diameter and directions and test conditions: small (S) facings produced significantly decreased Rmax roughness, while large (L) and medium (M) size facings had increased roughness values; Rmax results showed the highest deviations among roughness values in radial direction; tests run with trailer and among city conditions resulted in more than 2% thickness loss and a 40–50% roughness decrease.

Design of test method for noise emitted by light-duty vehicles in real driving conditions

Current UN Regulation No. 51.03 is the first noise regulation with an extended scope in its Additional Sound Emission Provisions (ASEP). Since the year 2017 these provisions are under revision to simplify ASEP tests and to track better the real driving situation. This thesis has devised a new noise test method for light-duty vehicle in multiple driving mode conditions with a focus to reflect the real driving conditions and road traffic noise issues in China. It covers real and diversified road use parameters like different speed ranges, gears and accelerations. The rationality of the devised test method is verified by behaviors of different vehicle types under China Automotive Test Cycle. The outlined test method has a more distinctive definition of driving conditions compared with the ongoing work of the UN IWG ASEP is, where the focus of the future RD-ASEP is on full randomized testing. Both test methods use the Statistical Sound Expectation Model, a brand-new assessment system for noise emitted by light-duty vehicles in real driving conditions based on the type approval reference situation. Both test strategies will provide benefit and improve technical principles for the traffic noise control.

Keeping Automotive Testing on Track

Nick Wignall, Tracks Manager at UTAC CERAM Millbrook explains the role physical test tracks play in vehicle testing and validation, and how recent developments ensure they remain crucial to the future of automotive engineering.

Time and temperature sensitivity of the hybrid III lumbar spine

Objective Researchers have found a variety of uses for the Hybrid III (HIII) dummy that fall beyond the scope of its original purpose as an automotive crash test dummy. Some of these expanded roles for the HIII introduce situations that were not envisioned in the dummy’s original design parameters, such as a relatively rapid succession of tests or outdoor testing scenarios where temperature is not easily controlled. This study investigates how the axial compressive stiffness of the HIII lumbar spine component is affected by the duration of the time interval between tests. Further, it measures the effect of temperature on the compressive stiffness of the lumbar spine through a range of temperatures relevant to indoor and outdoor testing. Methods High-rate axial compression tests were run on a 50th percentile male HIII lumbar component in a materials testing machine. To characterize the effects of tests recovery intervals, between-test recovery was varied from 2 hours to 1 minute. To quantify temperature effects, environmental temperature conditions of 12.5°, 25°, and 37.5 °C were tested. Results During repeated compressive loading, the force levels decreased consistently across long and short rest intervals. Even after 2 hours of rest between tests, full viscoelastic recovery was not observed. Temperature effects were pronounced, resulting in compressive force differences of 261% over the range of 12.5° to 37.5 °C. Compared to the stiffness of the lumbar at 25 °C, the stiffness at 37.5 °C fell by 40%; at 12.5 °C, the stiffness more than doubled, increasing by 115%. Conclusions A modest decrease in temperature can be sufficient to dramatically change the response and repeatability of the lumbar HIII component in compressive loading. The large magnitude of the temperature effect has severe implications in its ability to overwhelm the contributions of targeted test variables. These findings highlight the importance of controlling, monitoring and reporting temperature conditions during HIII testing, even in indoor laboratory environments.

Manual material handling in an automotive testing department using work movement task analysis

Manual material handling in an automotive testing department using work movement task analysis

Next Generation X-in-the-Loop Validation Methodology for Automated Vehicle Systems

Testing self-driving vehicles is still a new and immature process; the globally harmonised procedure expected much later. The resource-demanding nature of real-world tests makes it indispensable to develop and improve the efficiency of virtual environment based testing methods. Accordingly, a novel X-in-the-Loop framework is proposed to fully exploit the recent advances in info-communication technologies, vehicle automation, and testing and validation requirements. This methodology real-time connects physical and virtual testing with high correlation while completely blurs the sharp boundaries between them. Measurement results confirm the superior performance of the 5G communication link in providing a stable, real-time connection between the real world and its virtual representation. The live demonstration proved the presented concept at the newly constructed Hungarian proving ground for automated driving. The performed investigation also includes comprehensive benchmarking, focusing on the most up-to-date automotive testing frameworks. The analysis considers the methodologies and techniques applied by the most relevant actors in the automotive testing sector worldwide. Accordingly, the newly developed testing framework is evaluated and validated in light of the state-of-the-art methods used by the automotive industry.

Clustering Natural Language Test Case Instructions as Input for Deriving Automotive Testing DSLs.

Clustering Natural Language Test Case Instructions as Input for Deriving Automotive Testing DSLs.

Influence of Test Cycles on Energy Consumption Test of Electric Vehicles

In order to verify the necessity of the application of China Automotive Test Cycle which is constructed through actual driving data in china of more than 55 million kilometers in the energy consumption test of electric vehicles in China, this paper compares the characteristics of New European Test Cycle (NEDC), World-wide harmonized Light duty Test Cycle (WLTC) and China light-duty vehicle test cycle for passenger car(CLTC-P), and analyzes the differences of vehicle energy demand under different test cycles from theoretical and simulation point, simulation results show that the endurance mileage is longest and the energy recovery strategy is more effective under CLTC-P cycle. Finally, four types of vehicles are selected to carry out the endurance mileage test under these three test cycles. The test results are consistent with the simulation results. Therefore, in order to make the test results of electric vehicle energy consumption closer to the actual use of our country, CLTC-P should be selected to replace NEDC and WLTC cycle.

Real-Time Multiplexing of Mixed-Criticality Data Streams for Automotive Multi-Core Test Systems

Historically, automotive test systems were designed for single core architectures on both the Electronic Control Unit (ECU) and the Verification and Validation (V&V). This, however, limited the utilization of shared resources, such as memory management or network interfaces. In this paper we present a redesign of an automotive test system that is based on a multi-core architecture and capable of managing mixed-criticality data that is exchanged between the ECU and V&V system. As part of the redesign, we implemented a Connectivity Manager (CM) that is in charge of multiplexing several data streams from multiple cores across a shared network. Due to the increased complexity of our system, a more flexible communication scheduling approach is required. Our solution to this problem is a novel dynamic prioritization approach that adapts to bandwidth changes on the shared communication network. Through simulations with realistic workloads on the CAN bus, we demonstrate the proper functioning of our algorithm with the result that higher critical data streams are favoured over less critical data streams in case of bus overloads or temporary bottlenecks.

Analysis of the engine test cycles from China VI heavy duty vehicle standard and China automotive test cycle

This paper studied the engine test cycles including world harmonized steady cycle (WHSC), world harmonized transient cycle (WHTC) , china heavy-duty steady cycle (CHSC) and china heavy-duty transient cycle (CHTC) based on a diesel engine which meet the China VI heavy duty vehicle emission standard. The results show that regression analysis of speed, torque and power all meet the requirements of the China VI heavy duty vehicle standard. For this engine, NOx, PM and THC pollutants under CHSC are 134.5%, 29.6% and 94.4% higher than those under WHSC, respectively. PN emissions of CHSC is 65.6% lower than that of WHSC. NOx, PM and PN pollutants under CHTC are 62.9%, 96.4% and 64.3% higher than those under WHTC, respectively. The exhaust temperature of the first 350 seconds at CHTC is lower, which poses a greater challenge to the conversion efficiency of the after-treatment system at low speed and low load.

Ranking the Key Areas for Autonomous Proving Ground Development Using Pareto Analytic Hierarchy Process

Autonomous or highly automated road vehicles and all related technologies are under intensive research and development. Moreover, internationally a massive investment increase can be observed in the automotive industry. According to this megatrend, new automotive test tracks appear or older ones transform to be capable of testing and proving for autonomous vehicles. Therefore, the question emerges: what are the key areas for automated drive development, which must be financed in case of autonomous proving ground design? It is a real challenge to be able to make the right decisions due to a lack of numerous experiences in this field. In this research, experts of automated driving technology have been surveyed and their opinion and knowledge have been synthesized. As a strong purpose of gaining robust results, the conventional AHP has been amended by the Pareto approach to ensure that the derived weights correspond to the expert scoring intention so perfectly that it cannot be more improved. Since the non-Pareto optimal weight results might cause rank reversal in the final prioritization, the applied Pareto test guarantees that the final outcome reflects the expert evaluators’ incentive. The conducted analysis has indicated that the obtained results are robust not only from the sensitivity point of view but also from the Pareto optimality approach. The proposed hierarchical decision model is therefore applicable to assist decision making for autonomous proving ground developments. The main contribution of the article, however, is to present the first reliable prioritization of the autonomous proving ground elements to extend the body of professional knowledge.

Energy consumption analysis of a parallel PHEV with different configurations based on a typical driving cycle

Representative driving cycles and specific vehicle types play an important role in analyzing energy consumption to provide valuable references for manufacturers and government inspections. In this study, a parallel plug-in hybrid electric vehicle with different driven configurations is employed to analyze energy consumption under a typical driving cycle. Specifically, a typical driving cycle of Tianjin is constructed by integrating the clustering and Markov chain algorithms. Considering the various layouts of energy systems in plug-in hybrid electric vehicles, three different driven configurations (P2, P3, P4) of the parallel plug-in hybrid electric vehicle are established. Finally, the energy consumptions of the different configurations are analyzed under the proposed typical driving cycle and the compared China Automotive Test Cycle. Results of two driving cycles demonstrate that the fuel consumption of the P3 configuration is lower than that of the P2 and P4 configurations, respectively, while the purely electric driving range of the P3 configuration is longer than the other two configurations, respectively. These results provide a basis for the formulation of China’s new light vehicle emission standards and reduce exhaust emission by making the vehicles more economically suitable for the road conditions in Tianjin.

Experimental Data for the Validation of Numerical Methods: DrivAer Model

As the automotive industry strives to increase the amount of digital engineering in the product development process, cut costs and improve time to market, the need for high quality validation data has become a pressing requirement. While there is a substantial body of experimental work published in the literature, it is rarely accompanied by access to the data and a sufficient description of the test conditions for a high quality validation study. This paper addresses this by reporting on a comprehensive series of measurements for a 25% scale model of the DrivAer automotive test case. The paper reports on the measurement of the forces and moments, pressures and off body PIV measurements for three rear end body configurations, and summarises and compares the results. A detailed description of the test conditions and wind tunnel set up are included along with access to the full data set.

Challenges concerning test case specifications in automotive software testing: assessment of frequency and criticality

Automotive test case specifications document test cases to be performed for a specific test object at a defined test level. They are a fundamental part of a structured automotive testing process, as required by the ISO 26262. The aim of our research is to identify challenges from a practitioner’s point of view that lead to poor quality of test case specifications and thus negatively impact time, cost, and probability of defect detection. We designed an exploratory case study to systematically identify challenges focusing on (C) creation, (P) processing, and (Q) quality assurance related aspects of test case specifications. We conducted 17 semi-structured interviews covering a German OEM as well as three of its automotive suppliers and analyzed them qualitatively. We investigated causes and consequences arising from the challenges. Additionally, we conducted a descriptive survey to assess frequency and criticality. The identified challenges were summarized in a taxonomy consisting of nine main categories: (1) availability and (2) content-related problems with input artifacts, problems related to (3) a lack of knowledge, (4) the test case description, (5) the test case specification content, (6) processes, (7) communication, (8) quality assurance, and (9) tools. The challenges were assessed by 26 internal and 10 external employees. Hence, we identified differences between these groups in terms of access to documents, incomplete requirements, scope of model series, process, and tool-related aspects. Overall, the study results underline the necessity of quality assurance measures for test case specifications. Based on the assessments, our research indicates a broad range of test case description related challenges that are promising candidates for improving test case specification quality.

Towards Cloud-supported Automotive Software Development and Test

The development of automotive software has been an evolving process for the last decades. As a result, the paradigm of software development which is independent of the target hardware platform has been adopted in almost all parts of the automotive industry. Deploying software to a hardware platform is now controlled by an enormous parameter set stored in a mapping configuration. This led to the creation of numerous vendor-specific tools for electronic control unit (ECU) development. While this approach simplifies and supports the re-usability of vehicle functions it also increases the complexity as well as the difficulty for integration tests and error localization. In this paper, we present a conceptual platform which allows to establish references between different development and test phase items in a developer-friendly way. It revolves around two self-developed tools supported by an extensive AUTOSAR knowledge base. The system creates inter-connectivity so that it becomes easier to locate the actual origin of a misbehavior or to find a test error manifestation in the actual end system for developers and testers alike.

Mixed-reality Automotive Testing with SENSORIS

Highly automated and autonomous vehicles become more and more widespread changing the classical way of testing and validation. Traditionally, the automotive industry has pursued testing rather in real-world or in pure virtual simulation environments. As a new possibility, mixed-reality testing has also appeared enabling an efficient combination of real and simulated elements of testing. Furthermore, vehicles from different OEMs will have a common interface to communicate with a test system. The paper presents a mixed-reality test framework for visualizing perception sensor feeds real-time in the Unity 3D game engine. Thereby, the digital twin of the tested vehicle and its environment are realized in the simulation. The communication between the sensors of the tested vehicle and the central computer running the test is realized via the standard SENSORIS interface. The paper outlines the hardware and software requirements towards such a system in detail. To show the viability of the system a vehicle in the loop test has been carried out.

Model predictive air path control for a two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation

Innovative air path concepts for turbocharged spark-ignition engines with exhaust gas recirculation impose high demands on the control due to nonlinearities and cross-couplings. This contribution investigates the control of the air and exhaust gas recirculation paths of a two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation. Using exhaust gas recirculation at high loads, the in-cylinder temperature can be lowered, reducing the knock tendency, while at the same time preventing the need for the enrichment of the air/fuel ratio. Air and exhaust gas recirculation paths are cross-coupled and show different delay times. To tackle these challenges, a data-based two-stage model predictive controller is proposed: The target selector accounts for the overactuated system structure, while the dynamic controller adjusts the charging pressure and exhaust gas recirculation rate. The prediction model setup is based on a small amount of dyno-run measurement data. To ensure real-time capability, the model is kept as simple as possible. This allows for fast turnaround times of the algorithm, while maintaining the necessary accuracy in steady-state and transient operation. This study focuses on a two-stage control concept based on a target selector for optimal stationary control inputs and the dynamic controller considering the dynamic behavior of the air and exhaust gas recirculation paths. Subsequently, the control concept for the two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation is validated via experimental tests under real-driving conditions on an automotive test track, using a prototype test vehicle. Results show that boost pressure as well as exhaust gas recirculation rate setpoints are met without overshoot and control deviation with settling times being close to the boundaries set by the hardware.

Analysis of vehicle CO and NOx road emissions test based on PEMS

ABSTRACT To provide a corresponding preparation and foundation for the implementation and testing of China 6, as well as provide a strong reference for the formulation of China automotive test cycle (CATC) in the future, portable emission measurement system (PEMS) was applied to carry out CO and NOx emissions test on conventional roads for a light-duty gasoline vehicle (Toyota Levin) and a heavy-duty diesel vehicle (KING LONG bus) in Nanjing. The results showed that the CO emission rate of the Toyota car was mainly determined by the speed. As the vehicle speed increased, the CO emission rate increased rapidly while it was below 0.035 g/s. The CO emission rate of KING LONG bus accelerated with the increase of the vehicle speed at the lower speed and began to decrease when the speed reached 60 km/h. In terms of NOx emission rate, as the vehicle speed increased, the NOx emission rates of both vehicles increased. The CO and NOx emission factors of the two models showed similar patterns, both of which decreased significantly as the vehicle speed increased. Compared with the corresponding emission limits, the CO emission of both vehicles was higher, especially for light vehicle, and it was more than 3 times the limit. The NOx emission of both vehicles met the corresponding emission standards. The CO and NOx emission rates of light vehicles were positively correlated with specific power of vehicle (VSP). When VSP was less than 16, the two pollutants emission rate variation with VSP of heavy vehicle showed the same trend, while it was different when VSP was more than 16.