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Vehicles, Volume 3, Issue 2 (June 2021) – 6 articles

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Open AccessArticle
Study on Friction in Automotive Shock Absorbers Part 1: Friction Simulation Using a Dynamic Friction Model in the Contact Zone of an FEM Model
by and
Vehicles 2021, 3(2), 212-232; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020014 (registering DOI) - 14 May 2021
Abstract
The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common [...] Read more.
The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorber with two friction types: The intended viscous friction dissipates the chassis vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In this article, a simulation approach is introduced to model damper friction based on the most friction-relevant parameters. Since damper friction is highly dependent on geometry, which can vary widely, three-dimensional (3D) structural FEM is used to determine the deformations of the damper parts resulting from mounting and varying operation conditions. In the respective contact zones, a dynamic friction model is applied and parameterized based on the single friction point measurements. Subsequent to the parameterization of the overall friction model with geometry data, operation conditions, material properties and friction model parameters, single friction point simulations are performed, analyzed and validated against single friction point measurements. It is shown that this simulation method allows for friction prediction with high accuracy. Consequently, its application enables a wide range of parameters relevant to damper friction to be investigated with significantly increased development efficiency. Full article
(This article belongs to the Special Issue Dynamics and Control of Automated Vehicles)
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Open AccessArticle
Study on Friction in Automotive Shock Absorbers Part 2: Validation of Friction Simulations via Novel Single Friction Point Test Rigs
Vehicles 2021, 3(2), 197-211; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020013 - 13 May 2021
Viewed by 84
Abstract
The most important change in the transition from partial to high automation is that the vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two [...] Read more.
The most important change in the transition from partial to high automation is that the vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorbers with two friction types. The intended viscous friction dissipates the chassis’ vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In the current article, the simulation approach introduced in part 1 of this study is validated against a single friction point and full damper friction measurements. To achieve that, a friction measurement method with novel test rigs has been developed, which allows for reliable determination of the friction behavior of each single friction point, while appropriately resembling the operating conditions of the real damper. The subsequent presentation of a friction simulation using friction model parameters from different geometry shows the general applicability of the overall friction investigation methodology. Accordingly, the presented simulation and measurement approaches enable the investigation of dynamic friction in automotive shock absorbers with significantly increased development efficiency. Full article
(This article belongs to the Special Issue Dynamics and Control of Automated Vehicles)
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Open AccessArticle
Macroscopic Traffic Simulation of Autonomous Vehicle Effects
Vehicles 2021, 3(2), 187-196; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020012 - 29 Apr 2021
Viewed by 344
Abstract
The increasing worldwide demand on urban road transportation systems requires more restrictive measures and policies to reduce congestion, time delay and pollution. Autonomous vehicle mobility services, both shared and private, are possibly a good step towards a better road transportation future. This article [...] Read more.
The increasing worldwide demand on urban road transportation systems requires more restrictive measures and policies to reduce congestion, time delay and pollution. Autonomous vehicle mobility services, both shared and private, are possibly a good step towards a better road transportation future. This article aims to study the expected impact of private autonomous vehicles on road traffic parameters from a macroscopic level. The proposed methodology focuses on finding the different effects of different combinations of autonomous vehicle penetration and Passenger Car Units (PCU) on the chosen road traffic model. Four parameters are studied: traveled daily kilometers, daily hours, total daily delay and average network speed. The analysis improves the four parameters differently by implementing autonomous vehicles. The parameter total delay has the most significant reduction. Finally, several mathematical models are developed for the percentage of improvement for each chosen parameter. Full article
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Open AccessArticle
Comparative Analysis of Machine Learning-Based Approaches for Anomaly Detection in Vehicular Data
Vehicles 2021, 3(2), 171-186; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020011 - 25 Apr 2021
Viewed by 368
Abstract
The rapid growth of demand for transportation, both for people and goods, as well as the massive accumulation of population in urban centers has augmented the need for the development of smart transport systems. One of the needs that have arisen is to [...] Read more.
The rapid growth of demand for transportation, both for people and goods, as well as the massive accumulation of population in urban centers has augmented the need for the development of smart transport systems. One of the needs that have arisen is to efficiently monitor and evaluate driving behavior, so as to increase safety, provide alarms, and avoid accidents. Capitalizing on the evolution of Information and Communication Technologies (ICT), the development of intelligent vehicles and platforms in this domain is getting more feasible than ever. Nowadays, vehicles, as well as highways, are equipped with sensors that collect a variety of data, such as speed, acceleration, fuel consumption, direction, and more. The methodology presented in this paper combines both advanced machine learning algorithms and open-source based tools to correlate different data flows originating from vehicles. Particularly, the data gathered from different vehicles are processed and analyzed with the utilization of machine learning techniques in order to detect abnormalities in driving behavior. Results from different suitable techniques are presented and compared, using an extensive real-world dataset containing field measurements. The results feature the application of both supervised univariate anomaly detection and unsupervised multivariate anomaly detection methods in the same dataset. Full article
(This article belongs to the Special Issue The New Devices to Assist the Driver (ADAS))
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Open AccessArticle
Analysis of the Deviation Factors between the Actual and Test Fuel Economy
Vehicles 2021, 3(2), 162-170; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020010 - 22 Apr 2021
Viewed by 228
Abstract
The Worldwide harmonized Light duty Test Procedure saw its light first as the United Nations Economic Commission for Europe Global Technical Regulation in 2017. However, it remains unclear how much the deviation is between the actual and test fuel economy. In this study, [...] Read more.
The Worldwide harmonized Light duty Test Procedure saw its light first as the United Nations Economic Commission for Europe Global Technical Regulation in 2017. However, it remains unclear how much the deviation is between the actual and test fuel economy. In this study, we analyzed the deviation between the actual and test (JC08 and WLTC) fuel economy and examined how well regional characteristics such as average travel speed and temperature could explain the deviation using 182–1035 drivers and 19–52 car models data in Japan. As a result, (1) more than a 30% discrepancy was observed between the actual and JC08 mode test fuel economy, and the higher the test fuel economy, the larger the deviation; (2) regarding WLTC mode fuel economy, the deviation is 19% and constant regardless of the test fuel economy; (3) average travel speed and temperature can explain approximately 8% of the discrepancy. Full article
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Open AccessArticle
Integrated Braking Control for Electric Vehicles with In-Wheel Propulsion and Fully Decoupled Brake-by-Wire System
Vehicles 2021, 3(2), 145-161; https://0-doi-org.brum.beds.ac.uk/10.3390/vehicles3020009 - 25 Mar 2021
Viewed by 753
Abstract
This paper introduces a case study on the potential of new mechatronic chassis systems for battery electric vehicles, in this case a brake-by-wire (BBW) system and in-wheel propulsion on the rear axle combined with an integrated chassis control providing common safety features like [...] Read more.
This paper introduces a case study on the potential of new mechatronic chassis systems for battery electric vehicles, in this case a brake-by-wire (BBW) system and in-wheel propulsion on the rear axle combined with an integrated chassis control providing common safety features like anti-lock braking system (ABS), and enhanced functionalities, like torque blending. The presented controller was intended to also show the potential of continuous control strategies with regard to active safety, vehicle stability and driving comfort. Therefore, an integral sliding mode (ISM) and proportional integral (PI) control were used for wheel slip control (WSC) and benchmarked against each other and against classical used rule-based approach. The controller was realized in MatLab/Simulink and tested under real-time conditions in IPG CarMaker simulation environment for experimentally validated models of the target vehicle and its systems. The controller also contains robust observers for estimation of non-measurable vehicle states and parameters e.g., vehicle mass or road grade, which can have a significant influence on control performance and vehicle safety. Full article
(This article belongs to the Special Issue Dynamics and Control of Automated Vehicles)
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