Comparative study on the friction behaviour and the particle formation process between a laser cladded brake disc and a conventional grey cast iron disc. - In: Metals, ISSN 2075-4701, Bd. 13 (2023), 2, 300, S. 1-19
Brake-wear particle emissions are the result of the components of a friction brake being in tribological contact, and they are classified as non-exhaust emissions. Since most of the emitted particles belong to the size classes of particulate matter (≤10 μm) and differ significantly in terms of their physico-chemical properties from automotive exhaust emissions, this source is of particular relevance to human health and, therefore, the focus of scientific studies. Previous studies have shown that coated brake discs offer significant wear and emission reduction potential. Nevertheless, no studies are available that describe the specific particle formation process, the contact conditions, the structure of the friction layer and the differences compared to conventional grey cast iron discs. The aim of this study is to describe those differences. For this purpose, the tribological behaviour, the structure of the friction layer and the associated particle dynamics within the friction contact between a laser cladding coated disc and a conventional grey cast iron disc are compared. The required investigations are carried out both ex situ (stationary) and in situ (dynamic). Parallel to the tribological investigations, the particle emission behaviour is determined on an inertia dynamometer using a constant volume sampling system (CVS) and equipment for particle number and particle size distribution measurement. The results show that, for two different brake pads, the laser cladding brake disc has lower wear and less particulate emissions than the grey cast iron brake disc. The wear behaviour of the coating varies significantly for the two brake pads. By contrast, the grey cast iron brake disc shows a significantly lower influence.
Development of torque vectoring controller tuned with neural networks. - In: Advances in dynamics of vehicles on roads and tracks II, (2022), S. 1175-1182
The paper introduces an adaptive Torque Vectoring (TV) controller for all-wheel-drive electric vehicles. The main focus of this study lies in tuning procedures of controller gains in accordance with the manoeuvre conditions. For this purpose, a pre-trained neural network predicts the vehicle behaviour and adjusts the PID gains of the TV controller. The proposed method extends the applicability of the TV system and increases its efficiency as compared to the non-adaptive baseline control methods.
Validation of integrated EV chassis controller using a geographically fistributed X-in-the-loop network. - In: IEEE Xplore digital library, ISSN 2473-2001, (2022), insges. 7 S.
This paper presents the validation of an integrated chassis controller that unites three groups of actuators for the electric vehicle (EV) with independent in-wheel electric motors (IWMs) for each wheel. Controlled actuators are the IWMs, the active suspension, and the braking system. The models of test benches and the designed architecture of the X-in-the-loop network are presented. The proposed design approach allows testing the developed controller on a vehicle model in real-time and on hardware components.
Brake blending design using distributed and shared X-in-the-loop test environment. - In: IEEE Xplore digital library, ISSN 2473-2001, (2022), insges. 6 S.
Brake blending design is a complex task in the development of electric vehicles (EV) and requires coordinated control on electric powertrain and friction brake system. The presented study discusses the architecture, control strategy, and functional validation of the brake blending as applied to an all-wheel drive EV equipped with four in-wheel motors (IWMs) and the decoupled electro-hydraulic brake system. The main focus is on the use of distributed and shared X-in-the-loop (XIL) test environment as a relevant development methodology enabling a wide spectrum of validation procedures. The paper introduces XIL-based experiments, where the brake blending operation has been evaluated for several test scenarios as the service braking and the Worldwide harmonized Light Duty Test Cycle (WLTC).
Towards brand-independent architectures, components and systems for next generation electrified vehicles optimised for the infrastructure. - In: SAE international journal of advances and current practices in mobility, ISSN 2641-9645, Bd. 4 (2022), 5, S. 1906-1922
E-mobility is a game changer for the automotive domain. It promises significant reduction in terms of complexity and in terms of local emissions. With falling prices and recent technological advances, the second generation of electric vehicles (EVs) that is now in production makes electromobility an affordable and viable option for more and more transport mission (people, freight). Still, major challenges for large scale deployment remain. They include higher maturity with respect to performance (e.g., range, interaction with the grid), development efficiency (e.g., time-to-market), or production costs. Additionally, an important market transformation currently occurs with the co-development of automated driving functions, connectivity, mobility-as-a-service. New opportunities arise to customize road transportation systems toward application-driven, user-centric smart mobility solutions. The target of this paper is to provide a consolidated view of several related European research programs having the common goal to develop innovative, brand-independent architectures, components and systems for next generation electrified vehicles optimised for the infrastructure under the umbrella of the E-VOLVE cluster. This regroups the projects ACHILES, SYS2WHEEL, EVC1000 introducing innovative in-wheel motors for different vehicle segments, CEVOLVER introducing optimized concepts for energy and thermal management, and Multi-Moby focusing on the development of safe, efficient and affordable urban electric vehicles.
Electric vehicle corner architecture: driving comfort evaluation using objective metrics. - In: SAE technical papers, ISSN 2688-3627, (2022), 2022-01-0921, S. 1-7
The presented paper is dedicated to the driving comfort evaluation in the case of the electric vehicle architecture with four independent wheel corners equipped with in-wheel motors (IWMs). The analysis of recent design trends for electrified road vehicles indicates that a higher degree of integration between powertrain and chassis and the shift towards a corner-based architecture promises improved energy efficiency and safety performances. However, an in-wheel-mounted electric motor noticeable increases unsprung vehicle mass, leading to some undesirable impact on chassis loads and driving comfort. As a countermeasure, a possible solution lies in integrated active corner systems, which are not limited by traditional active suspension, steer-by-wire and brake-by-wire actuators. However, it can also include actuators influencing the wheel positioning through the active camber and toe angle control. Such a corner configuration is discussed in the paper as applied to a sport utility vehicle (SUV). A new chassis design was developed and tested for this reference vehicle using multi-body dynamics simulation. The integrated operation of the active suspension and the wheel positioning control has been analyzed in this study with different driving scenarios and objective metrics for driving comfort evaluation. Additionally, handling and stability tests have also been performed to confirm that new systems do not deteriorate driving safety. The obtained results contribute to a comprehensive assessment of IWM-based architecture, formulated from a driving comfort perspective that is helpful for further designs of electric vehicle corners.
Active control of Camber and Toe angles to improve vehicle ride comfort. - In: SAE technical papers, ISSN 2688-3627, (2022), 2022-01-0920, S. 1-14
This paper is part of the European OWHEEL project. It proposes a method to improve the comfort of a vehicle by adaptively controlling the Camber and Toe angles of a rear suspension. The purpose is achieved through two actuators for each wheel, one that allows to change the Camber angle and the other the Toe angle. The control action is dynamically determined based on the error between the reference angle and the actual angles. The reference angles are not fixed over time but dynamically vary during the maneuver. The references vary with the aim of maintaining a Camber angle close to zero and a Toe angle that follows the trajectory of the vehicle during the curve. This improves the contact of the tire with the road. This solution allows the control system to be used flexibly for the different types of maneuvers that the vehicle could perform. An experimentally validated sports vehicle has been used to carry out the simulations. The original rear suspension is a Trailing-arm suspension. It has been modified via Adams Car. The simulations have been carried out using the same software in cosimulation with Simulink. The suspension has been tested through a Parallel Wheel Travel analysis and an Opposite Wheel Travel analysis. The maneuvers carried out have been two variations of Constant Radius Cornering, two variations of Fish-Hook and two variations of Swept-Sine Steer. A decrease in the vertical acceleration of the center of gravity has been achieved by controlling the Camber angle for maneuvers where a trajectory or rotation of the steering is imposed. The Toe angle control has allowed a decrease in vertical acceleration when a trajectory is imposed. In particular, the decrease of the Root Mean Square and the maximum absolute value have been obtained. These results demonstrate an improvement in Ride Comfort.
Hardware-in-the-loop testing of a hybrid brake-by-wire system for electric vehicles. - In: SAE International journal of vehicle dynamics, stability, and NVH, ISSN 2380-2170, Bd. 6 (2022), 4, S. 477-487
Recent trends in automotive engineering, such as electrification and automatization, are opening chances as well as challenges due to the increased demand on new chassis components (e.g., drivetrain, brakes, steering, suspension, etc.) and control methods. This fast-growing market requires new methods to frontload as much efforts as possible to early design stages. The present article deals with a relevant case study on anti-lock braking system (ABS) design and tuning via hardware-in-the-loop (HIL) tests and rapid control prototyping (RCP) techniques on a hybrid brake-by-wire (BBW) system. Three types of wheel slip control algorithms are tested and benchmarked against each other. It was demonstrated that HIL simulations are suitable to develop vehicle subsystems and control strategies in a quite realistic manner even if the target vehicle or prototype is not available yet. Moreover, the benefits of continuous control approaches against classical rule-based wheel slip control were shown. In the article, aspects such as brake system architecture, control design, HIL testing environment, validation studies, and their analysis are further being discussed.
Methodology for virtual prediction of vehicle-related particle emissions and their influence on ambient PM10 in an urban environment. - In: Atmosphere, ISSN 2073-4433, Bd. 13 (2022), 11, 1924, S. 1-14
As a result of rising environmental awareness, vehicle-related emissions such as particulate matter are subject to increasing criticism. The air pollution in urban areas is especially linked to health risks. The connection between vehicle-related particle emissions and ambient air quality is highly complex. Therefore, a methodology is presented to evaluate the influence of different vehicle-related sources such as exhaust particles, brake wear and tire and road wear particles (TRWP) on ambient particulate matter (PM). In a first step, particle measurements were conducted based on field trials with an instrumented vehicle to determine the main influence parameters for each emission source. Afterwards, a simplified approach for a qualitative prediction of vehicle-related particle emissions is derived. In a next step, a virtual inner-city scenario is set up. This includes a vehicle simulation environment for predicting the local emission hot spots as well as a computational fluid dynamics model (CFD) to account for particle dispersion in the environment. This methodology allows for the investigation of emissions pathways from the point of generation up to the point of their emission potential.
A PID-based active control of camber angles for vehicle ride comfort improvement. - In: Advances in Italian mechanism science, (2022), S. 397-404
In the automotive industry, one of the principal issues is to ensure the comfort of vehicles as much as possible. High vertical accelerations of the vehicle body transmit undesired vibration, causing malaise to passengers. Car vehicles are subjected to vibrations induced by the road roughness or, during a curve travelling, by the roll motion. These factors contribute to generating the total vertical acceleration. The vertical acceleration due to the first factor can be decreased by correctly dimensioning the stiffness and damping of the suspension. In this paper, the active control of the camber angle of the rear wheels is proposed to reduce the vertical acceleration due to the roll motion. The proposed technique has been applied to a validated vehicle model developed in the ADAMS Car environment. The trailing-arm type rear suspension has been modified to include actuators functional for the control system implementation. The tracking of the variable vehicle body roll angle by rear wheels is allowed exploiting two PID controllers to improve the contact of the tire with the road and, therefore, the ride comfort. Two manoeuvres called Sine Steer and Fish-hook have been employed to validate the designed controllers. The RMS and the maximum value of the vehicle body's vertical acceleration decrease, demonstrating the employability of the proposed control system to improve ride comfort.