1,720,984 research outputs found
A SIMULATION TOOL FOR OPTIMIZATION AND PERFORMANCE PREDICTION OF A GENERIC HYBRID ELECTRIC SERIES POWERTRAIN
No full textHybrid and electric vehicles are taking an increasingly important slice of the market, gaining much interest from major car manufacturers which have decided to invest in this sector, taking as example the pioneers like Toyota.
The key factor to hybrid and electric vehicle success is a good overall mileage achieved from the battery back or powertrain.
The purpose of this work is to provide a support to design, testing, and development of such vehicles through the implementation of a mathematical model in order to simulate the operation and predict the performance of a generic ground vehicle equipped with either a purely electric or a hybrid-electric type powertrain. The model should enable the user to estimate the impact of various control strategies on mileage range, efficiency, energy consumption, etc. The model should also allow for a significant time to market reduction with all the related benefits in terms of cost etc.
A validation is also provided, based on the application of this tool on a so-called micro-car (0.5t GVW class). Thanks to a joint research project with the manufacturer it has been possible to compare model results with real-world data directly obtained during road testing with the help of a data acquisition system
What is the most representative Standard Driving Cycle to estimate Diesel emissions of a Light Commercial Vehicle?
No full textThe paper presents a comparison between the emission levels produced along the most used standard driving cycles (NEDC, WLTC, CADC) by a Light Commercial Vehicle (LCV). A proven simulation tool based on real-world emission data (RDE, Real Driving Emissions) has been used instead of a demanding test campaign. Emission levels have been computed for each cycle in three conditions (urban, combined, extra-urban/highway). Then the results have been compared with Euro 5 limits and real-world emission levels to highlight each driving cycle objectivity and representativeness. Among others, the WLTC driving cycle seems to be the most plausible one yet, as expected, it is not very representative of the real world
Estimation of vehicle side-slip angle using an artificial neural network
No full textIn this work a reliable and effective method to predict the vehicle side-slip angle is given by means of an artificial neural network. It is well known that artificial neural networks are a very powerful modelling tool. They are largely used in many engineering fields to model complex and strongly non-linear systems. For this application, the
network has to be as simple as possible in order to work in real-time within built-in applications such as active safety systems. The network has been trained with the data coming from a custom manoeuvre designed in order to keep the method simple and light from the computational point of view. Therefore, a 5-10-1 (input-hidden-output layer) network layout has been used. These aspects allow the network to give a proper estimation despite its simplicity. The proposed methodology has been tested by means of the CarSim® simulation package, which is considered one of the reference tools in the field of vehicle dynamics simulation. To prove the effectiveness of the method, tests have been
carried out under different adherence conditions
A neurofuzzy-controlled power management strategy for a series hybrid electric vehicle
No full textThis paper focuses on the design of the power management strategy as the key factor in improving the performance in terms of the efficiency, the range and the fuel consumption for a small-scale series hybrid electric vehicle. A complex hybrid vehicle system is considered, and a practically realisable and traceable neurofuzzy strategy for improving the vehicle efficiency is introduced. The method results in extending the vehicle's range while deciding when to switch the internal-combustion engine on or off as a function of the state of charge of the battery and the electrical power produced from the generator. Consequently, the speed of the internal-combustion engine (i.e. the current produced) is determined as a function of the driving conditions. Suitable tests were performed in order to verify the effectiveness of the proposed strategy; the verification tests were carried out using a consolidated model which also includes real-world experimental vehicle data. The results show that, by using the proposed power management strategy, good compromise between the efficiency, the range and the fuel consumption can be obtained in many practically useful driving conditions
Design of a double wishbone front suspension for an orchard-vineyard tractor: Kinematic analysis
No full textThis paper deals with the design and implementation of a double wishbone front suspension for a small vineyard-orchard tractor, developed in conjunction with a major tractor manufacturer. To date there are just medium or heavy weight machines and no small size tractors with independent front suspension on the market. The front suspended axle is recognized as a leading option in improving tractor ride performance on larger vehicles. Moreover, despite their narrow track, vineyard-orchard tractors are required to have good lateral and slope stability (i.e. at least 28 deg rollover angle) and an extremely tight turning diameter (less than 7m).
The design analysis is based on retrofitting an existing vehicle with a double wishbone front suspension. The design process, with all related issues, was conducted in collaboration with the vehicle manufacturer. Specification of the suspension pick-up points was determined by means of an iterative process using CAE design and kinematic analysis.
Results show that such an improvement is feasible. The final kinematic turning diameter is about 6.4 m, with a ±65mm suspension travel available. The roll centre height value is not very sensitive to steering (about 95 mm excursion), therefore offering slope stability in extreme turning manoeuvres
A Comprehensive Method for Computing Non-Linear Elastokinematic Properties of Passenger Car Suspension Systems: Double Wishbone Case Study
Full text linkSuspension and steering design play a major role in ensuring the correct dynamic behaviour of road vehicles. Passenger
cars are especially demanding from this point of view: NVH and ride comfort requirements often collide with active
safety-related requirements such as road holding in steady-state conditions and stability in transients. Driving pleasure is
also important for market success, therefore accurate steering feedback and predictable handling properties are additional
priorities.
Since flexible bushings are used as interface between the suspension arms and the chassis, extra degrees of freedom make
the design process a complex task. While the use of a multibody software is common practice in the industry, a dedicated
computational tool can be more practical and straightforward, especially when undertaking the design of a new suspension
concept ground-up.
The paper presents a computational methodology for the design of an independent suspension with the associated
kinematic and compliance attributes. Typical elastokinematic properties like toe, camber, wheelbase, and track variations
vs tyre forces and moments can be computed by means of a dedicated software tool. A sort of validation was performed
either by means of a comparison with a MathWorks Simscape® Multibody based model. Finally, a sensitivity analysis is
given as an example.
Computationally, the method proposed is intuitively based on the equilibrium equations. The nonlinear equations are then
solved with Newton-Raphson algorithm. The method can be also optimized for computational efficiency and is
thoroughly described so that the reader can easily replicate it in the desired programming environment
Teaching automotive suspension design to engineering students: bridging the gap between CAD and CAE tools through an integrated approach
No full textThe paper presents an integrated approach to suspension design with educational purposes. A dedicated design tool was created to instruct automotive engineering students in the whole process of suspension design across the various CAE tools involved, from early kinematics studies to CAD, vehicle dynamics simulations and FEM modelling. The tool has given birth to a proven design procedure that the authors would like to share in this paper with focus on the educational side, although suspension kinematics design is not certainly a novel subject in itself. The tool includes geometries like the widely used McPherson strut, complex five-link schemes for high-end road cars, and typical racing car geometries like the so-called push/pull rod systems used on Formula 1 and Le Mans racecars. It has been applied successfully to various projects developed by professionals as well as by students, including the latest three Formula SAE (FSAE) single-seaters of the University of Brescia (UniBS) team. The paper is structured as follows. The introduction describes the role student design competitions play in higher engineering education, and within the frame of the Automotive Engineering course at UniBS in
particular. A selection of relevant bibliography on the topic is listed. Section 2 deals with the specific case of the Automotive Engineering course at UniBS and the requirements posed by student competitions, also in the frame of the Dublin Descriptors, and shows how suspension design can play a pivot role in a FSAE project. Section 3 presents the software tool in itself. The math underlying the user interface is outlined. Finally, the integration features towards other CAE tools are presented with the related
advantages
Reproduction of real-world road profiles on a four-poster rig for indoor vehicle chassis and suspension durability testing
No full textIndoor testing should reproduce the real-world environment in order to be effective. In this article, an efficient methodology to reproduce road profiles on a four-poster rig is presented: such a method includes a complex rig control strategy based on an iterative process. Road profiles come from a purposely designed set of sensors fitted on the car which remains the same regardless of the vehicle or surface type. Particular stresses such as speed humps, potholes and manholes can be reproduced as well. Since there are no previous similar studies, a validation is provided by comparing road and rig data streams and using the maximum absolute error and root mean square error as performance indexes. Results show that the rig is able to reproduce road profiles and the related inputs to the vehicle successfully; hence, the method is reliable and effective
Regenerative Braking Logic That Maximizes Energy Recovery Ensuring the Vehicle Stability
No full textThis paper presents a regenerative braking logic that aims to maximize the recovery of energy during braking without compromising the stability of the vehicle. This model of regenerative braking ensures that the regenerative torque of the electric motor (for front- and rear-wheel drive vehicles) or electric motors (for all-wheel drive vehicles equipped with one motor for each axle) is exploited to the maximum, avoiding the locking of the driving wheels and, subsequently, if necessary, integrating the braking with the traditional braking system. The priority of the logic is that of maximizing energy recovery under braking, followed by the pursuit of optimal braking distribution. This last aspect in particular occurs when there is an integration of braking and, for vehicles with all-wheel drive, also when choosing the distribution of regenerative torque between the two electric motors. The logic was tested via simulation on a front-, rear-, and all-wheel drive compact car, and from the simulations, it emerged that, on the WLTC driving cycle, the logic saved between 29.5 and 30.3% in consumption compared to the same vehicle without regenerative recovery, and 22.6–23.5% compared to a logic commonly adopted on the market. On cycle US06, it saves 23.9–24.4% and 19.0–19.5%, respectively
Analyzing Porpoising on High Downforce Race Cars: Causes and Possible Setup Adjustments to Avoid It
Full text linkThe so-called porpoising is a well-known problem similar to bouncing that is affecting the dynamic behavior of basically all the field of 2022 Formula 1 racing cars. It is due to the extreme sensitivity of aerodynamic loads to ride height variations along a lap. Mid-way through the season race engineers are still struggling to cope with this phenomenon and its consequences, with regard to either physiological stress experienced by the drivers or to overall vehicle performance and stability. The paper introduces two kinds of models based on real-world chassis and aerodynamic data, where the above-mentioned downforce sensitivity has been arbitrarily recreated through the application of a decay function to aero maps. The first one is a quasi-static model, usually adopted as a trackside tool for controlling ride heights and aero balance, while the second, a fully dynamic model, recreates the interaction between oscillating aerodynamic loads and suspension dynamics resulting in a visible porpoising phenomenon. Basic setup changes have been tested, including significant static ride height variations. The paper should be seen as a proposal of guidelines in the search of a trade-off between aerodynamic stability and overall performance, without pretention of quantitative accuracy due to the highly confidential topic, which makes numerical validation impossible
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