Marco Gadola

A neurofuzzy-controlled power management strategy for a series hybrid electric vehicle

This 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, a good compromise between the efficiency, the range and the fuel consumption can be obtained in many practically useful driving conditions.

The influence of suspension components friction on race car vertical dynamics

ABSTRACT This work analyses the effect of friction in suspension components on a race car vertical dynamics. It is a matter of fact that race cars aim at maximising their performance, focusing the attention mostly on aerodynamics and suspension tuning: suspension vertical and rolling stiffness and damping are parameters to be taken into account for an optimal setup. Furthermore, friction in suspension components must not be ignored. After a test session carried out with a F4 on a Four Poster rig, friction was detected on the front suspension. The real data gathered allow the validation of an analytical model with friction, confirming that its influence is relevant for low frequency values closed to the car pitch natural frequency. Finally, some setup proposals are presented to describe what should be done on actual race cars in order to correct vehicle behaviour when friction occurs.

Impact of reduced mass of light commercial vehicles on fuel consumption, CO2 emissions, air quality, and socio-economic costs

This study presents a modelling system to evaluate the impact of weight reduction in light commercial vehicles with diesel engines on air quality and greenhouse gas emissions. The PROPS model assesses the emissions of one vehicle in the aforementioned category and its corresponding reduced-weight version. The results serve as an input to the RIAT+ tool, an air quality integrated assessment modelling system. This paper applies the tools in a case study in the Lombardy region (Italy) and discusses the input data pre-processing, the PROPS-RIAT+ modelling system runs, and the results.

Reproduction of real-world road profiles on a four-poster rig for indoor vehicle chassis and suspension durability testing

Indoor 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.

Semi-Active Strategies for Racing Car Suspension Control

Quite a lot has been written on active suspension, the topic being suitable for theoretical studies. Unfortunately only a few applications has seen the road and even less went into production; by now very few road cars equipped with a real active suspension system are available on the market, and the interest to this kind of application seems to be reduced, perhaps because of high costs and restrictive regulations applied to the race car world. For this reason this paper presents the results of a study conducted on the vertical dynamics of a two wheel car model with a semi active suspension system, a possible alternative way to a fully active system to considerably improve suspension performance. Here the damping force of each suspension is obtained by modulating its damping factor according to opportune functions of the system state variables. This allows to reach several of the objectives achievable with a fully active suspension, without the need of a big amount of energy.

Development of a New Software for Racecar Suspension Kinematics

In the racecar design process the definition of suspension type and geometry is an important stage. A good design of the main parameters, in terms of static and dynamic angles in bump and steer, is the basis of a successful racecar quite often. This paper aims at introducing the development of a new software tool, called MLKrace, that can analyse the suspensions kinematics for a wide range of different layouts. There are today a lot of commercial tools that analyse or simulate suspension behaviour. In general their application is restricted to the classic double wishbone suspension and in this case the calculation of the kinematics is not so difficult. This layout is used on both ends of the majority of formula and sports race cars but it isn’t the only possible one. Figure 1 – Example of multilink suspension The MLKrace software is instead more suitable to analyse innovative suspension geometries, the mathematics being based on the resolution of the socalled Stewart platform, a method originally devised for parallel robot kinematics. Therefore full multilink or hybrid systems can be designed as easily as a double wishbone. In addition push rod, pull rod or outboard spring systems can be added and the driveshaft required float is computed. Multilink-McPherson hybrid suspensions can be designed as well. The flexibility is the great advantage of this new software. Apart from the mathematic model, a massive effort was devoted to the design of the Windows interface with the aim of making the designer’s job particularly easy and effective compared to outdated MS-Dos interfaces of most of the existing software. The output is shown in the form of 2D and 3D animations, a large number of predefined diagrams, numeric tables and regression functions. INTRODUCTION The suspension design process is an important point in the development of a new car or in the tuning of an existing car. As a matter of fact tyres can produce forces to generate high lateral and longitudinal acceleration only if they work in the proper way, where this means with a good contact area and angles. These angles are camber and toe. Figure 2 shows the effect of camber angle in cornering force. A general rule is that negative angles give more lateral force. But the optimum angle depends on the type of tyre and its application. The designer tries to keep it constant to have the best performance. In the design phase the suspension is conceived in a static configuration that defines the main parameters of the geometry. On the track, road bumps, load transfer and aerodynamic downforce produce a relative movement of the wheel. It is also important to study the variation of these parameters when the wheel is moving in bump and steer. A typical problem is to avoid “bump steer” or the toe change along the bump motion; this is a negative characteristic as it can upset the vehicle behaviour. Figure 2 – Camber effects on tyres The developed software “MLKrace” allows the designer to analyse the suspension system and to modify its characteristics for improvement. The choice of the suspension type is the first step in suspension design and MLKrace gives the opportunity to analyse different layouts to compare parameters, performance and overall dimensions. When the main layout is defined the design phase begins where the designer can move links and rods to obtain the best compromise for the specific car and application (road car, sportscar or formula). MLKrace aims to simplify the design process with the following features: • Modelling of the most common configurations • High quality and user-friendly interface • Fast and accurate calculation • Graphic representation of the suspension • Wide selection of displayed results Compared to other commercial suspension design software MLKrace is easy to use and complete and results are particularly accurate. SUSPENSION DESCRIPTION In the description of a new suspension the designer needs to input a lot of information. MLKrace’s main screen presents various options to define the suspension type and layout. The first parameter to set in the suspension is the layout. There are 5 possibilities: 1. Multilink: the most general type of suspension that gives the possibility to have virtual steering axis and a good control of angles. 2. Bottom multilink Top wishbone: a multilink where top arms are connected to form a wishbone. 3. Top Multilink – Bottom wishbone: a multilink where bottom arms are connected to form a wishbone. 4. Double wishbone: top and bottom arms are connected to form a wishbone. 5. McPherson: A strut geometry where the bottom links can be separated or connected to form a wishbone. 1 – Multilink 2 – Bottom Multilink 3 – Top Multilink 4 – Double wishbone

Minimum time optimal control simulation of a GP2 race car

In this work, optimal control theory is applied to minimum lap time simulation of a GP2 car, using a multibody car model with enhanced load transfer dynamics. The mathematical multibody model is formulated with use of the symbolic algebra software MBSymba and it comprises 14 degrees of freedom, including full chassis motion, suspension travels and wheel spins. The kinematics of the suspension is exhaustively analysed and the impact of tyre longitudinal and lateral forces in determining vehicle trim is demonstrated. An indirect optimal control method is then used to solve the minimum lap time problem. Simulation outcomes are compared with experimental data acquired during a qualifying lap at Montmeló circuit (Barcelona) in the 2012 GP2 season. Results demonstrate the reliability of the model, suggesting it can be used to optimise car settings (such as gearing and aerodynamic setup) before executing track tests.

Lightweighting in light commercial vehicles: cradle-to-grave life cycle assessment of a safety-relevant component

PurposeCurrently, the reduction of weight in automotive is a very important topic in order to lower the air pollution. In this context, the purpose of the present paper was to analyze a real case study through a comparison of the environmental sustainability between a conventional steel crossbeam for light commercial vehicles and an innovative lightweight aluminum one.MethodsFor both scenarios, a cradle-to-grave life cycle assessment methodology and a sensitivity analysis has been used through the study of the following phases: mineral extraction, component manufacturing, use on vehicle, and end of life. In particular, many primary data and a complete vehicle model simulation with three different European driving cycles have been used in order to reach the highest possible level of accuracy during the analysis.Results and discussionRegarding the manufacturing phase, the aluminum component’s production gave the highest impact because of the high energy required in the mineral reduction. Anyway, this stage of the analysis had a low effect on the entire LCA, because the benefit of weight reduction during vehicle use showed a strongly higher contribution. The urban driving cycle had the most relevant impact, as a consequence of the frequent start and stop operations and the longest time with engine at idle speed, while the extra-urban cycle is the less demanding due to its higher average speed and no start and stop.ConclusionsIn conclusion, the present research demonstrated the environmental importance of the lightweight for an actual case study in the commercial vehicles field.

High downforce race car vertical dynamics: aerodynamic index

ABSTRACT Race car performance is strongly affected by aerodynamics. Due to downforce generated by the vehicle floor (i.e. diffuser), vehicle ride heights are key parameters to improve performance, and the coupling of aerodynamics and suspension is one of the key points of race car setting. This work focuses on the suspension and aerodynamic coupling from the vertical dynamics point of view. Besides road holding performance, for race cars, aerodynamic performance and stability are major factors. Downforce decreases laptime (the main performance target) but pitch instability is a non-desired effect that can happen in high downforce race cars. A new vertical dynamic performance index is proposed through the use of simulation to improve aerodynamic performance and understand the pitch instability phenomenon. This new index uses all relevant vehicle nonlinearities related to vertical dynamics and can handle a specific track profile and vehicle speed range, allowing the analysis be conducted according to a circuit specification. A previously validated Formula 3 car model was used as an example.

Teaching automotive suspension design to engineering students: Bridging the gap between CAD and CAE tools through an integrated approach

The 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 (Brescia, Italy) 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. The Educational scenario section 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. The A tool for suspension kinematics: requirements, description, solution section 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.