Daniel Álvarez Mántaras

Ride comfort performance of different active suspension systems

This paper presents a comparative of different active and semi-active suspension systems in order to research the improvement in ride comfort and handling stability compared with the equivalent passive systems. The two-degrees-of-freedom model (quarter-car model) is employed in the analysis of seven different active suspension control strategies: LQR-LQG, Robust design, Kalman filter, Skyhook damper, Pole-assignment, Neural network and Fuzzy logic. Computer simulations of the different active models and the equivalent passive systems are performed to obtain the vertical acceleration of the sprung mass and the vertical wheel load variation. The vertical acceleration of the sprung mass is processed to evaluate the ride comfort behaviour and the vertical wheel load variation is used to evaluate the handling stability of the different active suspension control systems.

A smartphone application to extract safety and environmental related information from the OBD-II interface of a car

This paper introduces a methodology for the identification of events or potentially dangerous situations in road traffic by extracting information from the OBD-II interface. The proposed system for identifying hazardous locations includes a GNSS positioning system. As such, with the use of existing navigation systems or with the use of newly installed equipment, the exact geographic location where a given risk occurs will be identified.

Virtual test rig to improve the design and optimisation process of the vehicle steering and suspension systems

A virtual test rig is presented using a three-dimensional model of the elasto-kinematic behaviour of a vehicle. A general approach is put forward to determine the three-dimensional position of the body and the main parameters which influence the handling of the vehicle. For the design process, the variable input data are the longitudinal and lateral acceleration and the curve radius, which are defined by the user as a design goal. For the optimisation process, once the vehicle has been built, the variable input data are the travel of the four struts and the steering wheel angle, which is obtained through monitoring the vehicle. The virtual test rig has been applied to a standard vehicle and the validity of the results has been proven.

Tyre–road grip coefficient assessment – Part II: online estimation using instrumented vehicle, extended Kalman filter, and neural network

The main objective of this work is to determine the limit of safe driving conditions by identifying the maximal friction coefficient in a real vehicle. The study will focus on finding a method to determine this limit before reaching the skid, which is valuable information in the context of traffic safety. Since it is not possible to measure the friction coefficient directly, it will be estimated using the appropriate tools in order to get the most accurate information. A real vehicle is instrumented to collect information of general kinematics and steering tie-rod forces. A real-time algorithm is developed to estimate forces and aligning torque in the tyres using an extended Kalman filter and neural networks techniques. The methodology is based on determining the aligning torque; this variable allows evaluation of the behaviour of the tyre. It transmits interesting information from the tyre–road contact and can be used to predict the maximal tyre grip and safety margin. The maximal grip coefficient is estimated according to a knowledge base, extracted from computer simulation of a high detailed three-dimensional model, using Adams® software. The proposed methodology is validated and applied to real driving conditions, in which maximal grip and safety margin are properly estimated.

Tyre–road grip coefficient assessment. Part 1: off-line methodology using multibody dynamic simulation and genetic algorithms

A key factor to understand the vehicle dynamic behaviour is to know as accurately as possible the interaction that occurs between the tyre and the road, since it depends on many factors that influence the dynamic response of the vehicle. This paper aims to develop a methodology in order to characterise the tyre–road behaviour, applying it to obtain the tyre–road grip coefficient. This methodology is based on the use of dynamic simulation of a virtual model, integrated into a genetic algorithm that identifies the tyre–road friction coefficient in order to adjust the response obtained by simulation to real data. The numerical model was developed in collaboration with SEAT Technical Centre and it was implemented in multibody dynamic simulation software Adams®, from MSC®.

Sensitivity-Based, Multi-Objective Design of Vehicle Suspension Systems

This article deals with the dynamic response optimization of mechanical systems, based on the computation of independent state sensitivities. Specifically, the dynamic behavior of a coach is analyzed in detail so as to improve its response in terms of handling and ride comfort behaviors. To that end, the coach is modeled as an 18DOF multibody system, whose equations of motion are posed using an efficient dynamic formulation based on Maggis equations. Next, a direct-automatic differentiation approach for the computation of independent state sensitivities is applied. This allows one to quantify the effect of 19 design parameters on the vehicle dynamic response and to compute the design sensitivities or objective function gradients. Finally, handling and ride comfort objective functions are defined and are used to carry out a multi-objective suspension design optimization process, improving the vehicle response by 70% in an effective yet automatic way.

Racing car chassis optimization using the finite element method, multi-body dynamic simulation and data acquisition

This paper presents an optimization methodology applicable to racing car chassis. The proposed procedure is sequentially structured, and starts with analysis of an existing vehicle, goes through an intermediate prototype and finishes with a final design. It is applied to a real case, the redesign of a steel tubular chassis for the ‘Copa de España de vehículos CM’, as part of a full vehicle development. The dynamic response of the existing chassis is modelled using finite element application techniques for structural design and validated with lab tests. In this way, through various modifications using basic static load cases for primary optimization, a completely new design (intermediate) is defined. Then a prototype is built, instrumented and tested in real field conditions (road and circuit). With acquired data from the dynamic behaviour of the car (suspension, steering, engine and transmission, etc.), using multi-body dynamic simulation software, an optimized load case is put forward in order to refine the first prototype. The ultimate goal is a chassis with much increased torsional and bending stiffness, with minimum weight gain, with regard to its interaction with the suspension and steering systems and to the manufacturing feasibility. It is shown that, with an adequate chassis elements configuration, stiffness can be increased by a 300% with just a 5% weight gain. The proposed methodology can be extended to other design (or re-engineering) procedures with rigid limitations in time and resources.

Low-Cost Monitoring System of Sensors for Evaluating Dynamic Solicitations of Semitrailer Structure

Analysis of the fatigue life of a semitrailer structure necessitates identification of the loads and dynamic solicitations in the structure. These forces can be introduced in computer simulation software (multibody

ESTUDIO DE LA VIDA FRENTE A FATIGA DE SEMIRREMOLQUES. BANCO DE ENSAYO Y SIMULACIÓN POR ORDENADOR

El transporte de mercancias por carretera supone en la actualidad uno de los medios de mayor importancia en el sector logistico a nivel mundial, debido a una serie de caracteristicas y ventajas que presenta respecto a otros medios que operan dentro del mismo sector. Este transporte por carretera se realiza en gran medida gracias a la utilizacion de semirremolques. Durante los ultimos anos ha existido una tendencia a optimizar el peso de los semirremolques con objeto de aligerarlos de cara a reducir el consumo y las emisiones contaminantes y aumentar la capacidad de carga. Por supuesto, esta optimizacion tiene que realizarse sin perjudicar la seguridad del vehiculo. En este sentido, un especial interes requiere el analisis de la resistencia frente a fatiga, puesto que las posibles roturas en este tipo de vehiculos aparecen por la aplicacion de cargas ciclicas en zonas proximas a las uniones soldadas. Hasta fechas recientes, las metodologias de diseno aplicadas estaban basadas fundamentalmente en la experiencia y en el analisis experimental, quedando en un segundo plano las operaciones de optimizacion. Sin embargo, en el presente articulo se resume el trabajo realizado por las Universidades participantes y la empresa Lecitrailer S.A. para lograr semirremolques aligerados con un comportamiento optimo frente a fatiga. Esta labor de optimizacion se basa en el desarrollo y aplicacion de una bancada de ensayo frente a fatiga de semirremolques, en combinacion con herramientas numericas de simulacion del comportamiento frente a fatiga de estos vehiculos, y especificamente en las zonas de soldadura.

Sistema para la reducción de costes operativos en una flota de autobuses urbanos a través de la aplicación de técnicas de conducción eficiente

One of the biggest operating costs in a road transport company is the fuel. Fuel consumption accounts for a significant percentage of spending and the change in its price tends to force immediate changes in rates to maintain profitability. This paper presents a method for reducing fuel consumption through the implementation of a system to support fuel-efficient driving. The system consists of a number of technical tools and seminars with experts who promote a learning process that is maintained over time. Technical tools are composed of an on-board system that generates indications in order toinduce the driver to efficient driving and a web platform that allows to check routes and a series of indicators to analyse driving afterwards. Seminars and meetings with experts seek to give guidance and advice to strengthen the role of technical tools. The cost of implementing the system is very small making it easy finance through reduced consumption that can reach values higher than 10%. The system has been successfully tested in the Urban Transport Company of Gijon (EMTUSA) was achieved by a reduction in consumption of 7 % in an urban environment that is usually the hardest for efficient