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.

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This paper presents a study for assessing the dynamic structural deformations of one of the most modern, and portable, measurement equipment: the Coordinate Measuring Arms (CMAs or AACMMs). The study of the measurement errors derived from the use of these instruments is still controversial due to a certain lack of traceability and reliability in measurements due to the influence of the human factor acting on a complex 3D structure (with 6 or 7 degrees-of-freedom). When contact measurements are taken into account, the human factor variable originates non-uniform contact forces, lack of stability, different velocities and accelerations, among unpredictable probing trajectories. All these factors lead to conclude that in every manual measurement involving a CMA there is a structural dynamic deformation caused by the approach movement before probing a contact point as well as by the force exerted during probing. In order to determine the amplitude of this deformation and its distribution along the CMA structure a new methodology has been developed. Both depend on the followed trajectory and on the probing force amplitude and orientation. This work presents the methodology and steps required for the construction of the virtual simulation model. The method employs 3D modelling of all elements of the CMA structure, Finite Element Analysis (FEA) software and multibody simulation techniques with flexible bodies. This set of software tools is nowadays capable of creating dynamic virtual models for the dynamic analysis of complex mechanisms (machines, vehicles…) in optimization tasks. The application of these tools supposes a novel approach to the study of the CMA metrological behaviour.

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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 Maggi's 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.

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