1 IDENTIFICATION OF THE DYNAMIC PARAMETERS OF A CAR: SIMULATION AND EXPERIMENTAL RESULTS Gentiane Venture* Wisama Khalil** Maxime Gautier** Philippe Bodson* *P.S.A. Peugeot Citroºn  Direction Plates-formes, Techniques et Achats Route de Gisy  78943 VØlizy-Villacoublay  France venture@mpsa.com bodson@mpsa.com **Institut de recherche en Communications et CybernØtique de Nantes (IRCCyN) 1, rue de la Noº  B.P. 92101  44321 Nantes Cedex 3  France Wisama.Khalil@irccyn.ec-nantes.fr Maxime.Gautier@irccyn.ec-nantes.fr Abstract: This paper presents a dynamic modelling of a car using robotic formalism in order to estimate the dynamic parameters of a car and more particularly the dynamic parameters of the chassis and the suspensions. The inverse dynamic model is used to identify the dynamic parameters of the car. They are estimated using a weighted least squares method. Both simulation and experimental results are given for a 406 Peugeot car. Key words: parameter identification, automobiles, dynamic modelling, least squares. 1. INTRODUCTION Car manufacturers need to design their vehicles faster than ever but with a higher range of quality and security to satisfy the customers. Computation and simulation become more frequent particularly during the conception of the vehicle, but they remain poor used for the tuning. This is not because of the lack of tools to simulate the behaviour of the car but only because the car itself is not well known and it is not trivial to correlate computation and real test. This paper presents a method to estimate the dynamic parameters of a car using a simple modelling based on robotic formalism. This method allows the unknown parameters with some trajectories commonly used for the tests and straightforward computations. The modelling of the car and the identification method will be briefly presented. The model has been validated with simulated data obtained with a dynamic model of the vehicle developed by PSA which is different from the identification model. Finally the instrumentation required for the tests will be developed, as well as the tests, and practical results are given for a real vehicle: Peugeot 406.