Page  75 ï~~Modular modelisation and simul Jean-Loup FLORENS,Cla A.C.R.O.E. L.I Institut IMAG (Informatique et de Mathema 46 Av. Felix Viallet - 38000 GRE Tel: 33 76 57 46 61 - Fax "3 Abstract. Musical synthesis by physical mod simulation processes. In this paper we shall be dis the modular specification and construction of sucl for the constraints linked to their execution in r between the instrumentalist. the system V constructed by assembling mechanical component principles, specification modes for more macr introduced that enable, depending on the case, t model complexity, variability, and simulation qual notably make use of the instruments general specif

Page  76 ï~~3) When two masses are assembled by liaison, we position variables to the mass positions. In a complemen is the (resulting) sum of the forces associated to the liaisc A composite object is thus described by a list of co parameters and a connection plan. In practice, the connec of the liaison elemonts of which the indexes of the massc; Algrih, algorithmic modularzity. The simulation algorithm is constructed in an immediate algorithmic module and these moduics interconnect acc mass elemeonts arc processed by modules that receive on to, and produce a position. Liaison m odule M ass i c

Page  77 ï~~This rupture brings out one of the nodes of the initial:i We refer to this second category as an M point. This de 1) Liaison may only be established between two 1 2) An L point may only be linked to one M poi different L points, so therefore M points mask L point 3) An M point connexion produces a position az points it is connected to. The L point receives a positio 4) All connexion topology data is associated to L Although this is defined from the preceding modeli general and induces no constraint on the internal stru point is not necessarily associated with the simulation We should also point out that total.compatibility with objects constructed on an atomic level into libraries can remain atomised or, on the contrary, if the object i can be optimised by specific means external to the sys can choose the best balance between the variabilil simulation. Application instrument modelisation. Vt~h-.cvctntmv to PnahP a cnnifc crcrrintinn mnrlr

Page  78 ï~~A number of non-linear physical behaviour types C tridimensional displacement area. For example, the occupation zone around any material point, induce non-i substantial. These properties can be integrated into an initial model tri- dimensional space and are provided with interact otherwise for image synthesis enables most of the ges mechanical functions to be modelised [7]. A certain nun exciter simulation process to be connected to the vibrati with spatial images of the vibrating structure defined in This system has been used to represent scenes of simj vibrated and excited by percussion. Representing instru the framework of spatial modelisation is however ver adequate for processing the gesture/exciter mass chain, mass chain. 2) 'Topological" Modelisation The system presented in the first part enables ) components and of assembly. The displacement area i principle induces "implicit" non-linearities. Non-linearit