Summary Industrial robots are optimized structures to be contradictorily used to work under different loading conditions: masses in motion are very important and dynamic actions may be dominant. Their dynamic modelisation is essential, both, in regard to their designing in order to better adjust them to requirements, and concerning their working period, to use them without fearing any overloading, as efficiently as possible; furthermore, a precise dynamic model is necessary if the system is to be fitted with a dynamic control. In this article, we propose a method of modelisation of multi-articulated mechanisms in the shape of open loop chains. It is based on d'Alembert's formalism and enables us, for given kinematics, to calculate the interface forces and torques, and to find the equations of motions. Recurrences will permit the obtaining of these expressions which can be simple, condensed, or automatically generated. The validity of this model is set up by theoretical and experimental means. Its competitiveness estimated in terms of operations, additions, multiplications used in a calculating loop, is also set up as follows: the gain is nearly 100% for a six-degree-rotating system. We also propose some possible uses of numerical simulation to answer the requirements which designing and working demand.