Abstract: Dynamic modelling and control of flexible-link robotic systems is an important field of scientific investigations. Indeed, nowadays, the research effort focuses on the improvement of the dynamic performances of the robotic systems by increasing the velocity and lightening the structure while maintaining a high degree of precision and accuracy. Thus, complex and effective dynamic models have to be used since both inertial and elastic effects have to be taken into account being the hypothesis of rigid links no longer valid. In this paper, an effective method in dynamic modelling of spatial flexible link robots under large displacements and small deformations is discussed (a) and a generic Matlab software simulator based on it, suitable for modelling and dynamic simulating serial flexible link 3D robots, is presented (b) and validated (c):
a) the adopted method is based on an Equivalent Rigid Link System (ERLS)  that enables to decouple the kinematic equations of the ERLS from the compatibility equations of the displacements at the joints allowing an easy and recursive procedure. The mutual influence between rigid body motion and vibration is taken into account and the notation of the rigid link robotic systems kinematics, i.e. the Denavit-Hartenberg notation (DH), is exploited allowing to approach a flexible robotic system as in the case of a rigid one;
b) the developed Matlab simulator allows to model generic 3D flexible-link spatial robotic systems and is structured in three main parts: the first is related to the DH, geometrical and mechanical parameters definition; the second is related to the dynamic model symbolic matrix calculus and visualization of the mechanism; the third is related to the dynamic simulation and results evaluation;
c) the simulator validation is made with respect to the Adams-Flex commercial software, which implements the floating frame of Reference (FFR) formulation , one of the most used methods for dynamic modelling of multibody flexible link mechanisms with large displacements and small deformations. Different robotic systems have been built and simulated both under gravity and under different input conditions. in this work, different behaviours of specific robots with respect to different working conditions and mechanical parameters are presented.
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