Identification of the Dynamic Parameters of NaVARo, a parallel robot with multiple actuation modes

Alberto Landini (1) , Stéphane Caro (2, 3, 4) , Damien Chablat (5)

1 ECN - École Centrale de Nantes
2 LS2N - Laboratoire des Sciences du Numérique de Nantes
3 CNRS - Centre National de la Recherche Scientifique
4 LS2N - équipe RoMas - Robots and Machines for Manufacturing, Society and Services
5 LS2N - équipe ReV - Robotique Et Vivant

The identification of the dynamic parameters of a 3-DOF planar parallel manipulator with multiple actuation modes, called NAVARO, is the purpose of this paper. Conversely to classical parallel robots, a transmission system permits to the robot to change the location of its actuated joints and thus changes its kinematic and dynamic performance. For the identification of the dynamic parameters of the NAVARO, the continuous acceleration blends method for trajectories with via points is used. Then, its dynamic parameters are identified for two actuation modes through some simulations and experiments. Finally, the robot dynamic model is improved with the identified parameters and experimental results show the quality of the new model. Extended abstract A drawback of serial and parallel mechanisms is the inhomogeneity of the kinetostatic performance within their workspace. For instance, dexterity, accuracy and stiffness are usually bad in the neighbourhood of singularities that can appear in the workspace of such mechanisms [1]. Nevertheless, it is difficult to come up with a large operational workspace free of singularity.. As the singularity loci depend on the actuation scheme, the NaVARo has eight actuation modes thanks to three double-clutch systems located at the first revolute joint of each leg. (Figure 1). Fig. 1: The NAVARO prototype Fig. 2: The NAVARO transmission system Each transmission system has four actuation schemes, namely,(i) None of the brake is active; (ii) Brake 1 is active; (iii) Brake 2 is active; Both brakes are active. By activating only one brake per leg, the robot admits eight actuation modes (Figure 2) [2]. The dynamic models of the legs are expressed as a function of the generalized coordinates, obtained using the classical method for serial robots, while the dynamic model of the platform is expressed as a function of its Cartesian coordinates, obtained by Newton-Euler approach giving the total wrench exerted on the platform. The leg dynamic model is the same for all the legs because NAVARO has three identical legs. The first step is to open the closed loop chain of the leg, leading to the equivalent tree structure. As shown in Fig. 3, the chosen cut

Domaines: Génie mécanique [physics.class-ph]; Automatique / Robotique

Alberto Landini, Stéphane Caro, Damien Chablat. Identification of the Dynamic Parameters of NaVARo, a parallel robot with multiple actuation modes. The 4th Joint International Conference on Multibody System Dynamics, May 2016, Montreal, Canada. ⟨hal-02947175⟩