Dynamics analysis, offline–online tuning and identification of base inertia parameters for the 3-DOF Delta parallel robot under insufficient excitations

Abstract

In this paper, the dynamics model of the 3-Degrees-Of-Freedom (DOF) Delta parallel manipulator is elaborated by means of a Screw-based formulation of the virtual works method in a linear regression form. Moreover, a reduced dynamics model is obtained by exploiting the singular value decomposition, leading to the determination of the base inertial parameters. This method is an offline tuning approach for which an optimized path containing several harmonics is required to establish the desired bandwidth. Additionally, this paper presents an algorithm to address the singularity problem by mapping the regressors to an orthogonal space and obtaining an optimal set of base parameters in an online manner, namely the online base inertial parameter tuning method. Thereafter, through a set of simulations, the effectiveness of the proposed method has been illustrated for different paths. Finally, a change in the value of an inertial parameter of the system, which can be regarded as a disturbance, is exerted and the obtained results reveal that the proposed method can compensate for extrinsic mass effect. In summary, it can be deduced that the the proposed approach is also able to identify the changed model under insufficient excitations for real-time purposes.