Otimização de trajetórias de robôs com estrutura paralela

Abstract

Parallel manipulators are of great interest mainly because they present advantages in several applications, showing great resistance, positioning accuracy, load capacity larger than serial manipulators and they can be operated to high-speeds and accelerations. In the Laboratory of Robotics and Mechatronics in Casino, Italy, a parallel mechanism was created with three degrees of freedom, called CaPaMan (Cassino Parallel Manipulator). The main objective of this work is obtains the optimal trajectory of the CaPaMan parallel structure. The multi-objective optimization problem is written taking into account the mechanical energy of the actuators, the total traveling time and jerk. The trajectory is calculated assuming that the input angles are given by a function of the time, represented by a uniform B-splines. The kinematic modelling is obtained by deriving the trajectory equation according the time. The analytic model for the inverse dynamics of CaPaMan uses the equations of Newton-Euler. The peculiar kinematic chain and the properties of symmetry of the CaPaMan architecture are useful in this formulation, which allows, for each trajectory, to calculate the input torques and the mechanical energy. The multicriterion vector function is transformed to a scalar function by using the Weighting Objectives Method. The optimization problem is investigated by using genetic algorithms. Some numeric examples are presented for verification and validation of the methodology.