A novel proposed approach for optimal design of a 2-Dof manipulator arm

Abstract

The manipulator arm design is generally related to a search for a compromise between conflicting requirements. Finding this compromise requires the resolution of a bi-level optimization problem (the respect of some specific constraints involves solving other optimization sub-problems). In this paper, we propose a novel approach for the optimal dimensioning of a two-degrees-of-freedom manipulator arm, where the objective function is defined by the minimization of the structure’s overall mass. The constraints that are taken into consideration can be divided into three categories: geometrical (bounds on design variables, admissible limit of the static deflection at the endpoint of the effector), kinematic (bounds on joint velocities and the accelerations of the actuators), and dynamic (admissible limit of the dynamic deflection at the endpoint of the effector). To achieve the penalizing dynamic configurations in terms of actuator torques and dynamic deflection, a quasi-static deformation model and a recurrent dynamic model were used. The static and dynamic deflection constraints are treated as optimization sub-problems, where their outcomes are integrated, at each iteration, into the global optimization process. The validation of the developed quasi-static deformation model as well as the proposed optimal dimensioning approach is conducted by comparing results with Ansys software simulations. Notably, The proposed approach demonstrates a significantly faster computation time compared to the Ansys software (06 s for the proposed approach vs 21 h for Ansys). Even though Ansys software performs optimal dimensioning for an imposed trajectory.