Otimização do desempenho dinâmico de um manipulador robótico planar em série com redundância no espaço das tarefas

Abstract

Robotic manipulators are increasingly present in current industrial activities. They are used in tasks such as: painting, drilling and welding operations, material handling, etc. Although these robots are widely used, their tasks are often not performed optimally. There are different characteristics that can be used to define the optimization of a manipulator, such as manipulability, torque, energy, conditioning, among others. Task space redundancy occurs when the end-effector has more degrees of freedom than the task needs, so it is possible to optimize performance using the excess degrees of freedom. This excess of degrees of freedom defines a problem with infinite solutions for the robot joint positions. Defining these positions through an optimization process is called redundancy resolution. There are two types of resolution: local and global. The local observes the gradient of a cost function at each instant of time and decides the joint positions from that. The global one observes a cost function throughout the task execution period to define these positions. Therefore, this work aims to study a planar serial robotic manipulator using task space redundancy to optimize its dynamic performance in order to compare the different redundancy resolution methods. The local and global methods were compared with each other and with the performance of a non-redundant robotic manipulator. In addition to this analysis, the impact of other factors on the optimization of dynamic performance was studied, such as the initial orientation of the end-effector and the use of a weighting factor for gravitational forces in the dynamic equations. The manipulator implementation, simulation and optimization were done using the software MATLAB. The results obtained indicate that the resolution of the redundancy by the local method presented a better dynamic performance and that the joint optimization of the initial orientation and of the weighting factor of the gravitational forces collaborates for this.