This paper presents a method for optimizing the trajectories of robotic arms having manipulators with six degrees of freedom (DOFs) and spherical wrists. The trajectories are optimized by maximizing the manipulator performance (manipulability). For this purpose, kinematics models of the robot arms are defined, such that they can be integrated into an algorithm based on the Kalman filter. This algorithm is implemented through the simulation of trajectories in a serial industrial robot, which is a robotic arm with six DOFs and a fitted welding tool with a material contribution. During the trajectory optimization for such a manipulator robot, the orientation of the welding gun (e.g., the position of the final effector) must be preserved to guarantee correct welding. Applications of this method to two trajectories in the automotive industry are presented, and remarkable improvements in the performance of the manipulator itself are observed. The results obtained demonstrate that the proposed algorithm is an appropriate method for optimizing trajectories because of its various advantages, such as ease of implementation and states of calculation based only on the previous states. Therefore, this method allows the trajectories to be optimized in the work environment of the robot once the kinematic parameters of a robotic manipulator arm are known.

Currently, the high demand for new products in the automotive sector requires large investments in factories. The automotive industry is characterized by high automatization, largely achieved by manipulator robots capable of multitasking. This work presents a method for the optimization of trajectories in robots with six degrees of freedom and a spherical wrist. The optimization of trajectories is based on the maximization of manipulability and the minimization of electrical energy. For this purpose, it is necessary to take into account the kinematics and dynamics of the manipulator in order to integrate an algorithm for calculation. The algorithm is based on the Kalman method. This algorithm was implemented in a simulation of the trajectories of a serial industrial robot, in which the robot has a sealer gun located on its sixth axis and the quality of the sealer application depends directly on the orientation of the gun. During the optimization of the trajectory, the application of the sealer must be guaranteed. This method was also applied to three different trajectories in the automotive sector. The obtained results for manipulability and electrical energy consumption prove the efficiency of the algorithm. Therefore, this method searches for the optimal solution within the limits of the manipulator and maintains the orientation of the final effector. This can be used for a known trajectory.

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