3D vibration control of flexible manipulator by inverse systems using inner and outer decomposition

Abstract

This paper presents vibration control of a flexible manipulator that has two links and three degrees of freedom and that performs three-dimensional motion and verified the suppression of vibration in threedimensional space using an actual manipulator using an inverse system. At present, industrial robots are required to increase the speed of operation in order to reduce the weight of the robot and improve the work efficiency for the purpose of energy saving and cost reduction. However, if the weight of the arm is reduced, the rigidity is inevitably low, which causes vibration of the entire arm. In addition, if the operation speed is increased, vibration will occur in the arm even if the robot is highly rigid. For these reasons, the development of a control method that takes into account the flexibility of the manipulator is an important issue, and various studies have been conducted, but the study of vibration suppression in three-dimensional motion is also difficult to model and control. One of the approaches is to suppress vibration using an inverse system. Previous studies have shown that vibration suppression is possible with the inverse system. Problems such as the resonance frequency component in the torsional direction remaining and overshooting with respect to the target angle remain. Therefore, in this research, we aimed to improve the vibration suppression performance in the torsional direction and the tracking performance to the target angle, which remained as issues in the conventional research. First, we applied and verified a new inverse system design method. We constructed a stable inverse system using inner and outer decomposition for the unstable zero of the flexible manipulators and confirmed the effectiveness for vibration suppression by simulation. After that, the vibration suppression performance of the controller was confirmed in a mounting experiment, and it was confirmed that it was effective in suppressing vibration in the torsion direction and the motor drive direction. In addition, it was confirmed that overshoot with respect to the target angle, which was the subject of conventional research, did not occur. From the results, it was confirmed that the proposed inverse system is effective for vibration control of the flexible manipulator that moves in three dimensions