Enhancement of the dynamic response characteristics of classical drives with smart actuators for high-speed and precision machinery applications

One of the primary factors limiting the performance of high speed and precision computer controlled machinery such as robotic systems is the dynamic response limitation of their actuation mechanisms. This is particularly the case when revolute joints are used in the construction of a machine, thereby resulting in systems with highly nonlinear dynamics. In such systems, even if the joint motion trajectories were synthesized with low harmonic contents, the actuating torques required for accurate tracking of the synthesized motions would contain high harmonic components. The higher harmonic components are generated to the nonlinearity in the dynamics and kinematics of the system. As the operating sped of such machines is increased, the high harmonic component of the required actuating torques become more significant and at some point move beyond the dynamic response limitations of the main drives. The performance of the system would therefore start to degrade and vibration and control begins to become problematic. In this paper, a method is presented for minimizing the high harmonic components of the required actuating torques using smart materials based actuators. The effective dynamic response of the system drives is thereby enhanced. In this paper, the development of the general methodology is presented. The method is then applied to a plane 2R robot manipulator. The effectiveness of the proposed approach in reducing the higher harmonic components of the primary drives and thereby enhancing the performance of the system is illustrated by computer simulation.