(Georgia Institute of Technology, 1995-09)
Lew, Jae Young; Cannon, David W.; Magee, David P.; Book, Wayne J.
Pacific Northwest Laboratory (PNL) researchers investigated the combined use of two control approaches to minimize micro/macro-manipulator structural vibration: 1) modified input shaping and 2) inertial force active damping control. Modified input shaping (MIS) is , used as a feedforward controller to modify reference input by canceling the vibratory motion. Inertial force active damping (IF AD) is applied as a feedback controller to increase the system damping and robustness to unexpected disturbances. Researchers implemented both control schemes in the PNL micro/macro flexible-link manipulator testbed collaborating with Georgia Institute of Technology. The experiments, successfully demonstrated the effectiveness of two control approaches in reducing structural vibration. Based on the results of the experiments, the combined use of two controllers is recommended for a micro/macro manipulator to achieve the fastest response to commands while canceling disturbances from unexpected forces.
(Georgia Institute of Technology, 1983-12)
Book, Wayne J.
Improving the performance of most engineering systems requires the ability to model the system’s behavior with improved accuracy. The evolution of the mechanical arm from teleoperator and crane to present day industrial and space robots and large space manipulators is no exception. Initial simple kinematic and dynamic models are no longer adequate to improve performance in the most critical applications. 130th the mechanical system and control system require improved models for design simulation. Proposed new control algorithms require dynamic models for control calculation. Manning and programming activities as well as man-in-the-loop simulation also require accurate models of the arms. Accuracy is usually acquired at some cost. 'The application of mechanical arms to economically sensitive endeavors in industry and space also gives incentive to improve the efficiency of the formulation and simulation of dynamic models. Control algorithms and man-in-the-loop simulation require "real time" calculation of dynamic behavior. Formulation of the dynamics in an easy to understand conceptual approach is also important if maximum use of the results is to be obtained. The nonlinear equations of motion for flexible manipulator arms consisting of rotary joints connecting two flexible links are developed. Kinematics of both the rotary joint motion and the link deformation are described by 4x4 transformation matrices. The link deflection is assumed small so that the link transformation can be composed of summations of assumed link shapes. The resulting equations are presented as scalar and 4x4 matrix operations ready for programming. The efficiency of this formulation is compared to rigid link cases reported in the literature.