Vibration control of a slewing smart link

Document Type

Conference Proceeding

Publication Date



Department of Mechanical Engineering-Engineering Mechanics


In this paper we present an Output Feedback Sliding Mode Control (OFSMC) architecture for a slewing flexible structure. This system consists of (1) a single-axis servo DC motor and encoder for rigid motion slewing and (2) a graphite/epoxy composite smart link with embedded strain sensors/actuators for active vibration suppression. The results of this study include the analytical development, numerical simulation and preliminary experimental results. The OFSMC algorithm uses the output sensor data from the encoder and strain sensor along with filters to derive velocity information to compute the control for the motor and strain actuators. Near-minimum time maneuvers based on an equivalent rigid structure are used to slew the flexible active structure. Numerical simulation studies were performed to compare the benefits of using active rather than passive structures. A nonlinear optimization algorithm was used to determine optimal gains for the OFSMC to produce a rest-to-rest, residual vibration-free, 90° near-minimum time maneuver. Several case studies are reviewed that involve optimization of controller gains to minimize a cost function composed of tracking error and residual tip deflection errors. Preliminary experimental studies were performed for both passive and active operational modes. Only empirical controller gains were used. Both numerical and experimental results show a reduction in residual vibration for the active structure case.

Publisher's Statement

© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Publisher’s version of record:

Publication Title

Proceedings of SPIE - The International Society for Optical Engineering