CONFIGURATION-DEPENDENT VIBRATION CONTROLLABILITY OF FLEXIBLE-LINK MANIPULATORS

In this article, the structural vibration controllability of flexible- link manipulators is discussed For some spatial flexible-link manipula tors, the structural vibration controllability is configuration-depend ent. Therefore, the flexible-link manipulator may have some vibration- uncontrollable configurations. To understand the physical interpretati on of vibration-uncontrollable configurations, we propose the modal ac cessibility concept, which indicates how well the actuators can affect the structural vibration modes. The configuration in which all of the actuators cannot affect at least one of the manipulator's vibration m odes is vibration uncontrollable. Main contributions of this article a re the following two points: first, interesting structural vibration-u ncontrollable configurations are found within the two-link three-joint -type manipulator's workspace and are verified experimentally; second, the modal accessibility index is introduced to indicate how well the corresponding vibration mode is controllable. Experimental results sho w that even in the controllable configurations, it becomes difficult t o suppress vibration if the modal accessibility is small.