Abstract
This paper presents a method of collision detection and control for parallel-structured two-link flexible manipulators based on the unscented Kalman filter. The exact dynamics of parallel-structured two-link flexible manipulators are described by quite complex nonlinear partial and ordinary differential equations. In this paper, the proposed parallel-structured two-link flexible manipulators are approximately modeled by a two-link flexible manipulator consisting of a couple of flexible beams with the same boundary conditions. In order to find the time when the flexible manipulator collides with the unlooked-for obstacle, the innovation process of the unscented Kalman filter which is one of the nonlinear state estimators is introduced. As the controller for the manipulator, the sliding mode controller is employed. In the normal situation, the sliding mode controller generates the control torques so that the tip position follows the reference trajectory. When the collision between the flexible manipulator and an unlooked-for obstacle is detected, the objective of the controller is switched from the position control to the suspend control, which is achieved by changing the reference trajectories. The performance of the proposed collision detection algorithm and controller is demonstrated by several numerical simulations.
