Trajectory control of flexible link robots, overhead cranes and mobile robots in formation
Description
This thesis presents trajectory-tracking control of flexible-link robots, overhead cranes, and multiple mobile robots in formation. Firstly, a new model-based trajectory control is proposed for the control of one-link flexible robots. The proposed control guarantees asymptotic stability with all internal signals bounded. Next, a distributed-parameter dynamic model, consisting of two ordinary differential equations and one partial differential equation, is derived using the extended Hamilton's principle for a two-link rigid/flexible robot. A collocated trajectory-tracking control scheme is designed based on the distributed-parameter dynamic model. With only two joint actuators, the proposed control guarantees stability throughout the entire trajectory control and asymptotic stability at desired goal positions. The proposed control is free from the so-called spillover instability Secondly, a sliding-mode anti-swing trajectory control is proposed for overhead cranes with high-speed load hoisting. In association with a new anti-swing motion-planning scheme, the proposed control realizes a typical anti-swing trajectory control in practice, allowing high-speed load-hoisting motion and sufficient damping of load swing. Lyapunov stability theorem is applied for the stability analysis of all of the above theoretical results, and the effectiveness is evaluated with control experiments Thirdly, a new formation control scheme is proposed for a group of mobile robots based on multi-objective potential forces. The angle of the potential force, with respect to the global coordinate system, is used to generate trajectories for the navigation of a group of nonholonomic mobile robots. A smooth and continuous control law is designed to reduce the global orientation error asymptotically to zero while maintaining proper formation for a target configuration. Finally, a trajectory-tracking control is designed for a group of nonholonomic mobile robots in a virtually structured formation. A real-time trajectory modification scheme is presented such that the center of the mobile robots tracks a desired trajectory. Lyapunov stability theorem is applied as the mathematical design tool. Moreover, an obstacle avoidance mechanism is designed based on a formation controller such that a mobile robot can escape from concave-shaped obstacles