The Tip Trajectory Tracking Of Flexible Manipulators Based On Advanced Control Algorithms

Flexible manipulators are more and more widely used in industry and space, for their quick-speed, light-weight and high ratio of load to self-weight. However, flexible manipulators will vibrate during motion owing to its flexibility, which decreased the accuracy of tip trajectory tracking. To solve the problem, in this paper, the tip trajectory tracking of flexible manipulators based on advanced control algorithms is mainly studied, including:1,Current research progress of the tip trajectory tracking of flexible manipulators is summarized. The methods of modeling of flexible manipulators are introduced, the background and meaning of tip trajectory tracking is analyzed, and the existing problems as well as strategies of the tip trajectory tracking flexible manipulators are discussed and compared.2,The dynamic modeling of flexible manipulators is studied. Flexible manipulators are complex system of non-linear, tight-coupling and time-varying. Based on model of Euler-Berlouli beam, assumed modes methods are used to describe flexible deflection and Lagrange equation are introduced to develop the dynamic equation of flexible manipulators. After some simplification to the dynamic equation, simulation test is taken to study the characteristic of flexible manipulators.3,The tip trajectory tracking control strategies of flexible manipulators with exact modeling are studied. The internal dynamics instability is the prime problem encountered in tip trajectory tracking of flexible manipulators. Using the technique of input-output linearization, the optimal control theory is introduced to constitute state feedback. Through the design of linear quadratic tracker, a trade-off among the tracking performance, the elastic variables and the control input is made in the control system to avoid the unstable internal dynamics, and high accurate tip tracking is obtained. Simulation results show that exact tip tracking is accomplished if the model of flexible manipulators is totally exact.4,The tip trajectory tracking control strategies of flexible manipulators with inexact modeling are studied. Model inaccuracy is another problem in tip trajectory tracking of flexible manipulators. Predictive control algorithm is utilized here, whose inner optimal control character can assure internal dynamics stability. Besides, the optimal control law and the torques to drive the joints of the flexible manipulator are separately computed to improve computation speed, and the actual output data are brought in to compensate for model deviation. Simulation results show that the algorithm can effectively overcome the adversity of internal dynamics instability and model inaccuracy with desirable real-time computation speed. 5,SimMechanics toolbox is used to build flexible manipulator model, and the validity of control strategies present in this paper are testified through this model.Finally, the work of this dissertation is summarized and the prospective of further research on the tip trajectory tracking of flexible manipulators is discussed.