ADAPTIVE-CONTROL OF FLEXIBLE STRUCTURES USING MODAL POSITIVE POSITIONFEEDBACK

An adaptive modal positive position feedback (AMPPF) method is present ed for controlling the vibration and shape of flexible structures. The proposed strategy combines the attractive attributes of the independe nt modal space control (IMSC) of Meirovitch and the positive position feedback (PPF) of Goh and Caughey. The controller is designed in the u ncoupled modal space using only modal position signals to damp the vib ration of undamped modes. The parameters of the AMPPF controller are a lso adjusted in an adaptive manner in order to follow the performance of an optimal reference model. In this way, optimal damping and zero s teady state errors can be achieved even in the presence of uncertain o r changing structural parameters. The adaptation laws governing the st able variation in the AMPPF controller parameters are derived using th e Lyapunov stability theorem. The effectiveness of the AMPPF in contro lling the vibration and shape of a variable mass cantilevered beam is demonstrated experimentally. The performance obtained with the AMPPF a lgorithm is compared with those of other classical control algorithms. The results obtained emphasize the potential of the AMPPF algorithm a s an efficient means for controlling flexible structures with uncertai nties in real time. (C) 1997 by John Wiley & Sons, Ltd.