Kougen Ma

This paper focuses on a novel adaptive filtering algorithm, hybrid adaptive control scheme and their application to real-time vibration control of smart structures. A novel adaptive filtering algorithm is presented and compared with the least mean square algorithm, showing a faster convergence rate, better noise-smoothing capability and wider search field. A hybrid adaptive control scheme is then proposed and analyzed. The scheme takes advantage of both feedback control and feedforward control and provides the high damping, fast vibration suppression, good robustness and easy realization due to small computation complexity. The novel adaptive filtering algorithm and the hybrid control scheme are verified on a cantilever beam with four bonded PZT patches. Satisfactory vibration reduction has been observed for both single-input and single-output, and multi-input and multi-output, control cases under sinusoidal, swept frequency sinusoidal and random disturbances, confirming the reliability and validity of the novel adaptive filtering algorithm and the hybrid adaptive control scheme.

This paper focuses on a frequency-weighted hybrid adaptive control with application to simultaneous precision positioning and vibration suppression of smart composite structures. Following the introduction of the structure and materials system of an active composite panel (ACP) with a surface-mounted and two embedded piezoelectric ceramic patches, the sensor selection for the purpose of precision positioning or vibration control is discussed, and the function assignment of a laser displacement sensor as well as the embedded piezoelectric sensor is determined for the ACP. The frequency-weighted hybrid adaptive control approach is then developed. The approach consists of an adaptive feedforward position controller for precision positioning, an adaptive feedforward vibration controller for vibration suppression as well as an adaptive feedback controller for both precision positioning and vibration suppression. The frequency-weighted filters introduced in the approach realize the signal fusion of the two sensors. Finally, experiments are also performed for harmonic disturbances at the first two natural frequencies of the ACP and a random disturbance for both cases of with/without the adaptive feedforward vibration controller, demonstrating that the frequency-weighted hybrid adaptive control approach can provide satisfactory precision positioning and vibration suppression in both cases, and that better position accuracy can be achieved if the adaptive feedforward vibration controller is also employed.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Simultaneous adaptive positioning and vibration control of a flexible active composite manipulator with two piezoelectric patches and an active strut are investigated in this paper. First, the configuration of the manipulator is described, and then its dynamics is analyzed. An adaptive fuzzy logic control (AFLC) strategy and an independent modal space adaptive control (IMSAC) scheme are proposed for the active strut motion control and for the manipulator vibration control, respectively. In the AFLC, an adaptive input scaling concept is introduced to adaptively adjust the input of a traditional fuzzy logic controller. As a result, an inverse dead zone is gained to compensate the existing strut dead zone and overcome the dead zone effects. In the IMSAC, a novel adaptive feedback control scheme is developed using the adaptive filtered-x algorithm that is commonly used for adaptive feedforward control. Simulations and experiments demonstrate that the AFLC can provide very accurate positioning control with a relative steady-state positioning error of 0.06%, and that the IMSAC raises the damping ratios of the first two modes of the flexible manipulator 10 times and substantially suppresses the vibration induced by the manipulator motion. </para>