Research On Vibration Control Of Flexible Plate Using Laser Displacement Sensors

Flexible structures like solar panels, manipulators and antennas have played an important role in space field. However, the characteristics that the natural frequencies are low and vibrations of the low-frequency modes are easy to be excited have limited their application development. The large flexible structures like solar panels often consist of several plates which are connected by hinges, which makes the low frequencies denser. The coupled bending and torsional modes vibration will last for along time because there is no air resistance in the space. The long time vibration will have a serious impact on the normal operation of the spacecraft. Therefore, it is particularly important to suppress the vibration of this kind of flexible structures.The laser displacement sensors and piezoelectric patches were selected as the sensor element and actuate element, respectively. The decoupling of the bending and torsional modes on measurement was realized by using two laser displacement sensors. And the decoupling of the bending and torsional modes on driving was realized by placing the bending and torsional actuators separately.The finite element modeling analysis of the two-connected flexible plate on which are bonded several piezoelectric patches was realized by using the four node rectangular plate element. And the influence of the piezoelectric to the modeling was considered. The dynamic equation of the two-connected flexible plate was obtained by using the Hamilton principle, which established the foundation of the simulations of the active vibration control.The PD, RBF neural network sliding mode and fuzzy fast terminal sliding mode controllers were designed for the active vibration control of the flexible plates. The softening of the sign function by using the hyperbolic tangent function has reduced the chattering phenomenon greatly, at the same time, the switching characteristic was partial maintained. The simulations of the vibration control of the first two bending modes and the first torsional mode of the two-connected flexible plate were realized by using the PD and fuzzy fast terminal sliding mode controllers.The experimental platform of the active vibration control system based on non-contact measurement technique was established. The experiments of the vibration control of the flexible cantilever plate using PD and RBF neural network sliding mode controllers were conducted. The experiments of the vibration control of the two-connected flexible plate using PD and fuzzy fast terminal sliding mode controllers were conducted. The experimental results indicated that compared with PD controller, the other two controllers have better control performance, especially for the vibration with low amplitude. The experimental results also verified the validity of the decoupling method.