This paper compares between three different input shaping feedforward techniques, traditional (TIS), extra insensitive (EI), and modified input shaping (MIS), to reduce the vibration of a flexible link QUANSER system. The main challenge is that the system under test is an underactuated system: it has one input and two outputs. This makes the application of the input shaping techniques not utilizable directly. We therefore first propose to use a variable change at the output in order to make the process equivalent to a monovariable system without modification of the behavior and of the objective of the control. The experimental tests demonstrate the efficiency of the technique and the different results from the three control techniques are compared and discussed. It comes out that EI shapers are the most efficient in term of robustness. MIS shaper has a shorter length than that of a corresponding TIS shaper; however both shapers have the same ability of vibration suppression. Also MIS scheme is easier than the traditional scheme because the numerical optimization is unnecessary in the design of the MIS shaper. MIS shaper has an advantage over a TIS corresponding shaper in being capable of suppressing multimode of vibration.
KEYWORDS: Feedback control, Actuators, Feedback control, Sensors, Control systems, Vibration control, Systems modeling, Data modeling, Matrices, Control systems design, Error control coding
This paper deals with the control of a two degrees of freedom (2-DOF) piezoelectric cantilever actuator which is characterized by badly damped oscillations, hysteresis nonlinearity and cross-couplings. First, a feedforward control scheme based on the zero placement technique is introduced to annihilate the oscillations. Then a disturbance observer and a disturbance compensator are introduced to reduce the effects of low frequencies phenomena (hysteresis and creep) which were approximated by a fictive disturbance. Finally an output feedback scheme based on the linear quadratic regulator is added in order to reduce the cross-couplings effects to improve the tracking performances, and eventually to add robustness. Experiments were carried out and confirm the predicted performances.
This paper deals with the feedforward control of the vibrations of a 2-DOF piezoelectric micropositioner in order to damp the vibrations in the direct axes and in the cross-couplings. The actuator exhibit badly damped vibrations in its direct transfers as well as in the cross-couplings transfers. We therefore propose a bivariable control which does not require sensors to reduce the vibrations in the different axes. The proposed scheme reduces all modes of vibrations for both outputs through extending the monovariable zero placement input shaping technique into bivariable. Experimental tests have been carried out and demonstrate the efficiency of the proposed method.
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