Real-time control of a shape memory alloy adaptive vibration absorber

Abstract

The tuned vibration absorber (TVA) is a well established vibration control device. An adaptive TVA (ATVA) is one whose properties can be continuously adapted to maintain optimal tuning. This paper concerns an ATVA with shape memory alloy (SMA) elements: heating or cooling the SMA changes its elastic modulus and hence the effective stiffness and tuned frequency of the ATVA.The emphasis of this paper is placed on control algorithms for real-time adaptation of the ATVA. An error signal is defined in terms of the phase between the velocities of the ATVA mass and the host structure. Various control algorithms are discussed, including proportional, proportional-plus-derivative (PD) and fuzzy control. Discrete and continuous-time implementations are considered, together with control parameter optimization. Numerical simulations and experimental results are presented and compared. The SMA ATVA is seen to be able to adaptively re-tune in the face of a changing disturbance frequency within a fixed range, although the adaptation time is limited primarily by the thermal time constant of the system. The PD controller gives close to the optimum performance while being very simple to implement.<br/