Implementation of an adaptive piezoelectric sensoriactuator

Abstract

An adaptive algorithm implemented on a digital signal processor is used in conjunction with an analog multiplier circuit to compensate for the feedthrough capacitance of a piezoelectric sensoriactuator. The mechanical response of the piezoelectric sensoriactuator is resolved from the electrical response by adaptively altering the gain imposed on the electrical circuit used for compensation. For broadband, stochastic input disturbances, the feedthrough dynamic capacitance of the sensoriactuator can be identified on-line, providing a means of implementing directrate-feedback control in analog hardware. Rate feedback control is demonstrated on a cantilevered beam using the hybrid/adaptive circuit. The ability of the circuit to readapt to a change in capacitance is demonstrated by a simple experiment.= volts, voltage w = digital filter weight 3 = partial differential operator S (n) = Dirac delta function 0 = electromechanical coupling matrix of piezoceramic I.L = convergence parameter </>xy(n) -discrete correlation function between x(n) and y(ri) J7 2 = matrix of natural frequencies V = gradient operator Subscripts DSP = digital signal processor elec = electrical mech = mechanical Out = output signal p = piezoceramic pa = power amplifier R = reference leg 01 = leg 1 of conditioning circuit 02 = leg 2 of conditioning circuit 03 = leg 3 of conditioning circuit

Modal Sensitivity and Selectivity of Small, Rectangle-Shaped Piezoelectric Transducers Used as Sensors and Actuators in Active Vibroacoustic Control Systems

“…The examples of implementations of the first method have been described i.e. by Dosch [12], Anderson and Hagood [11] and Vipperman [13,14]. One of the main disadvantages of this solution is the presence of the high actuator driving signal and the low sensing signal simultaneously at the input of the signal conditioning circuit.…”

“…The excitation function can be then expressed as follows [1]: (13) where δ′(·) is the derivative of the Dirac delta function, H(·) is the Heaviside step function, E is the Young's modulus of the structure, K f is the material-geometric constant dependent of material properties of the piezo-ceramics and type of actuator (symmetric or antisymmetric) [1] and s a is the strain of the actuator (the same in the x-and y-direction, because of the transversal-isotropy in the xy-plane) caused by the applied driving voltage V which generates within the piezo-element a uniform electric field in the z-direction, E 3 = V/h p , therefore: (14) where d 3 is the relevant piezoelectric material constant (d 3 ϵ d 311 = d 322 from the strain-charge form of piezoelectric constitutive relation). The effects of added mass and stiffness introduced by the actuator as well as a longitudinal strain of the structure (resulting from the transverse asymmetry of the actuator) are neglected in the present considerations.…”

“…The first one -which is simpler and more practical, yet not always feasible due to the possible lack of access to both sides of a structure -is to attach the transducers symmetrically to the both surfaces of a thin beam or plate [1,10]. The second solution involves the use of a single piezoelectric element as sensor and actuator simultaneously [11][12][13][14][15]. The advantages of such a solution with respect to the functionality of the control system are significant, but the necessary complications of the corresponding electronic circuits together with a requirement to meet very stringent parameters make it impractical.…”

Experimental robust control of structural acoustic radiation

“…An adaptive algorithm actively adjusts reference circuitry so that the piezoelectrics can accurately sense vibrations while simultaneously being used as actuators. Theory behind the sensoriactuator design can be found in Cole and Clark, (1994) and details of its implementation are described in Vipperman and Clark (1996).…”

Active self-sensing scheme development for structural health monitoring

“…One of the important characteristics of the PZT materials is that it can be used for simultaneous sensing and actuation. This feature of the PZT materials is called self-sensing here, and the advantages of a self-sensing scheme include: (1) the pulse-echo time reversal method can be achieved using only a single PZT wafer (Fink, 1999), (2) sensor diagnosis schemes can be implemented based on self-sensing to monitor sensors' performance and integrity (Lee et al,2006), (3) a single PZT wafer can be used to suppress undesired vibrations (Cole and Clark, 1994;Dosch et al, 1992;Vipperman and Clark, 1996). The ultimate goal of this study is to apply self-sensing to guided wave propagation.…”