Robust control with unknown dynamic estimation for multi-axial piezoelectric actuators with coupled dynamics

Transactions of the Institute of Measurement and Control

Rezaei

Sarhan

et al. 2014

Self Cite

In micromanipulation applications, controlling the force exerted on the object is of great importance. In such cases, any uncontrolled forces may damage the object or cause system failure. However, the presence of disturbances such as impedance uncertainties and hysteresis can strongly degrade force control performance and even lead to instability. Therefore, accurate force control when internal and external disturbances occur is a significant challenge. Conventional control methods usually have a number of restrictive conditions especially on the disturbance bounds. To rectify those issues, a modified robust disturbance rejection-based force control approach is proposed in this paper. For this purpose, an appropriate disturbance observer is utilized to estimate the disturbance effect regardless of amplitude. Then a robust control method is employed to achieve the disturbance-free desired dynamic. A modification is also performed to rectify the need for acceleration measurement in the control design. Finally, the force control for an unknown environment in the presence of disturbances is accomplished. The efficiency of the proposed approach is evaluated through simulation studies and compared with the well-known PI method. The experimental results validate the force control performance for the micropositioning piezoelectric actuator.

Section: Control Design For Micropositioning Piezoelectric Actuatorsmentioning

confidence: 99%

Modified robust external force control with disturbance rejection with application to piezoelectric actuators

Transactions of the Institute of Measurement and Control

Rezaei

Sarhan

et al. 2014

Self Cite

“…The second part describes the nonlinear portion of the dynamics, i.e. the hysteresis nonlinearity effect [21]. Fig.…”

Section: Dynamic Modelling Of Micropositioning Piezoelectric Actuatorsmentioning

confidence: 99%

“…The positive definite Lyapunov function candidate V = 1 dT d would be considered. By substituting the closed-loop dynamics(20) and(21) in the time derivative of the Lyapunov function:…”

mentioning

confidence: 99%

Disturbance rejection-based robust control for micropositioning of piezoelectric actuators

Comptes Rendus. Mécanique

Rezaei

Zareinejad

et al. 2013

Self Cite

Precise control of piezoelectric actuators used in micropositioning applications is strongly under the effect of internal and external disturbances. Undesired external forces, unmodelled dynamics, parameter uncertainties, time variation of parameters and hysteresis are some sources of disturbances. These effects not only degrade the performance efficiency, but also may lead to closed-loop instability. Several works have investigated the positioning accuracy for constant and slow time-varying disturbances. The main concern is controlling performance and also the presence of time-varying perturbations. Considering unknown source and magnitude of disturbances, the estimation of the existing disturbances would be inevitable. In this paper, a compound disturbance observer-based robust control is developed to achieve precise positioning in the presence of time-varying disturbances. In addition, a modified disturbance observer is proposed to remedy the effect of switching behaviour in the case of slow time variations. A modified Prandtl-Ishlinskii (PI) operator and its inverse are utilized for both identification and real-time compensation of the hysteresis effect. Experimental results depict that the proposed approach achieves precise micropositioning in the presence of estimated disturbances.

Nonlinear vibration analysis of piezoelectric bending actuators: Theoretical and experimental studies

Shahabi

Comptes Rendus. Mécanique

Taghvaeipour

2019

Piezoelectric bimorph actuators are used in a variety of applications, including micro positioning, vibration control, and micro robotics. The nature of the aforementioned applications calls for the dynamic characteristics identification of actuator at the embodiment design stage. For decades, many linear models have been presented to describe the dynamic behavior of this type of actuators; however, in many situations, such as resonant actuation, the piezoelectric actuators exhibit a softening nonlinear behavior; hence, an accurate dynamic model is demanded to properly predict the nonlinearity. In this study, first, the nonlinear stress-strain relationship of a piezoelectric material at high frequencies is modified. Then, based on the obtained constitutive equations and Euler-Bernoulli beam theory, a continuous nonlinear dynamic model for a piezoelectric bending actuator is presented. Next, the method of multiple scales is used to solve the discretized nonlinear differential equations. Finally, the results are compared with the ones obtained experimentally and nonlinear parameters are identified considering frequency response and phase response simultaneously. Also, in order to evaluate the accuracy of the proposed model, it is tested out of the identification range as well.