Sliding mode control design of an electrostatic microactuator using LPV schemes

Abstract

This paper presents preliminary results of a robust linear parameter varying (LPV)-based sliding mode voltage controller for a parallel-plate electro-static microactuator. The controller design aims to extend the travelling range of the microactuator plates beyond the, so-called, `pull-in' condition, thus taking advantage of an increased range of operation. The designed controller is successful in extending the microactuator's plates operation beyond the pull-in condition with moderate controller complexity, while guaranteeing robustness against matched uncertainty. Results illustrate, that the controller also provides a degree of robustness to unmatched uncertainty (i.e. spring stiffness variation). Appropriate simulation studies, on the nonlinear normalized microactuator model, are employed to assess the efficacy of the proposed controller

Gain Scheduling Control of a Nonlinear Electrostatic Microgripper: Design by an Eigenstructure Assignment With an Observer-Based Structure

“…As such, considering the reference model (13), to assign the eigenvalues to the frozen parameter system (12), we propose to add an observer-based structure by using Proposition 2 [28].…”

“…This is very problematic because large displacements of the actuator are often required to allow the gripping arms to come into contact with objects of various sizes [e.g., [9] reported that most animal cells (including human) range in size between 1 and 100 μm]. These nonlinearities arise from several physical phenomena among which the inplane tension [10], the structural damping [11], the external electrostatic potentials [12], and the side instability [13]. Satisfying robust closed loop performance to comb drive actuators over a wide operating range is very challenging and few studies tackle this problem [14] although it is essential for micromanipulation.…”

Positional Regulation of Electrostatic Micro-electromechanical Actuator via Adaptive Two-stage Sliding Mode Control

“…In practical applications, voltage control is more easily implemented than charge control. (9) Many studies have been published on voltage control approaches, such as static and dynamic output feedback, (10) nonlinear control, (11) passive control, (12) back-stepping control, (13) gain scheduling H∞ control, (14) linear parameter-varying control, (15,16) adaptive fuzzy control, (17) an artificial algorithm method, (18) and extended state observer-based control. (9,19) Among these studies, in Ref.…”

An output feedback LPV control strategy of a nonlinear electrostatic microgripper through a singular implicit modeling

“…Nonlinearities of comb drive actuators are due to electrostatic potentials (Lee et al [2007]) and axial forces acting on compliant mechanisms (Legtenberg et al [1996]). The side instability is also a non-linearity that occurs when the gap spacing between fixed and movable electrodes of the actuator is no longer constant (Alwi et al [2012]). It is therefore very difficult to control such actuators with E-mail: mokrane.boudaoud@isir.upmc.fr;marcelo.gaudenzi@femtost.fr;legorrec@femto-st.fr;yassine.haddab@femto-st.fr; philippe.lutz@femto-st.fr robust performances in a wide operating range.…”

“…They are based on input/output linearization (Maithripala et al [2003]), differential flatness (Zhu et al [2005]), backstepping (Salah et al [2010]) or robust PID (Vagia et al [2008]). Recent works demonstrated the interest of Linear Parameter Varying (LPV) controllers to deal with this non-linearity (Shirazi et al [2011]; Alwi et al [2012]). Such controllers allow driving the actuator beyond the side instability (generally less than 10 µm displacement).…”