Jamil M. Renno

Modeling of piezoelectric energy harvesting from an l-shaped beam-mass structure with an application to UAVs

Cantilevered piezoelectric energy harvesters have been extensively investigated in the literature of energy harvesting. As an alternative to conventional cantilevered beams, this article presents the L-shaped beam-mass structure as a new piezoelectric energy harvester configuration. This structure can be tuned to have the first two natural frequencies relatively close to each other, resulting in the possibility of a broader band energy harvesting system. This article describes the important features of the L-shaped piezoelectric energy harvester configuration and develops a linear distributed parameter model for predicting the electromechanically coupled voltage response and displacement response of the harvester structure. After deriving the coupled distributed parameter model, a case study is presented to investigate the electrical power generation performance of the L-shaped energy harvester. A direct application of the L-shaped piezoelectric energy harvester configuration is proposed for use as landing gears in unmanned air vehicle applications and a case study is presented where the results of the L-shaped — energy harvester — landing gear are favorably compared against the published experimental results of a curved beam configuration used for the same purpose.

Generalized Design of an Anti-swing Fuzzy Logic Controller for an Overhead Crane with Hoist

The behavior of many mechanical systems, such as overhead cranes, can be predicted through intuitive observation of their motion under various forces. Mathematical modeling of an overhead crane shows that it is highly coupled. Nonetheless, it is surprisingly easy for an experienced crane operator to drive payloads to target positions with minimal cable swing. This observation naturally promotes the use of fuzzy logic to control overhead cranes. Traditionally, fuzzy logic controllers of overhead cranes were presented for specific crane system/motion parameters. This work presents a novel approach for automatically creating anti-swing fuzzy logic controllers for overhead cranes with hoisting. The model of the crane includes the distributed mass of the cable. The presented approach uses the inverse dynamics of the overhead crane and the desired motion parameters to determine the ranges of the variables of the controllers. The control action is distributed among three fuzzy logic controllers (FLCs): The travel controller, hoist controller, and anti-swing controller. Simulation examples show that the proposed controller can successfully drive overhead cranes under various operating conditions.

Inverse Dynamics Based Tuning of a Fuzzy Logic Controller for a Single-Link Flexible Manipulator

Since its introduction to engineering applications, fuzzy logic has attracted many researchers because of its simplicity and robustness. Experience with a system is translated into heuristic rules which can be used to control that system. This article proposes a novel method for a generalized inverse dynamics based fuzzy logic controller (FLC) of a single-link flexible manipulator. The deflection of the flexible link was modeled using the assumed modes method. The control action is distributed between two FLCs: A joint angle controller and a tip controller. Each controller produces a torque value. The torque values are summed, and the resulting control action is used to drive the manipulator. A novel method for varying the ranges of the variables of the two controllers as a function of the motion parameters and the inverse dynamics of the system is presented. The relative shapes and distribution of the fuzzy membership sets (with respect to each other) are kept fixed. Simulation results show that joint trajectory tracking is accomplished, and that the residual vibration of the flexible link is suppressed.

Effects of system parameters and damping on an optimal vibration-based energy harvester

The authors present a comprehensive study of the effects of damping and electromechanical coupling on the power optimality of a vibration-based energy harvester. The harvester under consideration utilizes a piezoceramic element operating in the {33} mode to scavenge mechanical energy emanating from a sinusoidal-base excitation. Under typical operating conditions, the piezoceramic element is subjected to small strains and low electric fields, which allows for the adaptation of the linear small-signal constitutive law to model its behavior. To optimize the harvested power, previous researches neglected the role of mechanical damping. This lead to results suggesting that the optimal-harvesting frequencies are not effected by mechanical damping. However, in this paper, exact expressions for the optimal frequency ratios that account for damping are derived. The results show that mechanical damping affects the optimal frequency ratios and optimal harvested power qualitatively and quantitatively. The effects of the electromechanical coupling coefficient is also explored. It is observed that there is an optimal value of the coupling coefficient beyond which the harvested power decreases. This result breaks the taboo suggesting that larger electromechanical coupling culminates in more efficient energy harvesting devices. Additionally, it is shown that at the optimal frequencies, and optimal load resistance, increasing the electromechanical coupling saturates the harvested power

Experimentally Validated Model of a Membrane Strip with Multiple Actuators

This paper presents the modeling and experimental validation of a membrane strip actuated in bending and tension. This investigation is a prelude to the modeling of a circular membrane augmented with smart actuators around its outer rim. Two macrofiber composite bimorph actuators are attached near the ends of the membrane strip.Wetreat two configurations. In the first configuration, both bimorph actuators are excited in bending to change the shape of the membrane strip. In the second configuration, one bimorph acts in bending and the other bimorph acts in tension. The membrane strip is modeled as a nonuniform, nonhomogenous, Euler–Bernoulli beam under tension. The finite element method is used to facilitate the handling of the nonuniformities of the combined structure. Experimental results are used to validate the model developed. The prediction of the finite element model and the experimental results are in agreement

A General Anti-swing Fuzzy Controller for an Overhead Crane with Hoisting

Several fuzzy control schemes of overhead cranes have been proposed. Most of these schemes are valid for a specific crane configuration only. Extensive experimentation is needed to apply such schemes to a different crane. This paper presents an approach for automatically creating anti-swing fuzzy logic controllers for two-dimensional overhead cranes with hoisting. Inverse dynamics and desired motion parameters of the overhead crane are used to determine the ranges of the variables of the controllers. The control action is divided into two phases. In the first phase, two fuzzy logic controllers (FLCs) drive the system toward its final destination: travel controller and hoist controller. The second phase is initiated after this point. It includes an anti-swing controller in addition to the travel and hoist controllers. The simulation example presented shows that the proposed controller can successfully drive overhead cranes under various operating conditions.

Piezoelectric energy harvesting from an L-shaped beam-mass structure

Cantilevered piezoelectric harvesters have been extensively considered in the energy harvesting literature. Mostly, a traditional cantilevered beam with one or more piezoceramic layers is located on a vibrating host structure. Motion of the host structure results in vibrations of the harvester beam and that yields an alternating voltage output. As an alternative to classical cantilevered beams, this paper presents a novel harvesting device; a flexible L-shaped beam-mass structure that can be tuned to have a two-to-one internal resonance to a primary resonance ω2 ≅ 2ω1 which is not possible for classical cantilevers). The L-shaped structure has been well investigated in the literature of nonlinear dynamics since the two-to-one internal resonance, along with the consideration of quadratic nonlinearities, may yield modal energy exchange (for excitation frequency ω≅ ω1or the so-called saturation phenomenon (for ω≅ω2). As a part of our ongoing research on piezoelectric energy harvesting, we are investigating the possibility of improving the electrical outputs in energy harvesting by employing these features of the L-shaped structure. This paper aims to introduce the idea, describes the important features of the L-shaped harvester configuration and develops a linear distributed parameter model for predicting the electromechanically coupled response. In addition, this work proposes a direct application of the L-shaped piezoelectric energy harvester configuration for use as landing gears in unmanned air vehicle applications.

Dynamic Modeling of Segmented Ionic Polymer Metal Composite (IPMC) Actuator

In this paper, we introduce an analytical modeling approach for dynamic shape characterization of the ionic polymer metal composite (IPMC) actuator under the input voltages based on the RC electrical model and mechanical beam model. The proposed method can be used for modeling the general IPMC bending actuator in a single segment or multiple segments or patterned form. The segmented design offers more flexibility in controlling the shape of the actuator when compared with the single-segment design as it can be used to generate undulatory wave form instead of a simple oscillation form. Considering the inherent nature of large deformation in the IPMC actuator, a large deflection beam model is developed and augmented with the electrical RC model to present a state space model of the actuator system. Experimental results are compared with the computer simulated IPMC actuator model to validate the proposed model

Nonlinear Control of a Membrane Mirror Strip Actuated Axially and in Bending

The sliding mode technique is used to control the deformation of a membrane mirror strip augmented with two macrofiber composite bimorphs located near the ends of the strip. The first bimorph is actuated in bending and the second is actuated axially. The structure is modeled as an Euler-Bernoulli beam under tensile load and the macrofiber composite patches are modeled as monolithic piezoceramic wafers. To cast the system into a finite-dimensional state-space form, the finite element method is used, and the model presented accounts for the dynamics of the augmented bimorphs. The membrane strip is placed under uniform tension. Because one of the bimorphs acts axially, the resulting tension in the membrane strip is discontinuous at the location of this bimorph and, consequently, the obtained model is nonlinear. First, we validate the model experimentally by considering the system in its quasi-linear state, then we consider the control problem. We formulate the regulation problem by using the sliding mode technique. Additionally, to allow coupling this system with an adaptive optics scheme, the shape-control problem is considered as well. The control law uses both actuators: the bending and axial bimorphs. However, a system singularity dictates using a switching command to avoid this singularity. Various examples are presented for the regulation and shape-control problems. The simulation results demonstrate the efficacy of the proposed control law.

Anti-Swing Adaptive Fuzzy Controller for an Overhead Crane with Hoisting

This paper presents a novel method for adaptive anti-swing fuzzy logic control for overhead cranes with hoisting. The control action is distributed between three fuzzy logic controllers (FLC’s): trolley controller, hoist controller, and anti-swing controller. A method for varying the ranges of the variables of the three controllers as a function of the crane’s parameters and/or motion variables is presented. Simulation examples show that the proposed controller can successfully drive overhead cranes under various operating conditions.Copyright