Bistable morphing composites have shown promising applications in energy harvesting due to their capabilities to change their shape and maintain two different states without any external loading. In this review article, the application of these composites in energy harvesting is discussed. Actuating techniques used to change the shape of a composite structure from one state to another is discussed. Mathematical modeling of the dynamic behavior of these composite structures is explained. Finally, the applications of artificial-intelligence techniques to optimize the design of bistable structures and to predict their response under different actuating schemes are discussed.

https://www.mdpi.com/2073-4360/14/9/1893/pdf?version=1651762488

Bistable Morphing Composites for Energy-Harvesting Applications

Piezoelectric transduction has been an emerging concept, especially in the aerospace industry for sensor networking and onboard generation of reliable electrical energy. A significant gap has been noticed in the generalized and multimodal analytics of piezoelectric sensors for wind energy harvesting. Therefore, herein, a simplified yet effective transfer‐function ‐based, experimentally validated analytical model of the piezoelectric sensor is presented. MATLAB is utilized to analyze the proposed model for two different categories of piezoelectric sensors (ie, PIC‐255, and PZT‐5A) under the various conditions of wind speed, piezoelectric configuration, and piezoelectric geometrical features. The developed model has also shown the promising features of flutter energy harvesting, and limit cycle oscillations (LCOs) that play an imperative role in aerospace applications such as energy harvesting from unmanned aerial vehicles (UAVs). Results emphasize that under the same parametric, and geometric conditions, the PZT‐5A harvester reaches quickly to critical flutter mode as compared to PIC‐255. Subsequently, the PZT‐5A harvester is capable of generating 7.105 mW during the particular region of the limit cycle oscillations (LCOs). Based on the outcomes of multimodal analytics, the proposed model is best suited to both conventional wind energy harvesting (Up to nominal range) and flutter harvesting (Critical limit), making it suitable for aerospace applications. It is also recommended to utilize the model for piezoelectric vibrational energy scavengers by incorporating the additional parameters of the structure in the developed transfer function of the piezoelectric sensor.

Multimodal piezoelectric wind energy harvester for aerospace applications

Vibration energy harvesters in industrial applications usually take the form of cantilever oscillators covered by a layer of piezoelectric material and exploit the resonance phenomenon to improve the generated power. In many aeronautical applications, the installation of cantilever harvesters is not possible owing to the lack of room and/or safety and durability requirements. In these cases, strain piezoelectric harvesters can be adopted, which directly exploit the strain of a vibrating aeronautic component. In this research, a mathematical model of a vibrating slat is developed with the modal superposition approach and is coupled with the model of a piezo-electric patch directly bonded to the slat. The coupled model makes it possible to calculate the power generated by the strain harvester in the presence of the broad-band excitation typical of the aeronautic environment. The optimal position of the piezoelectric patch along the slat length is discussed in relation with the modes of vibration of the slat. Finally, the performance of the strain piezoelectric harvester is compared with the one of a cantilever harvester tuned to the frequency of the most excited slat mode.

/pdf/vibration-energy-harvesting-by-means-of-piezoelectric-1jc7fk04.pdf

Vibration Energy Harvesting by Means of Piezoelectric Patches: Application to Aircrafts

Biomedical electric devices provide great assistance for health and life quality. However, their maintainable need remains a serious issue for the restricted duration of energy storage. Therefore, scientists are investigating alternative technologies such as nanogenerators that could harvest the mechanical energy of the human heart to act as the main source of energy for the pacemaker. Cardiac contraction is not a source for circulation; it utilizes body energy as an alternative energy source to recharge pacemaker devices. This is a key biomedical innovation to protect patients’ lives from possible risks resulting from repeated surgery. A batteryless pacemaker is possible via an implantable energy collecting tool, exchanging the restriction of the current batteries for a sustainable self-energy resource technique. In this context, the physiology of heart energy in the preservation of blood distribution pulse generation and the effects of cardiac hormones on the heart’s pacemaker shall be outlined. In this review, we summarized different technologies for the implantable energy harvesters and self-powered implantable medical devices with emphasis on nanogenerator-based sensors for energy harvesting from cardiac contraction. It could conclude that recent hybrid bio-nanogenerator systems of both piezoelectric and triboelectric devices based on biocompatible biomaterials and clean energy are promising biomedical devices for harvesting energy from cardiac and body movement. These implantable and wearable nanogenerators become self-powered biomedical tools with high efficacy, durability, thinness, flexibility, and low cost. Although many studies have proven their safety, there is a need for their long-term biosafety and biocompatibility. A further note on the biocompatibility of bio-generator sensors shall be addressed.

/pdf/nanogenerator-based-sensors-for-energy-harvesting-from-2923gn77.pdf

Nanogenerator-Based Sensors for Energy Harvesting From Cardiac Contraction

Direct visual servoing and interaction control for a two-arms on-orbit servicing spacecraft

In robotic teleoperation, hard impacts between a tool and the manipulated object may impair the success of a task. In order to develop a robotic system that is able to minimize the final velocity of an object after impact, a comprehensive approach is adopted in this work, and the effect on the impact of the parameters of the tool and of the robot is studied. Mass, contact stiffness and damping, robot compliance and control and tool compliance are taken into account. A mathematical model including the tool and the robot moving along the approach direction shows that, in most conditions, robot compliance is not enough to mitigate the impact. A mechanical decoupling between the inertia of the tool and the inertia of the robot is needed. An elastic system based on a bi-stable mechanism is developed and its validity is shown by means of numerical simulations.

https://www.mdpi.com/2076-3417/10/24/9077/pdf

Effect of End-Effector Compliance on Collisions in Robotic Teleoperation

The vibrations of a Cartesian cutting machine caused by the pneumatic tool are studied with a sub-system approach. The cutting head is modeled as an equivalent robot arm which is able to mimic the measured resonances. The Cartesian structure is modeled according to the mode superposition approach. A global analytical model is obtained coupling the aforementioned models, and is solved in MATLAB. The full model is able to predict the variations in the response of the machine to tool excitation that are caused by the motion of the head along the rails of the Cartesian structure. Comparisons with experimental results are made.

https://www.mdpi.com/2075-1702/9/8/162/pdf

Analysis and Control of Vibrations of a Cartesian Cutting Machine Using an Equivalent Robotic Model


 In robotics the risk of collisions is present both in industrial applications and in remote handling. If a collision occurs, the impact may damage both the robot and external equipment, which may result in successive imprecise robot tasks or line stops, reducing robot efficiency. As a result, appropriate collision avoidance algorithms should be used or, if it is not possible, the robot must be able to react to impacts reducing the contact forces. For this purpose, this paper focuses on the development of a special end-effector that can withstand impacts. It is able to protect the robot from impulsive forces caused by collisions of the end-effector, but it has no effect on possible collisions between the links and obstacles. The novel end-effector is based on a bi-stable mechanism that decouples the dynamics of the end-effector from the dynamics of the robot. The intrinsically non-linear behavior of the endeffector is investigated with the aid of numerical simulations. The effect of design parameters and operating conditions are analyzed and the interaction between the functioning of the bi-stable mechanism and the control system is studied. In particular, the effect of the mechanism in different scenarios characterized by different robot velocities is shown. Results of numerical simulations assess the validity of the proposed end-effector, which can lead to large reductions in impact forces. Numerical results are validated by means of specific laboratory tests.

Development and validation of an end-effector for mitigation of collisions

This paper deals with the control of the vibrations of an automatic cutting machine with a cartesian kinematic chain. A particular application of the method of structural modifications is considered, since a small number of frequency response function is available. The Sherman-Morrison formula is used to predict the effect of a tuned vibration absorber (TVA) on the vibrations of the machine generated by the cutting tool; the advantages and the limits of this method are discussed. In order to improve the cutting speed, the cutting head moves along the linear guides with relevant accelerations that can excite the TVA, motion induced vibrations are analyzed with a lumped element model.

Domenico Tommasino

Papers

Vibration Energy Harvesting by Means of Piezoelectric Patches: Application to Aircrafts

Effect of End-Effector Compliance on Collisions in Robotic Teleoperation

Analysis and Control of Vibrations of a Cartesian Cutting Machine Using an Equivalent Robotic Model

Development and validation of an end-effector for mitigation of collisions

Control of the Vibrations of a Cartesian Automatic Machine