Search Results (39)

Shape Memory Alloy (SMA) actuators are pivotal in modern engineering due to their unique thermomechanical properties, but their inherent non-linearities, hysteresis, and temperature sensitivity pose significant control challenges. This systematic review evaluates artificial intelligence (AI)-based control methodologies to address these limitations, analyzing their efficacy in enhancing precision, adaptability, and reliability for SMA and Magnetic SMA (MSMA) systems. A PRISMA-guided literature review (2003–2025) identified 24 studies, which were categorized by control architectures (hybrid AI-linear, pure AI, adaptive, and model predictive control) and evaluated through quantitative metrics, including Root Mean Square Error (RMSE%) and a weighted scoring system for experimental rigor. Results revealed hybrid AI-linear controllers as the dominant approach (36%), with online-trained neural networks achieving superior accuracy (+2.4%) over offline methods. Feedforward neural networks outperformed recurrent architectures (+3.1%), while Model Predictive Control (MPC) excelled for SMA actuators (+5.8% accuracy) but underperformed for MSMAs (−7.7%). Sensorless strategies proved advantageous for MSMAs (+5.0%), leveraging intrinsic material properties like electrical resistance for state estimation. The analysis underscores AI’s capacity to mitigate hysteresis and non-linear dynamics, though material-specific optimization is critical: SMA systems favor dynamic control and MPC, whereas MSMAs benefit from sensorless AI and pure neural networks. Challenges persist in computational demands for online training and reinforcement learning’s exploration–exploitation trade-offs. Future research should prioritize adaptive algorithms for fatigue compensation, lightweight AI models for embedded deployment, and standardized benchmarking to bridge material-specific performance gaps. This synthesis establishes AI as a transformative paradigm for SMA actuation, enabling precise control in aerospace, biomedical, and soft robotics applications. Full article

Magnetic shape memory alloy-based actuators (MSMA-BAs) have extensive applications in the field of micro-nano positioning technology. However, complex hysteresis seriously affects its performance. To describe the hysteresis of MSMA-BA, this study proposes integrating a hysteresis operator and the rate-of-change function of the input signal into the least squares support vector machine (LS-SVM) framework to construct a rate-dependent dynamic hysteresis model for MSMA-BAs. The hysteresis operator converts the multi-valued mapping of hysteresis into a one-to-one mapping, while the rate-of-change function of the input signal captures the rate dependence of the hysteresis, thereby enhancing the model’s ability to describe complex hysteresis. In addition, with the powerful nonlinear fitting capability and good generalization of LS-SVM, the dynamic performance of the proposed model is effectively improved. Experimental results show that the proposed model accurately describes the hysteresis of MSMA-BA. Full article

This paper explores integrating advanced materials, including magnetic shape memory alloys, magnetorheological fluids, and classical shape memory alloys, within structural elements to achieve exceptional physical properties. When these materials are integrated within structures—whether as wires, actuators, or dampers—they provide the structures with unique static, dynamic, and damping characteristics not commonly found in nature. This study aimed to evaluate the efficacy of these active materials in enhancing the performance of beam-like structures. This investigation was conducted through a comprehensive numerical analysis, focusing on a composite beam. The study examined the impact of different active elements, their position within the structure, and their influence on key dynamic properties. Additionally, a simplified damage scenario was considered, wherein the adverse effects of structural damage were mitigated through the strategic application of these materials. Numerical simulations were carried out using the finite element method, with custom computational codes developed in MATLAB. The findings of these simulations are presented and discussed in this paper. Full article

Flexible grippers are a promising and pivotal technology for robotic grasping and manipulation tasks. Remarkably, magnetorheological (MR) materials, recognized as intelligent materials with exceptional performance, are extensively employed in flexible grippers. This review aims to provide an overview of flexible robotic grippers and highlight the application of MR materials within them, thereby fostering research and development in this field. This work begins by introducing various common types of flexible grippers, including shape memory alloys (SMAs), pneumatic flexible grippers, and dielectric elastomers, illustrating their distinctive characteristics and application domains. Additionally, it explores the development and prospects of magnetorheological materials, recognizing their significant contributions to the field. Subsequently, MR flexible grippers are categorized into three types: those with viscosity/stiffness variation capabilities, magnetic actuation systems, and adhesion mechanisms. Each category is comprehensively analyzed, specifying its unique features, advantages, and current cutting-edge applications. By undertaking an in-depth examination of diverse flexible robotic gripper types and the characteristics and application scenarios of MR materials, this paper offers a valuable reference for fellow researchers. As a result, it facilitates further advancements in this field and contributes to the provision of efficient gripping solutions for industrial automation. Full article

The flexibility and adaptability of soft robots enable them to perform various tasks in changing environments, such as flower picking, fruit harvesting, in vivo targeted treatment, and information feedback. However, these fulfilled functions are discrepant, based on the varied working environments, driving methods, and materials. To further understand the working principle and research emphasis of soft robots, this paper summarized the current research status of soft robots from the aspects of actuating methods (e.g., humidity, temperature, PH, electricity, pressure, magnetic field, light, biological, and hybrid drive), materials (like hydrogels, shape-memory materials, and other flexible materials) and application areas (camouflage, medical devices, electrical equipment, and grippers, etc.). Finally, we provided some opinions on the technical difficulties and challenges of soft robots to comprehensively comprehend soft robots, lucubrate their applications, and improve the quality of our lives. Full article

Shape memory and self-healing polymer nanocomposites have attracted considerable attention due to their modifiable properties and promising applications. The incorporation of nanomaterials (polypyrrole, carboxyl methyl cellulose, carbon nanotubes, titania nanotubes, graphene, graphene oxide, mesoporous silica) into these polymers has significantly enhanced their performance, opening up new avenues for diverse applications. The self-healing capability in polymer nanocomposites depends on several factors, including heat, quadruple hydrogen bonding, π–π stacking, Diels–Alder reactions, and metal–ligand coordination, which collectively govern the interactions within the composite materials. Among possible interactions, only quadruple hydrogen bonding between composite constituents has been shown to be effective in facilitating self-healing at approximately room temperature. Conversely, thermo-responsive self-healing and shape memory polymer nanocomposites require elevated temperatures to initiate the healing and recovery processes. Thermo-responsive (TRSMPs), light-actuated, magnetically actuated, and Electrically actuated Shape Memory Polymer Nanocomposite are discussed. This paper provides a comprehensive overview of the different types of interactions involved in SMP and SHP nanocomposites and examines their behavior at both room temperature and elevated temperature conditions, along with their biomedical applications. Among many applications of SMPs, special attention has been given to biomedical (drug delivery, orthodontics, tissue engineering, orthopedics, endovascular surgery), aerospace (hinges, space deployable structures, morphing aircrafts), textile (breathable fabrics, reinforced fabrics, self-healing electromagnetic interference shielding fabrics), sensor, electrical (triboelectric nanogenerators, information energy storage devices), electronic, paint and self-healing coating, and construction material (polymer cement composites) applications. Full article

Biological species can walk, swim, fly, jump, and climb with fast response speeds and motion complexity. These remarkable functions are accomplished by means of soft actuation organisms, which are commonly composed of muscle tissue systems. To achieve the creation of their biomimetic artificial counterparts, various biomimetic stimuli-responsive materials have been synthesized and developed in recent decades. They can respond to various external stimuli in the form of structural or morphological transformations by actively or passively converting input energy into mechanical energy. They are the core element of soft actuators for typical smart devices like soft robots, artificial muscles, intelligent sensors and nanogenerators. Significant progress has been made in the development of bioinspired stimuli-responsive materials. However, these materials have not been comprehensively summarized with specific actuation mechanisms in the literature. In this review, we will discuss recent advances in biomimetic stimuli-responsive materials that are instrumental for soft actuators. Firstly, different stimuli-responsive principles for soft actuators are discussed, including fluidic, electrical, thermal, magnetic, light, and chemical stimuli. We further summarize the state-of-the-art stimuli-responsive materials for soft actuators and explore the advantages and disadvantages of using electroactive polymers, magnetic soft composites, photo-thermal responsive polymers, shape memory alloys and other responsive soft materials. Finally, we provide a critical outlook on the field of stimuli-responsive soft actuators and emphasize the challenges in the process of their implementation to various industries. Full article

The mobility of today and tomorrow is characterized by technological change and new challenges in drive concepts such as electric or hydrogen vehicles. Abolishing conventional combustion engines creates even more need for switching or valve technology in mobility systems. For switching and controlling purposes, solenoids are used in large numbers and in a wide variety of applications, thus making a significant contribution to the overall success of the energy transition, and not only in the automotive sector. Despite their long existence, continued research is being carried out on solenoids involving new materials and actuator concepts. Great interest is focused on providing an adjustable force–displacement characteristic while simultaneously reducing the noise during switching. At IKFF, research is being conducted on hybrid electromagnets in the border area of switching and holding solenoids. This paper aims to present the major advantages of this hybrid drive concept based on an electromagnetic FEA simulation study of two drive concepts and specially developed and characterized prototypes with magnetic shape memory (MSM) alloys. The concepts differ in the spatial orientation of the MSM sticks to generate an active stroke of the plunger, which contributes to a beneficial force–displacement characteristic and lower power consumption while minimizing switching noise. Full article

Ferromagnetic shape memory alloys (FSMAs), which are potential candidates for future technologies (i.e., actuators in robots), have been paid much attention for their high work per volume and rapid response as external stimulation, such as a magnetic field, is imposed. Among all the FSMAs, the Ni–Mn–Ga-based alloys were considered promising materials due to their appropriate phase transformation temperatures and ferromagnetism. Nevertheless, their intrinsic embrittlement issue and sluggish twin motion due to the inhibition of grain boundaries restrict their practicability. This study took advantage of the single-crystal Ni–Mn–Ga cube/silicone rubber composite materials to solve the two aforementioned difficulties. The single-crystal Ni–Mn–Ga cube was prepared by using a high-temperature alloying procedure and a floating-zone (FZ) method, and the cubes were verified to be the near-{100}_p Ni–Mn–Ga alloy. Various room temperature (RT) curing silicone rubbers were utilized as matrix materials. Furthermore, polystyrene foam particles (PFP) were used to provide pores, allowing a porous silicone rubber matrix. It was found that the elastic modulus of the silicone rubber was successfully reduced by introducing the PFP. Additionally, the magnetic field-induced martensite variant reorientation (MVR) was greatly enhanced by introducing a porous structure into the silicone rubber. The single-crystal Ni–Mn–Ga cube/porous silicone rubber composite materials are considered to be promising materials for applications in actuators. Full article

To meet the great requirements of future technologies, such as robots, single-crystal (SC) Ni-Mn-Ga alloys and their composites were designed and investigated in this study. Ferromagnetic shape memory alloys (FSMAs) are promising materials for applications in high-speed actuators, which are core components of robots; however, there are some issues of embrittlement and small deformation strain. Therefore, in this work, we first prepared SC Ni-Mn-Ga alloys for fundamental investigations of the shape deformations under the application of different fields (e.g., compressive and magnetic fields). Second, the SC Ni-Mn-Ga alloys were integrated with polymers of epoxy resin or silicone rubber to solve the embrittlement problem. The obvious two-stage yielding and sudden intensifying of the magnetization both suggest martensite variant reorientation (MVR) under the compressive and magnetic fields, respectively. Micro-computed tomography (μCT) and an X-ray diffractometer were utilized for the observations of shape deformation brought about by the MVR of the SC Ni-Mn-Ga particles in the polymer matrix. Clear MVR and shape deformation could be found in the compressed composites. Full article

We present the design, simulation, and characterization of a magnetic shape-memory alloy (MSMA) film actuator that transitions from bistable switching to resonant self-actuation when subjected to a stationary heat source. The actuator design comprises two Ni-Mn-Ga films of 10 µm thickness integrated at the front on either side of an elastic cantilever that moves freely between two heatable miniature permanent magnets and, thus, forms a bistable microswitch. Switching between the two states is induced by selectively heating the MSMA films above their Curie temperature Tc. When continuously heating the permanent magnets above Tc, the MSMA film actuator exhibits an oscillatory motion in between the magnets with large oscillation stroke in the frequency range of 50–60 Hz due to resonant self-actuation. A lumped-element model (LEM) is introduced to describe the coupled thermo-magnetic and magneto-mechanical performance of the actuator. We demonstrate that this performance can be used for the thermomagnetic energy generation of low-grade waste heat (T < 150 °C) with a high power output per footprint in the order of 2.3 µW/cm². Full article

High-speed actuators are greatly required in this decade due to the fast development of future technologies, such as Internet-of-Things (IoT) and robots. The ferromagnetic shape memory alloys (FSMAs), whose shape change could be driven by applying an external magnetic field, possess a rapid response. Hence, these materials are considered promising candidates for the applications of future technologies. Among the FSMAs, the Ni-Mn-Ga-based materials were chosen for their large shape deformation strain and appropriate phase transformation temperatures for near-room temperature applications. Nevertheless, it is widely known that both the intrinsic brittleness of the Ni-Mn-Ga alloy and the constraint of shape deformation strain due to the existence of grain boundaries in the polycrystal inhibit the applications. Therefore, various Ni-Mn-Ga-based composite materials were designed in this study, and their shape deformation behaviors induced by compressive or magnetic fields were examined by the in situ micro CT observations. In addition, the dependence of the martensite variant reorientation (MVR) on the crystallographic directions was also investigated. It was found that most of the MVRs are active within the magnetic field range applied in the regime of the <100>_p, <110>_p, and <111>_p of the single-crystal {100}_p Ni-Mn-Ga cubes. Full article

The objective of this review is to investigate the potential of functionalized magnetic polymer composites for use in electromagnetic micro-electro-mechanical systems (MEMS) for biomedical applications. The properties that make magnetic polymer composites particularly interesting for application in the biomedical field are their biocompatibility, their adjustable mechanical, chemical, and magnetic properties, as well as their manufacturing versatility, e.g., by 3D printing or by integration in cleanroom microfabrication processes, which makes them accessible for large-scale production to reach the general public. The review first examines recent advancements in magnetic polymer composites that possess unique features such as self-healing capabilities, shape-memory, and biodegradability. This analysis includes an exploration of the materials and fabrication processes involved in the production of these composites, as well as their potential applications. Subsequently, the review focuses on electromagnetic MEMS for biomedical applications (bioMEMS), including microactuators, micropumps, miniaturized drug delivery systems, microvalves, micromixers, and sensors. The analysis encompasses an examination of the materials and manufacturing processes involved and the specific fields of application for each of these biomedical MEMS devices. Finally, the review discusses missed opportunities and possible synergies in the development of next-generation composite materials and bioMEMS sensors and actuators based on magnetic polymer composites. Full article

Movements in plants, such as the coiling of tendrils in climbing plants, have been studied as inspiration for coiling actuators in robotics. A promising approach to mimic this behavior is the use of multimaterial systems that show different elastic moduli. Here, we report on the development of magnetically controllable/triggerable multimaterial fibers (MMFs) as artificial tendrils, which can reversibly coil and uncoil on stimulation from an alternating magnetic field. These MMFs are based on deformed shape-memory fibers with poly[ethylene-co-(vinyl acetate)] (PEVA) as their core and a silicone-based soft elastomeric magnetic nanocomposite shell. The core fiber provides a temperature-dependent expansion/contraction that propagates the coiling of the MMF, while the shell enables inductive heating to actuate the movements in these MMFs. Composites with mNP weight content ≥ 15 wt% were required to achieve heating suitable to initiate movement. The MMFs coil upon application of the magnetic field, in which a degree of coiling N = 0.8 ± 0.2 was achieved. Cooling upon switching OFF the magnetic field reversed some of the coiling, giving a reversible change in coiling ∆n = 2 ± 0.5. These MMFs allow magnetically controlled remote and reversible actuation in artificial (soft) plant-like tendrils, and are envisioned as fiber actuators in future robotics applications. Full article

Shape memory nanocomposites are excellent smart materials which can switch between a variable temporary shape and their original shape upon exposure to external stimuli such as heat, light, electricity, magnetic fields, moisture, chemicals, pH, etc. Numerous nanofillers have been introduced in shape memory polymers such as carbon nanotubes, graphene, nanodiamonds, carbon nanofibers, etc. Among nanocarbons, graphene has attracted research interest for the development of shape memory polymer/graphene nanocomposites. Graphene is a unique one-atom-thick two-dimensional nanosheet of sp²-hybridized carbon atoms. Graphene has been used as an effective nanofiller in shape memory polymeric nanocomposites owing to its remarkable electrical conductivity, flexibility, strength, and heat stability. Thermoplastics as well as thermoset matrices have been used to form the shape memory nanomaterials with graphene nanofiller. In shape memory polymer/graphene nanocomposites, their shape has been fixed above the transition temperature and then transformed to the original shape through an external stimulus. The inclusion of graphene in nanocomposites can cause fast switching of their temporary shape to their original shape. Fine graphene dispersion, matrix–nanofiller interactions, and compatible interface development can lead to high-performance shape memory graphene-derived nanocomposites. Consequently, this review focuses on an important class of shape memory graphene-based nanocomposites. The fabrication, physical properties, and shape memory actuation of polymer/graphene nanocomposites are discussed. The stimuli-responsive polymer/graphene nanocomposites mostly revealed heat-, electricity-, and light-induced effects. The inclusion of graphene enhanced the physical/covalent linking, shape recovery, shape fixity, flexibility, and crystallization effects in the polymers. Furthermore, potential applications of these materials are observed in the aerospace/automobile industries, civil engineering, and biomaterials. Full article