Shape memory alloy (SMA) in the family of smart materials has unique shape memory effect, superelasticity, high damping , self-sensing and biocompatibility. Shape memory alloy actuators (SMAA) have the characteristics of high power-to-weight ratio, high strain stress, high driving frequency and high degree of design freedom. Currently, relevant theoretical research and application design work have been carried out in the fields of aerospace, robotics, biomedicine, automotive automation and information electronics. Compared with traditional technologies based on electromagnetic, pneumatic and hydraulic principles, the new modern drive technology based on shape memory alloy actuators has the advantages of high power density, high precision and low cost in certain fields and application scenarios. Therefore, shape memory alloy actuators have great engineering application prospects and potential.
However, the ontology design, system modeling and control of shape memory alloy actuators involve multi-disciplinary theoretical analysis and design ideas, and a comprehensive design theory has not yet been developed. Therefore, Harbin Institute of Technology Electric Drive and Electric Propulsion Technology Key Laboratory of the Ministry of Education , Xu Dianguo ht of Shanghai Aerospace Intelligent Equipment Co., Ltd. ml3, Bai Fengqiang, Zhang Xiangjun, Yang Shihua, and Gu Jixiang wrote an article in the 20th issue of "Journal of Electrical Engineering" in 2022, summarizing and analyzing the current status and trends of theoretical research and application development of shape memory alloy actuators, further exploring the comprehensive design theory of shape memory alloy actuators, providing a reference for the future development of comprehensive design theory of shape memory alloy actuators, and providing a reference for theoretical research and practical applications for researchers in the related fields of shape memory alloy actuators.
Advanced material technology, as one of the cores of high-tech, is the embodiment of the country's core competitiveness. Among the fourth generation materials, smart materials are the most active and advanced direction in the research and development of modern high-tech new materials. They not only promote the integration and development of functional materials and structural materials, but also promote the development of research and application of intelligent electromechanical equipment.
Intelligent materials usually refer to materials with sensing, driving, response, diagnosis, repair or adaptation properties, mainly including shape memory materials, piezoelectric materials, magnetostrictive materials, electrostrictive materials and intelligent polymer materials. Shape memory alloy (SMA) belongs to the metal category of shape memory materials. It has the ability to remember or retain its original shape under specific external excitation conditions, such as thermal or magnetic excitation. When selecting smart materials as driving materials, shape memory alloys have higher key performance indicators such as driving stress, driving strain, driving frequency, energy density and power-to-weight ratio than other types of smart materials, and are suitable for application scenarios of high power density, high power-to-weight ratio, high driving force and large-stroke actuators. Compared with traditional actuators based on electromagnetic, pneumatic and hydraulic principles,
shape memory alloy actuator (SMAA) has a simple structure, a large power-to-weight ratio, and no noise (electromagnetic noise). It also has self-sensing function, low-voltage drive, lightweight, miniaturization, and structural diversification. After years of exploration and application in academia and industry, it has been applied in some special fields. Shape memory alloy actuators can not only replace traditional actuators in function and surpass traditional actuators in performance, but also can effectively reduce the manufacturing and use costs of actuators, especially in the application fields of high power-to-weight ratio, lightweight and miniaturized actuators.
shape memory alloy actuators have broad application prospects, such as those with special needs in the fields of aerospace, robotics, biomedicine, automotive automation and information electronics.Although there are currently many electromechanical structures using shape memory alloy actuators as actuators at home and abroad, the number of published articles and patent applications is increasing year by year, and various countries have also carried out a large number of initial research works. However, the designs that can be truly applied in actual systems are very limited, and the excellent characteristics of shape memory alloy actuators cannot be fully utilized. The main reason is that the shape The theory and application of memory alloy actuators involve multi-disciplinary theoretical analysis and comprehensive design, mainly involving theoretical analysis methods and comprehensive application of technologies such as materials science, mechanics, thermodynamics, mechanics, microelectronics, power electronics, control theory, and signal detection and processing.
Therefore, a complete set of comprehensive design theory has not yet been developed, which can start from design requirements → design specifications → design theory calculation → simulation verification → physical test and evaluation → design optimization → final product. There are still insufficient research and explorations on the theory, structure, drive control and practical application of shape memory alloy actuators.
Researchers from the Key Laboratory of Electric Drive and Electric Propulsion Technology of the Ministry of Education at Harbin Institute of Technology and Shanghai Aerospace Intelligent Equipment Co., Ltd. have systematically summarized and summarized in order to provide a comprehensive theoretical research and application design reference for future research on shape memory alloy actuators. This paper describes the development history, basic characteristics, application research status, theoretical research status, key issues that need to be solved, and future development directions of shape memory alloy actuators. It also preliminarily explores the comprehensive design theory of shape memory alloy actuators to provide a more comprehensive reference for future research in the field of shape memory alloy actuators.
In order to develop comprehensive design theory, the researchers summarized a large number of current theoretical research and engineering design literature, and exploratoryly proposed the basic process of ontology comprehensive design theory as shown in Figure 1. The analysis concluded that shape memory alloy actuators are suitable for micro-actuator application scenarios with low frequency response, high stress and large stroke.
Figure 1 Comprehensive design theory of shape memory alloy actuators
In the engineering design requirements analysis stage in Figure 1, it is necessary to clarify whether the shape memory alloy actuator is suitable for this scenario and the specific functional requirements and performance requirements, such as power (force or load), displacement (stroke or Angle), bandwidth (speed or frequency), working conditions (temperature, voltage, current), shape (volume, mass), drive type (linear or rotational), life requirements and price, etc. The determination of these parameters can be determined based on actual needs and the relevant research content mentioned in this topic. In the
mechatronics design stage, the mechanical structure and electrical drive circuit of the prototype are designed based on the parameters in the design requirements analysis stage. This part of the design content can refer to the relevant research content of the ontology design research mentioned in this topic and the basic engineering design practice ideas in the field of mechatronics. After the ontology design and electrical drive circuit design are completed, a simplified engineering ontology model should be established and appropriate modeling and control methods should be selected based on the control model research and control strategy research proposed in this topic. This part can also propose new modeling and control methods based on the actual situation.
When the ontology structure design, control model and control strategy are initially determined, computer simulation methods should first be used to verify the correctness and rationality of the ontology, modeling and control. After simulation verification, if it meets the basic requirements of the design, physical production and experimental testing will be carried out. If problems occur during the simulation verification stage, you should first return to mechatronics design and control model and control Optimization design is carried out in the strategy stage. If problems occur in the physical experiment stage, the optimization design is also returned. The final prototype of the optimized design needs to be verified in the engineering stage of the product. Only through engineering inspection can a qualified product be determined. However, the current related research is generally strong in theory and weak in engineering. Therefore, the comprehensive design theory of shape memory alloy actuators needs to be further improved through continuous exploration by scientists and engineers.
Key issues of shape memory alloy actuators
1. Theoretical research issues
mainly include material properties theory, ontology design theory, control model theory and control strategy theory.At present, shape memory alloy materials with better material properties and more stability all undergo low-temperature phase change. NiTi-based alloys not only limit the application of shape memory alloy actuators in high-temperature environments, but are also more expensive. Therefore, it is necessary to further study the theoretical characteristics of shape memory alloy materials and develop high-temperature phase change shape memory alloy materials with better performance and low price.
At present, the main topics of research on shape memory alloys focus on material properties, processing processes and metallurgical properties. There is a disconnect between material scientists and engineers. The application of shape memory alloys is too specialized. Therefore, how to effectively organize relevant material information to facilitate engineers to use and develop comprehensive design theory of shape memory alloy actuators is also one of the main issues in the research of shape memory alloy actuators. The development of
shape memory alloy actuator control models is slow and engineering is difficult. The control models established in the past are all from the material field and cannot match the system control goals well. Therefore, it is particularly important to develop control models suitable for engineering. The control strategy of shape memory alloy actuators can effectively solve the nonlinear hysteresis problem, but there is currently no unified control method. Scholars in the field of control are trying various control methods to apply to shape memory alloy actuators.
2. Engineering application issues
mainly include issues such as design requirements, design specifications and design methods in comprehensive design theory. Before designing an actuator, engineers need to conduct an in-depth analysis of the design requirements, accurately determine the function, performance, mechanical environment and thermal environment requirements of the shape memory alloy actuator, and determine the design goals. Appropriate materials, action mechanisms, design types, heating and control methods, etc. should be accurately selected in the design specifications. In the design method, multidisciplinary theoretical design analysis tools must be comprehensively used, and ultimately simulation and prototype testing, evaluation, and optimization processes must be carried out.
In addition, the engineering application fields of shape memory alloy actuators also need to be further expanded, such as execution sensing integrated actuators, microelectromechanical and microsystems. The future development direction of
shape memory alloy actuators
The future development of shape memory alloy actuators mainly revolves around new materials, new theories and new applications.
1, New Materials
Currently, good results have been achieved in the research and development of shape memory alloy materials, but new shape memory alloy materials need to be further developed and improved in the future, such as improving the mechanical properties, mechanical properties, working life and operating temperature range of shape memory alloys, such as increasing the phase transition temperature of shape memory alloys by changing material composition and adding other elements, improving heat treatment or improving the driving performance and lifespan of shape memory alloys through other processing methods.
can also carry out research on composite materials of shape memory alloys and other materials to realize the complementary advantages of different materials and enhance the performance and functions of shape memory composite materials. In addition, the development of shape memory material thin film technology will be beneficial to the application of shape memory alloys in microelectromechanical systems and can promote the application of shape memory alloys in the field of microelectromechanical systems.
2, new theory
The application of shape memory alloy actuators in high temperature, multi-axial loads and micro-electromechanical microsystems should consider the establishment of cyclic loading, creep, multi-axial load, cross-scale and multi-dimensional constitutive models. The new model will contribute to the application of shape memory alloys in engineering, and is conducive to accurate modeling and simulation in the simulation phase of the engineering design process, improving the reliability and speed of engineering implementation of shape memory alloy actuators.
needs to continue to develop control strategies for shape memory alloy actuators based on the nonlinear hysteresis characteristics of shape memory alloy actuators to meet the control performance and multiple application scenario requirements for stability, rapidity, accuracy and robustness in shape memory alloy actuator control. Ontology design theory should develop a unified comprehensive design theory, develop formal guidelines and related design tools, such as databases and reliable and effective simulation models.
3, New Applications
The automotive and aerospace fields can continue to develop self-healing, self-sensing structures and components (such as smart tires and airbags), deformable structures, high-temperature actuators, active noise suppression structures and rotating actuators, etc. The field of robotics can continue to develop micro, fast, efficient, stable and accurate actuators, bionic robots , humanoid robots and soft robots. The biomedical field can continue to develop minimally invasive surgical instruments and auxiliary rehabilitation treatment equipment.
Information electronic products can continue to develop miniature camera anti-shake focus actuators, and can combine visual feedback to design visual servo feedback devices. In addition, shape memory alloys can be applied to sensors, integrated sensing actuators, micro drives and micro electromechanical systems, which will expand the application scope and fields of shape memory alloys and give full play to the advantages of shape memory alloy materials.
This article is compiled from the 20th issue of "Journal of Electrical Engineering and Technology" in 2022. The title of the paper is "Research Review of Shape Memory Alloy Actuators". This project was supported by the Natural Science Foundation of Heilongjiang Province.
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