SMA-Net: A Deformable Morphology Robot Using Shape Memory Alloy

2002 ◽  
Vol 14 (3) ◽  
pp. 290-297 ◽  
Author(s):  
Takashi Nagai ◽  
◽  
Hiroshi Yokoi ◽  
Yukinori Kakazu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Design Research ◽  
Control Method ◽  
Lattice Structure ◽  
Physical Property ◽  
Developmental Study ◽  
Passive Deformation ◽  
Robotics Design

Deformation of morphology is one goal of advanced robotics design research. This study started from a project of the development of a morph-functional machine, where the developmental study of a deformable robot which can behave like an ameba, is one of the main topics. This paper proposes the prototype design of a deformable morphology robot based on the lattice structure of elastic elements, shape memory alloy springs. The proposed structure of SMA-Net has both passively deformable functionality and active deformability. The functions of deformability of SMA-Net give new concepts of robotics design. However, it becomes difficult to control overall behavior because of the large degrees of freedom of the structure, external force comes into passive deformation and it makes change of physical property of motion control, and the relation between elements of robot yield nonlinear dynamics. Therefore, as first step for control, we investigated the movement mechanism of the robot. The proposed control method is periodic ON/OFF control, system parameters of SMA-Net are explored to find the resonance phase of the whole structure. Experiments show basic deformations of SMA-Net and the motion of translation and rotation.

scholarly journals Disturbance compensation-based output feedback adaptive control for shape memory alloy actuator system

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142199399
Author(s):  
Xiaoguang Li ◽  
Bi Zhang ◽  
Daohui Zhang ◽  
Xingang Zhao ◽  
Jianda Han
Keyword(s):  
Adaptive Control ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Control Law ◽  
Reference Trajectory ◽  
Disturbance Compensation ◽  
Comparison Results ◽  
Control Scheme ◽  
Actuator System

Shape memory alloy (SMA) has been utilized as the material of smart actuators due to the miniaturization and lightweight. However, the nonlinearity and hysteresis of SMA material seriously affect the precise control. In this article, a novel disturbance compensation-based adaptive control scheme is developed to improve the control performance of SMA actuator system. Firstly, the nominal model is constructed based on the physical process. Next, an estimator is developed to online update not only the unmeasured system states but also the total disturbance. Then, the novel adaptive controller, which is composed of the nominal control law and the compensation control law, is designed. Finally, the proposed scheme is evaluated in the SMA experimental setup. The comparison results have demonstrated that the proposed control method can track reference trajectory accurately, reject load variations and stochastic disturbances timely, and exhibit satisfactory robust stability. The proposed control scheme is system independent and has some potential in other types of SMA-actuated systems.

scholarly journals Design of Shape Memory Alloy-Based Soft Wearable Robot for Assisting Wrist Motion

2019 ◽  
Vol 9 (19) ◽  
pp. 4025 ◽  
Author(s):  
Jaeyeon Jeong ◽  
Ibrahim Bin Yasir ◽  
Jungwoo Han ◽  
Cheol Hoon Park ◽  
Soo-Kyung Bok ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Wrist Flexion ◽  
Wearable Robot ◽  
Maximum Torque ◽  
Wrist Motion ◽  
Contraction Ratio ◽  
Flexion Extension ◽  
The Average Range

In this paper, we propose a shape memory alloy (SMA)-based wearable robot that assists the wrist motion for patients who have difficulties in manipulating the lower arm. Since SMA shows high contraction strain when it is designed as a form of coil spring shape, the proposed muscle-like actuator was designed after optimizing the spring parameters. The fabricated actuator shows a maximum force of 10 N and a maximum contraction ratio of 40%. The SMA-based wearable robot, named soft wrist assist (SWA), assists 2 degrees of freedom (DOF) wrist motions. In addition, the robot is totally flexible and weighs 151g for the wearable parts. A maximum torque of 1.32 Nm was measured for wrist flexion, and a torque of larger than 0.5 Nm was measured for the other motions. The robot showed the average range of motion (ROM) with 33.8, 30.4, 15.4, and 21.4 degrees for flexion, extension, ulnar, and radial deviation, respectively. Thanks to the soft feature of the SWA, time cost for wearing the device is shorter than 2 min as was also the case for patients when putting it on by themselves. From the experimental results, the SWA is expected to support wrist motion for diverse activities of daily living (ADL) routinely for patients.

Helical Kirigami-Enabled Centimeter-Scale Worm Robot With Shape-Memory-Alloy Linear Actuators

2015 ◽  
Vol 7 (2) ◽  
Author(s):  
Ketao Zhang ◽  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Kinematic Model ◽  
Parallel Structure ◽  
Geometrical Parameters ◽  
Parallel Structures ◽  
Complete Procedure ◽  
Motion Characteristics

The wormlike robots are capable of imitating amazing locomotion of slim creatures. This paper presents a novel centimeter-scale worm robot inspired by a kirigami parallel structure with helical motion. The motion characteristics of the kirigami structure are unravelled by analyzing the equivalent kinematic model in terms of screw theory. This reveals that the kirigami parallel structure with three degrees-of-freedom (DOF) motion is capable of implementing both peristalsis and inchworm-type motion. In light of the revealed motion characteristics, a segmented worm robot which is able to imitate contracting motion, bending motion of omega shape and twisting motion in nature is proposed by integrating kirigami parallel structures successively. Following the kinematic and static characteristics of the kirigami structure, actuation models are explored by employing the linear shape-memory-alloy (SMA) coil springs and the complete procedure for determining the geometrical parameters of the SMA coil springs. Actuation phases for the actuation model with two SMA springs are enumerated and with four SMA springs are calculated based on the Burnside's lemma. In this paper, a prototype of the worm robot with three segments is presented together with a paper-made body structure and integrated SMA coil springs. This centimeter-scale prototype of the worm robot is lightweight and can be used in confined environments for detection and inspection. The study presents an interesting approach of integrating SMA actuators in kirigami-enabled parallel structures for the development of compliant and miniaturized robots.

Model Reference Adaptive Control Based on KP Model for Magnetically Controlled Shape Memory Alloy Actuators

2017 ◽  
Vol 15 (1_suppl) ◽  
pp. 31-37 ◽  
Author(s):  
Miaolei Zhou ◽  
Yannan Zhang ◽  
Kun Ji ◽  
Dong Zhu
Keyword(s):  
Adaptive Control ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Model Reference Adaptive Control ◽  
Positioning Accuracy ◽  
Model Reference ◽  
Hysteresis Nonlinearity ◽  
Adopted Model ◽  
Model Reference Adaptive

Introduction Magnetically controlled shape memory alloy (MSMA) actuators take advantages of their large deformation and high controllability. However, the intricate hysteresis nonlinearity often results in low positioning accuracy and slow actuator response. Methods In this paper, a modified Krasnosel'skii-Pokrovskii model was adopted to describe the complicated hysteresis phenomenon in the MSMA actuators. Adaptive recursive algorithm was employed to identify the density parameters of the adopted model. Subsequently, to further eliminate the hysteresis nonlinearity and improve the positioning accuracy, the model reference adaptive control method was proposed to optimize the model and inverse model compensation. Results The simulation experiments show that the model reference adaptive control adopted in the paper significantly improves the control precision of the actuators, with a maximum tracking error of 0.0072 mm. Conclusions The results prove that the model reference adaptive control method is efficient to eliminate hysteresis nonlinearity and achieves a higher positioning accuracy of the MSMA actuators.

Shape Memory Alloy Actuator Arrays Using Thermoelectric Devices for Dual Sensing and Actuation

2005 ◽  
Author(s):  
Lael Odhner ◽  
H. Harry Asada
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Thermal State ◽  
Thermoelectric Device ◽  
Measured Temperature ◽  
Thermoelectric Devices ◽  
Heating And Cooling ◽  
Actuator Arrays ◽  
Seebeck Voltage

A sensor-less control method for locally heating and cooling Shape Memory Alloy (SMA) actuators using an array of thermoelectric devices (TED) for both temperature measurement and actuation is presented in this paper. Each SMA wire is divided into many segments whose thermal state is controlled independently and selectively for generating a desired displacement of the SMA wire. In lieu of dedicated temperature sensors, each TED used to heat and cool the SMA wires can also be used to monitor the local temperature difference across each device via the Seebeck effect. A pulse width-modulated control system is implemented to drive the thermoelectric device and sample the Seebeck voltage of each TED between pulses. Least-squares system identification is employed to fit an auto-regressive/exogenous input model to the measured temperature of the SMA wires using the Seebeck voltage and the ambient temperature as inputs. A feedback controller is presented which, using this model, is able to control the temperature of the shape memory alloy wires to within 3 °C over a target temperature range between 30 °C and 80 °C.

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