A compact rotary motor actuated by shape memory alloy mini springs

2020 ◽  
Vol 31 (15) ◽  
pp. 1808-1820
Author(s):  
José Marques Basilio Sobrinho ◽  
Maxsuel Ferreira Cunha ◽  
Angelo Emiliavaca ◽  
Cícero da Rocha Souto ◽  
Andreas Ries
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Weight Ratio ◽  
Experimental Tests ◽  
Thermomechanical Characteristics ◽  
Electrical Drives ◽  
Rotation Mode ◽  
Torque Generation ◽  
Electronic Measurement ◽  
Rotary Motor

Shape memory alloys have recently gained attention for applications in motor driving components. The most expressive advantage of shape memory alloy components in that type of application is the high torque to motor weight ratio. Considering the importance of these studies, this article presents the design, manufacture, and theoretical and experimental analyses of a rotary motor driven by Ni–Ti shape memory alloy mini springs. The adopted motion mechanism allows the motor to run in continuous and bidirectional rotation mode, where speed and torque are determined by a drive sequence. A simplified analytical model was implemented, considering the thermomechanical characteristics of the shape memory alloy springs. Experimental tests with and without electrical drives were performed using properly designed electronic measurement instrumentation. The principal scientific contribution of this work is the demonstration of the motor’s functionality and torque generation. An energy density index of 1.41 × 10−3 Nmm/mm3 was attained, which is higher to those of other similarly constructed motors in the literature.

A shape memory alloy–actuated soft crawling robot based on adaptive differential friction and enhanced antagonistic configuration

2020 ◽  
Vol 31 (16) ◽  
pp. 1920-1934 ◽  
Author(s):  
Chen Liang ◽  
Yongquan Wang ◽  
Tao Yao ◽  
Botao Zhu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stride Length ◽  
Parametric Design ◽  
Thermoplastic Polyurethane ◽  
Interaction Mechanism ◽  
Experimental Tests ◽  
The Body ◽  
3D Printed ◽  
Miniature Robot

This article presents a soft crawling robot prototype with a simple architecture inspired by inchworms. The robot functionally integrates the torso (body) and feet in a monolithic curved structure that only needs a single shape memory alloy coil and differential friction to actuate it. A novel foot configuration is proposed, which makes the two feet, with an anti-symmetrical friction layout, can be alternately anchored, to match the contraction–recovery sequence of the body adaptively. Based on the antagonistic configuration between the shape memory alloy actuator and the elastic body, a vertically auxiliary spring was adopted to enhance the interaction mechanism. Force and kinematic analysis was undertaken, focusing on the parametric design of the special foot configuration. A miniature robot prototype was then 3D-printed (54 mm in length and 9.77 g in weight), using tailored thermoplastic polyurethane elastomer as the body material. A series of experimental tests and evaluations were carried out to assess its performance under different conditions. The results demonstrated that under appropriate actuation conditions, the compact robot prototype could accomplish a relative speed of 0.024 BL/s (with a stride length equivalent to 27% of its body length) and bear a load over five times to its own weight.

scholarly journals Flexible Fingers Based on Shape Memory Alloy Actuated Modules

Machines ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 40 ◽  
Author(s):  
Daniela Maffiodo ◽  
Terenziano Raparelli
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Basic Concept ◽  
Experimental Tests ◽  
Simple Mathematical Model ◽  
Joule Effect ◽  
Antagonistic Action ◽  
Preliminary Results

To meet the needs of present-day robotics, a family of gripping flexible fingers has been designed. Each of them consists of a number of independent and flexible modules that can be assembled in different configurations. Each module consists of a body with a flexible central rod and three longitudinally positioned shape memory alloy (SMA) wires. When heated by the Joule effect, one to two SMA wires shorten, allowing the module to bend. The return to undeformed conditions is achieved in calm air and is guaranteed by the elastic bias force exerted by the central rod. This article presents the basic concept of the module and a simple mathematical model for the design of the device. Experimental tests were carried out on three prototypes with bodies made of different materials. The results of these tests confirm the need to reduce the antagonistic action of the inactive SMA wires and led to the realization of a fourth prototype equipped with an additional SMA wire-driven locking/unlocking device for these wires. The preliminary results of this last prototype are encouraging.

Online force control of a shape-memory-alloy-based 2 degree-of-freedom human finger via inverse model and proportional–integral–derivative compensator

2019 ◽  
Vol 30 (10) ◽  
pp. 1538-1548 ◽  
Author(s):  
F Mirzakhani ◽  
SM Ayati ◽  
P Fahimi ◽  
M Baghani
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Tracking Error ◽  
Reference Signal ◽  
Experimental Tests ◽  
Degree Of Freedom ◽  
Heat Transfer Analysis ◽  
Proportional Integral Derivative ◽  
Proportional Integral ◽  
Arbitrary Reference

In this work, a model-based controller is developed to track the force at fingertip of an artificial hand. To do so, shape-memory-alloy wires are implemented as an actuator in the finger. Besides, different aspects of modeling, including force relations, kinematics, and heat transfer analysis, are investigated. A modified version of Brinson’s model is used to capture thermomechanical behavior of shape-memory-alloy wires. A controller is designed to control the applied potential difference between shape-memory-alloy wires and consequently control the electrical current in these wires based on the shape-memory-alloy wires model. The main goal of the proposed controller is force controlling of a 2-degree-of-freedom hand finger. This controller contains shape-memory-alloy constitutive model used for compensating system uncertainties. Furthermore, a proportional–integral–derivative controller/compensator is included in the closed-loop system. The compensator acts only on the derivative-type states, and this is one of the differences of this work compared to that of similar literature. The results of three arbitrary reference input signals are reported confirming the model prediction and simulation results are in good agreement with experimental tests. The analysis of the relative tracking error for an arbitrary reference signal is 11% in experimental test and 4% in the simulation.

Reinforcement learning control of a humanoid robotic hand actuated by shape memory alloy

2021 ◽  
pp. 095440622098201
Author(s):  
Mingfang Liu ◽  
Zhirui Zhao ◽  
Wei Zhang ◽  
Lina Hao
Keyword(s):  
Reinforcement Learning ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Pid Controller ◽  
Weight Ratio ◽  
Robotic Hand ◽  
Free System ◽  
Q Learning ◽  
Model Free ◽  
Wide Range

Humanoid robotic hand actuated by shape memory alloy (SMA) represents a new emerging technology. SMA has a wide range of potential applications in many different fields, ranging from industrial assembly to biomedicine applications, due to the characteristic of high power-to-weight ratio, low driving voltages and noiselessness. However, nonlinearities of SMA and complex dynamic models of SMA-based robotic hands result in difficulties in controlling. In this paper, a humanoid SMA-based robotic hand composed of five fingers is presented with the ability of adaptive grasping. Reinforcement learning as a model-free control strategy can search for optimal control of systems with nonlinear and uncertainty. Therefore, an adaptive SA-Q-Learning (ASA-Q-learning) controller is proposed to control the humanoid robotic finger. The performance of ASA-Q-learning controller is compared with SA-Q-learning and PID controller through experimentation. Results have shown that ASA-Q-learning controller can control the humanoid SMA-based robotic hand effectively with faster convergence rate and higher control precision than SA-Q-learning and PID controller, and is feasible for implementation in a model-free system.

Experimental and numerical analyses of a rotary motor using shape memory alloy mini springs

2020 ◽  
Vol 302 ◽  
pp. 111823 ◽  
Author(s):  
José M.B. Sobrinho ◽  
F.M.F. Filho ◽  
A. Emiliavaca ◽  
Maxsuel F. Cunha ◽  
Cícero R. Souto ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Numerical Analyses ◽  
Rotary Motor

scholarly journals Flexible shape memory alloy actuators for soft robotics: Modelling and control

2020 ◽  
Vol 17 (1) ◽  
pp. 172988141988674 ◽  
Author(s):  
Dorin-Sabin Copaci ◽  
Dolores Blanco ◽  
Alejandro Martin-Clemente ◽  
Luis Moreno
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Linear Models ◽  
Complex Dynamics ◽  
Weight Ratio ◽  
Model Free ◽  
Wearable Robots ◽  
Robotic Devices ◽  
Soft Actuators ◽  
And Control

One of the limitations in the development of really soft robotic devices is the development of soft actuators. In recent years, our research group has developed a new flexible shape memory alloy actuator that provides more freedom of movements and a better integration in wearable robots, especially in soft wearable robots. Shape memory alloy wires present characteristics such as force/weight ratio, low weight, and noiseless actuation, which make them an ideal choice in these types of applications. However, the control strategy must take into account its complex dynamics due to thermal phase transformation. Different control approaches based on complex non-linear models and other model-free control methods have been tested on real systems. Some exoskeleton prototypes have been developed, which demonstrate the utility of this actuator and the advantages offered by these flexible actuators to improve the comfort and adaptability of exoskeletons.

A millimeter-Sized Robot Using SMA and Its Control

1995 ◽  
Vol 7 (6) ◽  
pp. 449-457 ◽  
Author(s):  
Katsutoshi Kuribayashi ◽  
◽  
Seiji Shimizu
Keyword(s):  
Shape Memory Alloy ◽  
Laser Beam ◽  
Shape Memory ◽  
Electric Discharge ◽  
Joint Angle ◽  
Weight Ratio ◽  
Electric Discharge Machining ◽  
Strong Force ◽  
Wire Electric Discharge Machining ◽  
Sma Actuator

A millimeter-sized robot has been fabricated using shape memory alloy (SMA) actuators, focusing on its advantages including a strong force to weight ratio and extendibility to micro sizes. The Al links for the robot were made by wire-electric discharge machining (W-EDM). A push-pull type SMA actuator has been constructed with a couple of SMA sheets, each 50<I>μ</I>m thick, which were cut by using a laser beam. They were set on Al links after they had been bent spirally. The dynamics of a larger-size SMA actuator were analyzed theoretically and experimentally. This theory was then applied to estimate the dynamics of the millimeter-sized SMA actuator proposed here. The joint angle was controlled with and without the sensor feedback.

An Innovative Laser-Processed NiTi Self-Biasing Linear Actuator

2013 ◽  
Author(s):  
B. Panton ◽  
A. Michael ◽  
A. Pequegnat ◽  
M. Daly ◽  
Y. Zhou ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Laser Energy ◽  
Current Control ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Material Technology ◽  
Thermomechanical Characteristics ◽  
Alloy Material ◽  
Local Modification

The revolutionary multiple memory material technology allows local modification of shape memory alloy functional properties to create monolithic actuators that exhibit several different thermomechanical characteristics. In this work, high density laser energy was used to process a monolithic piece of NiTi shape memory alloy material to allow synergistic pseudoelastic and shape memory effect behavior. The resulting actuator contains self-biasing properties eliminating the need for a separate biasing mechanism for cyclic actuation. The characteristics of these different local behaviors were analyzed using tensile testing and differential scanning calorimetry. The stress and strain amplitude of the self-biasing linear actuation was characterized with relation to input current control. This work provides proof of concept for local modification of martensitic and austenitic phases; enabling self-biasing linear actuation.

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