Experimental Nonlinear Dynamics of a Shape Memory Alloy Wire Bundle Actuator

1999 ◽  
Vol 123 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Michael J. Mosley ◽  
Constantinos Mavroidis
Keyword(s):  
Nonlinear Dynamics ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Chaotic Behavior ◽  
Open Loop ◽  
Power Spectrum Density ◽  
System Response ◽  
Spectrum Density ◽  
Time Histories ◽  
Sma Actuator

In this paper, the nonlinear dynamics of a new Shape Memory Alloy (SMA) actuator that possesses impressive payload lifting capabilities are presented. This actuator consists of 48 SMA wires mechanically bundled in parallel forming one powerful muscle. It was designed to lift up to 45.4 kg (100 lbs), which is approximately 300 times its weight. This SMA actuator was tested in open-loop experiments with different loads and different inputs, such as step, ramp, sinusoid, and half sinusoid, and its dynamic characteristics were evaluated. An important observation made during the dynamic analysis was the unpredictability of the actuator’s response when low to moderate voltages were applied. This characteristic suggests possible chaotic behavior of the actuator, which could affect the system design and cause control difficulties in fine and high accuracy tasks. An investigation into chaos was conducted using time histories, phase plots, Poincare´ maps, and power spectrum density plots. As shown in the diagrams presented in this paper, system response to sinusoidal inputs with a larger mean voltage is periodic, whereas lower mean voltages produce unpredictable responses that indicate chaotic behavior.

Experimental Non-Linear Dynamics of a Shape Memory Alloy Wire Bundle Actuator

1999 ◽  
Author(s):  
Michael J. Mosley ◽  
Constantinos Mavroidis
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Chaotic Behavior ◽  
High Accuracy ◽  
Open Loop ◽  
System Response ◽  
Linear Dynamics ◽  
Non Linear ◽  
Time Histories ◽  
Sma Actuator

Abstract In this paper, the non-linear dynamics of a new Shape Memory Alloy (SMA) actuator that possesses impressive payload lifting capabilities are presented. This actuator consists of 48 SMA wires mechanically bundled in parallel forming one powerful muscle. It was designed to lift up to 100 lbs., which is approximately 300 times its weight. This SMA actuator was tested in open loop experiments with different loads and different inputs, such as step, ramp, sinusoid, and half sinusoid, and its dynamic characteristics were evaluated. An important observation made during the dynamic analysis was the unpredictability of the actuator’s response when low to moderate voltages are applied. This characteristic strongly suggests chaotic behavior of the actuator, which could potentially cause control difficulties in fine and high accuracy tasks. An investigation into chaos was conducted using time histories, phase plots, and Poincaré maps. As shown in the diagrams presented in this paper, system response to larger input voltages is periodic, whereas lower input voltages produce responses that strongly indicate chaotic behavior.

Design of a 2 DOF Shape Memory Alloy Actuator Using SMA Springs

2021 ◽  
Author(s):  
Hussein F. M. Ali ◽  
Youngshik Kim
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Open Loop ◽  
Degree Of Freedom ◽  
Biologically Inspired ◽  
Loop Control ◽  
Actuator System ◽  
Sma Actuator ◽  
Sma Spring ◽  
Two Degree Of Freedom

Abstract In this paper, we developed two degree of freedom shape memory alloy (SMA) actuator using SMA springs. This module can be applied easily to various applications: device holder, artificial finger, grippes, fish robot, and many other biologically inspired applications, where small size and small wight of the actuator are very critical. This actuator is composed of two sets of SMA springs: one set is for the rotation around the X axis (roll angle) and the other set is for the rotation around the Y axis (pitch angle). Each set contains two elements: one SMA spring and one antagonistic SMA spring. We used an inertia sensor (IMU) and two potentiometers for angles feedback. The SMA actuator system is modeled mathematically and then tested experimentally in open-loop and closed-loop control. We designed and experimentally tuned a proportional integrator derivative (PID) controller to follow the set points and to track the desired trajectories. The main goal of the presented controller is to control roll and pitch angles simultaneously in order to satisfy set points and trajectories within the work space. The experimental results show that the two degree of freedom SMA actuator system follows the desired setpoints with acceptable rise time and overshoot.

Control of Shape Memory Alloy Actuators Using Pulse Width Pulse Frequency (PWPF) Modulation

2001 ◽  
Author(s):  
G. Song ◽  
N. Ma
Keyword(s):  
Energy Consumption ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Pulse Width ◽  
Pulse Frequency ◽  
Open Loop ◽  
Parameter Analysis ◽  
Pd Controller ◽  
Sma Actuator ◽  
Control Accuracy

Abstract This paper presents the design and experimental results of control of an SMA actuator using PWPF modulation to reduce the energy consumption by the SMA actuator. An SMA wire test stand is used in this research. Based on results of open-loop testing of the SMA wire actuator and parameter analysis of the PWPF modulator, a PWPF modulator is designed to modulate a Proportional plus Derivative (PD) controller. Experiments demonstrate that control of the SMA actuator using PWPF modulation effectively save actuation energy whiling maintaining same control accuracy as compared to continuous PD control.

scholarly journals Multistrand, Fast Reaction, Shape Memory Alloy System for Uninhabited Aerial Vehicle Flight Control

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
M. Brennison ◽  
R. M. Barrett ◽  
L. Kerth
Keyword(s):  
Control System ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Flight Control ◽  
Alloy System ◽  
Open Loop ◽  
Flight Control System ◽  
Loop Design ◽  
Aerial Vehicle ◽  
Sma Actuator

This paper details an investigation of shape memory alloy (SMA) filaments which are used to drive a flight control system with precision control in a real flight environment. An antagonistic SMA actuator was developed with an integrated demodulator circuit from a JR NES 911 subscale UAV actuator. Most SMA actuator studies concentrate on modeling the open-loop characteristics of such a system with full actuator performance modeling. This paper is a bit different in that it is very practically oriented and centered on development of a flight-capable system which solves the most tricky, practical problems associated with using SMA filaments for aircraft flight control. By using well-tuned feedback loops, it is shown that intermediate SMA performance prediction is not appropriate for flight control system (FCS) design. Rather, capturing the peak behavior is far more important, along with appropriate feedback loop design. To prove the system, an SMA actuator was designed and installed in the fuselage of a 2 m uninhabited aerial vehicle (UAV) and used to control the rudder through slips and coordinated turns. The actuator was capable of 20 degrees of positive and negative deflection and was capable of 7.5 in-oz (5.29 N cm) of torque at a bandwidth of 2.8 Hz.

Neural Network Tracking Control of a Shape Memory Alloy Wire Actuator Without a Position Sensor

2001 ◽  
Author(s):  
G. Song ◽  
V. Chaudhry ◽  
C. Batur
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Tracking Control ◽  
Open Loop ◽  
Training Data ◽  
Position Sensor ◽  
The Neural Network ◽  
Sma Actuator

Abstract Tracking control of shape memory alloy (SMA) actuators is essential in many applications such as vibration controls. Due to the hysteresis, an inherent nonlinear phenomenon associated with SMAs, open-loop control design has proven inadequate for tracking control of these actuators. Aimed at to eliminate the position sensor to reduce cost of an SMA actuator system, in this paper, a neural network open loop controller is proposed for tracking control of an SMA actuator. A test stand, including a titanium-nickel (TiNi, or Nitinol) SMA wire actuator, a position sensor, bias springs, and a programmable current amplifier, is used to generate training data and to verify the neural networks open loop controller. A digital data acquisition and real-time control system was used to record experimental data and to implement the control strategy. Based on the training data obtained from the test stand, two neural networks are used to respectively model the forward and inverse hysteresis relations between the applied voltage and the displacement of the SMA wire actuator. To control the SMA actuator without using a position sensor, the neural network inverse model is used as a feedforward controller. The experimental results demonstrate the effectiveness of the neural network open loop controller for tracking control of the SMA wire actuator.

scholarly journals Bio-inspired Miniature Suction Cups Actuated by Shape Memory Alloy

10.5772/7228 ◽  
2009 ◽  
Vol 6 (3) ◽  
pp. 29 ◽  
Author(s):  
Hu Bing-Shan ◽  
Wang Li-Wen ◽  
Fu Zhuang ◽  
Zhao Yan-zheng
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Analytical Model ◽  
Basic Structure ◽  
Thin Elastic Plate ◽  
Climbing Robots ◽  
Suction Cup ◽  
Sma Actuator ◽  
Suction Cups ◽  
Pressure Suction

Wall climbing robots using negative pressure suction always employ air pumps which have great noise and large volume. Two prototypes of bio-inspired miniature suction cup actuated by shape memory alloy (SMA) are designed based on studying characteristics of biologic suction apparatuses, and the suction cups in this paper can be used as adhesion mechanisms for miniature wall climbing robots without air pumps. The first prototype with a two-way shape memory effect (TWSME) extension TiNi spring imitates the piston structure of the stalked sucker; the second one actuated by a one way SMA actuator with a bias has a basic structure of stiff margin, guiding element, leader and elastic element. Analytical model of the second prototype is founded considering the constitutive model of the SMA actuator, the deflection of the thin elastic plate under compound load and the thermo-dynamic model of the sealed air cavity. Experiments are done to test their suction characteristics, and the analytical model of the second prototype is simulated on Matlab/simulink platform and validated by experiments.

Development of a Shape Memory Alloy (SMA) Based Assistive Hand

2015 ◽  
Vol 1115 ◽  
pp. 454-457 ◽  
Author(s):  
Alala M. Ba Hamid ◽  
Mohatashem R. Makhdoomi ◽  
Tanveer Saleh ◽  
Moinul Bhuiyan
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Sensory System ◽  
Open Loop ◽  
Rehabilitation Robotics ◽  
Robotic Hand ◽  
After Effect ◽  
Conventional Structure ◽  
Force Mechanism ◽  
Gripping Force

In Malaysia, every year approximately 40000 people suffer from stroke and many of them become immobilized as an after effect. Rehabilitation robotics to assist disabled people has drawn significant attention by the researchers recently. This project also aims to contribute to this field. This paper presents a Shape Memory Alloy (SMA) actuated wearable assistive robotic hand for grasping. The proposed design is compact and sufficiently light to be used as an assistive hand. It is a joint less structure, has the potential because the human skeleton and joint replace the robot’s conventional structure. This design has been implemented on index and thumb fingers to enable grasping. Shape memory alloy springs and bias force mechanism are used for purpose of hand’s flexion and extension. This paper describes the mechatronic design of the wearable hand, experimental study of actuation unit and sensory system. Open loop experiments are conducted to understand the hand characterization and grip force provided by index finger. Current, temperature, extension and contraction of shape memory alloy springs are reported. This mechanism requires approximately 2A current for the SMA to actuate which provides maximum of 1.6N of gripping force. Conducted experiments show promising results that encourage further developments.

scholarly journals Development of Subcarangiform Bionic Robotic Fish Propelled by Shape Memory Alloy Actuators

2021 ◽  
Vol 71 (1) ◽  
pp. 94-101
Author(s):  
M. Muralidharan ◽  
I.A. Palani
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Kinematic Model ◽  
Open Loop ◽  
Robotic Fish ◽  
Water Medium ◽  
Light Weight ◽  
Caudal Fin ◽  
Locomotion Pattern ◽  
Sma Spring

In this paper, a shape memory alloy (SMA) actuated subcarangiform robotic fish has been demonstrated using a spring based propulsion mechanism. The bionic robotic fish developed using SMA spring actuators and light weight 3D printed components can be employed for under water applications. The proposed SMA spring-based design without conventional motor and other rotary actuators was able to achieve two-way shape memory effect and has reproduced the subcarangiform locomotion pattern. The positional kinematic model has been developed and the dynamics of the proposed mechanism were analysed and simulated using Automated Dynamic Analysis of Mechanical Systems (ADAMS). An open loop Arduino-relay based switching control has been adopted to control the periodic actuation of the SMA spring mechanism. The undulation of caudal fin in air and water medium has been analysed. The caudal fin and posterior body of the developed fish prototype have taken part in undulation resembling subcarangiform locomotion pattern and steady swimming was achieved in water with a forward velocity of 24.5 mm/s. The proposed design is scalable, light weight and cost effective which may be suitable for underwater surveillance application.

Discrete Preisach Model of a Shape Memory Alloy Actuator

2016 ◽  
Vol 248 ◽  
pp. 227-234
Author(s):  
Waldemar Rączka ◽  
Jarosław Konieczny ◽  
Marek Sibielak ◽  
Janusz Kowal
Keyword(s):  
Mathematical Model ◽  
Shape Memory Alloy ◽  
Parameter Identification ◽  
Shape Memory ◽  
Preisach Model ◽  
Discrete Form ◽  
Nonlinear Characteristics ◽  
Shape Memory Alloy Actuator ◽  
Sma Actuator ◽  
Identification Model

Shape Memory Alloy is a material used to designing actuators. These actuators have many advantages. They are light, strong and silent. They are building in laboratory and tested because beside advantages they have disadvantages too. SMA actuators have nonlinear characteristics with hysteresis loop.In the first part of the paper Shape Memory Alloys are shortly described. Next mathematical model was formulated. In the paper the Preisach model was developed. Discrete form of the model was considered and implemented. After parameter identification model was implemented in LabView. Tests of the model were conducted and results were worked. Obtained characteristics of the SMA actuator are shown in the paper. At the end of the paper the conclusions were formulated.

Nonlinear dynamics of a rotordynamic nonsmooth shape memory alloy system

2013 ◽  
Vol 332 (3) ◽  
pp. 608-621 ◽  
Author(s):  
Leandro C. Silva ◽  
Marcelo A. Savi ◽  
Alberto Paiva
Keyword(s):  
Nonlinear Dynamics ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Alloy System
Sign in / Sign up

Export Citation Format

Share Document