scholarly journals Integrated Temperature and Position Sensors in a Shape-Memory Driven Soft Actuator for Closed-Loop Control

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 520
Author(s):  
Johannes Mersch ◽  
Najmeh Keshtkar ◽  
Henriette Grellmann ◽  
Carlos Alberto Gomez Cuaran ◽  
Mathis Bruns ◽  
...  
Keyword(s):  
Shape Memory ◽  
Closed Loop ◽  
Maximum Error ◽  
Closed Loop Control ◽  
Human Machine Interaction ◽  
Loop Control ◽  
Soft Actuator ◽  
Fiber Placement ◽  
Soft Actuators ◽  
Body Joints

Soft actuators are a promising option for the advancing fields of human-machine interaction and dexterous robots in complex environments. Shape memory alloy wire actuators can be integrated into fiber rubber composites for highly deformable structures. For autonomous, closed-loop control of such systems, additional integrated sensors are necessary. In this work, a soft actuator is presented that incorporates fiber-based actuators and sensors to monitor both deformation and temperature. The soft actuator showed considerable deformation around two solid body joints, which was then compared to the sensor signals, and their correlation was analyzed. Both, the actuator as well as the sensor materials were processed by braiding and tailored fiber placement before molding with silicone rubber. Finally, the novel fiber-rubber composite material was used to implement closed-loop control of the actuator with a maximum error of 0.5°.

Adaptive Control Concept for Shape Memory Alloy Actuators

2013 ◽  
Author(s):  
Kenny Pagel ◽  
Welf-Guntram Drossel ◽  
Wolfgang Zorn ◽  
André Bucht ◽  
Holger Kunze
Keyword(s):  
Adaptive Control ◽  
Shape Memory ◽  
Closed Loop ◽  
Numerical Models ◽  
Closed Loop Control ◽  
Loop Control ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Control Concept ◽  
Working Principle

Machine tools for small work pieces are characterized by an extensive disproportion between workspace and cross section. This is mainly caused by limitations in the miniaturization of drives and guidance elements, since their physical working principle necessitates certain minimum sizes. Due to their high specific workloads and relatively small spatial requirements, Thermal Shape-Memory-Alloys (SMA) possesses an outstanding potential to serve as miniaturized positioning devices in small machines. Antagonistically arranged SMA actuators are especially feasible to fulfill these requirements. This paper describes an adaptive closed loop control concept for actuators based on spring loaded or antagonistic arrangements of electrically-heated SMA elements. Due to their nonlinear stress-strain behavior such actuators are characterized by strain dependent load conditions at the activated SMA element. Consequently the actuator dynamic depends on its position. Hence an adaptive closed loop control concept to ensure a constant actuator dynamic over the entire stroke has to be developed. The approach is based on the determination of the transient transfer dynamics of the SMA Element. Two possible strategies are investigated and evaluated. Numerical models of both SMA wire arrangements are used to develop the adaptive control theoretically. An SMA wire test bench is designed to investigate the proof of the adaptive approach experimentally. Measurements of a conventional PI control are further compared to the achieved results of the new concept.

scholarly journals Shape Memory Alloy (SMA) Actuator With Embedded Liquid Metal Curvature Sensor for Closed-Loop Control

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhijian Ren ◽  
Masoud Zarepoor ◽  
Xiaonan Huang ◽  
Andrew P. Sabelhaus ◽  
Carmel Majidi
Keyword(s):  
Shape Memory Alloy ◽  
Liquid Metal ◽  
Shape Memory ◽  
Closed Loop ◽  
Loop Control ◽  
Soft Actuator ◽  
Special Case ◽  
Activation Cycle ◽  
Curvature Sensor

We introduce a soft robot actuator composed of a pre-stressed elastomer film embedded with shape memory alloy (SMA) and a liquid metal (LM) curvature sensor. SMA-based actuators are commonly used as electrically-powered limbs to enable walking, crawling, and swimming of soft robots. However, they are susceptible to overheating and long-term degradation if they are electrically stimulated before they have time to mechanically recover from their previous activation cycle. Here, we address this by embedding the soft actuator with a capacitive LM sensor capable of measuring bending curvature. The soft sensor is thin and elastic and can track curvature changes without significantly altering the natural mechanical properties of the soft actuator. We show that the sensor can be incorporated into a closed-loop “bang-bang” controller to ensure that the actuator fully relaxes to its natural curvature before the next activation cycle. In this way, the activation frequency of the actuator can be dynamically adapted for continuous, cyclic actuation. Moreover, in the special case of slower, low power actuation, we can use the embedded curvature sensor as feedback for achieving partial actuation and limiting the amount of curvature change.

The Impact of Visual Feedback Type on the Mastery of Visuo-Motor Transformations

2012 ◽  
Vol 220 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Sandra Sülzenbrück
Keyword(s):  
Empirical Research ◽  
Visual Feedback ◽  
Closed Loop ◽  
Motor Planning ◽  
Visual Input ◽  
Closed Loop Control ◽  
Loop Control ◽  
Feedback Type ◽  
Effective Use ◽  
The Impact

For the effective use of modern tools, the inherent visuo-motor transformation needs to be mastered. The successful adjustment to and learning of these transformations crucially depends on practice conditions, particularly on the type of visual feedback during practice. Here, a review about empirical research exploring the influence of continuous and terminal visual feedback during practice on the mastery of visuo-motor transformations is provided. Two studies investigating the impact of the type of visual feedback on either direction-dependent visuo-motor gains or the complex visuo-motor transformation of a virtual two-sided lever are presented in more detail. The findings of these studies indicate that the continuous availability of visual feedback supports performance when closed-loop control is possible, but impairs performance when visual input is no longer available. Different approaches to explain these performance differences due to the type of visual feedback during practice are considered. For example, these differences could reflect a process of re-optimization of motor planning in a novel environment or represent effects of the specificity of practice. Furthermore, differences in the allocation of attention during movements with terminal and continuous visual feedback could account for the observed differences.

118-LB: Glucose Variability throughout the Menstrual Cycle on Closed-Loop Control in Type 1 DM

Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 118-LB
Author(s):  
CAROL J. LEVY ◽  
GRENYE OMALLEY ◽  
SUE A. BROWN ◽  
DAN RAGHINARU ◽  
YOGISH C. KUDVA ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Closed Loop ◽  
Glucose Variability ◽  
Closed Loop Control ◽  
Loop Control ◽  
Type 1 Dm

101-LB: Eighteen-Month Use of Closed-Loop Control (CLC): A Randomized, Controlled Trial

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 101-LB
Author(s):  
SUE A. BROWN ◽  
DAN RAGHINARU ◽  
BRUCE A. BUCKINGHAM ◽  
YOGISH C. KUDVA ◽  
LORI M. LAFFEL ◽  
...  
Keyword(s):  
Randomized Controlled Trial ◽  
Closed Loop ◽  
Controlled Trial ◽  
Closed Loop Control ◽  
Loop Control ◽  
Randomized Controlled
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