scholarly journals A Soft 3D-Printed Robotic Hand Actuated by Coiled SMA

Actuators ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Eric Deng ◽  
Yonas Tadesse

Robotic hands with unique designs, capabilities and applications have been presented in the literature focusing on sensing, actuation, control, powering and manufacturing, most of which are created by manual assembly process. However, due to advancements in additive manufacturing, new capabilities have replaced traditional methods of manufacturing. In this paper, we present a soft 3D-printed robotic hand actuated by custom-made coiled shape memory alloy (SMA) actuators. The hand uses additive manufacturing of flexible thermoplastic polyurethane (TPU) material, which allows flexing at the joint and hence eliminates the need for additional assembly. Here, we present the full characteristics of the robotic hand such as object grasping categorized by size and weight from the ARAT kit and others. The robotic hand is 425 mm in length, weighs 235 g and is able to operate at a frequency of 0.125 Hz without active cooling. It can grasp an object of 55–81 mm widths, weighing up to 133 g, while consuming an average power of 7.82 W. We also show the time domain response of our custom-made coiled SMA to different current inputs, and its corresponding force and displacement. The current design yields a lightweight and low cost artificial hand with significantly simplified manufacturing for applications in robotics and prosthetics.

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Dana Ashkenazi ◽  
Alexandra Inberg ◽  
Yosi Shacham-Diamand ◽  
Adin Stern

Additive manufacturing (AM) revolutionary technologies open new opportunities and challenges. They allow low-cost manufacturing of parts with complex geometries and short time-to-market of products that can be exclusively customized. Additive manufactured parts often need post-printing surface modification. This study aims to review novel environmental-friendly surface finishing process of 3D-printed AlSi10Mg parts by electroless deposition of gold, silver, and gold–silver alloy (e.g., electrum) and to propose a full process methodology suitable for effective metallization. This deposition technique is simple and low cost method, allowing the metallization of both conductive and insulating materials. The AlSi10Mg parts were produced by the additive manufacturing laser powder bed fusion (AM-LPBF) process. Gold, silver, and their alloys were chosen as coatings due to their esthetic appearance, good corrosion resistance, and excellent electrical and thermal conductivity. The metals were deposited on 3D-printed disk-shaped specimens at 80 and 90 °C using a dedicated surface activation method where special functionalization of the printed AlSi10Mg was performed to assure a uniform catalytic surface yielding a good adhesion of the deposited metal to the substrate. Various methods were used to examine the coating quality, including light microscopy, optical profilometry, XRD, X-ray fluorescence, SEM–energy-dispersive spectroscopy (EDS), focused ion beam (FIB)-SEM, and XPS analyses. The results indicate that the developed coatings yield satisfactory quality, and the suggested surface finishing process can be used for many AM products and applications.


Author(s):  
Frank Celentano ◽  
Nicholas May ◽  
Edward Simoneau ◽  
Richard DiPasquale ◽  
Zahra Shahbazi ◽  
...  

Professional musicians today often invest in obtaining antique or vintage instruments. These pieces can be used as collector items or more practically, as performance instruments to give a unique sound of a past music era. Unfortunately, these relics are rare, fragile, and particularly expensive to obtain for a modern day musician. The opportunity to reproduce the sound of an antique instrument through the use of additive manufacturing (3D printing) can make this desired product significantly more affordable. 3D printing allows for duplication of unique parts in a low cost and environmentally friendly method, due to its minimal material waste. Additionally, it allows complex geometries to be created without the limitations of other manufacturing techniques. This study focuses on the primary differences, particularly sound quality and comfort, between saxophone mouthpieces that have been 3D printed and those produced by more traditional methods. Saxophone mouthpieces are commonly derived from a milled blank of either hard rubber, ebonite or brass. Although 3D printers can produce a design with the same or similar materials, they are typically created in a layered pattern. This can potentially affect the porosity and surface of a mouthpiece, ultimately affecting player comfort and sound quality. To evaluate this, acoustic tests will be performed. This will involve both traditionally manufactured mouthpieces and 3D prints of the same geometry created from x-ray scans obtained using a ZEISS Xradia Versa 510. The scans are two dimensional images which go through processes of reconstruction and segmentation, which is the process of assigning material to voxels. The result is a point cloud model, which can be used for 3D printing. High quality audio recordings of each mouthpiece will be obtained and a sound analysis will be performed. The focus of this analysis is to determine what qualities of the sound are changed by the manufacturing method and how true the sound of a 3D printed mouthpiece is to its milled counterpart. Additive manufacturing can lead to more inconsistent products of the original design due to the accuracy, repeatability and resolution of the printer, as well as the layer thickness. In order for additive manufacturing to be a common practice of mouthpiece manufacturing, the printer quality must be tested for its precision to an original model. The quality of a 3D print can also have effects on the comfort of the player. Lower quality 3D prints have an inherent roughness which can cause discomfort and difficulty for the musician. This research will determine the effects of manufacturing method on the sound quality and overall comfort of a mouthpiece. In addition, we will evaluate the validity of additive manufacturing as a method of producing mouthpieces.


2020 ◽  
Author(s):  
Mark Platt ◽  
Eugenie Hunsicker ◽  
Marcus Pollard

Technologies that can detect and characterise particulates in liquids have applications in health, food and environmental monitoring. Here we present a low-cost and high-throughput multiuse counter that classifies a particle’s size, concentration, porosity and shape. Using an additive manufacturing process, we have assembled a reusable flow resistive pulse sensor. The device remains stable for several days with repeat measurements. We demonstrate its use for characterising algae with spherical and rod structures as well as microplastics shed from teabags. We present a methodology that results in a specific signal for microplastics, namely a conductive pulse, in contrast to particles with smooth surfaces such as calibration particles or algae, allowing the presence of microplastics to be easily confirmed and quantified. In addition, the shape of the signal and particle are correlated, giving an extra physical property to characterise suspended particulates. The technology can rapidly screen volumes of liquid, 1 mL/ min, for the presence of microplastics and algae.<br>


Author(s):  
Mark Platt ◽  
Eugenie Hunsicker ◽  
Marcus Pollard

Technologies that can detect and characterise particulates in liquids have applications in health, food and environmental monitoring. Here we present a low-cost and high-throughput multiuse counter that classifies a particle’s size, concentration, porosity and shape. Using an additive manufacturing process, we have assembled a reusable flow resistive pulse sensor. The device remains stable for several days with repeat measurements. We demonstrate its use for characterising algae with spherical and rod structures as well as microplastics shed from teabags. We present a methodology that results in a specific signal for microplastics, namely a conductive pulse, in contrast to particles with smooth surfaces such as calibration particles or algae, allowing the presence of microplastics to be easily confirmed and quantified. In addition, the shape of the signal and particle are correlated, giving an extra physical property to characterise suspended particulates. The technology can rapidly screen volumes of liquid, 1 mL/ min, for the presence of microplastics and algae.<br>


2019 ◽  
Author(s):  
Noha Hamada Mohamed ◽  
Hossam Kandil ◽  
Iman Ismail Dakhli

Abstract In dentistry, 3D printing already has diverse applicability, and holds a great deal of promise to make possible many new and exciting treatments and approaches to manufacturing dental restorations. Better availability, shorter processing time, and descending costs have resulted in the increased use of RP. Concomitantly the development of medical applications is expanding. (Zaharia et al., 2017)Many different printing technologies exist, each with their own advantages and disadvantages. Unfortunately, a common feature of the more functional and productive equipment is the high cost of the equipment, the materials, maintenance, and repair, often accompanied by a need for messy cleaning, difficult post-processing, and sometimes onerous health and safety concerns (Dawood et al., 2015)Low-cost 3D printers represent a great opportunity in the dental and medical field, as they could allow surgeons to use 3D models at a very low cost and, therefore, democratize the use of these 3D models in various indications. However, efforts should be made to establish a unified validation protocol for low-cost RP 3D printed models, including accuracy, reproducibility, and repeatability tests. Asaumi et al., suggested that dimensional changes may not affect the success of surgical applications if such changes are within a 2% variation .However, the proposed cut-off of 2% should be furthermore discussed, as the same accuracy may be not required for all types of indications. (Silva et al., 2008; Maschio et al., 2016)This aim of the present study is to evaluate the dimensional accuracy of the 3D printed mandibular models fabricated by two different additive manufacturing techniques, using highly precise one as selective laser sintering (SLS) and a low-cost one as fused filament fabrication and whether they are both comparable in terms of precision. In addition to evaluation of dimensional accuracy of linear measurements of the mandible in CBCT scans.7 mandibular models will be recruited. Radio-opaque markers of gutta-percha balls will be applied on the model to act as guide pointsTen linear measurements (5 long distances: Inter-condylar, inter-coronoidal, inter-mandibular notch, length of left ramus, length of right ramus; as well as 5 short distances: Length of the body of the mandible at midline, length of the body of the mandible in the area of last left molar, as well as that of the last right molar, the distance between the tip of right condyle to the tip of the right coronoid, as well as that of their left counterparts) will be obtained using digital calliper, to act as the reference standard later. Scanning of the model by CBCT will be next , 3D printing of the scanned image using SLS and FFF printers will be done. Recording of same linear measurment will be done on printed models. Comparison of the recorded values vs reference standard is the last step


2020 ◽  
Vol 4 (3) ◽  
pp. 94 ◽  
Author(s):  
Arash Afshar ◽  
Roy Wood

Additive manufacturing, or 3D printing, has had a big impact on the manufacturing world through its low cost, material recyclability, and fabrication of intricate geometries with a high resolution. Three-dimensionally printed polymer structures in aerospace, marine, construction, and automotive industries are usually intended for service in outdoor environments. During long-term exposures to harsh environmental conditions, the mechanical properties of these structures can be degraded significantly. Developing coating systems for 3D printed parts that protect the structural surface against environmental effects and provide desired surface properties is crucial for the long-term integrity of these structures. In this study, a novel method was presented to create 3D printed structures coated with a weather-resistant material in a single manufacturing operation using multi-material additive manufacturing. One group of specimens was 3D printed from acrylonitrile-butadiene-styrene (ABS) material and the other group was printed from ABS and acrylic-styrene-acrylonitrile (ASA) as a substrate and coating material, respectively. The uncoated ABS specimens suffered significant degradation in the mechanical properties, particularly in the failure strain and toughness, during exposure to UV radiation, moisture, and high temperature. However, the ASA coating preserved the mechanical properties and structural integrity of ABS 3D printed structures in aggressive environments.


2019 ◽  
Vol 86 (10) ◽  
pp. 609-618
Author(s):  
Benedikt Hampel ◽  
Marco Tollkühn ◽  
Meinhard Schilling

AbstractMagnetic sensors are employed for dimensional measurements by detection of sensor motion relative to a small magnet. This is widely used everywhere in industrial automation, car industry and in many home appliances. The use of magnetic sensors in machines for additive manufacturing improves control and long term reliability by non contact position measurements. Magnetic sensors with linearized characteristic based on the anisotropic magnetoresistance (AMR) effect can replace mechanical switches, while specialized AMR angle sensors are preferred for the measurement of rotational motions. Both are easy to use and can be integrated with help of 3D printed holders at low cost. In this work, appropriate sensors are selected, integrated and discussed regarding magnetic disturbance signals apparent in low-cost 3D printers.


Author(s):  
Scott Hill ◽  
Stephen Canfield

There is a significant rise in the design of robots performing ever-more complicated tasks. This has motivated more-anthropomorphic grasping hands for these robots. These hands or grippers are complex machines requiring numerous joints to provide high mobility within a relatively small device. Compliant mechanisms and grippers based on compliant joints provide a viable approach to design improved grippers. The use of compliant joints in the design of a hand yields a number of features that can potentially benefit the design; it allows for more lifelike mobility and can eliminate the need for traditional bearings that yield high contact stresses. This allows for much more variety in material choices. The freedom of choosing from a wider range of materials provides many benefits. For example, plastics can provide softer finger members, improved gripping characteristics and components that are less stiff, making them inherently safer for systems that operate in proximity to people. They can provide the flexibility to more naturally conform to the contour of a particular object when grasping it and reduce the necessary gripping forces to achieve reliable operation. Additionally, a solid-state design compliant mechanism design allows more freedom in designing mechanisms that will be constructed for high mobility and operating in a small space. This approach is further enhanced by the increased availability of additive manufacturing tools that enables ready implementation of compliant mechanism designs with almost any topology. This paper will examine the application additive manufacturing tools to create an anthropomorphic gripper based on compliant mechanism components. The primary contribution of this paper is the empirical evaluation of a set of compliant joints for use as the fingers in an anthropomorphic robotic hand produced using additive manufacturing. Three compliant joints will be considered: the simple straight-axis flexural pivot, cross-axis flexural pivot, and leaf-type isosceles-trapezoidal flexural pivot. Each joint type has demonstrated characteristics that may be suitable for fingers in gripping mechanism and are readily suited to be manufactured using low-cost fused deposition modeling techniques that allow for quick and low-cost production. Further, three materials are evaluated for application as the build material of each compliant joint individually and as a complete solid-state anthropomorphic gripper. These materials are: acrylonitrile butadiene styrene (ABS), Nylon 6, and thermoplastic polyurethane (TPU). Each joint and each material option is compared on the basis of their feasibility for rapid prototyping and suitability for substitution of the interphalangeal joints of the human hand. Deflection tests and finite element analysis are used to gather the empirical data for comparison. An evaluation of the tests is provided to determine which compliant joints are well suited for this application. The paper will also consider the as-built material characteristics relative to their application as gripper elements and will compare and contrast the suitability and any impact on the empirical testing and design. This work will provide information on the combination of joint topology, material and manufacturing processes and can be used to inform the design of soft or highly compliant mechanisms.


2020 ◽  
Vol 1 ◽  
pp. 1027-1036
Author(s):  
A. Orabona ◽  
A. Palazzi ◽  
S. Graziosi ◽  
F. Ferrise ◽  
M. Bordegoni

AbstractThe recent interest in human-robot interaction requires the development of new gripping solutions, compared to those already available and widely used. One of the most advanced solutions in nature is that of the human hand, and several research contributions try to replicate its functionality. Technological advances in manufacturing technologies and design tools are opening possibilities in the design of new solutions. The paper reports the results of the design of an underactuated artificial robotic hand, designed by exploiting the benefits offered by additive manufacturing technologies.


Author(s):  
Heather L. Lai ◽  
Aaron Nelson

Abstract The purpose of this investigation is to study the effects of perimeter inflation on the dynamic behavior of a flexible / rigid multi-material interface. The results of this study can be applied to applications where there is a need for low cost, multi-material 3D printed parts which have both flexibility and strength at the material interfaces designed to undergo simultaneous axial strain and flexural strain. A non-homogeneous 3D printed structure with the desired static and dynamic mechanical behavior was designed using a flexible thermoplastic polyurethane substrate (NinjaFlex) and stiff ABS segment. The multi-material part was printed using a consumer grade dual extruder desktop FDM 3D printer. This project focused on the evaluation of the mechanical behavior of the 3D multi-material due to delamination at the interfaces between the materials undergoing simultaneous flexural and axial loading. In order to reduce the occurrences of delamination, overlap at the interfaces was imposed by using perimeter inflation of both the two different materials. The purpose of the project was to develop a test methodology for the evaluation of the use of perimeter inflation in order to improve the behavior of the multi-material fused deposition printed parts. A modified 3 point bending test was developed to measure the equivalent stiffness and internal damping of the material interface. As a result of this testing, increasing the perimeter inflation was found to cause a modest increase in the stiffness of the interface, with little effect on the internal damping of the interface.


Sign in / Sign up

Export Citation Format

Share Document