The use of low pressure plasma surface modification for bonded joints to assembly a robotic gripper designed to be additive manufactured

The paper explores how different surface preparations modify the mechanical performance of bonded joints on components made in acrylonitrile butadiene styrene (ABS) processed by fused filament fabrication (FFF) additive manufacturing. Two alternative treatments are considered: surface abrasion compliant to the standard ASTM D2093-03 (17) and using low pressure plasma, an innovative solution. The assessment is performed on standard lap shear test specimens and structural epoxy adhesive. The bonding layer with abraded surfaces shows adhesive failure while after the low-pressure plasma treatment shows adherends failure. As case of study the bonding solution to perform the assembly is considered a jaw finger of a robotic gripper for the picking of garments from a table. The redesign of the finger availing of the performance of bonding with the new plasma treatment is proposed and discussed. Experimental testing assessed the feasibility of this innovative technical solution

Development of a gripper for garment handling designed for additive manufacturing

The paper presents how a robotic gripper specific for grasping and handling of textiles and soft flexible layers can be miniaturized and improved by polymeric additive manufacturing-oriented re-design. Advantages of polymeric additive manufacturing are to allow a re-design of components with integrated functions, to be cost-effective equipment for small batches production and the availability of suitable materials for many applications. The drawback is that for design validation extended testing is still necessary because of lacks in standardization and that the mechanical properties are building parameters dependent. The outcomes are a lower complexity of the design overall and lower number of components. These are pursued taking advantage of the anisotropy of the additive manufacturing processed polymer and assigning appropriate shapes and linkages in the mechanisms. Set of common materials (polylactide, polyethylene terephthalate, acrylonitrile butadiene styrene) and technical (acrylonitrile styrene acrylate, polycarbonate/polybutylene terephthalate blend) are tested to obtain data for the modelling

Development and analysis of a new specialized gripper mechanism for garment handling

This paper reports ongoing work on the design of a new gripper for garments handling. The development of this device is part of the CloPeMa European Project creating a robot system for automated manipulation of clothing and other textile items. First, we analyze the specificity of the application determining the requirements for the design and functioning of the grasping system. Textiles do not have a stable shape and cannot be manipulated on the basis of a priori geometric knowledge. The necessary exploration of the material and the environment is performed with the help of tactile sensors embedded in the fingertips of the gripper, complementing the vision system of the robotic work cell. The chosen design solution is a simple mechanism able to perform adequately the grasping task and to permit exploratory finger motions. The kinematics and statics of the mechanism are outlined briefly and, in accord with initial experiments, used to validate the design

ADDITIVE MANUFACTURING PROCESS PARAMETER INFLUENCE ON MECHANICAL STRENGTH OF ADHESIVE JOINTS, PRELIMINARY ACTIVITIES

open7The work illustrates how building parameters of the Additive Manufacturing (AM) process fused filament fabrication can affect not only the mechanical properties [1] but also the surface wettability and morphology. Wettability and morphology are relevant factors in bonded joints performance [2]. Advantages of polymeric AM are to allow a re-design of components with locally controlled properties [3] and integrated functions. Major limitations are related to the lack of material testing standardization and constraints due to the build volume and to the object orientation for printability: the latter problem can be addressed with the use of bonded joints that allow to create bigger assemblies from smaller parts optimally designed to take advantage of the anisotropy of the material and without the structural drawbacks due to other joining method, such as stress concentration in bolted joints. As for the Mechanical properties, they are obtained with uniaxial tensile tests using MaCh3D [4], an innovative cost effective solution for materials testing. The as built surface properties are investigated quantitatively and qualitatively using a plate specimen of 15 × 15 × 1.2 mm. Roughness parameters are measured by surface scanning with a CCI Taylor-Hobson 3D optical profilometer while contact angle values between specimens and a drop of Milli-Q water are measured in order to evaluate wettability. Different materials, such as ABS and PLA, are characterized at different combinations of nozzle temperature, print speed and layer thickness. The analysis of the collected data provide information on how building parameters can modify two fundamental aspects in adhesive joints such as surface roughness and wettability in order to maximize joint performance.openM. Frascio, L. Bergonzi, F. Moroni, A. Pirondi, M. Avalle, M. Monti, M. VettorFrascio, M.; Bergonzi, L.; Moroni, F.; Pirondi, A.; Avalle, M.; Monti, M.; Vettor, M

Application of a Biphasic Actuator in the Design of the CloPema Robot Gripper

The paper (a first version of this work was presented in Aug. 2014 at ASME-DETC in Buffalo, NY) describes a novel robot gripper for garment handling. The device has been designed, developed, prototyped, and tested within the CloPeMa European Project creating a robot system for automated manipulation of clothing and other textile items. The gripper has two degrees of freedom (dof) and includes both rigid and flexible elements. A variable-stiffness actuator has been implemented to add controlled compliance in the gripper's operation allowing the combining of various grasping and manipulation tasks. First, we analyze the specific application-determined task requirements, focusing on the need for adaptive flexibility and the role of compliant elements in the design. The chosen solution is a simple planar mechanism, equipped with one standard and one variablestiffness actuator. The mechanical design of the gripper, including the hydraulic system used in the biphasic actuator, is outlined, and the control architecture, using sensor feedback, is described

The Effect of Latent Toxoplasma gondii Infection on the Immune Response in HIV-Infected Patients

A relationship between latent toxoplasmosis and the immune system during HIV disease is poorly understood. Therefore, the aim of this follow-up study was to characterize immunological parameters in HIV-infected patients with latent toxoplasmosis and noninfected individuals. A total of 101 HIV-infected patients were enrolled in the study. The patients were classified into two groups based on anti-Toxoplasma gondii antibodies: a group of 55 toxoplasma-positive persons (TP) and a group of 46 toxoplasmanegative persons (TN). Absolute counts of several lymphocyte subsets decreased in the TP group, namely, T cells ( = 0.007), B cells ( = 0.002), NK cells ( = 0.009), CD4 T cells ( = 0.028), and CD8 T cells ( = 0.004). On the other hand, the percentage of CD8 T cells expressing CD38 and HLA-DR significantly increased during the follow-up in the TP group ( = 0.003, = 0.042, resp.) as well as the intensity of CD38 and HLA-DR expression (MFI) on CD8 T cells ( = 0.001, = 0.057, resp.). In the TN group, analysis of the kinetics of immunological parameters revealed no significant changes over time. In conclusion, the results suggest that latent T. gondii infection modulates the immune response during HIV infection

The Effect of Latent Toxoplasma gondii Infection on the Immune Response in HIV-Infected Patients

A relationship between latent toxoplasmosis and the immune system during HIV disease is poorly understood. Therefore, the aim of this follow-up study was to characterize immunological parameters in HIV-infected patients with latent toxoplasmosis and noninfected individuals. A total of 101 HIV-infected patients were enrolled in the study. The patients were classified into two groups based on anti-Toxoplasma gondii antibodies: a group of 55 toxoplasma-positive persons (TP) and a group of 46 toxoplasma-negative persons (TN). Absolute counts of several lymphocyte subsets decreased in the TP group, namely, T cells (p=0.007), B cells (p=0.002), NK cells (p=0.009), CD4 T cells (p=0.028), and CD8 T cells (p=0.004). On the other hand, the percentage of CD8 T cells expressing CD38 and HLA-DR significantly increased during the follow-up in the TP group (p=0.003, p=0.042, resp.) as well as the intensity of CD38 and HLA-DR expression (MFI) on CD8 T cells (p=0.001, p=0.057, resp.). In the TN group, analysis of the kinetics of immunological parameters revealed no significant changes over time. In conclusion, the results suggest that latent T. gondii infection modulates the immune response during HIV infection