Evert Fuenmayor

Digital twin (DT) technology has become a cornerstone in the simulation and analysis of real-world systems, offering unparalleled insights into the lifecycle management of physical assets. By providing a real-time synchronized replica of the physical entity, DTs enable predictive maintenance, performance optimization, and lifecycle extension, which are pivotal for industries aiming for digital transformation. This paper presents a comprehensive comparative study of DT development of a robotic arm using two prominent simulation platforms: Unity and Gazebo. Unity, with its roots in the gaming industry, offers robust real-time rendering and a user-friendly interface, making it a versatile choice for various industries. Gazebo, traditionally used in robotics, provides detailed physics simulations and sensor data emulation, which is ideal for precise engineering applications. We explored the performance of both platforms in creating accurate and dynamic digital replicas. Through qualitative and quantitative analyses, this study evaluates each platform’s strengths and limitations. The study assesses these platforms across key performance metrics such as accuracy, latency, graphic quality, and integration with the Robot Operating System (ROS). The DTs were developed using a consistent physical setup and communication layer to ensure fair comparisons. The results indicate that Unity performed better in terms of accurately mimicking the robotic arm with lower latency, making it ideal for applications requiring high-fidelity visualizations and real-time responsiveness. However, Gazebo excels in its ease of ROS integration and cost-effectiveness, making it a suitable choice for smaller robotics and automation projects. This study conducts an empirical comparison of these platforms in terms of their performance in creating DTs of robotic arms which is not readily available. This paper aims to guide developers and organizations in selecting the appropriate platform for their DT initiatives, ensuring efficient resource utilization and optimal outcomes.

A digital twin (DT) is a virtual/digital model of any physical object (physical twin), interconnected through data exchange. In the context of Industry 4.0, DTs are integral to intelligent automation driving innovation at scale by providing significant improvements in precision, flexibility, and real-time responsiveness. A critical challenge in developing DTs is achieving a model that reflects real-time conditions with precision and flexibility. This paper focuses on evaluating latency and accuracy, key metrics for assessing the efficacy of a DT, which often hinder scalability and adaptability in robotic applications. This article presents a comprehensive framework for developing DTs using Unity and Robot Operating System (ROS) as the main layers of digitalization and communication. The MoveIt package was used for motion planning and execution for the robotic arm, showcasing the framework’s versatility independent of proprietary constraints. Leveraging the versatility and open-source nature of these tools, the framework ensures interoperability, adaptability, and scalability, crucial for modern smart manufacturing applications. Our approach was validated by conducting extensive accuracy and latency tests. We measured latency by timestamping messages exchanged between the physical and digital twin, achieving a latency of 77.67 ms. Accuracy was assessed by comparing the joint positions of the DT and the physical robotic arm over multiple cycles, resulting in an accuracy rate of 99.99%. The results highlight the potential of DTs in enhancing operational efficiency and decision-making in manufacturing environments.

The use of biodegradable polymers in tissue engineering has been widely researched due to their ability to degrade and release their components in a controlled manner, allowing for the potential regeneration of tissues. Melt blending is a common method for controlling the degradation rate of these polymers, which involves combining these materials in a molten state to create a homogenous mixture with tailored properties. In this study, polycaprolactone (PCL) was melt blended with hydrophilic poly (ethylene oxide) (PEO) of different molecular weights to assess its effect on PCL material performance. Hydrolytic degradation, thermal and viscoelastic properties, and surface hydrophilicity were performed to contrast the properties of the blends. DSC, DMA, and FTIR were performed on selected degraded PCL/PEO specimens following mass loss studies. The results showed that adding PEO to PCL reduced its melt viscosity-torque and melt temperature while increasing its hydrophilicity, optimizing PCL/PEO blend for soft tissue engineering applications and could contribute to the development of more effective and biocompatible materials for soft tissue regeneration.

Since 3D printing allows for patient-specific dosage forms, it has become a major focus in pharmaceutical research. However, it is difficult to scale up drug product manufacturing. Injection molding has been used in conjunction with hot-melt extrusion to mass produce drug products, but making tailored solid dosage forms with this technology is neither cost-effective nor simple. This study explored the use of a combination of fused filament fabrication and injection molding to create patient-specific solid dosage forms. A tablet fixation and location template was used to overprint directly on injection-molded tablet bases, and theophylline was combined with polycaprolactone and Kollidon^® VA64 via hot-melt extrusion to produce the filament. Dynamic mechanical analysis was used to evaluate the brittleness of the filament, and differential scanning calorimetry was used to analyze the thermal results. The results showed that theophylline had a flow promoting effect on the polymer blend and that overprinted tablets were manufactured faster than 3D-printed tablets. Drug release studies also showed that overprinted tablets released faster than injection-molded tablets. This method demonstrates the potential of hybrid manufacturing for the pharmaceutical industry as a means of bridging the gap between personalized dosage forms and mass production.

Significant advances have been made in recent years in the materials development of liquid-based 4D printing. Nevertheless, employing additive materials such as nanoparticles for enhancing printability and shape memory characteristics is still challenging. Herein, we provide an overview of recent developments in liquid-based 4D printing and highlights of novel 4D-printable polymeric resins and their nanocomposite components. Recent advances in additive manufacturing technologies that utilise liquid resins, such as stereolithography, digital light processing, material jetting and direct ink writing, are considered in this review. The effects of nanoparticle inclusion within liquid-based resins on the shape memory and mechanical characteristics of 3D-printed nanocomposite components are comprehensively discussed. Employing various filler-modified mixture resins, such as nanosilica, nanoclay and nanographene, as well as fibrous materials to support various properties of 3D printing components is considered. Overall, this review paper provides an outline of liquid-based 4D-printed nanocomposites in terms of cutting-edge research, including shape memory and mechanical properties.

Mass customization is the development of items tailored to specific customers, but produced at low unit cost in high-volume. In this context, hybrid manufacturing (HM) combines fused deposition modeling (FDM) and injection molding (IM) to fabricate a single personalized part with minimum manufacturing cost. In this technique, inserts with different physical features are first FDM-fabricated and then IM-overmolded. This study investigated the effect of hybrid FDM-IM production technology, FDM insert geometry on mechanical properties, and micro-structural evolution of Polylactic Acid (PLA) samples. The findings indicated a comparable tensile properties of FDM-IM samples (68.38 MPa) to IM batch (68.95 MPa), emphasizing the potential of HM in the manufacturing industry. Maximum tensile stress of FDM-IM specimens shows an upward trend due to the increased infill density of preforms. In addition, overmolding interface direction results in a big gap for the maximum tensile strengths between half-length series specimens (12.99 MPa to 19.09 MPa) and half-thickness series specimens (53.83 MPa to 59.92 MPa). Furthermore, four joint configurations resulted in different mechanical performances of finished specimens, in which the female cube sample exhibits the highest tensile stress (68.38 MPa), while the batch with male T joint shows a lower value in maximum tensile strength (59.51 MPa), exhibiting a similar tensile performance with the half-thickness 75% batch without joint configuration. This study lays the groundwork for using HM to produce bespoke and mechanically improved parts over FDM alone.

Acrylonitrile Butadiene Styrene (ABS) is a common thermoplastic polymer that has been widely employed in the manufacturing industry due to its impact resistance, tensile strength, and rigidity. Additive manufacturing (AM) is a promising manufacturing technique being used to manufacture products with complex geometries, but it is a slow process producing mechanically inferior products when compared to traditional production processes like injection molding (IM). Thus, our hybrid manufacturing (HM) process combining materials extrusion AM and IM to create a single article was investigated in this study, in which eleven batches of specimens were made and extensively tested. These include the AM, IM, and hybrid manufactured (HYM) samples, in which the HYM samples were made by inserting AM substrates into the IM tool and were varied in infill density of AM preforms and geometries. The HYM samples outperformed AM parts in terms of mechanical performance while retaining customizability dependent on the HYM processing parameters, and the best mechanical performance for HYM samples was found to be comparable to that of IM samples, implying that the overmolding process in HM had primarily improved the mechanical performance of AM products. This work leads to a deeper knowledge of applications to confirm the optimal component fabrication in high design flexibility and mass production.

Injection moulding is a polymer processing method of choice for making plastic parts on industrial scale, but its traditional mould is made from tooling steel with time-consuming and costly production. Additive manufacturing technologies arise as an alternative for creating mould inserts at lower costs and shorter lead times. In this context, this study describes a series of stereolithography (SLA)-printed injection mould inserts fabricated from two photopolymer resins, utilised to mould standard tensile specimens of a commercial-grade polypropylene, aiming to evaluate effects on the polymer’s thermal and mechanical properties. Our results demonstrated that the glass fibre-filled resin inserts withstood more moulding cycles before failure, had superior mechanical properties, higher T_g and greater thermal conductivity. Calorimetric data revealed that PP thermal properties and degree of crystallinity were little affected, while mechanical testing suggests a significant effect in the elongation at break. Thus, these findings highlight the importance of adequate heat extraction during injection moulding and endorse further application of SLA mould inserts for the manufacturing of injection-moulded plastic parts in the case of prototypes or small batches, provided suitable cooling is made available, contributing to the feasibility and affordability of employing this approach for an industrial setting.