AN ALGORITHM FOR RECONSTRUCTING THREE-DIMENSIONAL IMAGES FROM OVERLAPPING TWO-DIMENSIONAL INTENSITY MEASUREMENTS WITH RELAXED CAMERA POSITIONING REQUIREMENTS, WITH APPLICATION TO ADDITIVE MANUFACTURING

Cameras are everywhere for security purposes and there are often many cameras installed close to each other to cover areas of interest, such as airport passenger terminals. These systems are often designed to have overlapping fields of view to provide different aspects of the scene to review when, for example, law enforcement issues arise. However, these cameras are rarely, if ever positioned in a way that would be conducive to conventional stereo image processing. To address this, issue an algorithm was developed to rectify images measured under such conditions, and then perform stereo image reconstruction. The initial experiments described here were set up using two scientific cameras to capture overlapping images in various cameras positons. The results showed that the algorithm was accurately reconstructing the three-dimensional (3-D) surface locations of the input objects. During the research an opportunity arose to further develop and test the algorithms for the problem of monitoring the fabrication process inside a 3-D printer. The geometry of 3-D printers prevents the location of cameras in the conventional stereo imaging geometry, making the algorithms described above seem like an attractive solution to this problem. The emphasis in 3-D printing on using extremely low cost components and open source software, and the need to develop the means of comparing observed progress in the fabrication process to a model of the device being fabricated posed additional development challenges. Inside the 3-D printer the algorithm was applied using two scientific cameras to detect the errors during the printing of the low-cost open-source RepRap style 3-D printer developed by the Michigan Tech’s Open Sustainability Technology Lab. An algorithm to detect errors in the shape of a device being fabricated using only one camera was also developed. The results show that a 3-D reconstruction algorithm can be used to accurately detect the 3-D printing errors. The initial development of the algorithm was in MATLAB. The cost of the MATLAB software might prevent it from being used by open-source communities. Thus, the algorithm was ported to Python and made open-source for everyone to use and customize. To reduce the cost, the commonly used and widely available inexpensive webcams were also used instead of the expensive scientific cameras. In order to detect errors around the printed part, six webcams were used, so there were 3 pairs of webcams and each pair were 120 degrees apart. The results indicated that the algorithms are precisely detect the 3-D printing errors around the printed part in shape and size aspects. With this low-cost and open-source approach, the algorithms are ready for wide range of use and applications

Printed polymers, patterned paper

In zijn onderzoek heeft Gert Salentijn gekeken naar een aantal manieren om de afhankelijkheid van stationaire laboratorium faciliteiten te verminderen voor chemische analyses, om het zo toegankelijker te maken, of, zoals het ook wel gezegd wordt: “We brengen het lab naar het monster, in plaats van het monster naar het lab.” Deze benadering is tegenwoordig erg populair, mede omdat we ons bewust zijn van een sterke vraag naar snelle, flexibele en kosteneffectieve diagnosestelling in de buurt van de patiënt, of dat in een ontwikkelingsgebied is of in een huisartsenpraktijk in Nederland. Het project is gefinancierd door de Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) en richtte zich op de ontwikkeling van cartridges voor monstername voor een draagbaar analyse instrument. Cruciaal voor het onderzoek is een eenvoudig, doch elegant materiaal, welke reeds een lange geschiedenis kent binnen de wereld van de wetenschap, namelijk papier. Door dit materiaal te benaderen vanuit nieuwe invalshoeken, waaronder de integratie in een 3D-geprinte cartridge, kunnen we de toepassingen binnen de analytische chemie (en daar buiten) naar een nieuwe hoogte brengen. De technieken die in dit onderzoek zijn ontwikkeld stellen ons in staat om nieuwe soorten functionaliteit toe te kunnen voegen aan dergelijke tests, waardoor ze slimmer en beter worden, en tegelijkertijd betaalbaar blijven

A dynamic model for current-based nozzle condition monitoring in fused deposition modelling

Abstract: 3D printing and particularly fused deposition modelling (FDM) is widely used for prototyping and fabricating low-cost customised parts. However, present fused deposition modelling 3D printers have limited nozzle condition monitoring techniques to minimize nozzle clogging errors. Nozzle clogging is one of the significant process errors in fused deposition modelling 3D printers, and it affects the quality of prototyped parts in terms of mechanical properties and geometrical accuracy. This paper proposes a dynamic model for current-based nozzle condition monitoring in fused deposition modelling, which is briefly described as follows. First, all the process forces in filament extrusion of the fused deposition modelling were identified and derived theoretically, and theoretical equations of the feed rolling forces and flow-through-nozzle forces were derived. In addition, the effect of the nozzle clogging on the current of extruding motor were identified. Second, based on the proposed dynamic model, current-based nozzle condition monitoring method was proposed. Next, sets of experiments on FDM machine using polylactic acid (PLA) material were carried out to verify the proposed theoretical model, and the results were analysed and evaluated. Findings of the present study indicate that nozzle clogging in FDM 3D printing can be monitored by sensing the current of the filament extruding motor. The proposed model can be used efficiently for monitoring nozzle clogging conditions in fused deposition modelling 3D printers as it is based on the fundamental process modelling

A dynamic model for current-based nozzle condition monitoring in fused deposition modelling

Abstract: 3D printing and particularly fused deposition modelling (FDM) is widely used for prototyping and fabricating low-cost customised parts. However, present fused deposition modelling 3D printers have limited nozzle condition monitoring techniques to minimize nozzle clogging errors. Nozzle clogging is one of the significant process errors in fused deposition modelling 3D printers, and it affects the quality of prototyped parts in terms of mechanical properties and geometrical accuracy. This paper proposes a dynamic model for current-based nozzle condition monitoring in fused deposition modelling, which is briefly described as follows. First, all the process forces in filament extrusion of the fused deposition modelling were identified and derived theoretically, and theoretical equations of the feed rolling forces and flow-through-nozzle forces were derived. In addition, the effect of the nozzle clogging on the current of extruding motor were identified. Second, based on the proposed dynamic model, current-based nozzle condition monitoring method was proposed. Next, sets of experiments on FDM machine using polylactic acid (PLA) material were carried out to verify the proposed theoretical model, and the results were analysed and evaluated. Findings of the present study indicate that nozzle clogging in FDM 3D printing can be monitored by sensing the current of the filament extruding motor. The proposed model can be used efficiently for monitoring nozzle clogging conditions in fused deposition modelling 3D printers as it is based on the fundamental process modelling

Conceptual design and development of a progressive cavity pump for extrusion-based additive manufacturing applications

The present study aimed to develop a low-cost, scalable, easy-to-clean extrusion system based on the progressive cavity pump (PCP) principle for extrusion-based additive manufacturing, with a specific focus on bioprinting. Therefore, the study proposes a spiral development model to achieve a novel PCP with the help of additive manufacturing (AM). An application programming interface was developed to enable quick design iterations. User requirements were determined through literature research, a user questionnaire and interviews. Consequently, three novel PCP concepts were designed and developed using the developed model, and the proof of concept for the selected PCP design was presented

Functional Materials and Techniques for Additive Manufacturing in Soft Robotics

This thesis outlines the development of new elastomeric materials and manufacturing processes for soft robotics. Specifically, this work describes the development of custom material formulations for use in additive manufacturing, additive manufacturing processing techniques for silicone elastomers, and multi-component additive manufacturing techniques. Material synthesis and processing is a gap in the field that needs more research to produce more predictable, higher quality, and more scalable soft robot technologies. This thesis includes papers that address the above topics, preceded by an introduction and literature review into additive manufacturing and materials characterization for soft robotics. The first work (Chapter 2) outlines the development of a custom elastomer designed to make biodegradable soft robots via 3D printing. The second work (Chapter 3) shows how liquid silicone thermoset polymers 3d printing can be improved by controlling reaction kinetics and rheology. The last work (Chapter 4) describes the process of using silicone 3D printing to embed multiple discrete sensing and electronic components into a functioning soft wearable device, with a focus on customizability. Each work describes a different part of how materials science plays a role in soft robotics, including the creation of elastomeric material, control of the elastomeric material, and combining the multiple materials in custom device manufacturing. For each work, a soft robot actuator or robot system is developed to emphasize the importance of material behavior and process development in improving soft robot manufacturing