21 research outputs found

    Kinematics and Robot Design II (KaRD2019) and III (KaRD2020)

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    This volume collects papers published in two Special Issues “Kinematics and Robot Design II, KaRD2019” (https://www.mdpi.com/journal/robotics/special_issues/KRD2019) and “Kinematics and Robot Design III, KaRD2020” (https://www.mdpi.com/journal/robotics/special_issues/KaRD2020), which are the second and third issues of the KaRD Special Issue series hosted by the open access journal robotics.The KaRD series is an open environment where researchers present their works and discuss all topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. It aims at being an established reference for researchers in the field as other serial international conferences/publications are. Even though the KaRD series publishes one Special Issue per year, all the received papers are peer-reviewed as soon as they are submitted and, if accepted, they are immediately published in MDPI Robotics. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”.KaRD2019 together with KaRD2020 received 22 papers and, after the peer-review process, accepted only 17 papers. The accepted papers cover problems related to theoretical/computational kinematics, to biomedical engineering and to other design/applicative aspects

    Design, characterisation and testing of SU8 polymer based electrothermal microgrippers

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    Microassembly systems are designed to combine micro-component parts with high accuracy. These micro-components are fabricated using different manufacturing processes in sizes of several micrometers. This technology is essential to produce miniaturised devices and equipment, especially those built from parts requiring different fabrication procedures. The most important task in microassembly systems is the manipulator, which should have the ability to handle and control micro-particles. Different techniques have been developed to carry out this task depending on the application, required accuracy, and cost. In this thesis, the most common methods are identified and briefly presented, and some advantages and disadvantages are outlined. A microgripper is the most important device utilized to handle micro-objects with high accuracy. However, it is a device that can be used only in sequential microassembly techniques. It has the potential to become the most important tool in the field of micro-robotics, research and development, and assembly of parts with custom requirements. Different actuation mechanisms are employed to design microgrippers such as electromagnetic force, electrostatic force, piezoelectric effect, and electrothermal expansions. Also, different materials are used to fabricate these microgrippers, for example metals, silicon, and polymers such as SU-8. To investigate the limitation and disadvantages of the conventional SU-8 electrothermal based microgrippers, different devices designed and fabricated at IMT, Romania, were studied. The results of these tests showed a small end-effector displacement and short cycling on/off (lifetime). In addition, the actuator part of these microgrippers was deformed after each operation, which results in reduced displacement and inconsistent openings at off state every time it was operated in a power ON/OFF cycle. One of these limitations was caused by the existence of conductors in arms of the end-effectors. These conductor designs have two disadvantages: firstly, it raises temperature in the arms and causing an expansion in the opposite direction of the desired displacement. Secondly, since the conductors pass through the hinges, they should be designed wide enough to reduce the conductor resistance as much as possible. Therefore, the wider the hinges are, the higher the in-plane stiffness and the less out of plane deflection. As a result, it increases the reaction force of the arm reducing the effect of deformation. Based on these limitations a new actuatorstructure of L-shape was proposed to reduce the effects of these drawbacks. This actuator has no conductor in the hinges or the arms of the end-effectors which reduce limitation on the hinge width. . In addition, a further development of this actuator was proposed to increase the stiffness of the actuator by doubling its thickness compared with the other parts of the griper. The results of this actuator proved the improvement in performance and reduction of the actuator deformation. This new actuator structure was used to design several different microgrippers with large displacement and suitable for a wide range of applications. Demonstrations of the capabilities of the microgrippers to be used in microassembly are presented. In addition, a novel tri-directional microactuator is proposed in this thesis. This actuator’s end-effector is capable of displacements in three different directions. This actuator was used with the other designs to develop a novel three-arm (three fingers) multidirectional microgripper. To study the microgripper displacement as a function to the heater temperature, the TCR of the conductor layer of each device was measured. Because different configurations of conductor layers were studied, a significant effect of the metal layer structure on TCR was discovered. The TCR value of gold film is reduced significantly by adding the chromium layers below and about it which were used to improve the adhesion between the gold film and the SU layers. In this thesis, a new method based on a robotic system was developed to characterise these microgrippers and to study the steady state, dynamic response, and reliability (lifetime cycling on/off). An electronic interface was developed and integrated to the robotic system to control and drive the microgrippers. This new system was necessary to carry out automated testing of the microgrippers with accurate and reliable results. Four different new groups of microgrippers were designed and studied. The first group was indirectly actuated using an L-Shaped actuator and two different actuator widths. The initial opening was 120 μm for both designs. The maximum displacement was about 140 μm for both designs. However, the actuator in the wider heater width showed more stable behavior during the cycling and the dynamic tests. The second group was based on direct actuation approach using the L-Shaped actuator. There were eight different designs based on this method with different heater conductor shape, actuator width, and arm thickness. The initial opening was 100 μm and there were different displacements for the eight designs. The study of these microgrippers proved that the actuator stiffness has a significant effect on the microgripper displacement. In addition, the shape of the heater conductor has less effect. The largest displacement achieved using this method of design was about 70 μm. The third group was designed for dual mode operation and has three different designs. The initial openings were 90 μm and 250 μm. The displacement was about 170 μm in both modes. The last microgripper design was a tri-arm design for multi-mode operation. The lifetime study of SU8 based microgrippers in this thesis was the first time such an investigation was carried out. The results of IMT designs showed that the larger is the displacement the less stable is the gripper design because of the high rection force acting on the actuators. The L-shape based microgrippers had better performance and they did not break after more than 400 cycles. In addition, the studies of static displacement and dynamic response of different designed microgripper proved that better performance of the proposed actuator can be obtained by using double thickness for the actuator as compared to the arm thickness

    The design and analysis of a novel 5 degree of freedom parallel kinematic manipulator.

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    Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF

    Affordable flexible hybrid manipulator for miniaturised product assembly

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    Miniaturised assembly systems are capable of assembling parts of a few millimetres in size with an accuracy of a few micrometres. Reducing the size and the cost of such a system while increasing its flexibility and accuracy is a challenging issue. The introduction of hybrid manipulation, also called coarse/fine manipulation, within an assembly system is the solution investigated in this thesis. A micro-motion stage (MMS) is designed to be used as the fine positioning mechanism of the hybrid assembly system. MMSs often integrate compliant micro-motion stages (CMMSs) to achieve higher performances than the conventional MMSs. CMMSs are mechanisms that transmit an output force and displacement through the deformation of their structure. Although widely studied, the design and modelling techniques of these mechanisms still need to be improved and simplified. Firstly, the linear modelling of CMMSs is evaluated and two polymer prototypes are fabricated and characterised. It is found that polymer based designs have a low fabrication cost but not suitable for construction of a micro-assembly system. A simplified nonlinear model is then derived and integrated within an analytical model, allowing for the full characterisation of the CMMS in terms of stiffness and range of motion. An aluminium CMMS is fabricated based on the optimisation results from the analytical model and is integrated within an MMS. The MMS is controlled using dual-range positioning to achieve a low-cost positioning accuracy better than 2µm within a workspace of 4.4×4.4mm2. Finally, a hybrid manipulator is designed to assemble mobile-phone cameras and sensors automatically. A conventional robot manipulator is used to pick and place the parts in coarse mode while the aluminium CMMS based MMS is used for fine alignment of the parts. A high-resolution vision system is used to locate the parts on the substrate and to measure the relative position of the manipulator above MMS using a calibration grid with square patterns. The overall placement accuracy of the assembly system is ±24µm at 3σ and can reach 2µm, for a total cost of less than £50k, thus demonstrating the suitability of hybrid manipulation for desktop-size miniaturised assembly systems. The precision of the existing system could be significantly improved by making the manipulator stiffer (i.e. preloaded bearings…) and adjustable to compensate for misalignment. Further improvement could also be made on the calibration of the vision system. The system could be either scaled up or down using the same architecture while adapting the controllers to the scale.Engineering and Physical Sciences Research Council (EPSRC

    21st century manufacturing machines: Design, fabrication and controls

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    Advances in nanotechnology, microfabrication and new manufacturing processes, the revolution of open electronics, and the emerging internet of things will influence the design, manufacture, and control of manufacturing machines in the future. For instance, miniaturization will change manufacturing processes; additive and rapid prototyping will change the production of machine components; and open electronics offer a platform for new control architectures for manufacturing systems that are open, modular, and easy to reconfigure. Combined with the latest trends in cyber-physical systems and the internet of things, open architecture controllers for CNC systems can become platforms, oriented for numerical control as a service (NCaaS) and manufacturing as a service, tailored to the creation of cyber-manufacturing networks of shared resources and web applications. With this potential in mind, this research presents new design-for-fabrication methodologies and control strategies to facilitate the creation of next generation machine tools. It provides a discussion and examples of the opportunities that the present moment offers. The first portion of this dissertation focuses on the design of complex 3D MEMS machines realized from conventional 2.5D microfabrication processes. It presents an analysis of an example XYZ-MEMS parallel kinematics stage as well as of designs of the individual components of the manipulator, integrated into a design approach for PK-XYZ-MEMS stages. It seems likely that this design-for-fabrication methodology will enable higher functionality in MEMS micromachines and result in new devices that interact, in three full dimensions, with their surroundings. Novel and innovative research exemplifies the opportunities new and economical manufacturing technologies offer for the design and fabrication of modern machine tools. The second portion of this dissertation describes the demonstration of a new flexural joint designed with both traditional and additive manufacturing processes. It extrapolates principles based on the design of this joint that alleviate the effects of low accuracy and poor surface finishing, anisotropy, reductions in material properties of components, and small holding forces. Based on these results, the next section presents case examples of the construction of mesoscale devices and machine components using multilayered composites and hybrid flexures for precision engineering, medical training, and machine tools for reduced life applications and tests design-for-fabrication strategies. The results suggest the strategies effectively address existing problems, providing a repertory of creative solutions applicable to the design of devices with hybrid flexures. The implications for medical industry, micro robotics, soft robotics, flexible electronics, and metrology systems are positive. Chapter number five examines to positive impact of open architectures of control for CNC systems, given the current availability of micro-processing power and open-source electronics. It presents a new modular architecture controller based on open-source electronics. This component-based approach offers the possibility of adding micro-processing units and an axis of motion without modification of the control programs. This kind of software and hardware modularity is important for the reconfiguration of new manufacturing units. The flexibility of this architecture makes it a convenient testbed for the implementation of new control algorithms on different electromechanical systems. This research provides general purpose, open architecture for the design of a CNC system based on open electronics and detailed information to experiment with these platforms. This dissertation’s final chapter describes how applying the latest trends to the classical concepts of modular and open architecture controllers for CNC systems results in a control platform, oriented for numerical control as a service (NCaaS) and manufacturing as a service (MaaS), tailored to the creation of cyber-manufacturing networks of shared resources and web applications. Based on this technology, this chapter introduces new manufacturing network for numerical control (NC) infrastructure, provisioned and managed over the internet. The proposed network architecture has a hardware, a virtualization, an operating system, and a network layer. With a new operating system necessary to service and virtualize manufacturing resources, and a micro service architecture of manufacturing nodes and assets, this network is a new paradigm in cloud manufacturing

    SPRK: A Low-Cost Stewart Platform For Motion Study In Surgical Robotics

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    To simulate body organ motion due to breathing, heart beats, or peristaltic movements, we designed a low-cost, miniaturized SPRK (Stewart Platform Research Kit) to translate and rotate phantom tissue. This platform is 20cm x 20cm x 10cm to fit in the workspace of a da Vinci Research Kit (DVRK) surgical robot and costs $250, two orders of magnitude less than a commercial Stewart platform. The platform has a range of motion of +/- 1.27 cm in translation along x, y, and z directions and has motion modes for sinusoidal motion and breathing-inspired motion. Modular platform mounts were also designed for pattern cutting and debridement experiments. The platform's positional controller has a time-constant of 0.2 seconds and the root-mean-square error is 1.22 mm, 1.07 mm, and 0.20 mm in x, y, and z directions respectively. All the details, CAD models, and control software for the platform is available at github.com/BerkeleyAutomation/sprk

    Mikrofertigungstechnologien und ihre Anwendungen – ein theoretischer und praktischer Leitfaden

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    Dieses Buch beinhaltet Beiträge aus verschiedenen Bereichen der Mikrofertigungstechnologie und -ingenieurwesen und wurde im Rahmen des EU-Projektes MIMAN-T (Micro-manufacturing training for SMEs) verfasst. Dieses Buch richtet sich vorrangig an Techniker und zukünftige Fachkräfte, aber auch Studenten, die in diesem Gebiet tätig werden. Es soll als effektives Werkzeug dienen, dass dazu führt, dass wissenschaftliche Entwicklungen in konkrete industrielle Vorteile umgesetzt werden können

    The research of five-bar robot for pressurized autosampling for enhanced oil recovery research

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    Robots have been widely used in industry and are becoming popular in people’s daily lives. It makes production more efficient and everyday life more convenient. In this research, a robotic auto-sampler is designed, developed and tested to sample and collect two-phase fluids from a core flooding. First of all, this thesis introduces the history of parallel robot industry the state of the art. Then, based on the problem statement, the most reasonable concept is chosen as the Five-Bar parallel robot. Theoretical simulations are made including kinematic analysis to calculate its mechanical dimension and dynamic analysis to calculate the actuator torque. As a result of that, the theoretical dimensions can be obtained and actuators can be chosen. In the design and control phase, the entire integrated system is presented in detail. This thesis researches the design process of an auto-sampler based on a five-bar robot. From the proposed problem to the robot fabrication and programming, the entire system is designed, analyzed, built and tested

    Beitrag zur Gestaltung und Herstellung einer integrierten Mikropositionierungssystem

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    Modern positioning systems are significantly applied in many engineering fields dealing with products emerging from different technologies at macro-, micro- and nanoscale. These systems are the back-bone systems behind any manipulation task in these areas. Currently, miniaturization trend have led numerous scientific communities to realize down scaled versions of these systems with a footprint size up to few hundreds of millimeters. These miniature positioning systems are cost effective solutions in many micro applications. This thesis presents the development of a miniature positioning system integrated with a non-contact long range displacement sensor. The uniqueness of the presented positioning system lies in its simple design with ability to perform micrometer to millimeter level strokes with pre-embedded auto guidance feature. Its design consists of a mobile part driven with four electromagnetic linear motors. Each motor consists of a fixed two phase current carrying planar electric drive coil and permanent magnet array that is realized with 14 permanent magnets arranged in north-south configuration. In order to achieve smooth motion a four point contact technique with hemispherical glass beads has been adapted to minimize the adherence effect. The overall design of the planar positioning system have been optimized to achieve a footprint size of 80 mm × 80 mm. The device can deliver motion within working range of 10 mm × 10 mm in xy-plane with sub micrometer level resolution at a speed of 12 mm/s. The device is capable to deliver a rotation motion of ±11° about the z axis in the xy-plane. Secondly, in order to measure the displacement performed by the mobile part, a non-contact long range linear displacement sensor has been designed. The overall dimensions of the sensor were optimized using a geometrical model. The fabrication of the sensor has been carried out via microfabrication in silicon material to achieve compact dimensions, so that it could be integrated in the mobile part of the positioning system. The sensor is able to provide 30.8 nm resolution with a linear measurement range of 12.5 mm. At the end, a novel cross structure has been designed and fabricated using microfabrication with the perspective to integrate the long range sensor.Moderne Positioniersysteme werden in vielen aufstrebenden Bereichen der Technik eingesetzt. Die Produkte stammen hierbei aus unterschiedlichen Technologiebereichen, die den Makro-, Mikro- und Nano- Maßstab abdecken. Diese Systeme bilden die Basis jeder Manipulationsaufgabe, in diesen Bereichen. In jüngster Zeit hat der Miniaturisierungstrend dazu geführt, dass in zahlreichen wissenschaftlichen Bereichen immer kleinere Versionen von Systemen realisiert wurden. Die typischen Abmessungen wurden dabei auf einige hundert Millimeter reduziert. Diese Miniatur Positioniersysteme sind kostengünstige Lösungen in vielen Mikro Anwendungen. Die vorliegende Arbeit stellt die Entwicklung eines Miniatur-Positioniersystems dar, in welches ein berührungsloser Wegsensor für lange Distanzen integriert wurde. Die Einzigartigkeit dieses Positionierungssystems liegt in der Einfachheit der Konstruktion in Kombination mit der Fähigkeit Bewegungen vom Mikrometer bis zum Millimeter Bereich mittels einer eingebetteten Autopilotfunktion auszuführen. Das Design besteht aus einem beweglichen Teil, welches mit vier elektrischen Linearmotoren angetrieben wird. Jeder Motor besteht aus zwei Teilen: Einem planaren elektrisch angetriebenen Schlitten und einer Anordnung von Permanentmagneten. Die Anordnung ist mit 14 Permanentenmagneten in Nord-Süd Ausrichtung realisiert. Um eine sanfte Bewegung zu erreichen wird eine Vierpunktauflage mit halbkugelförmigen Glasperlen verwendet. Hierdurch werden Adhäsionseffekte minimiert. Das Positionierungssystem kann Bewegungen im Arbeitsbereich von 10 mm × 10 mm in der xy-Ebene mit Submikrometer Auflösung und einer Geschwindigkeit von 12 mm/s ausführen. Das Gerät ist in der Lage eine Drehbewegung von ±11° um die z-Achse in der xy-Ebene auszuführen. Weiterhin wurde, um die Verschiebung des beweglichen Teils zu messen, ein kontak tloser Langstrecken-Wegsensor entworfen. Die Gesamtabmessungen des Sensors wurden mit einem geometrischen Modell optimiert. Die Herstellung des Sensors wurde mittels Mikrostrukturierung in Silizium ausgeführt um eine kompakte Abmessung zu erreichen, so dass es in den beweglichen Teil des Positionierungssystems integriert werden konnte. Der Sensor erreicht eine Auflösung von 30,8 nm in einem linearen Messbereich von 12.5 mm. Am Ende der Arbeit wurde eine neue Kreuz-Struktur konzipiert und hergestellt, gleichfalls mit Hilfe der Mikrostrukturierungstechnik. Hieraus ergibt sich die Perspektive den Langstrecken Wegsensor problemlos zu integrieren

    Design of three degrees-of-freedom motion stage for micro manipulation

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    A miniaturized translational motion stage has potentials to provide not only performances equivalent to conventional motion stages, but also additional features from its small form factor and low cost. These properties can be utilized in applications requiring a small space such as a vacuum chamber in a scanning electron microscopy (SEM), where hidden surface can decrease by manipulating objects to measure. However, existing miniaturized motion stages still have several cm3 level volumes and provide simple operations. In this dissertation, Micro-electro-mechanical systems (MEMS)-based motion stages are utilized to replace a miniaturized motion stage for micro-scale manipulation and possible applications. However, most MEMS fabrication methods remain in monolithic fabrication methods and a lot of MEMS based multiple degrees-of-freedom (DOFs) motion stage also remain for in-plane motions. In this dissertation, a nested structure based on a serial kinematic mechanism is implemented in order to overcome these constraints and implement out-of-plane motion, where one independent stage is embedded into the other individual stage with additional features for structurally and electrically isolations among the engaged stages. MEMS actuators and displacement amplifiers are also investigated for reasonable performance. 3-axis motions are divided into two in-plane motions and one out-of-plane motion; an in-plane 1 DOF motion stage (called an X-stage) and one out-of-plane 1 DOF motion stage (called a Z-stage) are designed and characterized experimentally. Based on the two stages, the XY-stage is designed by merging one X-stage into the motion platform of the other X-stage with a different orientation (called an XY-stage). With this nested approach, the fabricated XY-stage demonstrated in-plane motions larger than 50 µm with ignorable coupled motion errors. Based on this nested approach, the 3-axis motion stage is also implemented by utilizing the nested structure twice; integrating the Z-stage with the motion platform of the XY-stage (called an XYZ-stage). The XYZ-stage demonstrated out-of-plane motions about 23 µm as well as the in-plane motions. Two presented motion stages have been utilized in the manipulation of micro-scale object by the cooperation of the two XY-stages inside a SEM chamber. The large motion platform of the X-stage is also utilized in a parallel plate type rheometer to measure the material properties of viscoelastic materials
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