2,025 research outputs found
Robust algorithm for calibration of robotic manipulator model
The paper focuses on the robust identification of geometrical and elastostatic parameters of robotic manipulator. The main attention is paid to the efficiency improvement of the identification algorithm. To increase the identification accuracy, it is proposed to apply the weighted least square technique that employs a new algorithm for assigning of the weighting coefficients. The latter allows taking into account variation of the measurement system precision in different directions and throughout the robot workspace. The advantages of the proposed approach are illustrated by an application example that deals with the elasto-static calibration of industrial robot.AN
Augmented Reality-based Feedback for Technician-in-the-loop C-arm Repositioning
Interventional C-arm imaging is crucial to percutaneous orthopedic procedures
as it enables the surgeon to monitor the progress of surgery on the anatomy
level. Minimally invasive interventions require repeated acquisition of X-ray
images from different anatomical views to verify tool placement. Achieving and
reproducing these views often comes at the cost of increased surgical time and
radiation dose to both patient and staff. This work proposes a marker-free
"technician-in-the-loop" Augmented Reality (AR) solution for C-arm
repositioning. The X-ray technician operating the C-arm interventionally is
equipped with a head-mounted display capable of recording desired C-arm poses
in 3D via an integrated infrared sensor. For C-arm repositioning to a
particular target view, the recorded C-arm pose is restored as a virtual object
and visualized in an AR environment, serving as a perceptual reference for the
technician. We conduct experiments in a setting simulating orthopedic trauma
surgery. Our proof-of-principle findings indicate that the proposed system can
decrease the 2.76 X-ray images required per desired view down to zero,
suggesting substantial reductions of radiation dose during C-arm repositioning.
The proposed AR solution is a first step towards facilitating communication
between the surgeon and the surgical staff, improving the quality of surgical
image acquisition, and enabling context-aware guidance for surgery rooms of the
future. The concept of technician-in-the-loop design will become relevant to
various interventions considering the expected advancements of sensing and
wearable computing in the near future
A magnetic internal mechanism for precise orientation of the camera in wireless endoluminal applications
Background and study aims: The use of magnetic
fields to control operative devices has been recently
described in endoluminal and transluminal
surgical applications. The exponential decrease of
magnetic field strength with distance has major
implications for precision of the remote control.
We aimed to assess the feasibility and functionality
of a novel wireless miniaturized mechanism,
based on magnetic forces, for precise orientation
of the camera.
Materials and methods: A remotely controllable
endoscopic capsule was developed as proof of
concept. Two intracapsular moveable permanent
magnets allow fine positioning, and an externally
applied magnetic field permits gross movement
and stabilization. Performance was assessed in ex
vivo and in vivo bench tests, using porcine upper
and lower gastrointestinal tracts.
Results: Fine control of capsule navigation and
rotation was achieved in all tests with an external
magnet held steadily about 15 cm from the capsule.
The camera could be rotated in steps of 1.8°.
This was confirmed by ex vivo tests; the mechanism
could adjust the capsule view at 40 different
locations in a gastrointestinal tract phantom
model. Full 360° viewing was possible in the gastric
cavity, while the maximal steering in the colonwas
45° in total. In vivo, a similar performance
was verified, where the mechanism was successfully
operated every 5 cm for 40 cm in the colon,
visually sweeping from side to side of the lumen;
360° views were obtained in the gastric fundus
and body, while antrally the luminal walls prevented
full rotation.
Conclusions: We report the feasibility and effectiveness
of the combined use of external static
magnetic fields and internal actuation to move
small permanent intracapsular magnets to
achieve wirelessly controllable and precise camera
steering. The concept is applicable to capsule
endoscopy as to other instrumentation for laparoscopic,
endoluminal, or transluminal procedures
Lunar base mission technology issues and orbital demonstration requirements on space station
The International Space Station has been the object of considerable design, redesign, and alteration since it was originally proposed in early 1984. In the intervening years the station has slowly evolved to a specific design that was thoroughly reviewed by a large agency-wide Critical Evaluation Task Force (CETF). As space station designs continue to evolve, studies must be conducted to determine the suitability of the current design for some of the primary purposes for which the station will be used. This paper concentrates on the technology requirements and issues, the on-orbit demonstration and verification program, and the space station focused support required prior to the establishment of a permanently manned lunar base as identified in the National Commission on Space report. Technology issues associated with the on-orbit assembly and processing of the lunar vehicle flight elements are also discussed
Near net shape manufacturing of metal : a review of approaches and their evolutions
In the last thirty years the concept of manufacturability has been applied to many different processes in numerous industries. This has resulted in the emergence of several different "Design for Manufacturing" methodologies which have in common the aim of reducing productions costs through the application of general manufacturing rules. Near net shape technologies have expanded these concepts, targeting mainly primary shaping process, such as casting or forging. The desired outcomes of manufacturability analysis for near-net-shape (NNS) processes are cost and lead/time reduction through minimization of process steps (in particular cutting and finishing operations) and raw material saving. Product quality improvement, variability reduction and component design functionality enhancement are also achievable through NNS optimization. Process parameters, product design and material selection are the changing variables in a manufacturing chain that interact in complex, non-linear ways. Consequently modeling and simulation play important roles in the investigation of alternative approaches. However defining the manufacturing capability of different processes is also a “moving target” because the various NNS technologies are constantly improving and evolving so there is challenge in accurately reflecting their requirements and capabilities. In the last decade, for example, CAD, CNC technologies and innovation in materials have impacted enormously on the development of NNS technologies. This paper reviews the different methods reported for NNS manufacturability assessment and examines how they can make an impact on cost, quality and process variability in the context of a specific production volume. The discussion identifies a lack of structured approaches, poor connection with process optimization methodologies and a lack of empirical models as gaps in the reported approaches
A comparison of processing techniques for producing prototype injection moulding inserts.
This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM.
PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer.
The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used.
The parts produced from the three processing methods are investigated and their respective merits and issues are
discussed
Reducing risk in pre-production investigations through undergraduate engineering projects.
This poster is the culmination of final year Bachelor of Engineering Technology (B.Eng.Tech) student projects
in 2017 and 2018. The B.Eng.Tech is a level seven qualification that aligns with the Sydney accord for a three-year engineering degree and hence is internationally benchmarked. The enabling mechanism of these projects is the industry connectivity that creates real-world projects and highlights the benefits of the investigation of process at the technologist level.
The methodologies we use are basic and transparent, with enough depth of technical knowledge to ensure the industry partners gain from the collaboration process. The process we use minimizes the disconnect between the student and the industry supervisor while maintaining the academic freedom of the student and the commercial sensitivities of the supervisor.
The general motivation for this approach is the reduction of the entry cost of the industry to enable consideration of new technologies and thereby reducing risk to core business and shareholder profits.
The poster presents several images and interpretive dialogue to explain the positive and negative aspects of the student process
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