Category: Publications

Abstract:

This paper presents a high-sensitivity fiber Bragg grating (FBG) displacement sensor with a novel configuration for structural health monitoring. The transverse movement of an optical fiber that has been configured as a tight suspension status with its two ends fixed has been utilized to measure displacement. The theoretical models for both static and dynamic displacements have been derived. The corresponding simulations have been conducted to determine the relationship between the model parameters and the sensor performance. This approach supports the sensor design improvement and structural optimization. Two small working ranges have been selected to determine the simplified linear model according to Taylor series. The sensitivity of this sensor can reach up to 490.1 pm/mm with a high resolution of 2.04 μ m in a range of 1.4~2.0 mm. The introduction of the supporting spring unit has significantly enhanced the sensor’s resonant frequency without sacrificing the sensitivity. The application of the stiffer spring unit has enlarged the working bandwidth from 0~8 Hz to exceed 50 Hz. Enhancing the damping ratio unit can effectively improve the flatness of the dynamic response within the working bandwidth, while it does not affect other dynamic properties of the sensor. These improvements and design guidelines have been validated by both dynamic experiments and theoretical modelling.

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The purpose of this paper is to design a model-based bilateral teleoperation method to improve the feedback force and velocity/position tracking for robotic-assisted tasks (such as palpation, etc.) under constant and/or varying time delay with environment dynamic property. Time delay existing in bilateral teleoperation easily destabilizes the system. Proper control strategies are able to make the system stable, but at the cost of compromised performance. Model-based bilateral teleoperation is designed to achieve enhanced performance of this time-delayed system, but an accurate model is required. Design/methodology/approach Viscoelastic model has been used to describe the robot tool-soft tissue interaction behavior. Kevin-Boltzmann (K-B) model is selected to model the soft tissue behavior due to its good accuracy, transient and linearity properties among several viscoelastic models. In this work, the K-B model is designed at the master side to generate a virtual environment of remote robotic tool-soft tissue interaction. In order to obtain improved performance, a self perturbing recursive least square (SPRLS) algorithm is developed to on-line update the necessary parameters of the environment with varying dynamics. Findings With fast and optimal on-line estimation of primary parameters of the K-B model, the reflected force of the model-based bilateral teleoperation at the master side is improved as well as the position/velocity tracking performance. This model-based design in the bilateral teleoperation avoids the stability issue caused by time delay in the communication channel since the exchanged information become position/velocity and estimated parameters of the used model. Even facing with big and varying time delay, the system keeps stably and enhanced tracking performance. Besides, the fast convergence of the SPRLS algorithm helps to track the time-varying dynamic of the environment, which satisfies the surgical applications as the soft tissue properties usually are not static. Originality/value The originality of this work lies in that an enhanced perception of bilateral teleoperation structure under constant/varying time delay that benefits robotic assisted tele-palpation (time varying environment dynamic) tasks is developed. With SPRLS algorithm to on-line estimate the main parameters of environment, the feedback perception of system can be enhanced with stable velocity/position tracking. The superior velocity/position and force tracking performance of the developed method makes it possible for future robotic-assisted tasks with long-distance communication.

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In this paper the displacement analysis of an under-constrained parallel robot supported by flexible shafts is addressed. The problem consists of identifying the equilibrium poses of a moving platform when the shaft lengths are changed. Similar to under-constrained cable-driven parallel robots, the moving platform preserves some freedoms once shaft lengths are fixed. Thus, kinematics and statics must be taken into account simultaneously. However in contrast to cables, shafts may also impose torsional resistance on the moving platform which is considered in this study. To investigate the effect of this torsional resistance the pose of the moving platform with respect to the changes of length of shafts is investigated and compared to the pose of moving platform driven by cables

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Robotic assistance in Minimally Invasive Surgery
(MIS) have extended the capabilities of surgeons via improved
precision dexterity and computer assistance. By tapping on
the capabilities of MIS, this paper aims to design a new
tendon Fixation mechanism which utilizes springs to actuate
surgical tools for the removal of osseous giant cell tumor.
We presents our preliminary design conceptualization and
prototype development using spring backbone and tendon-
driven mechanism. By investigating different tendon routing
mechanisms, for the first time this study shows that it is
potentially feasible to accomplish needle-size (outer diameter
of 1 mm) to catheter-size (outer diameter of 2-3 mm) single-
channel surgical instruments for minimally invasive surgery.
Through this mechanism, it is expected that our surgical robot
can provide completeness of tumor removal through a minimal
incision without compromising oncological principles

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Intravascular ultrasound (IVUS) imaging provides two-dimensional (2D) real-time luminal and transmural cross-sectional images of intravascular vessels with detailed pathological information. It has offered significant advantages in terms of diagnosis and guidance and has been increasingly introduced from coronary interventions into more generalized endovascular surgery. However, IVUS itself does not provide spatial pose information for its generated images, making it difficult to construct a 3D intravascular visualization. To address this limitation, IVUS imaging-driven 3D intravascular reconstruction techniques have been developed. These techniques enable accurate diagnosis and quantitative measurements of intravascular diseases to facilitate optimal treatment determination. Such reconstruction extends the IVUS imaging modality from pure diagnostic assistance to intraoperative navigation and guidance and supports both therapeutic options and interventional operations. This paper presents a comprehensive survey of technological advances and recent progress on IVUS imaging-based 3D intravascular reconstruction and its state-of-the-art applications. Limitations of existing technologies and prospects of new technologies are also discussed.

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Purpose: Origami-based biomedical device design is an emerging technology due to its ability to be deployed from a minimal foldable pattern to a larger volume. This paper aims to review state-of-the-art origami structures applied in the medical device field. Methods: Publications and reports of origami structure related to medical device design from the past 10 years are reviewed and categorized according to engineering specifications, including the application field, fabrication material, size/volume, deployment method, manufacturability, and advantages. Results: This paper presents an overview of the biomedical applications of devices based on origami structures, including disposable sterilization covers, cardiac catheterization, stent grafts, encapsulation and microsurgery, gastrointestinal microsurgery, laparoscopic surgical grippers, microgrippers, microfluidic devices, and drug delivery. Challenges in terms of materials and fabrication, assembly, modeling and computation design, and clinical adoptability are discussed at the end of this paper to provide guidance for future origami-based design in the medical device field. Conclusion: Concepts from origami can be used to design and develop novel medical devices. Origami-based medical device design is currently progressing, with researchers improving design methods, materials, fabrication techniques, and folding efficiency.

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To realize the stability of the passive magnetic robotic system, a novel combination of permanent magnets is proposed. As we know, a single passive magnetic levitation is impossible to suspend all degrees of freedom of a rigid body; this article researches the combination of multiple passive magnetic bearings by the finite element method (FEM) simulation. Through changing the magnetization direction of permanent magnets, the radial force and axial force can be changed correspondingly. Various magnetization angles of permanent magnets are analysed, and the relationships are analysed among radial force, axial force, and axial displacement. Finally, the optimized magnetization angle of the permanent magnets and their arrangements are proposed. According to the analytic results, it is feasible to realize the stability using the proposed configuration.

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