207 results found
Donder A, Rodriguez y Baena F, 2022, 3-D path-following control for steerable needles with fiber Bragg gratings in multi-core fibers, IEEE Transactions on Biomedical Engineering, Pages: 1-12, ISSN: 0018-9294
Steerable needles have the potential for accurateneedle tip placement even when the optimal path to a target tissueis curvilinear, thanks to their ability to steer, which is an essen-tial function to avoid piercing through vital anatomical features.Autonomous path-following controllers for steerable needles havealready been studied, however they remain challenging, especiallybecause of the complexities associated to needle localization. Inthis context, the advent of fiber Bragg Grating (FBG)-inscribedmulti-core fibers (MCFs) holds promise to overcome these diffi-culties. Objective: In this study, a closed-loop, 3-D path-followingcontroller for steerable needles is presented. Methods: The controlloop is closed via the feedback from FBG-inscribed MCFs embed-ded within the needle. The nonlinear guidance law, which is a well-known approach for path-following control of aerial vehicles, isused as the basis for the guidance method. To handle needle-tissueinteractions, we propose using Active Disturbance Rejection Con-trol (ADRC) because of its robustness within hard-to-model en-vironments. We investigate both linear and nonlinear ADRC, andvalidate the approach with a Programmable Bevel-tip SteerableNeedle (PBN) in both phantom tissue and ex vivo brain, with someof the experiments involving moving targets. Results: The mean,standard deviation, and maximum absolute position errors areobserved to be 1.79 mm, 1.04 mm, and 5.84 mm, respectively, for3-D, 120 mm deep, path-following experiments. Conclusion: MCFswith FBGs are a promising technology for autonomous steerableneedle navigation, as demonstrated here on PBNs. Significance:FBGs in MCFs can be used to provide effective feedback in path-following controllers for steerable needles
Donder A, Rodriguez y Baena F, 2022, Kalman filter-based, dynamic 3-D shape reconstruction for steerable needles with fiber bragg gratings in multi-core fibers, IEEE Transactions on Robotics, Vol: 38, Pages: 2262-2275, ISSN: 1552-3098
Steerable needles are a promising technology toprovide safe deployment of tools through complex anatomy inminimally invasive surgery, including tumor-related diagnosesand therapies. For the 3-D localization of these instruments in softtissue, fiber Bragg gratings (FBGs)-based reconstruction methodshave gained in popularity because of the inherent advantages ofoptical fibers in a clinical setting, such as flexibility, immunity toelectromagnetic interference, non-toxicity, the absence of line ofsight issues. However, methods proposed thus far focus on shapereconstruction of the steerable needle itself, where accuracy issusceptible to errors in interpolation and curve fitting methodsused to estimate the curvature vectors along the needle. In thisstudy, we propose reconstructing the shape of the path createdby the steerable needle tip based on the follow-the-leader natureof many of its variants. By assuming that the path made by thetip is equivalent to the shape of the needle, this novel approachpaves the way for shape reconstruction through a single set ofFBGs at the needle tip, which provides curvature informationabout every section of the path during navigation. We proposea Kalman Filter-based sensor fusion method to update thecurvature information about the sections as they are continuallyestimated during the insertion process. The proposed methodis validated through simulation, in vitro and ex vivo experimentsemploying a programmable bevel-tip steerable needle (PBN). Theresults show clinically acceptable accuracy, with 2.87 mm meanPBN tip position error, and a standard deviation of 1.63 mm fora 120 mm 3-D insertion.
Jamal A, Yuan T, Galvan S, et al., 2022, Insights into infusion-based targeted drug delivery in brain: perspectives, challenges and opportunities, International Journal of Molecular Sciences, Vol: 23, Pages: 3139-3139, ISSN: 1422-0067
Targeted drug delivery in the brain is instrumental in the treatment of lethal brain diseases, such as glioblastoma multiforme, the most aggressive primary central nervous system tumour in adults. Infusion-based drug delivery techniques, which directly administer to the tissue for local treatment, as in convection-enhanced delivery (CED), provide an important opportunity; however, poor understanding of the pressure-driven drug transport mechanisms in the brain has hindered its ultimate success in clinical applications. In this review, we focus on the biomechanical and biochemical aspects of infusion-based targeted drug delivery in the brain and look into the underlying molecular level mechanisms. We discuss recent advances and challenges in the complementary field of medical robotics and its use in targeted drug delivery in the brain. A critical overview of current research in these areas and their clinical implications is provided. This review delivers new ideas and perspectives for further studies of targeted drug delivery in the brain.
Darwood A, Hurst SA, Villatte G, et al., 2022, Novel robotic technology for the rapid intraoperative manufacture of patient-specific instrumentation allowing for improved glenoid component accuracy in shoulder arthroplasty: a cadaveric study, JOURNAL OF SHOULDER AND ELBOW SURGERY, Vol: 31, Pages: 561-570, ISSN: 1058-2746
Franco E, Garriga Casanovas A, Tang J, et al., 2022, Adaptive energy shaping control of a class of nonlinear soft continuum manipulators, IEEE-ASME Transactions on Mechatronics, Vol: 27, Pages: 280-291, ISSN: 1083-4435
Soft continuum manipulators are characterized by low stiffness which allows safe operation in unstructured environments but introduces under-actuation. In addition, soft materials such as silicone rubber, which are commonly used for soft manipulators, are characterized by nonlinear stiffness, while pneumatic actuation can result in nonlinear damping. Consequently, achieving accurate control of these systems in the presence of disturbances is a challenging task. This paper investigates the model-based adaptive control for soft continuum manipulators that have nonlinear uniform stiffness and nonlinear damping, that bend under the effect of internal pressure, and that are subject to time-varying disturbances. A rigid-link model with virtual elastic joints is employed for control purposes within the port-Hamiltonian framework. The effects of disturbances and of model uncertainties are estimated adaptively. A nonlinear controller that regulates the tip orientation of the manipulator and that compensates the effects of disturbances and of model uncertainties is then constructed by using an energy shaping passivity-based approach. Stability conditions are discussed highlighting the beneficial role of nonlinear damping. The effectiveness of the controller is assessed with simulations and with experiments on a soft continuum manipulator prototype.
Hu X, Rodriguez y Baena F, Cutolo F, 2022, Head-Mounted Augmented Reality Platform for Markerless Orthopaedic Navigation, IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS, Vol: 26, Pages: 910-921, ISSN: 2168-2194
Hu X, Anh N, Rodriguez y Baena F, 2022, Occlusion-Robust Visual Markerless Bone Tracking for Computer-Assisted Orthopedic Surgery, IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, Vol: 71, ISSN: 0018-9456
Cao MY, Laws S, Baena FRY, 2021, Six-Axis Force/Torque Sensors for Robotics Applications: A Review, IEEE SENSORS JOURNAL, Vol: 21, Pages: 27238-27251, ISSN: 1530-437X
D'Ettorre C, Mariani A, Stilli A, et al., 2021, Accelerating Surgical Robotics Research: A Review of 10 Years With the da Vinci Research Kit, IEEE ROBOTICS & AUTOMATION MAGAZINE, Vol: 28, Pages: 56-78, ISSN: 1070-9932
Bautista-Salinas D, Abdelaziz MEMK, Temelkuran B, et al., 2021, Towards a Functional Atraumatic Self-Shaping Cochlear Implant, MACROMOLECULAR MATERIALS AND ENGINEERING, Vol: 307, ISSN: 1438-7492
Pinzi M, Vakharia VN, Hwang BY, et al., 2021, Computer Assisted Planning for Curved Laser Interstitial Thermal Therapy, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 68, Pages: 2957-2964, ISSN: 0018-9294
Lima MR, Wairagkar M, Gupta M, et al., 2021, Conversational affective social robots for ageing and dementia support, IEEE Transactions on Cognitive and Developmental Systems, ISSN: 2379-8920
Socially assistive robots (SAR) hold significant potential to assist older adults and people with dementia in human engagement and clinical contexts by supporting mental health and independence at home. While SAR research has recently experienced prolific growth, long-term trust, clinical translation and patient benefit remain immature. Affective human-robot interactions are unresolved and the deployment of robots with conversational abilities is fundamental for robustness and humanrobot engagement. In this paper, we review the state of the art within the past two decades, design trends, and current applications of conversational affective SAR for ageing and dementia support. A horizon scanning of AI voice technology for healthcare, including ubiquitous smart speakers, is further introduced to address current gaps inhibiting home use. We discuss the role of user-centred approaches in the design of voice systems, including the capacity to handle communication breakdowns for effective use by target populations. We summarise the state of development in interactions using speech and natural language processing, which forms a baseline for longitudinal health monitoring and cognitive assessment. Drawing from this foundation, we identify open challenges and propose future directions to advance conversational affective social robots for: 1) user engagement, 2) deployment in real-world settings, and 3) clinical translation.
Schlueter-Brust K, Henckel J, Katinakis F, et al., 2021, Augmented-reality-assisted K-wire placement for glenoid component positioning in reversed shoulder arthroplasty: a proof-of-concept study, Journal of Personalized Medicine, Vol: 11, Pages: 1-8, ISSN: 2075-4426
The accuracy of the implant’s post-operative position and orientation in reverse shoulder arthroplasty is known to play a significant role in both clinical and functional outcomes. Whilst technologies such as navigation and robotics have demonstrated superior radiological outcomes in many fields of surgery, the impact of augmented reality (AR) assistance in the operating room is still unknown. Malposition of the glenoid component in shoulder arthroplasty is known to result in implant failure and early revision surgery. The use of AR has many promising advantages, including allowing the detailed study of patient-specific anatomy without the need for invasive procedures such as arthroscopy to interrogate the joint’s articular surface. In addition, this technology has the potential to assist surgeons intraoperatively in aiding the guidance of surgical tools. It offers the prospect of increased component placement accuracy, reduced surgical procedure time, and improved radiological and functional outcomes, without recourse to the use of large navigation or robotic instruments, with their associated high overhead costs. This feasibility study describes the surgical workflow from a standardised CT protocol, via 3D reconstruction, 3D planning, and use of a commercial AR headset, to AR-assisted k-wire placement. Post-operative outcome was measured using a high-resolution laser scanner on the patient-specific 3D printed bone. In this proof-of-concept study, the discrepancy between the planned and the achieved glenoid entry point and guide-wire orientation was approximately 3 mm with a mean angulation error of 5°.
Iqbal H, Tatti F, Baena FRY, 2021, Augmented reality in robotic assisted orthopaedic surgery: A pilot study, JOURNAL OF BIOMEDICAL INFORMATICS, Vol: 120, ISSN: 1532-0464
Franco E, Garriga Casanovas A, Tang J, et al., 2021, Position regulation in Cartesian space of a class of inextensible soft continuum manipulators with pneumatic actuation, Mechatronics, Vol: 76, Pages: 1-21, ISSN: 0957-4158
This work investigates the position regulation in Cartesian space of a class of inextensible soft continuum manipulators with pneumatic actuation subject to model uncertainties and to unknown external disturbances that act on the tip. Soft continuum manipulators are characterised by high structural compliance which results in a large number of degrees-of-freedom, only a subset of which can be actuated independently or instrumented with sensors. External disturbances, which are common in many applications, result in uncertain dynamics and in uncertain kinematics thus making the control problem particularly challenging. We have investigated the use of integral action to model the uncertain kinematics of the manipulators, and we have designed a new control law to achieve position regulation in Cartesian space by employing a port-Hamiltonian formulation and a passivity-based approach. In addition, we have compared two adaptive laws that compensate the effects of the external disturbances on the system dynamics. Local stability conditions are discussed with a Lyapunov approach and are related to the controller parameters. The performance of the controller is demonstrated by means of simulations and experiments with two different prototypes.
Giles JW, Broden C, Tempelaere C, et al., 2021, Development and ex-vivo assessment of a novel patient specific guide and instrumentation system for minimally invasive total shoulder arthroplasty, PLOS ONE, Vol: 16, ISSN: 1932-6203
Trovatelli M, Brizzola S, Zani DD, et al., 2021, Development and in vivo assessment of a novel MRI-compatible headframe system for the ovine animal model, INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Vol: 17, ISSN: 1478-5951
Pinzi M, Watts T, Secoli R, et al., 2021, Path replanning for orientation-constrained needle steering, IEEE Transactions on Biomedical Engineering, Vol: 68, Pages: 1459-1466, ISSN: 0018-9294
Introduction: Needle-based neurosurgical procedures require high accuracy in catheter positioning to achieve high clinical efficacy. Significant challenges for achieving accurate targeting are (i) tissue deformation (ii) clinical obstacles along the insertion path (iii) catheter control. Objective: We propose a novel path-replanner able to generate an obstacle-free and curvature bounded three-dimensional (3D) path at each time step during insertion, accounting for a constrained target pose and intraoperative anatomical deformation. Additionally, our solution is sufficiently fast to be used in a closed-loop system: needle tip tracking via electromagnetic sensors is used by the path-replanner to automatically guide the programmable bevel-tip needle (PBN) while surgical constraints on sensitive structures avoidance are met. Methods: The generated path is achieved by combining the ”Bubble Bending” method for online path deformation and a 3D extension of a convex optimisation method for path smoothing. Results: Simulation results performed on a realistic dataset show that our replanning method can guide a PBN with bounded curvature to a predefined target pose with an average targeting error of 0.65 ± 0.46 mm in position and 3.25 ± 5.23 degrees in orientation under a deformable simulated environment. The proposed algorithm was also assessed in-vitro on a brain-like gelatin phantom, achieving a target error of 1.81 ± 0.51 mm in position and 5.9 ± 1.42 degrees in orientation. Conclusion: The presented work assessed the performance of a new online steerable needle path-planner able to avoid anatomical obstacles while optimizing surgical criteria. Significance: This method is particularly suited for surgical procedures demanding high accuracy on the desired goal pose under tissue deformations and real-world inaccuracies.
Hu X, Liu H, Rodriguez y Baena FM, 2021, Markerless navigation system for orthopaedic knee surgery: a proof of concept study, IEEE Access, Vol: 9, Pages: 64708-64718, ISSN: 2169-3536
Current computer-assisted surgical navigation systems mainly rely on optical markers screwed into the bone for anatomy tracking. The insertion of these percutaneous markers increases operating complexity and causes additional harm to the patient. A markerless tracking and registration algorithm has recently been proposed to avoid anatomical markers for knee surgery. The femur points were directly segmented from the recorded RGBD scene by a neural network and then registered to a pre-scanned femur model for the real-time pose. However, in a practical setup such a method can produce unreliable registration results, especially in rotation. Furthermore, its potential application in surgical navigation has not been demonstrated. In this paper, we first improved markerless registration accuracy by adopting a bounded-ICP (BICP) technique, where an estimate of the remote hip centre, acquired also in a markerless way, was employed to constrain distal femur alignment. Then, a proof-of-concept markerless navigation system was proposed to assist in typical knee drilling tasks. Two example setups for global anchoring were proposed and tested on a phantom leg. Our BICP-based markerless tracking and registration method has better angular accuracy and stability than the original method, bringing our straightforward, less invasive markerless navigation approach one step closer to clinical application. According to user tests, our proposed optically anchored navigation system achieves comparable accuracy with the state-of-the-art (3.64± 1.49 mm in position and 2.13±0.81° in orientation). Conversely, our visually anchored, optical tracker-free setup has a lower accuracy (5.86± 1.63 mm in position and 4.18±1.44° in orientation), but is more cost-effective and flexible in the operating room.
Franco E, Tang J, Garriga Casanovas A, et al., 2021, Position control of soft manipulators with dynamic and kinematic uncertainties, 21st IFAC World Congress, Publisher: Elsevier, Pages: 9847-9852, ISSN: 2405-8963
This work investigates the position control problem for a soft continuum manipulator in Cartesian space intended for minimally invasive surgery. Soft continuum manipulators have a large number of degrees-of-freedom and are particularly susceptible to external forces because of their compliance. This, in conjunction with the limited number of sensors typically available, results in uncertain kinematics, which further complicates the control problem. We have designed a partial state feedback that compensates the effects of external forces employing a rigid-link model and a port-Hamiltonian approach and we have investigated in detail the use of integral action to achieve position regulation in Cartesian space. Local stability conditions are discussed with a Lyapunov approach. The performance of the controller is compared with that achieved with a radial-basis-functions neural network by means of simulations and experiments on two prototypes.
Jamal A, Mongelli M, Vidotto M, et al., 2021, Infusion mechanisms in brain white matter and its dependence of microstructure: an experimental study of hydraulic permeability, IEEE Transactions on Biomedical Engineering, Vol: 68, Pages: 1229-1237, ISSN: 0018-9294
Objective: Hydraulic permeability is a topic of deep interest in biological materials because of its important role in a range of drug delivery-based therapies. The strong dependence of permeability on the geometry and topology of pore structure and the lack of detailed knowledge of these parameters in the case of brain tissue makes the study more challenging. Although theoretical models have been developed for hydraulic permeability, there is limited consensus on the validity of existing experimental evidence to complement these models. In the present study, we measure the permeability of white matter (WM) of fresh ovine brain tissue considering the localised heterogeneities in the medium using an infusion based experimental set up, iPerfusion. We measure the flow across different parts of the WM in response to applied pressures for a sample of specific dimensions and calculate the permeability from directly measured parameters. Furthermore, we directly probe the effect of anisotropy of the tissue on permeability by considering the directionality of tissue on the obtained values. Additionally, we investigate whether WM hydraulic permeability changes with post-mortem time. To our knowledge, this is the first report of experimental measurements of the localised WM permeability, showing the effect of axon directionality on permeability. This work provides a significant contribution to the successful development of intra-tumoural infusion-based technologies, such as convection-enhanced delivery (CED), which are based on the delivery of drugs directly by injection under positive pressure into the brain.
Favaro A, Secoli R, Rodriguez y Baena F, et al., 2021, Optimal pose estimation method for a multi-segment, programmable bevel-tip steerable needle, IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2020), Publisher: IEEE, Pages: 3232-3238
Pose tracking is fundamental to achieve preciseand safe insertion of a surgical tool for minimally invasiveinterventions. In this work, a method for the estimation of thefull pose of steerable needles is presented. Our approach uses aProgrammable Bevel Tip (PBN) needle with four-segment designas a case study. A novel 3D kinematic model of the PBN isdeveloped and used to predict the full needle pose during theinsertion. The pose prediction is estimated through an ExtendedKalman Filter using the position measurements provided byan electromagnetic sensor located at each tip of the needlesegments. The method estimates also the torsion of the needleshaft that can arise over the insertion of the needle becauseof the shear forces exerted between the needle and the insertionmedium. The feasibility of the proposed solution was validated ina number of experiments in gelatin demonstrating a small errorin position reconstruction (RMSE<0.6mm) and good accuracy incomparison to a bespoke geometric pose reconstruction method.
Treratanakulchai S, Baena FRY, 2021, A Passive Decoupling Mechanism for Misalignment Compensation in Master-Slave Teleoperation, IEEE Transactions on Medical Robotics and Bionics, Vol: 3, Pages: 285-288
Teleoperated robots are commonly used in minimally invasive surgery as they can control surgical instruments at a distance. An operator sends the motion command via a master console, which must convert these into suitable slave instrument actuator inputs for intuitive interaction. However, most master-slave systems available to date use incremental task-space control and clutching, which introduces a discontinuity and orientation misalignment between the master control handle and slave instrument, with a consequent impact on task performance. In this article, we proposed a new master manipulator design to compensate for misalignment mechanically. The modular gimbal consists of a passive decoupling mechanism and a wrist locking feature. After describing the mechanisms and its kinematic configuration, we report on a comparative study under controlled conditions, developed to measure the end effector orientation in both compensated and non-compensated scenarios. The results demonstrate that the compensated master console maintains a near constant end effector orientation over the workspace during clutching, showing great promise as a solution to this outstanding open challenge in master-slave manipulation.
Bautista-Salinas D, Kundrat D, Kogkas A, et al., 2021, Integrated Augmented Reality Feedback for Cochlear Implant Surgery Instruments, IEEE Transactions on Medical Robotics and Bionics, Vol: 3, Pages: 261-264
In this article, we present a visualization system to provide assistance in cochlear implant surgery which can be seamlessly integrated within the devices that are currently used in surgery. The system is intended to improve tool alignment in positioning and during insertion, with the aim of reducing the problems encountered during perimodiolar electrode array insertion. Our system is composed of a semi-autonomous hand-held surgical tool, coupled with an optical tracker to monitor the tool position and an operating microscope. The microscope live view is overlaid with guidance information in the form of augmented reality to assist the surgeon in positioning the surgical tool and maintain that position during insertion. Our approach shows promising results in tool alignment, which are comparable to the state of the art.
The supervisory-control method is used in the majority of neurosurgical robots to date where the surgeon makes the high-level decisions, which are then autonomously performed by the robot. In this chapter the differences in the roles of the robots during preoperative and intraoperative procedures are explained. During intraoperative procedures the robot can have either direct interaction or no direct interaction with the human tissues, called active and passive systems, respectively. The flow of information between the robots, the surgical environment, and the surgeons, to enable these forms of interaction, is also discussed. Examples of currently available robotic systems are provided.
Koenig A, Rodriguez y Baena F, Secoli R, 2021, Gesture-Based Teleoperated Grasping for Educational Robotics, 30th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN), Publisher: IEEE, Pages: 222-228, ISSN: 1944-9445
Franco E, Brown T, Astolfi A, et al., 2021, Adaptive energy shaping control of robotic needle insertion, Mechanism and Machine Theory, Vol: 155, ISSN: 0094-114X
This work studies the control of a pneumatic actuator for needle insertion in soft tissue without using axial rotation or additional needle supports. Employing a simplified rigid-link model description of an axial-symmetric tip needle supported at the base, two energy shaping controllers are proposed. The friction forces of the pneumatic actuator are compensated adaptively and the stability conditions for the closed-loop equilibrium are discussed. The controllers are compared by means of simulations and experiments on two different silicone rubber phantoms. The results indicate that the proposed controllers effectively compensate the actuator's friction, which is comparable to the insertion forces for the chosen pneumatic actuators. The first controller only depends on the actuator's position thus it achieves the prescribed insertion depth but results in a larger tip rotation and corresponding deflection. The second controller also accounts for the rotation of the needle tip on the bending plane, which can consequently be reduced by over 70% for this specific system. This is achieved by modulating the actuator force and, in case of harder phantoms, by automatically limiting the insertion depth.
Ng KCG, Bankes M, El Daou H, et al., 2021, Cam osteochondroplasty for femoroacetabular impingement increases microinstability in deep flexion: A cadaveric study, Arthroscopy: The Journal of Arthroscopy and Related Surgery, Vol: 37, Pages: 159-170, ISSN: 0749-8063
Purpose: The purpose of this in vitro cadaveric study was to examine the contributions of each surgical stage during cam femoroacetabular impingement (FAI) surgery (i.e., intact cam hip, T8 capsulotomy, cam resection, capsular repair) towards hip range of motion, translations, and microinstability.Methods: Twelve cadaveric cam hips were denuded to the capsule and mounted onto a robotic tester. Hips were positioned in several flexion positions: Full Extension, Neutral 0°, Flexion 30°, and Flexion 90°; and performed internal-external rotations to 5-Nm torque in each position. Hips underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested after each stage. Changes in range of motion, translation, and microinstability (overall translation normalized by femoral head radius) were measured after each stage.Results: For range of motion, cam resection increased internal rotation at Flexion 90° (ΔIR = +6°, P = .001), but did not affect external rotation. Capsular repairs restrained external rotations compared to the cam resection stage (ΔER = –4 to –8°, P ≤ .04). For translations, the hip translated after cam resection at Flexion 90° in the medial-lateral plane (ΔT = +1.9 mm, P = .04), relative to the intact and capsulotomy stages. For microinstability, capsulotomy increased microinstability in Flexion 30° (ΔM = +0.05; P = .003), but did not further increase after cam resection. At Flexion 90°, microinstability did not increase after capsulotomy (ΔM = +0.03; P = .2, d = .24), but substantially increased after cam resection (ΔM = +0.08; P = .03), accounting for a 31% change with respect to the intact stage.Conclusions: Cam resection increased microinstability by 31% during deep hip flexion relative to the intact hip. This suggests that iatrogenic microinstability may be due to separation of the labral seal and resected contour of the femoral head.
Hu X, Rodriguez y Baena F, Cutolo F, 2020, Alignment-free offline calibration of commercial optical see-through head-mounted displays with simplified procedures, IEEE Access, Vol: 8, Pages: 223661-223674, ISSN: 2169-3536
Despite the growing availability of self-contained augmented reality head-mounted displays (AR HMDs) based on optical see-through (OST) technology, their potential applications across highly challenging medical and industrial settings are still hampered by the complexity of the display calibration required to ensure the locational coherence between the real and virtual elements. The calibration of commercial OST displays remains an open challenge due to the inaccessibility of the user’s perspective and the limited hardware information available to the end-user. State-of-the-art calibrations usually comprise both offline and online stages. The offline calibration at a generic viewpoint provides a starting point for the subsequent refinements and it is crucial. Current offline calibration methods either heavily rely on the user-alignment or require complicated hardware calibrations, making the overall procedure subjective and/or tedious. To address this problem, in this work we propose two fully alignment-free calibration methods with less complicated hardware calibration procedures compared with state-of-the-art solutions. The first method employs an eye-replacement camera to compute the rendering camera’s projection matrix based on photogrammetry techniques. The second method controls the rendered object position in a tracked 3D space to compensate for the parallax-related misalignment for a generic viewpoint. Both methods have been tested on Microsoft HoloLens 1. Quantitative results show that the average overlay misalignment is fewer than 4 pixels (around 1.5 mm or 9 arcmin) when the target stays within arm’s reach. The achieved misalignment is much lower than the HoloLens default interpupillary distance (IPD)-based correction, and equivalent but with lower variance than the Single Point Active Alignment Method (SPAAM)-based calibration. The two proposed methods offer strengths in complementary aspects and can be chosen according to the user&rsqu
Matheson E, Baena FRY, 2020, Biologically Inspired Surgical Needle Steering: Technology and Application of the Programmable Bevel-Tip Needle, BIOMIMETICS, Vol: 5
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