193 results found
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
Hu X, Rodriguez Y Baena F, Cutolo F, 2021, Head-Mounted Augmented Reality Platform for Markerless Orthopaedic Navigation., IEEE J Biomed Health Inform, Vol: PP
Visual augmented reality (AR) has the potential to improve the accuracy, efficiency and reproducibility of computer-assisted orthopaedic surgery (CAOS). AR Head-mounted displays (HMDs) further allow non-eye-shift target observation and egocentric view. Recently, a markerless tracking and registration (MTR) algorithm was proposed to avoid the artificial markers that are conventionally pinned into the target anatomy for tracking, as their use prolongs surgical workflow, introduces human-induced errors, and necessitates additional surgical invasion in patients. However, such an MTR-based method has neither been explored for surgical applications nor integrated into current AR HMDs, making the ergonomic HMD-based markerless AR CAOS navigation hard to achieve. To these aims, we present a versatile, device-agnostic and accurate HMD-based AR platform. Our software platform, supporting both video see-through (VST) and optical see-through (OST) modes, integrates two proposed fast calibration procedures using a specially designed calibration tool. According to the camera-based evaluation, our AR platform achieves a display error of 6.31 2.55 arcmin for VST and 7.72 3.73 arcmin for OST. A proof-of-concept markerless surgical navigation system to assist in femoral bone drilling was then developed based on the platform and Microsoft HoloLens 1. According to the user study, both VST and OST markerless navigation systems are reliable, with the OST system providing the best usability. The measured navigation error is 4.90 1.04 mm, 5.96 2.22 for VST system and 4.36 0.80 mm, 5.65 1.42 for OST system.
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.
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
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.
Franco E, Garriga Casanovas A, Tang J, et al., 2021, Adaptive energy shaping control of a class of nonlinear soft continuum manipulators, IEEE-ASME Transactions on Mechatronics, 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.
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
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
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.
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.
Pinzi M, Hwang B, Vakharia VN, et al., 2021, Computer Assisted Planning for Curved Laser Interstitial Thermal Therapy, IEEE Transactions on Biomedical Engineering, ISSN: 0018-9294
Laser interstitial thermal therapy (LiTT) is a minimally invasive alternative to conventional open surgery for drug-resistant focal mesial temporal lobe epilepsy (MTLE). Recent studies suggest that higher seizure freedom rates are correlated with maximal ablation of the mesial hippocampal head, whilst sparing of the parahippocampal gyrus (PHG) may reduce neuropsychological sequelae. Current commercially available laser catheters are inserted following manually planned straight-line trajectories, which cannot conform to curved brain structures, such as the hippocampus, without causing collateral damage or requiring multiple insertions. The clinical feasibility and potential of curved LiTT trajectories through steerable needles has yet to be investigated. This is the focus of our work. We propose a GPU-accelerated computer-assisted planning (CAP) algorithm for steerable needle insertions that generates optimized curved 3D trajectories with maximal ablation of the amygdalohippocampal complex and minimal collateral damage to nearby structures, while accounting for a variable ablation diameter (<formula><tex>$5-15mm$</tex></formula>). Simulated trajectories and ablations were performed on 5 patients with mesial temporal sclerosis (MTS), which were identified from a prospectively managed database. The algorithm generated obstacle-free paths with significantly greater target area ablation coverage and lower PHG ablation variance compared to straight line trajectories. The presented CAP algorithm returns increased ablation of the amygdalohippocampal complex, with lower patient risk scores compared to straight-line trajectories. This is the first clinical application of preoperative planning for steerable needle based LiTT. This study suggests that steerable needles have the potential to improve LiTT procedure efficacy whilst improving the safety and should thus be investigated further.
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
Denham TLDO, Cleary K, Baena FRY, et al., 2020, Guest Editorial Medical Robotics: Surgery and Beyond, IEEE Transactions on Medical Robotics and Bionics, Vol: 2, Pages: 509-510
Laws SG, Souipas S, Davies BL, et al., 2020, Toward Automated Tissue Classification for Markerless Orthopaedic Robotic Assistance, IEEE Transactions on Medical Robotics and Bionics, Vol: 2, Pages: 537-540
Terzano M, Dini D, Rodriguez y Baena F, et al., 2020, An adaptive finite element model for steerable needles, Biomechanics and Modeling in Mechanobiology, Vol: 19, Pages: 1809-1825, ISSN: 1617-7940
Penetration of a flexible and steerable needle into a soft target material is a complex problem to be modelled, involving several mechanical challenges. In the present paper, an adaptive finite element algorithm is developed to simulate the penetration of a steerable needle in brain-like gelatine material, where the penetration path is not predetermined. The geometry of the needle tip induces asymmetric tractions along the tool–substrate frictional interfaces, generating a bending action on the needle in addition to combined normal and shear loading in the region where fracture takes place during penetration. The fracture process is described by a cohesive zone model, and the direction of crack propagation is determined by the distribution of strain energy density in the tissue surrounding the tip. Simulation results of deep needle penetration for a programmable bevel-tip needle design, where steering can be controlled by changing the offset between interlocked needle segments, are mainly discussed in terms of penetration force versus displacement along with a detailed description of the needle tip trajectories. It is shown that such results are strongly dependent on the relative stiffness of needle and tissue and on the tip offset. The simulated relationship between programmable bevel offset and needle curvature is found to be approximately linear, confirming empirical results derived experimentally in a previous work. The proposed model enables a detailed analysis of the tool–tissue interactions during needle penetration, providing a reliable means to optimise the design of surgical catheters and aid pre-operative planning.
Favaro A, Secoli R, Rodriguez y Baena F, et al., 2020, Model-Based Robust Pose Estimation for a Multi-Segment, Programmable Bevel-Tip Steerable Needle, IEEE ROBOTICS AND AUTOMATION LETTERS, Vol: 5, Pages: 6780-6787, ISSN: 2377-3766
Tatti F, Iqbal H, Jaramaz B, et al., 2020, A novel computer-assisted workflow for treatment of osteochondral lesions in the knee, CAOS 2020. The 20th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery, Publisher: EasyChair, Pages: 250-253
Computer-Assisted Orthopaedic Surgery (CAOS) is now becoming more prevalent, especially in knee arthroplasty. CAOS systems have the potential to improve the accuracy and repeatability of surgical procedures by means of digital preoperative planning and intraoperative tracking of the patient and surgical instruments.One area where the accuracy and repeatability of computer-assisted interventions could prove especially beneficial is the treatment of osteochondral defects (OCD). OCDs represent a common problem in the patient population, and are often a cause of pain and discomfort. The use of synthetic implants is a valid option for patients who cannot be treated with regenerative methods, but the outcome can be negatively impacted by incorrect positioning of the implant and lack of congruency with the surrounding anatomy.In this paper, we present a novel computer-assisted surgical workflow for the treatment of osteochondral defects. The software we developed automatically selects the implant that most closely matches the patient’s anatomy and computes the best pose. By combining this software with the existing capabilities of the Navio™ surgical system (Smith & Nephew inc.), we were able to create a complete workflow that incorporates both surgical planning and assisted bone preparation.Our preliminary testing on plastic bone models was successful and demonstrated that the workflow can be used to select and position an appropriate implant for a given defect.
We present a two-part hands-on science outreach demonstration utilizing composite hydrogels to produce realistic models of the human brain. The blends of poly(vinyl alcohol) and Phytagel closely match the mechanical properties of real brain tissue under conditions representative of surgical operations. The composite hydrogel is simple to prepare, biocompatible, and nontoxic, and the required materials are widely available and inexpensive. The first part of the demonstration gives participants the opportunity to feel how soft and deformable our brains are. The second part allows students to perform a mock brain surgery on a simulated tumor. The demonstration tools are suitable for public engagement activities as well as for various student training groups. The activities encompass concepts in polymer chemistry, materials science, and biology.
Khan F, Donder A, Galvan S, et al., 2020, Pose Measurement of Flexible Medical Instruments Using Fiber Bragg Gratings in Multi-Core Fiber, IEEE SENSORS JOURNAL, Vol: 20, Pages: 10955-10962, ISSN: 1530-437X
Franco E, Rodriguez y Baena F, Astolfi A, 2020, Robust dynamic state feedback for underactuated systems with linearly parameterized disturbances, International Journal of Robust and Nonlinear Control, Vol: 30, Pages: 4112-4128, ISSN: 1049-8923
This article investigates the control problem for underactuated port‐controlled Hamiltonian systems with multiple linearly parameterized additive disturbances including matched, unmatched, constant, and state‐dependent components. The notion of algebraic solution of the matching equations is employed to design an extension of the interconnection and damping assignment passivity‐based control methodology that does not rely on the solution of partial differential equations. The result is a dynamic state‐feedback that includes a disturbance compensation term, where the unknown parameters are estimated adaptively. A simplified implementation of the proposed approach for underactuated mechanical systems is detailed. The effectiveness of the controller is demonstrated with numerical simulations for the magnetic‐levitated‐ball system and for the ball‐on‐beam system.
Favaro A, Secoli R, Rodriguez y Baena F, et al., 2020, 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
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.
Hu X, Fabrizio C, Tatti F, et al., 2020, Automatic calibration of commercial optical see-through head-mounted displays for medical applications, 2020 IEEE Conference on Virtual Reality and 3D User Interfaces, Publisher: IEEE, Pages: 754-755
The simplified, manual calibration of commercial Optical See-Through Head-Mounted Displays (OST-HMDs) is neither accurate nor convenient for medical applications. An interaction-free calibration method that can be easily implemented in commercial headsets is thus desired. State-of-the-art automatic calibrations simplify the eye-screen system as a pinhole camera and tedious offline calibrations are required. Furthermore, they have never been tested on original commercial products. We present a gaze-based automatic calibration method that can be easily implemented in commercial headsets without knowing hardware details. The location of the virtual target is revised in world coordinate according to the real-time tracked eye gaze. The algorithm has been tested with the Microsoft HoloLens. Current quantitative and qualitative user studies show that the automatically calibrated display is statistically comparable with the manually calibrated display under both monocular and binocular rendering mode. Since it is cumbersome to ask users to perform manual calibrations every time the HMD is re-positioned, our method provides a comparably accurate but more convenient and practical solution to the HMD calibration.
Virdyawan V, Dessi O, Rodriguez y Baena F, 2020, A novel sensing method to detect tissue boundaries during robotic needle insertion based on laser Doppler flowmetry, IEEE Robotics and Automation Letters, Vol: 5, Pages: 1524-1531, ISSN: 2377-3766
This study investigates the use of Laser Doppler Flowmetry (LDF) as a method to detect tissue transitions during robotic needle insertions. Insertions were performed in gelatin tissue phantoms with different optical and mechanical properties and into ex-vivo sheep brain. The effect of changing the optical properties of gelatin tissue phantoms was first investigated and it was shown that using gelatin concentration to modify the stiffness of samples was suitable. Needle insertion experiments were conducted into both one-layer and two-layer gelatin phantoms. In both cases, three stages could be observed in the perfusion values: tissue loading, rupture and tissue cutting. These were correlated to force values measured from the tip of the needle during insertion. The insertions into ex-vivo sheep brain also clearly showed the time of rupture in both force and perfusion values, demonstrating that tissue puncture can be detected using an LDF sensor at the tip of a needle.
Franco E, Garriga Casanovas A, Rodriguez y Baena F, et al., 2020, Model based adaptive control for a soft robotic manipulator, 58th IEEE Conference on Decision and Control, Publisher: IEEE, Pages: 1019-1024
The application of model based adaptive control to an underactuated system representative of a class of soft continuummanipulators is investigated. To this end, a rigid-linkmodel with elastic joints is employed and an energy shaping controller is designed. Additionally, model uncertainties and external disturbances, both matched and unmatched, are compensated with an adaptive algorithm. This results in a control law that only depends on the orientation and on the angular velocity of the distal link and it is therefore independent of the number of links. Finally, stability conditions are discussed and the effectiveness of the controller is verified via simulations.
Liu H, Rodriguez y Baena F, 2020, Automatic markerless registration and tracking of the bone for computer-assisted orthopaedic surgery, IEEE Access, Vol: 8, Pages: 42010-42020, ISSN: 2169-3536
To achieve a simple and less invasive registration procedure in computer-assisted orthopaedic surgery, we propose an automatic, markerless registration and tracking method based on depth imaging and deep learning. A depth camera is used to continuously capture RGB and depth images of the exposed bone during surgery, and deep neural networks are trained to first localise the surgical target using the RGB image, then segment the target area of the corresponding depth image, from which the surface geometry of the target bone can be extracted. The extracted surface is then compared to a pre-operative model of the same bone for registration. This process can be performed dynamically during the procedure at a rate of 5-6 Hz, without any need for surgeon intervention or invasive optical markers. Ex vivo registration experiments were performed on a cadaveric knee, and accuracy measurements against an optically tracked ground truth resulted in a mean translational error of 2.74 mm and a mean rotational error of 6.66°. Our results are the first to describe a promising new way to achieve automatic markerless registration and tracking in computer-assisted orthopaedic surgery, demonstrating that truly seamless registration and tracking of the limb is within reach. Our method reduces invasiveness by removing the need for percutaneous markers. The surgeon is also exempted from inserting markers and collecting registration points manually, which contributes to a more efficient surgical workflow and shorter procedure time in the operating room.
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