Imperial College London

ProfessorFerdinandoRodriguez y Baena

Faculty of EngineeringDepartment of Mechanical Engineering

Professor of Medical Robotics
 
 
 
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Contact

 

+44 (0)20 7594 7046f.rodriguez Website

 
 
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Location

 

718City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

156 results found

Watts TE, Secoli R, Rodriguez y Baena F, 2019, A mechanics-based model for 3D steering of programmable bevel-tip needles, IEEE Transactions on Robotics, Vol: 35, Pages: 371-386, ISSN: 1552-3098

We present a model for the steering of programmable bevel-tip needles, along with a set of experiments demonstrating the 3D steering performance of a new, clinically viable, 4-segment, pre-production prototype. A multi-beam approach, based on Euler-Bernoulli beam theory, is used to model the novel multi-segment design of these needles. Finite element simulations for known loads are used to validate the multi-beam deflection model. A clinically sized (2.5 mm outer diameter), 4-segment programmable bevel-tip needle, manufactured by extrusion of a medical-grade polymer, is used to conduct an extensive set of experimental trials to evaluate the steering model. For the first time, we demonstrate the ability of the 4-segment needle design to steer in any direction with a maximum achievable curvature of 0.0192±0.0014 mm⁻¹. Finite element simulations confirm that the multi-beam approach produces a good model fit for tip deflections, with a root-mean-square deviation (RMSD) in modeled tip deflection of 0.2636 mm. We perform a parameter optimization to produce a best-fit steering model for the experimental trials, with a RMSD in curvature prediction of 1.12×10⁻³ mm⁻¹.

Journal article

Pinzi M, Galvan S, Rodriguez y Baena F, 2019, The adaptive hermite fractal tree (AHFT): a novel surgical 3D path planning approach with curvature and heading constraints, International Journal of Computer Assisted Radiology and Surgery, Vol: 14, Pages: 659-670, ISSN: 1861-6429

PurposeIn the context of minimally invasive neurosurgery, steerable needles such as the one developed within the Horizon2020-funded EDEN2020 project (Frasson et al. in Proc Inst Mech Eng Part H J Eng Med 224(6):775–88, 2010. https://doi.org/10.1243/09544119JEIM663; Secoli and y Baena in IEEE international conference on robotics and automation, 2013) aspire to address the clinical challenge of better treatment for cancer patients. The direct, precise infusion of drugs in the proximity of a tumor has been shown to enhance its effectiveness and diffusion in the surrounding tissue (Vogelbaum and Aghi in Neuro-Oncology 17(suppl 2):ii3–ii8, 2015. https://doi.org/10.1093/neuonc/nou354). However, planning for an appropriate insertion trajectory for needles such as the one proposed by EDEN2020 is challenging due to factors like kinematic constraints, the presence of complex anatomical structures such as brain vessels, and constraints on the required start and target poses.MethodsWe propose a new parallelizable three-dimensional (3D) path planning approach called Adaptive Hermite Fractal Tree (AHFT), which is able to generate 3D obstacle-free trajectories that satisfy curvature constraints given a specified start and target pose. The AHFT combines the Adaptive Fractal Tree algorithm’s efficiency (Liu et al. in IEEE Robot Autom Lett 1(2):601–608, 2016. https://doi.org/10.1109/LRA.2016.2528292) with optimized geometric Hermite (Yong and Cheng in Comput Aided Geom Des 21(3):281–301, 2004. https://doi.org/10.1016/j.cagd.2003.08.003) curves, which are able to handle heading constraints.ResultsSimulated results demonstrate the robustness of the AHFT to perturbations of the target position and target heading. Additionally, a simulated preoperative environment, where the surgeon is able to select a desired entry pose on the patient’s skull, confirms the ability of the method to generate multiple feasible trajectories for a patient-specific case

Journal article

Garriga Casanovas A, Rodriguez y Baena F, 2019, Kinematics of continuum robots with constant curvature bending and extension capabilities, Journal of Mechanisms and Robotics, Vol: 11, ISSN: 1942-4302

Continuum robots are becoming increasingly popular due to the capabilities they offer, especially when operating in cluttered environments, where their dexterity, maneuverability, and compliance represent a significant advantage. The subset of continuum robots that also belong to the soft robots category has seen rapid development in recent years, showing great promise. However, despite the significant attention received by these devices, various aspects of their kinematics remain unresolved, limiting their adoption and obscuring their potential. In this paper, the kinematics of continuum robots with the ability to bend and extend are studied, and analytical, closed-form solutions to both the direct and inverse kinematics are presented. The results obtained expose the redundancies of these devices, which are subsequently explored. The solution to the inverse kinematics derived here is shown to provide an analytical, closed-form expression describing the curve associated with these redundancies, which is also presented and analyzed. A condition on the reachable end-effector poses for robots with six actuation degrees-of-freedom (DOFs) is then distilled. The kinematics of robot layouts with over six actuation DOFs are subsequently considered. Finally, simulated results of the inverse kinematics are provided, verifying the study.

Journal article

Ng KCG, El Daou H, Bankes M, Rodriguez y Baena F, Jeffers Jet al., 2019, Hip joint torsional loading before and after cam femoroacetabular impingement surgery, American Journal of Sports Medicine, Vol: 47, Pages: 420-430, ISSN: 0363-5465

Background: Surgical management of cam femoroacetabular impingement (FAI) aims to preserve the native hip and restore joint function, though it is unclear how the capsulotomy, cam deformity, and capsular repair influence joint mechanics to balance functional mobility.Purpose: The purpose was to examine the contributions of the capsule and cam deformity to hip joint mechanics. Using in vitro, cadaveric methods, we examined the individual effects of the surgical capsulotomy, cam resection, and capsular repair towards passive range of motion and resistance of applied torque.Study Design: Descriptive laboratory study.Methods: Twelve cadaveric hips with cam deformities (n = 12) were skeletonized to the capsule and mounted onto a robotic testing platform. The robot positioned each intact hip in multiple testing positions: 1) Extension, 2) Neutral 0°, 3) Flexion 30°, 4) Flexion 90°, 5) flexion-adduction and internal rotation (FADIR), 6) flexion-abduction and external rotation (FABER); and performed applicable internal and external rotations, recording the neutral path of motion until a 5-Nm torque was reached in each rotational direction. Each hip then underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested to reach 5 Nm internal and external torque again after each stage. In addition, during the capsulotomy and cam resection stages, the initial intact hip’s recorded path of motion was replayed to measure changes in resisted torque.Results: Examining changes in motion, external rotation increased substantially after capsulotomies, but internal rotation only further increased at Flexion 90° (change = +32%, P = .001, d = .58) and FADIR (change = +33%, P < .001, d = .51) after cam resections. Capsular repair provided marginal restraint for internal rotation, but restrained the external rotation compared to the capsulotomy stage. Examining changes in torque, both internal and external torque resistance dec

Journal article

El Daou H, Ng KC, van Arkel R, Jeffers J, Rodriguez y Baena Fet al., 2019, Robotic hip joint testing: Development and experimental protocols, Medical Engineering and Physics, Vol: 63, Pages: 57-62, ISSN: 1350-4533

The use of robotic systems combined with force sensing is emerging as the gold standard for in vitro biomechanical joint testing, due to the advantage of controlling all six degrees of freedom independently of one another. This paper describes a novel robotic platform and the experimental protocol used for hip joint testing. An experimental protocol implemented optical tracking and registration techniques in order to define the position of the hip joint centre of rotation (COR) in the coordinate system of the robot's end effector. The COR coordinates defined the origin of the task-related coordinate system used to control the robot, with a hybrid force/position law to simulate standard clinical tests. The axes of this frame were defined using the International Society of Biomechanics (ISB) anatomical coordinate system.Experiments were carried out on two cadaveric hip joint specimens using the robotic testing platform and a mechanical testing rig previously developed and described by our group. Simulated internal-external and adduction/abduction laxity tests were carried out with both systems and the resulting peak range of motion (ROM) was measured. Similarities and differences were observed in these experiments, which were used to highlight some of the limitations of conventional systems and the corresponding advantages of robotics, further emphasising their added value in vitro testing.

Journal article

Tan Z, Dini D, Rodriguez y Baena F, Forte Aet al., 2018, Composite hydrogel: A high fidelity soft tissue mimic for surgery, Materials and Design, Vol: 160, Pages: 886-894, ISSN: 0264-1275

Accurate tissue phantoms are difficult to design due to the complex non-linear viscoelastic properties of real soft tissues. A composite hydrogel, resulting from a mix of poly(vinyl) alcohol and phytagel, is able to reproduce the viscoelastic responses of different soft tissues due to its compositional tunability. The aim of this work is to demonstrate the flexibility of the composite hydrogel in mimicking the interactions between surgical tools and various soft tissues, such as brain, lung and liver. Therefore compressive stiffness, insertion forces and frictional forces were used as matching criteria to determine the hydrogel compositions for each soft tissue. A full map of the behaviour of the synthetic material is provided for these three characteristics and the compositions found to best match the mechanical response of brain, lung and liver are reported. The optimised hydrogel samples are then tested and shown to mimic the behaviour of the three tissues with unprecedented fidelity. The effect of each hydrogel constituent on the compressive stiffness, needle insertion and frictional forces is also detailed in this work to explain their individual contributions and synergistic effects. This study opens important opportunities for the realisation of surgical planning and training devices and tools for in-vitro tissue testing.

Journal article

Franco E, Rodriguez y Baena F, Astolfi A, 2018, Robust balancing control of flexible inverted-pendulum systems, Mechanism and Machine Theory, Vol: 130, Pages: 539-551, ISSN: 0094-114X

This work studies the balancing control problem for flexible inverted-pendulum systems and investigates the relationship between system parameters and robustness to disturbances. To this end, a new energy-shaping controller with adaptive disturbance-compensation for a class of underactuated mechanical systems is presented. Additionally, a method for the identification of key system parameters that affect the robustness of the closed-loop system is outlined. The proposed approach is applied to the flexible pendulum-on-cart system and a simulation study is conducted to demonstrate its effectiveness. Finally, the control problem for a classical pendulum-on-cart system with elastic joint is discussed to highlight the similarities with its flexible-link counterpart.

Journal article

Watts T, Secoli R, Rodriguez y Baena F, Needle Steerability Measures: Definition and Application for Optimized Steering of the Programmable Bevel-tip Needle, 2018 IEEE International Conference on Robotics and Biomimetics (IEEE ROBIO 2018)

Conference paper

Matheson E, Watts T, Secoli R, Rodriguez y Baena Fet al., Cyclic motion control for programmable bevel-tip needles 3D steering: a simulation study, ROBIO - IEEE International Conference on Robotics and Biomimetics, Publisher: IEEE

Flexible, steerable, soft needles are desirable inMinimally Invasive Surgery to achieve complex trajectorieswhile maintaining the benefits of percutaneous interventioncompared to open surgery. One such needle is the multi-segmentProgrammable Bevel-tip Needle (PBN), which is inspired by themechanical design of the ovipositor of certain wasps. PBNscan steer in 3D whilst minimizing the force applied to thesurrounding substrate, due to the cyclic motion of the segments.Taking inspiration also from the control strategy of the wasp toperform insertions and lay their eggs, this paper presents thedesign of a cyclic controller that can steer a PBN to produce adesired trajectory in 3D. The performance of the controller isdemonstrated in simulation in comparison to that of a directcontroller without cyclic motion. It is shown that, while thesame steering curvatures can be attained by both controllers,the time taken to achieve the configuration is longer for thecyclic controller, leading to issues of potential under-steeringand longer insertion times.

Conference paper

Garriga Casanovas A, Collison I, Rodriguez y Baena F, 2018, Towards a common framework for the design of soft robotic manipulators with fluidic actuation, Soft Robotics, Vol: 5, Pages: 622-649, ISSN: 2169-5172

Soft robotic manipulators with fluidic actuation are devices with easily deformable structures that comprise a set of chambers that can be pressurized to achieve structural deflection. These devices have experienced a rapid development in recent years, which is not least due to the advantages they offer in terms of robustness, affordability, and compliance. Nowadays, however, soft robotic manipulators are designed mostly by intuition, which complicates design improvement and hampers the advancement of the field. In this paper, a general study of the the design of soft robotic manipulators with fluidic actuation is presented, using an analytical derivation. The study relies on a novel approach that is applicable to a general design, and thus provides a common framework for the design of soft robots. In the study, two design layouts of interest are first justified, which correspond to extending and contracting devices. Design principles for each of the layouts are subsequently derived, both for planar and 3D scenarios, and considering operation to support any external loading and to provide any desired deflection. These principles are found to agree with the main design trends in literature, although they also highlight the potential for improvement in specific aspects of the design geometry and stiffness distribution. The principles are used to identify the most suitable design for both extending and contracting devices in 2D and 3D, and extract insight into their behavior.. To showcase the use of these design principles, a prototypical scenario in minimally invasive surgery requiring a manipulator segment capable of bending in any direction is defined, where the objective is to maximize its lateral force. The principles are applied to determine the most suitable design. These also highlight the need for numerical analysis to optimize two design parameters. Finite element simulations are developed, and their results are reported.

Journal article

Liu H, Auvinet E, Giles J, Rodriguez y Baena Fet al., 2018, Augmented reality based navigation for computer assisted hip resurfacing: a proof of concept study, Annals of Biomedical Engineering, Vol: 46, Pages: 1595-1605, ISSN: 0090-6964

Implantation accuracy has a great impact on the outcomes of hip resurfacing such as recovery of hip function. Computer assisted orthopedic surgery has demonstrated clear advantages for the patients, with improved placement accuracy and fewer outliers, but the intrusiveness, cost, and added complexity have limited its widespread adoption. To provide seamless computer assistance with improved immersion and a more natural surgical workflow, we propose an augmented-reality (AR) based navigation system for hip resurfacing. The operative femur is registered by processing depth information from the surgical site with a commercial depth camera. By coupling depth data with robotic assistance, obstacles that may obstruct the femur can be tracked and avoided automatically to reduce the chance of disruption to the surgical workflow. Using the registration result and the pre-operative plan, intra-operative surgical guidance is provided through a commercial AR headset so that the user can perform the operation without additional physical guides. To assess the accuracy of the navigation system, experiments of guide hole drilling were performed on femur phantoms. The position and orientation of the drilled holes were compared with the pre-operative plan, and the mean errors were found to be approximately 2 mm and 2°, results which are in line with commercial computer assisted orthopedic systems today.

Journal article

Virdyawan V, Rodriguez y Baena F, Vessel pose estimation for obstacle avoidance in needle steering surgery using multiple forward looking sensors, 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems, Publisher: IEEE

During percutaneous interventions in the brain, puncturing a vessel can cause life-threatening complications. To avoid such a risk, current research has been directed towards the development of steerable needles. However, there is a risk that vessels of a size which is close to or smaller than the resolution of commonly used preoperative imaging modalities (0.59 x 0.59 x 1 mm) would not be detected during procedure planning, with a consequent increase in risk to the patient. In this work, we present a novel ensemble of forward-looking sensors based on laser Doppler flowmetry, which are embedded within a biologically inspired steerable needle to enable vessel detection during the insertion process. Four Doppler signals are used to classify the pose of a vessel in front of the advancing needle with a high degree of accuracy (2$^{\circ}$ and 0.1 mm RMS errors), where relative measurements between sensors are used to correct for ambiguity. By using a robotic-assisted needle insertion process, and thus a precisely controlled insertion speed, we also demonstrate how the setup can be used to discriminate between tissue bulk motion and vessel motion. In doing so, we describe a sensing apparatus applicable to a variety of needle steering systems, with the potential to eliminate the risk of haemorrhage during percutaneous procedures.

Conference paper

Tan Z, Forte A, Rodriguez y Baena F, Dini Det al., Needle-tissue interactions during convection enhanced drug delivery in neurosurgery, International Conference on BioTribology

Conference paper

Watts T, Secoli R, Rodriguez y Baena F, 2018, Modelling the deformation of biologically inspired flexible structures for needle steering, The first International Congress for the Advancement of Mechanism, Machine, Robotics and Mechatronics Sciences 2017, Publisher: Springer, Pages: 67-80, ISSN: 2211-0984

Recent technical advances in minimally invasive surgery have been enabled by the development of new medical instruments and technologies. To date, the vast majority of mechanisms used within a clinical context are rigid, contrasting with the compliant nature of biological tissues. The field of robotics has seen an increased interest in flexible and compliant systems, and in this paper we investigate the behaviour of deformable multi-segment structures, which take their inspiration from the ovipositor design of parasitic wood wasps. These configurable structures have been shown to steer through highly compliant substrates, potentially enabling percutaneous access to the most delicate of tissues, such as the brain. The model presented here sheds light on how the deformation of the unique structure is related to its shape, and allows comparison between different potential designs. A finite element study is used to evaluate the proposed model, which is shown to provide a good fit (root-mean-square deviation 0.2636 mm for 4-segment case). The results show that both 3-segment and 4-segment designs are able to achieve deformation in all directions, however the magnitude of deformation is more consistent in the 4-segment case.

Conference paper

Matheson E, Secoli R, Burrows C, Leibinger A, Rodriguez y Baena Fet al., 2018, Cyclic motion control for programmable bevel-tip needles to reduce tissue deformation, Journal of Medical Robotics Research, Vol: 4, ISSN: 2424-905X

Robotic-assisted steered needles aim to accurately control the deflection of the flexible needle’s tip to achieve accurate path following. In doing so, they can decrease trauma to the patient, by avoiding sensitive regions while increasing placement accuracy. This class of needle presents more complicated kinematics compared to straight needles, which can be exploited to produce specific motion profiles via careful controller design and tuning. Motion profiles can be optimized to minimize certain conditions such as maximum tissue deformation and target migration, which was the goal of the formalized cyclic, low-level controller for a Programmable Bevel-tip Needle (PBN) presented in this work. PBNs are composed of a number of interlocked segments that are able to slide with respect to one another. Producing a controlled, desired offset of the tip geometry leads to the corresponding desired curvature of the PBN, and hence desired path trajectory of the system. Here, we propose a cyclical actuation strategy, where the tip configuration is achieved over a number of reciprocal motion cycles, which we hypothesize will reduce tissue deformation during the insertion process. A series of in vitro, planar needle insertion experiments are performed in order to compare the cyclic controller performance with the previously used direct push controller, in terms of targeting accuracy and tissue deformation. It is found that there is no significant difference between the target tracking performance of the controllers, but a significant decrease in axial tissue deformation when using the cyclic controller.

Journal article

Secoli R, Rodriguez y Baena F, 2018, Experimental validation of curvature tracking with a programmable bevel-tip steerable needle, International Symposium on Medical Robotics, Publisher: IEEE

Needle steering systems are a topic of increasing research interest due to the many potential advantages associated with the ability to reach deep-seated targets while avoiding obstacles. Existing embodiments, such as those designed around a fixed bevel tip, are necessarily disruptive to the substrate, with the potential to cause a target to move away from the insertion trajectory, as well as potentially increasing the extent of tissue trauma at the needle interface, when compared to straight needles. To alleviate these issues, we proposed a biologically inspired design, which can steer without the need for duty-cycle spinning along the insertion axis or any active mechanisms at the tip. In this work, we demonstrate for the first time that our needle is able to steer within a deformable substrate, along with a user-defined trajectory in three-dimensional space. A simplified kinematic model is reported, which is subsequently used to design an adaptive strategy enabling the tracking of arbitrary curvatures along any given reference plane. Experimental results in gelatin are used to validate our model, as well as the performance of the controller under laboratory conditions.

Conference paper

Brett PN, Du X, Assadi MZ, Rodriguez y Baena F, Liu F, Hinchliffe R, Thompson Met al., 2018, Design and experimental demonstration of a mechatronic solution for endovascular catheters, Mechatronics and Machine Vision in Practice 3, Pages: 247-252, ISBN: 9783319769462

© Springer International Publishing AG, part of Springer Nature 2018. This paper describes a mechatronics approach that provides vascular surgeons with the perception of movement and tissue interaction in the vicinity of the tip of a catheter in endovascular procedures. The current system described is experimental and used in phantom units. It integrates 3D visualization generated from scan with real-time tactile sensing in the vicinity of the tip of the catheter to update on the nature of tissue interaction, the curvature and relative orientation of the catheter sleeve and guide wire. This approach offers superior perception by the clinician, in contrast with current application of catheters used in this application. By being well informed of conditions at the working environment of the catheter tip the clinician will be able to administer therapies with greater precision in the surgical task and within a reduced operating time. The approach will reduce risk for patients and significantly reduce risks for the clinician, who is currently exposed to high doses of ionizing radiation during the process of catheter guidance.

Book chapter

Garriga Casanovas A, ’Athif Mohd Faudzi A, Hiramitsu T, Rodriguez y Baena F, Suzumori Ket al., 2018, Multifilament pneumatic artificial muscles to mimic the human neck, IEEE International Conference on Robotics and Biomimetics, 2017, Publisher: IEEE

Pneumatic Artificial Muscles (PAMs) are actuators that resemble human muscles, and offer an attractive performance in various aspects including robustness, simplicity, high specific power and high force for a given volume. These characteristics render them good candidates for use in humanoid robots. The use of traditional PAMs to closely mimic human structures, however, is difficult due to their relatively large size and relatively fixed designs. The recent development of multifilament PAMs enables the realization of humanoid robots that more closely mimic the human anatomy. In this paper, the application of multifilament PAMs to mimic the human neck is presented. First, the main structures of the human neck anatomy in terms of bones, ligaments and muscles are identified and detailed. The design to mimic each of these structures is subsequently described, together with the most relevant parts of the manufacturing process. The integrated neck is then presented, and the method to actuate it is outlined. The results of motion of the artificial neck when actuating different groups of muscles that mimic those in the human anatomy are reported, confirming a motion that is equivalent to that of the human neck. The results also indicate a range of motion of the robot neck somewhat lower than that of its human counterpart, and the reasons for this are discussed. Finally, future directions for improved motion range, stability, durability and efficiency are outlined.

Conference paper

Virdyawan V, Rodriguez y Baena F, Oldfield M, 2018, Laser Doppler sensing for blood vessel detection with a biologically inspired steerable needle, Bioinspiration and Biomimetics, Vol: 13, ISSN: 1748-3182

Puncturing blood vessels during percutaneous intervention in minimally invasive brain surgery can be a life threatening complication. Embedding a forward looking sensor in a rigid needle has been proposed to tackle this problem but, when using a rigid needle, the procedure needs to be interrupted and the needle extracted if a vessel is detected. As an alternative, we propose a novel optical method to detect a vessel in front of a steerable needle. The needle itself is based on a biomimetic, multi-segment design featuring four hollow working channels. Initially, a laser Doppler flowmetry probe is characterized in a tissue phantom with optical properties mimicking those of human gray matter. Experiments are performed to show that the probe has a 2.1 mm penetration depth and a 1 mm off-axis detection range for a blood vessel phantom with 5 mm/s flow velocity. This outcome demonstrates that the probe fulfills the minimum requirements for it to be used in conjunction with our needle. A pair of Doppler probes is then embedded in two of the four working channels of the needle and vessel reconstruction is performed using successive measurements to determine the depth and the off-axis position of the vessel from each laser Doppler probe. The off-axis position from each Doppler probe is then used to generate a "detection circle" per probe, and vessel orientation is predicted using tangent lines between the two. The vessel reconstruction has a depth Root Mean Square Error (RMSE) of 0.3 mm and an RMSE of 15° in the angular prediction, showing real promise for a future clinical application of this detection system.

Journal article

Garriga Casanovas A, Rodriguez y Baena F, 2018, Complete follow-the-leader kinematics using concentric tube robots, International Journal of Robotics Research, Vol: 37, Pages: 197-222, ISSN: 0278-3649

Concentric tube robots offer the capability of follow-the-leader motion, which is desirable when navigating in cluttered environments, such as in minimally invasive surgery or in-situ inspections. The follow-the-leader capabilities identified in the existing literature, however, are limited to trajectories with piecewise constant-curvature segments or piecewise helical segments. A complete study of follow-the-leader kinematics is, therefore, relevant to determine the full potential of these robots, and clarify an open question. In this paper, a general analysis of follow-the-leader motion is presented, and a closed-form solution to the complete set of trajectories where follow-the-leader is possible under the assumption of no axial torsion of the tubes composing the robot is derived. For designs with constant-stiffness tubes, the precurvatures required are found to be either circumference arcs, helices, or deformed helices with exponentially varying curvature magnitude. The analysis developed also elucidates additional motions of interest, such as the combination of follow-the-leader motion in a robot segment with general maneuvers in another part. To determine the applicability of the assumption regarding the tubes’ torsion, the general equilibrium of the robot designs of interest is considered, and a closed-form solution to torsion in two-tube robots with helical precurvatures is derived. Criteria to select a desired torsional behavior are then extracted. This enables one to identify stable trajectories where follow-the-leader is possible, for potential application to minimally invasive surgery. An illustrative case study involving simulation and experiment is conceived using one of these trajectories, and the results are reported, showcasing the research.

Journal article

Tan Z, Forte AE, Parisi C, Rodriguez Y Baena F, Dini Det al., 2017, Composite hydrogel: A new tool for reproducing the mechanicalbehaviour of soft human tissues, WTC 2017

Conference paper

El Daou H, Lord B, Amis A, Rodriguez y Baena Fet al., 2017, Assessment of pose repeatability and specimen repositioning of a robotic joint testing platform, MEDICAL ENGINEERING & PHYSICS, Vol: 47, Pages: 210-213, ISSN: 1350-4533

This paper describes the quantitative assessment of a robotic testing platform, consisting of an industrial robot and a universal force-moment sensor, via the design of fixtures used to hold the tibia and femur of cadaveric knees. This platform was used to study the contributions of different soft tissues and the ability of implants and reconstruction surgeries to restore normal joint functions, in previously published literature.To compare different conditions of human joints, it is essential to reposition specimens with high precision after they have been removed for a surgical procedure. Methods and experiments carried out to determine the pose repeatability and measure errors in repositioning specimens are presented. This was achieved using an optical tracking system (fusion Track 500, Atracsys Switzerland) to measure the position and orientation of bespoke rigid body markers attached to the tibial and femoral pots after removing and reinstalling them inside the rigs. The pose repeatability was then evaluated by controlling the robotic platform to move a knee joint repeatedly to/from a given pose while tracking the position and orientation of a rigid body marker attached to the tibial fixture.The results showed that the proposed design ensured a high repeatability in repositioning the pots with standard deviations for the computed distance and angle between the pots at both ends of the joint equal to 0.1 mm, 0.01 mm, 0.13° and 0.03° for the tibial and femoral fixtures respectively. Therefore, it is possible to remove and re-setup a joint with high precision. The results also showed that the errors in repositioning the robotic platform (that is: specimen path repeatability) were 0.11 mm and 0.12°, respectively.

Journal article

Tan Z, Bernardini A, Konstantinou I, Forte AE, Galvan S, Van Wachem B, Dini D, Rodriguez Y Baena Fet al., 2017, Diffusion Measurement and Modelling, European Robotics Forum 2017

Conference paper

Burrows C, Liu F, Leibinger A, Secoli R, Rodriguez y Baena Fet al., 2017, Multi-target Planar Needle Steering with a Bio-inspired Needle Design, 1st International Conference of IFToMM ITALY (IFIT), Publisher: Springer, Pages: 51-60, ISSN: 2211-0984

Percutaneous intervention is common practice in many diagnostic and therapeutic surgical procedures. Needle steering research aims to extend these by enabling therapies that are not possible with a straight rigid needle. Being able to address multiple targets in one insertion is an example of such a therapy, which would result in reduced overall trauma to the patient and surgery time. However, needle steering remains challenging, as soft tissue is highly compliant and deformable, and thus difficult to interact with. In this work, we develop a new biologically inspired needle design (4 mm outside diameter) and show its capabilities in multiple moving target scenarios. In vitro results in gelatin demonstrate accurate 2D tracking of two virtual targets over 3 target movement rates.

Conference paper

Athwal K, El Daou, Lord B, Davies AJ, Manning W, Rodriguez y Baena, Deehan DJ, Amiset al., 2016, Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability., Journal of Orthopaedic Science, Vol: 35, Pages: 1902-1909, ISSN: 0949-2658

Little information is available to surgeons regarding how the lateral structures prevent instability in the replaced knee. The aim of this study was to quantify the lateral soft‐tissue contributions to stability following cruciate‐retaining total knee arthroplasty (CR TKA). Nine cadaveric knees were tested in a robotic system at full extension, 30°, 60°, and 90° flexion angles. In both native and CR implanted states, ±90 N anterior–posterior force, ±8 Nm varus–valgus, and ±5 Nm internal–external torque were applied. The anterolateral structures (ALS, including the iliotibial band), the lateral collateral ligament (LCL), the popliteus tendon complex (Pop T), and the posterior cruciate ligament (PCL) were transected and their relative contributions to stabilizing the applied loads were quantified. The LCL was found to be the primary restraint to varus laxity (an average 56% across all flexion angles), and was significant in internal–external rotational stability (28% and 26%, respectively) and anterior drawer (16%). The ALS restrained 25% of internal rotation, while the PCL was significant in posterior drawer only at 60° and 90° flexion. The Pop T was not found to be significant in any tests. Therefore, the LCL was confirmed as the major lateral structure in CR TKA stability throughout the arc of flexion and deficiency could present a complex rotational laxity that cannot be overcome by the other passive lateral structures or the PCL. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1902–1909, 2017.

Journal article

Leibinger A, Forte AE, Tan Z, Oldfield M, Beyrau F, Dini D, Rodriguez Y Baena Fet al., 2016, Erratum to: Soft tissue phantoms for realistic needle insertion: a comparative study, Annals of Biomedical Engineering, Vol: 44, Pages: 3750-3750, ISSN: 0090-6964

Phantoms are common substitutes for soft tissues in biomechanical research and are usually tuned to match tissue properties using standard testing protocols at small strains. However, the response due to complex tool-tissue interactions can differ depending on the phantom and no comprehensive comparative study has been published to date, which could aid researchers to select suitable materials. In this work, gelatin, a common phantom in literature, and a composite hydrogel developed at Imperial College, were matched for mechanical stiffness to porcine brain, and the interactions during needle insertions within them were analyzed. Specifically, we examined insertion forces for brain and the phantoms; we also measured displacements and strains within the phantoms via a laser-based image correlation technique in combination with fluorescent beads. It is shown that the insertion forces for gelatin and brain agree closely, but that the composite hydrogel better mimics the viscous nature of soft tissue. Both materials match different characteristics of brain, but neither of them is a perfect substitute. Thus, when selecting a phantom material, both the soft tissue properties and the complex tool-tissue interactions arising during tissue manipulation should be taken into consideration. These conclusions are presented in tabular form to aid future selection.

Journal article

Blyth WA, Barr DRW, Rodriguez Y Baena F, 2016, A reduced actuation mecanum wheel platform for pipe inspection, 2016 IEEE International Conference on Advanced Intelligent Mechatronics (AIM), Publisher: IEEE, Pages: 419-424

This paper focuses on the design, development and assessment of a novel, 2 degrees-of-freedom magnetic pipe inspection robot. It consists of 4 mecanum wheels, with the diagonals functionally coupled and the system rotation constrained by the surface geometry, maintaining full translational mobility with reduced control and actuation requirements. The system uses positional encoding that is decoupled from the transmission system to overcome the main sources of positional/positioning errors when using mecanum wheels. The kinematic and dynamic models of the system are derived and integrated within the controller. The prototype robot is then tested and shown to follow a scan path at 20mm/s within ±1.5mm whilst correcting for gravitational drift and slip events.

Conference paper

Forte AE, Galvan S, Manieri F, Rodriguez y Baena F, Dini Det al., 2016, A composite hydrogel for brain tissue phantoms, Materials and Design, Vol: 112, Pages: 227-238, ISSN: 0264-1275

Synthetic phantoms are valuable tools for training, research and development in traditional and computer aided surgery, but complex organs, such as the brain, are difficult to replicate. Here, we present the development of a new composite hydrogel capable of mimicking the mechanical response of brain tissue under loading. Our results demonstrate how the combination of two different hydrogels, whose synergistic interaction results in a highly tunable blend, produces a hybrid material that closely matches the strongly dynamic and non-linear response of brain tissue. The new synthetic material is inexpensive, simple to prepare, and its constitutive components are both widely available and biocompatible. Our investigation of the properties of this engineered tissue, using both small scale testing and life-sized brain phantoms, shows that it is suitable for reproducing the brain shift phenomenon and brain tissue response to indentation and palpation.

Journal article

Tan Z, Forte AE, Galvan S, Dini D, Rodriguez Y Baena Fet al., 2016, Composite Hydrogel: a New Tool for Reproducing the Mechanical Behaviour of Soft Human Tissues, Biotribology 2016

Conference paper

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