This article introduces a novel approach to bile duct automatic segmentation from cholangio-MRI images. 3D reconstruction of bile ducts could be of great help for critical therapeutic interventions, especially for endoscopic retrograde cholangiopancreatography (ERCP). The approach is based on employing the U-Net neural network, incorporating a new loss function (BDU-Net). The study, conducted on 24 patient cases, utilized quantitative metrics and qualitative assessment to evaluate the segmentation results obtained by the proposed method against ground truth. Experimental results demonstrated that our model outperforms existing segmentation algorithms such as V-Net and U-Net++, achieving a Dice score of 0.72, representing a 16% improvement compared to the advanced U- Net++ segmentation method. From a qualitative point of view, our BDU-Net method generates fewer than one false communicating intrahepatic ducts (FC IHDs) and fewer than one false non-communicating intrahepatic ducts (FnC IHDs).

This paper deals with the control of a redundant robotic system for middle ear surgery (i.e., cholesteatoma tissues removal). The targeted robotic system is a macro-micro-scale robot composed of a redundant seven degrees of freedom (DoFs) on which is attached a two DoFs robotized flexible fiberscope. Two different control architectures are proposed to achieve a defined surgical procedure to remove the pathological tissue inside the middle ear cavity. The first proposed control mode is based on the position-based tele-operation of the entire system using a joystick (Phantom Omni) as a master arm. The second one combines comanipulation of the seven DoFs robotic arm using an embedded force/torque sensor and an end-frame tele-operation of the remaining two DoFs fiberscope using a lab-made in-hand joystick. Experimental validation is performed to evaluate and compare the performance of both developed control schemes. The obtained results using the lab-made platform and the proposed controllers are discussed.

This paper deals with the control of a laser spot in the context of minimally invasive surgery of the middle ear, e.g., cholesteatoma removal. More precisely, our work is concerned with the exhaustive burring of residual infected cells after primary mechanical resection of the pathological tissues since the latter cannot guarantee the treatment of all the infected tissues, the remaining infected cells cause regeneration of the diseases in 20%-25 % of cases, which require a second surgery 12–18 months later. To tackle such a complex surgery, we have developed a robotic platform that consists of the combination of a macro-scale system (7 degrees of freedoms (DoFs) robotic arm) and a micro-scale flexible system (2 DoFs) which operates inside the middle ear cavity. To be able to treat the residual cholesteatoma regions, we proposed a method to generate optimal laser automatically scanning trajectories inside the areas and between them. The trajectories are tacked using an image-based control scheme. The proposed method and materials were validated experimentally using the lab-made robotic platform. The obtained results in terms of accuracy and behaviour meet the laser surgery requirements perfectly.

This paper presents a biomechanical model for tissue deformations in the case of tangential micro-probe scanning for image acquisition. The tissue is modelled as a rigid body and its deformations - considered as elastic - as springs between this body and a fixed reference body. The contact between the probe and the tissue is then considered as a Hertzian sphere-plane contact with a Coulomb friction force. Given those hypotheses, an analytical model of the tissue deformations for 2D tangential movements along the locally planar tissue surface can be established. Similarly to the work of Erden et al. [1], the model has a unique parameter: the loading distance of the tissue. For given scan conditions, this parameter can be calibrated with a simple back-and-forth movement and image measurements. It is of particular interest in minimally invasive surgery where measurements of the friction forces or of the mechanical parameters of the tissue are complex to carry out. Simulations are in accordance with experiments and show that this model allows for accurate estimation of the probe/tissue trajectory in one dimension scans. Moreover, unlike previous studies, the model allows the estimation of the probe/tissue trajectory also for 2D scans. Both coupling behaviour and stick/slip transitions when scanning direction changes are taken into account. However experiments show that anisotropy is an important parameter when studying 2D coupling behaviour. Therefore, an extension of the model that takes anisotropic behaviour of the tissue into account is proposed. Experiments carried out on ex vivo bovine liver and chicken muscle tissues show that the probe/tissue trajectory is accurately predicted by the model. However, this increases the number of parameters to five. As a consequence, unlike in the isotropic case, the parameters can not be simply calibrated using a back-and-forth movement. Further work will be carried out towards finding an easy and effective calibration procedure that applies both to the isotropic and anisotropic cases.

This paper presents the mechanical design of a distal scanner to perform a spiral scan for mosaic-imaging with a confocal microlaparoscope. First, it is demonstrated with ex vivo experiments that a spiral scan performs better than a raster scan on soft tissue. Then a mechanical design is developed in order to perform the spiral scan. The design in this paper is based on a conic structure with a particular curved surface. The mechanism is simple to implement and to drive; therefore, it is a low-cost solution. A 5:1 scale prototype is implemented by rapid prototyping and the requirements are validated by experiments. The experiments include manual and motor drive of the system. The manual drive demonstrates the resulting spiral motion by drawing the tip trajectory with an attached pencil. The motor drive demonstrates the speed control of the system with an analysis of video thread capturing the trajectory of a laser beam emitted from the tip.

Current trends in robotic cardiac surgery presage for allowing physiological motion compensation in beating-heart surgery. However, interacting with fast moving soft organs by means of stiff instruments/robots is challenging. This paper concerns comanipulation with a hand-held instrument, the goal being to allow the surgeon to perform low frequency motions that correspond to the surgical task while a distal part of the instrument actively moves in synchronism with the heart motion in order to guarantee that the contact is maintained. This paper explores the difficulties of implementing low-impedance control on a novel hand-held motion compensation instrument. A force feedback control strategy is proposed and evaluated experimentally on a simulated surgical scene. Taking advantage of the sensory capacities of the prototype presented, a successful modulation of the dynamics of interaction is reached. Conclusive results on the performances of the system and possibilities of future improvements are given.

This paper presents an approach for understanding the soft tissue behavior in surface contact with a hard object scanning the tissue. The application domain is confocal microlaparoscope imaging, mostly used for imaging the outer surface of the organs in the abdominal cavity. The probe (optic-head) is swept over the tissue to collect sequential images to obtain a large field of view with mosaicing. The problem we address is that the tissue also moves with the probe due to its softness; therefore the resulting mosaic is not in the same shape and dimension as traversed by the probe. Our approach inspires from the finger slip studies and adapts the idea of load-and-slip that explains the movement of the finger when dragged on a hard surface. We propose the concept of loading-distance and perform measurements with in total 84 experiments on beef liver and chicken breast tissues. Our results indicate that the loading-distance can be measured prior to a scan and be used during the scan in order to compensate the movement of the probe. In this way we can have an image-mosaic of the tissue surface in a desired shape.

Probe-based confocal laser endomicroscopy is a recent tissue imaging technology that requires placing a probe in contact with the tissue to be imaged and provides real time images with a microscopic resolution. Additionally, generating adequate probe movements to sweep the tissue surface can be used to reconstruct a wide mosaic of the scanned region while increasing the resolution which is appropriate for anatomico-pathological cancer diagnosis. However, properly controlling the motion along the scanning trajectory is a major problem. Indeed, the tissue exhibits deformations under friction forces exerted by the probe leading to deformed mosaics. In this paper we propose a visual servoing approach for controlling the probe movements relative to the tissue while rejecting the tissue deformation disturbance. The probe displacement with respect to the tissue is firstly estimated using the confocal images and an image registration real-time algorithm. Secondly, from this real-time image-based position measurement, the probe motion is controlled thanks to a simple proportional-integral compensator and a feedforward term. Ex vivo experiments using a Stäubli TX40 robot and a Mauna Kea Technologies Cellvizio imaging device demonstrate the effectiveness of the approach on liver and muscle tissue.

Instruments used in many types of minimally invasive procedures, in particular laparoscopy, are rigid or only limitedly flexible and some tasks like suturing are difficult to perform with them. A novel hand-held, lightweight and ergonomic mechatronic instrument is presented in this paper. The instrument has a 3-DOF roll-pitch-roll end-effector controlled using an easy to use handle that provides the surgeon with a 6-DOF movement, including a distal circular movement which resembles the circular movement of stitching. The design of the instrument is based on a global study involving control, dexterity and ergonomic aspects, with the aim of developing an instrument that enhances the dexterity of the surgeon while having an intuitive and ergonomic interface. A proof of concept prototype was built and tested in vitro and in vivo.

Shape and mechanical structure of instruments play a large part in the lack of ergonomics during laparoscopic surgery. Providing intra-abdominal mobility and rethinking handles design are two solutions to increase comfort and precision of gestures. Based on previous work that determined the optimal intra-abdominal kinematics, this study analyses the influence of handle design on both gesture and ergonomic performance. A virtual reality laparoscopic simulator was developed to perform an experimental comparison between two novel robotized instruments and standard ones. A group of 10 surgeons and 6 researchers in robotics carried out two representative surgical tasks with each instrument. Based on instrument and arm segments tracking, a gesture performance index and an ergonomic performance index were computed. The study demonstrates that distal mobilities combined with improved handle design and integration increase ergonomic level during laparoscopy and facilitate complex gestures.

Probe-based confocal laser endomicroscopy is a promising technology for performing minimally-invasive optical biopsies. With the help of mosaicing algorithms, several studies reported successful results in endoluminal surgery. In this paper, we present a prototype for making robotized optical biopsies on a variety of organs inside the abdominal cavity. We chose a macro-micro association, with a macropositioner, a micropositioner and a passive mechanical compensation of physiological motion. The probe is actuated by three hydraulic micro-balloons and can be moved on the surface of an organ to generate a mosaic. This paper presents the design and experimental results of a first in vivo trial on a porcine model.

Middle ear surgery requires micro-surgical techniques and may benefit from robotic assistance. A prototype of tele-operated system is presented. Methods to determine design specifications, kinematic structure and optimization of the micro-manipulator are described. First evaluation of the robot by a stapedial removal through the external auditory meatus in human temporal bone specimens, simulating the surgery of otosclerosis, is presented. In this procedure, the robot yielded accessibility to the target area with a reduced visual impairment and, an enhanced tool stability compared to the surgeon's hand.

This paper presents a new miniature actuator, which is currently being used to design and develop high resolution, lightweight and compact interfaces for tactile binary information representation such as Braille. Since the main drawback of these devices is their high cost, the proposed actuator exploits the simplicity of its design to provide a low-cost actuation alternative. Based on shape memory alloy (SMA) technology, the actuator consists of an antagonist arranged pair of NiTi helical springs. The actuator of 1.5 mm diameter and 150 mg weight is capable of developing a 320 mN pull force and 1.5 Hz bandwidth by using simple forced-air convection. A combined computational/experimental study on the thermomechanical properties of both SMA active element and actuator is presented to evaluate characteristics such as actuation speed, force and stroke. In conclusion, the prototype and performance results are reported and discussed.

This paper proposes the distributed impedance approach as a new formulation of multiple robot systems control. In this approach, each cooperating manipulator is provided with its own independent impedance controller. In addition, along selected degrees of freedom, force control is achieved through an external loop, in order to improve control of the object's internal loading. Extensive stability analysis is performed based on a realistic model that includes robots impedance and object dynamics. Experiments are performed using two cooperating industrial robots holding an object through point contacts. Force and position control actions are suitably dispatched to achieve both internal loading control and object position control. The performance of the system is demonstrated for transporting tasks.