A model has been developed to design a new active, steerable end-effector for minimally invasive surgery. Active material is incorporated into the surgical instrument to increase the degrees of freedom available to the surgeon. This paper focuses on the modeling of the end-effector using both piezoelectric ceramic and electroactive polymer (EAP) materials. The end-effector design consists of a number of bimorph actuator sections in series with each active layer being individually controlled. Each section may behave as either a bimorph or a unimorph actuator, where in the case of unimorph one of the active layers is passive. By varying the strength and direction of the electric field across each section, a prescribed overall shape can be achieved to allow the user to steer the device. The piezoceramic device is modeled using strain energy methods to predict the quasi-static force-deflection behavior. In the EAP model, experimental data for the electrostrictive P(VDF-TrFE) copolymer is used to model the non-linear relationship between the electric field and the induced strain. Due to the large deflections achievable with the EAP, a model for large deflections beams is also used. Modeling is carried out using MATLAB and then the behavior of piezoelectric ceramic is compared to that of electro-active polymer (EAP).

This paper presents an improved design concept for a surgical robot that contributes to improved human-robot interaction and precise positioning of surgical tools. Based on a spherical wrist design, the robot incorporates new human-safe features limiting its ability to apply excessive force and uses a novel adaptation of the compliant rolling-element (CORE) joint suitable for conical rolling surfaces. The proposed safety features aim to provide novel functionality by mechanically disengaging the drive in overload conditions. This approach avoids the necessity of force sensing and control to detect and compensate for unintended device collisions. Further, proof of concept of a novel compliant rolling-element joint is presented as a low-backlash alternative to bevel gear pairs for heightened precision in angular positioning.

In this paper, the design of the robotic cannula for minimally invasive robotic lumbar discectomy is presented. Lumbar discectomy is the surgery to remove the herniated disc material that is pressing on a nerve root or spinal cord. Recently, a robotic approach to performing this procedure has been proposed that utilizes multiple teleoperated articulated instruments inserted into the surgical workspace using a single cannula. In this paper, we propose a new robotic cannula system to work in conjunction with this new procedure. It allows for the independent teleoperated control of the axial position and rotation of up to three surgical instruments at the same time. The mechanical design, controller design, and prototype of new system are presented in this paper demonstrating a fully functioning device for this application. A novel worm gear and rack system allow for the instrument translation while and embedded gear trains produce the rotational movement. Steady-state errors of less than 50 μm for translation and less than 2° for rotational motion are obtained.

Developable mechanisms conform to and emerge from developable, or specially curved, surfaces. The cylindrical developable mechanism can have applications in many industries due to the popularity of cylindrical or tube-based devices. Laparoscopic surgical devices in particular are widely composed of instruments attached at the proximal end of a cylindrical shaft. In this paper, properties of cylindrical developable mechanisms are discussed, including their behaviors, characteristics, and potential functions. One method for designing cylindrical developable mechanisms is discussed. Two example developable surgical devices that exemplify these behaviors, characteristics, and functions, along with the kinematic mechanisms comprising them, are discussed in detail.

Linear actuation is a basic need in robotized manipulation of surgical instruments, that must comply with a challenging environment in terms of safety, compactness and now often compatibility with imaging modalities like CT or MRI. In this paper, we focus on needle manipulation for interventional radiology. We propose a needle driver, i.e. a linear actuator for needle insertion, based on the inchworm principle combined with pneumatic energy. Our first contribution is to propose, model and implement the device using a so-called auxetic structure. Its use increases achievable displacement under pressure and provides sufficient off-axis stiffness to use the actuator without additional guidance. Simplified modeling is introduced for the actuator synthesis. Our second contribution is to implement the actuator with multimaterial additive manufacturing combining rigid and flexible materials to increase compactness. As a third contribution, initial assessment of component sterilization and compatibility with X-ray and MRI imaging modalities is presented.

In this paper, the design of disposable 3D printed surgical end-effectors for robotic lumbar discectomy is presented. Discectomy is the surgery to remove the herniated disc material that is pressing on a nerve root or spinal cord. This surgery is performed to relieve pain or numbness caused by the pressure on the nerve. The limited workspace of the spine (< 27 cm 3 ) results in challenging design requirements for surgical instruments. We propose a new cannula-based robotic lumbar discectomy procedure that can accommodate multiple articulated tools in the workspace at the same time and can be controlled teleoperatively by the surgeon. We present designs for two instruments for this proposed system: an articulated nerve retractor and an articulated grasper. The end-effectors of each are 3D printed with multiple materials, with flexible links acting as joints of the mechanism. These flexible links are actuated by cables which provide sufficient articulation and manipulation forces in the surgical workspace. The end-effector’s articulated flexible joint kinematics is modeled and tested for range of motion capabilities. The retraction forces for the nerve retractor and the grasping force for the grasper are also experimentally tested and verified to meet all the design requirements. Additionally, fatigue testing of the flexible joint is presented and teleoperated control for the instruments is demonstrated.

Remote manipulation during robot-assisted surgery requires proficiency in perception, cognition, and motor skills. We aim to understand human motor control in remote manipulation of robotic surgical instrument and attempt to measure motor skills. Three features, smoothness, normalized jerk score, and two-thirds power law coefficient, estimating the motor skills of surgeons were analyzed. These features were calculated through segments, extracted from continuous end-effector trajectories during suturing, knot-tying, and needle-passing surgical tasks, performed by 8 right-handed subjects on bench-top models using da vinci surgical kit control system. Each subject repeated each task five times. Totally 1567 segments were extracted, 413, 437, and 717 segments performed by experts, intermediates, and novice subjects, respectively. Dynamic change of kinematic properties was analyzed to evaluate the relationship between considered features and motor skill level. Results show smoothness is significantly correlated with normalized jerk score and both features are significant measures of expertise levels. Also, results show the power law is violated by many end-effector trajectories and there is no relationship between obeying two-thirds power law, smoothness and jerk. We conclude trajectory is improved from non-smooth and jerky in novices to smooth in expert surgeons. This property may be used for motor skill evaluation. It is unlikely that obeying two-thirds power law be a valid property of all end-effector trajectories. However, power law coefficient may be a discriminant feature for levels of expertise. The results are also applicable in a home-based monitoring platform, to monitor motor functioning improvement of stroke patients during rehabilitation process.

Imaging plays an important role in all clinical processes. One challenge in medical image data processing is detection and tracking objects and instruments, which faces complications arising from the developed medical image acquisition systems and also the nature of in-vivo medical images. Special properties of the in-vivo bio images such as noise, specular highlights, inhomogeneity, heterogeneity, varying luminosity, and background change, in addition to the changes of camera, out of camera view tools, and multiple moving tools (instrument tools, surgical suture, cutting instrument, tissue movement) make object detection and tracking in the biomedical image processing complicated. In this study, the k-means clustering method in combination with the level set active curve model are used to develop a platform for low-cost tracking of surgical tools in robotic surgery videos. After removing the image background, the smoothed image is used as input to the numerical method. This model tracks the robot tools even when the camera view changes, the tool is lost, the tissue is bleeding and moving, and the luminosity of the images changes. The developed model is validated using video frames of real and simulated robotic surgeries. The accuracy of model in tracking da vinci robot end-effectors for a video with 12000 frames, recorded at Roswell Park Cancer Institute, is 93 %. Accuracy of proposed framework is compared to those for existing numerical models, DRLSE and Chan-Vese. The results show that proposed surgical robot tool tracking model is more efficient than existing computational models.

Development of a mechanism with dual remote center of motion (dual-RCM mechanism) intended for teleoperated ophthalmic surgery is reported in this paper. First, characteristics of RCM mechanisms are analyzed. Then, a method to synthesize dual-RCM mechanisms is proposed. Further the mechanical design parameters are optimized to synthesize types of mechanisms meeting functional requirements as well as workspace constraints. The dual-RCM mechanism intended for teleoperated ophthalmic surgery includes two end-effectors: one provides the tool insertion, the other tracks eye movement. The superiority is embodied in the self-synchronized motion of double end-effectors, which allows RCM point of the working instrument to track the penetration point real-time, thereby enhancing microsurgical accuracy. In the proposed implementation, a conceptual helmet mechanical architecture integrating surgical tools with triple-parallelogram linkages is introduced to release the surgeon’s hands by enabling more robotic technologies during the procedures. The vision of the research is to help revolutionize the ophthalmic surgical procedures from bimanual fashion to master-slave teleoperation.

A static balancer is a mechanism used to force compensate mechanical systems and has been used in applications such as improving haptic feedback in surgical instruments and lowering motor loads in robotic systems. Currently no complete overview exists of all SB methods, this paper can be seen as an extension to earlier work by introducing more static balancing categories and methods. The goal is to have a comprehensive overview of state-of-the-art to aid designers in selecting the appropriate static balancer technology for mechanical systems. Existing designs are categorized based on the energy storage mechanism, e.g. elastic energy storage mechanisms. Critical design parameters are extracted from published literature to form the basis of comparison of the different categories. A performance criterium is defined to illustrate balancing capabilities as a function of system size. The three comparison parameters are: CompensatedForce Volume , SBStroke Volume , Energy Volume The comparison results show that compliant flexure balancers are the best selection for balancing systems while keeping minimal size. Theoretical calculations show that there is still ample room to improve current balancers with regard to the chosen balancer criteria.

Robotic minimally invasive surgery has achieved success in various procedures; however, the lack of haptic feedback is considered by some to be a limiting factor. The typical method to acquire tool-tissue reaction forces is attaching force sensors on surgical tools, but this complicates sterilization and makes the tool bulky. This paper explores the feasibility of using motor current to estimate tool-tissue forces, and demonstrates acceptable results in terms of time delay and accuracy. This sensorless force estimation method sheds new light on the possibility of equipping existing robotic surgical systems with haptic interfaces that require no sensors and are compatible with existing sterilization methods.

Minimally invasive (MIS) total hip arthroplasty is a recently advanced and popularized technique in orthopaedic surgery. The smaller incision site requires the use of small surgical instruments. The purpose of this study was to perform a biomechanical comparison of the cutting efficiency of traditional acetabular reamers and newly designed minimally invasive reamers for use in total hip arthroplasty. Both types of reamers were tested in two different sample materials, Bonesim™ and RenShape ® . This study concluded that the new MIS and the traditional acetabular reamers are comparable in their mechanical performances with respect to the force and torque produced while reaming.

Colorectal surgery is an area of active research within general surgery. However, over 80% of these procedures currently require an open surgery based on the size and location of the tumor. The current state-of-the-art surgical instruments are unintuitive, restricted by the incision site, and often require timely repositioning tasks during complex surgical procedures. A multi-quadrant miniature in vivo surgical robot has been developed to mitigate these limitations as well as the invasiveness of colorectal procedures. By reducing invasiveness, the patient benefits from improved cosmetics, decreased postoperative pain, faster recovery time, and reduced financial burden. A paradigm shift in invasiveness is often inversely proportional to surgeon benefits. Yet, through the use of a robotic device, the surgeon benefits from improved ergonomics, intuitive control, and fewer required repositioning tasks. This paper presents a two armed robotic device that can be controlled from a remote surgical interface. Each arm has six internally actuated degrees of freedom, decoupling the system from the incision site. Each arm is also equipped with a specialized interchangeable end effector. For the surgical procedure, visual feedback is provided through the use of a standard laparoscope with incorporated light source. The robotic device is introduced into the abdominal cavity through a hand-assisted laparoscopic surgery (HALS) port that is placed within the navel. The device is then grossly positioned to the site of interest within the abdominal cavity through the use of a protruding rod that is rigidly attached to each arm. The surgeon can then begin to manipulate tissue through the use of the surgical interface that is remotely located within the operating room. This interface is comprised of a monitor to provide visual feedback, foot pedals to control the operational state of the device, and two haptic devices to control the end point location of each arm and state of the end effectors.

In order to better understand the mechanical properties of biological cells, characterization and investigation of their material behavior is necessary. In this paper hyperelastic Neo-Hookean material is used to characterize the mechanical properties of mouse oocyte cell. It has been assumed that the cell behavior is continues, isotropic, nonlinear and homogenous material. Then, by matching the experimental data with finite element (FE) simulation result and using the Levenberg–Marquardt optimization algorithm, the nonlinear hyperelastic model parameters have been extracted. Experimental data of mouse oocyte captured from literatures. Advantage of the developed model is that it can be used to calculate accurate reaction force on surgical instrument or it can be used to compute deformation or force in virtual reality based medical simulations.

In this paper, we present the different steps towards the development of miniature compliant bending joint and gripper with high mechanical performances. These low encumbrance structures (5 mm cross-section) should deliver, with few actuation force, a large output displacement (90° bending, and 60° jaws opening respectively) under large output loads. Firstly, we describe the theoretical studies that have been investigated in order to optimally dimension these structures. For the bending joint, the design has been inspired from the literature and optimized. For the gripper, a non-intuitive design has been generated using a multi-objective optimal synthesis method. Finally, these compliant structures have been prototyped, and characterized. As an applicative example, they have been integrated into the end-effector of a surgical instrument. Despite the limited output load performances obtained (12.5 mN.m output torque with a 2.1 N actuation force, and 0.2 N gripping force respectively), these new building blocks demonstrate the ability of millimeter-size robotic devices further miniaturization.

This paper presents a design method dedicated to compliant mechanisms, with emphasis on the use of ant colony optimization to determine the optimal geometry of a mechanism. Ant colony optimization is of particular interest because it does not need any fine tuning of its internal parameters. This robustness and the efficiency of the design method are assessed in the context of the design of a surgical tool. The method is then used to propose a new architecture for an active cardiac stabilizer with integrated actuation, contrary to existing architectures.

This work is part of a multidisciplinary project developing design and manufacturing methods for narrow-gauge surgical instruments intended for advanced minimally invasive surgery. The instruments are designed specifically for Penn State’s lost mold rapid infiltration forming process, which is capable of fabricating hundreds of freestanding meso-scale parts. In previous work, a 1 mm diameter forceps case study demonstrated the design and fabrication process. The forceps is a monolithic compliant mechanism (CM) that relies on contact to re-distribute maximum stresses to generate larger elastic tip deflections; a phenomenon defined here as contact stress-relief. Prototypes were developed and evaluated in an end user surgical simulator. Feedback from 11 clinicians identified the total jaw opening of the forceps must be increased in the next generation of prototypes. This paper focuses on exploiting the benefits of contact-aided compliant mechanism (CCM) design to obtain larger elastic tip deflections and thus jaw openings. Using the commercially available finite element software package ANSYS to model large deformation and contact, an optimization problem is developed to determine the effects of incorporating additional contact elements in a CCM design on maximizing elastic tip deflection. Results show that designs with multiple contact elements generate larger elastic tip deflections due to a multi-stage contact stress-relief profile.

The use of robotics to enhance visualization and tissue manipulation capabilities is contributing to the advancement of minimally invasive surgery (MIS). For the development of surgical robot manipulators, the use of advanced dynamic control is an important aspect at the design stage to determine the driving forces and/or torques which must be exerted by the actuators in order to produce a desirable trajectory of the end effector. Therefore, this study focuses on the generation of inverse dynamic models for a spherical bevel-geared mechanism called CoBRASurge ( Co mpact B evel-geared R obot for A dvanced Surge ry), which is used as a surgical tool manipulator. For given typical trajectories of end effectors in clinical experiments, the motion of each element in the mechanism can be derived using the inverse kinematic equations. The driving torques exerted by actuators can be determined according to the presented inverse dynamic formulations. The simulation results of CoBRASurge reveal the nature of the driving torques in spherical bevel-geared mechanisms. Such models can be used for the design of advanced dynamic control systems, including gravity compensation and haptic interfaces for enhanced surgical functionality. In addition, sensitivity analysis of mass contribution has been performed to evaluate the effect of individual elements on the peak driving torques, which provides a solid guideline for the design of the next-generation CoBRASurge prototype. The present dynamic modeling methodology also presents a general dynamic analysis approach for other spherical articulated linkage mechanisms.

In the design of robotic manipulators for minimally invasive surgery (MIS), the spherical mechanism is a very important kinematic entity, since it can be used to mimic the constraint that the incision point provides to the surgical tool. In previous research by the authors, a bevel-gear-based spherical manipulator was designed whose actuators could be located on a fixed base link. In this paper, concepts of mechanism equivalency are applied to improving the manipulator design. The guidelines arrived at in this work can inform design of future spherical manipulators, especially those created with surgical tool manipulation in mind.

A novel fabrication process and design optimization method for a mesoscale forceps is presented. This work is part of a larger research effort to design and fabricate nanoparticulate enabled surgical instruments using an iterative fabrication-design technique. The current paper focuses on the fabrication of thick (∼hundreds of microns) two dimensional parts with large aspect ratios (length/width > 20). The paper also describes an optimization method that accounts for manufacturing requirements and material strength. The process begins with the fabrication of an array of molds on refractory substrates using a modified UV lithography technique. In parallel, engineered ceramic nanocolloidal slurries are prepared for gel-casting into the molds. Mold infiltration takes place via a squeegee technique adapted from screen printing with excess slurry removed using an ethanol bath. Finally, the photoresist molds are removed via pyrolysis, and ceramic parts sintered to full density. Employing this manufacturing technique for the compliant micro forceps design is advantageous because a large number of parts can be produced with large aspect ratios, sharp edges (∼ 1 μm), and a resolution of 2 μm. An optimization algorithm, using ANSYS optimization module, is formulated to determine the effect of dimensional parameters and material strength on the optimal design and predicted performance of the compliant meso forceps. Three ultimate strength values are separately implemented as a stress constraint in our optimization problem. Results conclude that our manufacturing process is capable of producing meso scale forceps considering the anticipated ultimate strength at this scale.