Indirect measurement of pinch and pull forces at the shaft of laparoscopic graspers

The grasping instruments used in minimally invasive surgery reduce the ability of the surgeon to feel the forces applied on the tissue, thereby complicating the handling of the tissue and increasing the risk of tissue damage. Force sensors implemented in the forceps of the instruments enable accurate measurements of applied forces, but also complicate the design of the instrument. Alternatively, indirect estimations of tissue interaction forces from measurements of the forces applied on the handle are prone to errors due to friction in the linkages. Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed. The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements. We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod

Tissue manipulation using nano-particles ferrofluids for minimal access surgical applications

Nano-scale Iron-Oxide ferrofluids exhibit a special property, ‘superparamagnetism’, that induces an attractive force toward an external magnetic field. The aim of this project is to investigate the use of ferrofluids for tissue retraction during Minimally Access Surgery (MAS). In the in-vivo porcine experiments, 0.3 ml of ferrofluid (200 mg/ml concentration) containing 10 nm particles is injected subserosally into the small bowel, respectively. A 0.6 T magnetic field is created using a combination of 10 mm and 20 mm diameter Neodymium Iron Boron magnets. The vertical retraction distance is measured up to 80 mm and video-recorded. The results demonstrate the capacity of ferrofluid to facilitate the tissue manipulation and analysis of the migration of the particles within the tissue using micro computed tomography (CT). A theoretical model developed to validate the experimental results is also beneficial for predicting retraction force. In conclusion, this feasibility study provides a protocol for systematically using small volumes of ferrofluid, without the need to mechanically grasp the tissue

Next generation of atraumatic laparoscopic instruments through analysis of the instrument-tissue interface

Mechanically induced (or iatrogenic) bowel injury from the use of laparoscopic instruments can result in devastating effects on patient outcomes both during and after surgery. The aim of this work was to investigate exactly how colonic tissue behaves both mechanically and structurally when it is subjected to a mechanical load. Analysis of force application in laparoscopic surgery is critical to understanding the nature of the instrument-tissue interaction. The development of a novel method of both histological analysis and mechanical analysis (by which the tool-tissue interaction can be characterised) has evolved through this thesis. Mechanical and histological analysis was undertaken to quantify the instrument-tissue interaction in laparoscopic surgery. This was done in both ex vivo and in vivo experiments, using an indentation method and laparoscopic instrument respectively, in porcine tissue. Mechanical stress was applied to the colon by indentation applied using the Modular Universal Surface Tester (MUST) (FalexTM Tribology USA) in ex vivo experiments to mechanically characterise the response of tissue to mechanical loading. Histological analysis was performed to examine the architecture of the tissue after loading. In vivo analysis of colon grasping was then performed to characterise grasper damage both mechanically and histologically. A mechanical measure of energy input into the tissue has been linked to consistent histological damage, above a 50 N grasping force and a loading input of 300 N.s This work has successfully identified specific loading conditions that result in tissue injury and is the first to make a link between the mechanical analyses of tissue manipulation with change to the architecture of the tissue

Anthropomorphic surgical system for soft tissue robot-assisted surgery

Over the past century, abdominal surgery has seen a rapid transition from open procedures to less invasive methods such as laparoscopy and robot-assisted minimally invasive surgery (R-A MIS). These procedures have significantly decreased blood loss, postoperative morbidity and length of hospital stay in comparison with open surgery. R-A MIS has offered refined accuracy and more ergonomic instruments for surgeons, further minimising trauma to the patient.This thesis aims to investigate, design and prototype a novel system for R-A MIS that will provide more natural and intuitive manipulation of soft tissues and, at the same time, increase the surgeon's dexterity. The thesis reviews related work on surgical systems and discusses the requirements for designing surgical instrumentation. From the background research conducted in this thesis, it is clear that training surgeons in MIS procedures is becoming increasingly long and arduous. Furthermore, most available systems adopt a design similar to conventional laparoscopic instruments or focus on different techniques with debatable benefits. The system proposed in this thesis not only aims to reduce the training time for surgeons but also to improve the ergonomics of the procedure.In order to achieve this, a survey was conducted among surgeons, regarding their opinions on surgical training, surgical systems, how satisfied they are with them and how easy they are to use. A concept for MIS robotic instrumentation was then developed and a series of focus group meetings with surgeons were run to discuss it. The proposed system, named microAngelo, is an anthropomorphic master-slave system that comprises a three-digit miniature hand that can be controlled using the master, a three-digit sensory exoskeleton. While multi-fingered robotic hands have been developed for decades, none have been used for surgical operations. As the system has a human centred design, its relation to the human hand is discussed. Prototypes of both the master and the slave have been developed and their design and mechanisms is demonstrated. The accuracy and repeatability of the master as well as the accuracy and force capabilities of the slave are tested and discussed

A Novel Haptic Simulator for Evaluating and Training Salient Force-Based Skills for Laparoscopic Surgery

Laparoscopic surgery has evolved from an \u27alternative\u27 surgical technique to currently being considered as a mainstream surgical technique. However, learning this complex technique holds unique challenges to novice surgeons due to their \u27distance\u27 from the surgical site. One of the main challenges in acquiring laparoscopic skills is the acquisition of force-based or haptic skills. The neglect of popular training methods (e.g., the Fundamentals of Laparoscopic Surgery, i.e. FLS, curriculum) in addressing this aspect of skills training has led many medical skills professionals to research new, efficient methods for haptic skills training. The overarching goal of this research was to demonstrate that a set of simple, simulator-based haptic exercises can be developed and used to train users for skilled application of forces with surgical tools. A set of salient or core haptic skills that underlie proficient laparoscopic surgery were identified, based on published time-motion studies. Low-cost, computer-based haptic training simulators were prototyped to simulate each of the identified salient haptic skills. All simulators were tested for construct validity by comparing surgeons\u27 performance on the simulators with the performance of novices with no previous laparoscopic experience. An integrated, \u27core haptic skills\u27 simulator capable of rendering the three validated haptic skills was built. To examine the efficacy of this novel salient haptic skills training simulator, novice participants were tested for training improvements in a detailed study. Results from the study demonstrated that simulator training enabled users to significantly improve force application for all three haptic tasks. Research outcomes from this project could greatly influence surgical skills simulator design, resulting in more efficient training

A Study on the Development of Surgical-Operation-By-Wire (SOBW) for Advanced Surgical Robot System

학위논문 (박사)-- 서울대학교 대학원 : 협동과정 바이오엔지니어링전공, 2015. 8. Sungwan Kim.기존의 개복 수술에 비해 최소 침습 수술은 많은 장점이 있다. 하지만 기존 복강경 도구를 이용한 최소 침습 수술의 한계를 극복하고자 로봇을 이용한 복강경 수술이 널리 시행되고 있다. 하지만 대표적인 복강경 수술 로봇인 다빈치 로봇의 경우 엔드이펙터의 집게가 다양한 자세에서 균일한 힘을 내지 못하는 것이 다른 연구진에 의해 밝혀졌다. 본 연구에서는 이를 가설로 두고 이를 구체적인 실험으로 규명하였으며, 문제의 원인이 금속 줄로 제어되는 엔드이펙터 때문임을 증명하였다. 이를 위해 엔드이펙터의 집는 힘, 자세에 따른 커넥터 각도, 전달 토크를 새로이 고안한 토크전달시스템으로 측정하였다. 측정 결과 의사의 균일한 의도에도 불구하고 27가지 자세에서 세가지 엔드이펙터가 모두 다른 힘을 내었으며 최소 1.84배에서 최대 3.37배의 차이가 나는 것을 확인하였다. 이러한 단점을 극복하고자 본 연구에서는 두 가지 측면에서 해결책을 제시하였다. 첫째로, 다빈치의 엔드이펙터 내부 메커니즘을 분석하여 엔드이펙터의 다양한 자세에서 균일한 힘을 내기 위한 보상 힘을 제시하는 모델을 개발하였다. 모델에서 계산되는 값과 실제 값을 비교하여 검증하였다. 토크전달시스템을 통해 얻은 파라미터로부터 10.69-16.25%의 오차 범위 내에서 예측 집는 힘을 계산하는 결과를 도출하였다. 본 모델을 이용하면 기존 다빈치 시스템의 구조적 문제를 소프트웨어적으로 극복하는데 도움을 줄 수 있다. 또한 의사는 엔드이펙터 집게에 작용하는 실제 힘에 대한 정보를 얻을 수 있으며, 마스터 인터페이스에 압력 센서 등이 구비되면 집는 힘을 원하는 대로 조정할 수도 있어서 수술 도중 발생할 수 있는 사고를 미연에 방지 할 수 있다. 둘째로, 다빈치 시스템의 구조적 문제를 근본적으로 해결하기 위하여 새로운 수술 로봇 엔드이펙터 시스템, Surgical-Operation-By-Wire (SOBW)를 개발하였다. 6축 로봇팔을 사용하여 새로운 엔드이펙터와 함께 수술에 쓰일 수 있는 추가의 자유도를 갖추었다. 제안된 수술 로봇 시스템은 항공우주공학기술에 널리 쓰이는 Hands-On-Throttle-And-Stick (HOTAS)을 활용하여 6축 힘/토크 센서가 추가된 iHOTAS 인터페이스를 통해 제어된다. 집게의 반응시간이 0.2초로 계산되었고, 본 시스템을 처음 접하는 참가자가 술기 테스트에서 평균 176초안에 수행하여 300초 컷오프 타임안에 수행할 수 있게 시스템이 잘 구성되었음을 확인하였다. 또한 시스템의 동작 범위는 11,157.0 cm3으로 계산되었다. 다양한 검증을 통해 제안된 수술 로봇 시스템이 실제 수술에 충분히 쓰일 수 있음을 확인하였다.Abstract i List of Tables iv List of Figures vi Contents x 1. Introduction 1 1.1. Robotic Laparoscopic Surgery 1 1.2. End-effectors and Master Interfaces in Robotic Laparoscopic Surgery 8 1.3. Objectives and Scope 12 1.3.1. Gripping Force Measurement for Various Postures and Mathematical Compensation Model 17 1.3.1.1. Torque Transfer System (TTS) 18 1.3.1.2. Calibration of the Sensors 21 1.3.1.3. Force Measurement with Respect to the EndoWrists Posture 23 1.3.2. Novel End-effector and Mater Interface 31 ? 2. Materials and Methods 34 2.1. EndoWrist Inner Mechanism Model 34 2.2. Development of the Laparoscopic Robot 37 2.2.1. Overview 40 2.2.2. External Arm 40 2.2.3. End-effector (KS-4) 42 2.2.3.1. Pneumatic Gripper System 48 2.2.4. Forward Kinematics of the System 53 3. Results 58 3.1.Prediction of the Compensation Force for EndoWrists 58 3.1.1. EndoWrists Gripping Force 58 3.1.2. Prediction Results and Validation 60 3.2. Pneumatic Type of End-effector (KS-4) and Novel Master Interfaces 63 3.2.1. End-effectors Gripping Force 63? 3.2.1.1. Gripping Force System Setup 63 3.2.1.2. Relationship between Compressors Pressure and Gripping Force 66 3.2.1.3. Reaction Time 68 3.2.1.4. Durability Test 71 3.2.2. Simple Peg Task 72 3.2.3. Workspace 76 3.2.4. System Specification 77 4. Discussion 80 5. Conclusion 89 References 90 Abstract in Korean 100Docto

Force Sensing Surgical Scissor Blades using Fibre Bragg Grating Sensors

This thesis considers the development and analysis of unique sensorised surgical scissor blades for application in minimally invasive robotic surgery (MIRS). The lack of haptic (force and tactile) feedback to the user is currently an unresolved issue with modern MIRS systems. This thesis presents details on smart sensing scissor blades which enable the measurement of instrument-tissue interaction forces for the purpose of force reflection and tissue property identification. A review of current literature established that there exists a need for small compact, biocompatible, sterilisable and robust sensors which meet the demands of current MIRS instruments. Therefore, the sensorised blades exploit the strain sensing capabilities of a single fibre Bragg grating (FBG) sensor bonded to their surface. The nature and magnitude of the strain likely to be experienced by the blades, and consequently the FBG sensor, while cutting soft tissue samples were characterised through the use of an application specific test-bed. Using the sensorised blades to estimate fracture properties is proposed, hence two methods of extracting fracture toughness information from the test samples are assessed and compared. Investigations were carried out on the factors affecting the transfer of strain from the blade material to the core of the FBG sensor for surface mounted or partially embedded arrangements. Results show that adhesive bond length, thickness and stiffness need to be carefully specified when bonding FBG sensors to ensure effective strain transfer. Calibration and dynamic cutting experiments were carried out using the characterisation test-bed. The complex nature of the blade interaction forces were modelled, primarily for the purpose of decoupling the direct, lateral, friction and fracture strains experienced by the bonded FBG sensor during cutting. The modelled and experimental results show that the approach taken in sensorising the blade enables detailed cutting force data to be obtained and consequently leads to a unique method in estimating the kinetic friction coefficient for the blades. The forces measured using the FBG are validated against a commercial load cell used in the test-bed. This research work demonstrates that this unique approach of placing a single optical fibre onto the scissor blades can, in an unobtrusive manner, measure interblade friction forces and material fracture properties occurring at the blade-tissue interface

Haptic Enhancement of Sensorimotor Learning for Clinical Training Applications

Modern surgical training requires radical change with the advent of increasingly complex procedures, restricted working hours, and reduced ‘hands-on’ training in the operating theatre. Moreover, an increased focus on patient safety means there is a greater need to objectively measure proficiency in trainee surgeons. Indeed, the existing evidence suggests that surgical sensorimotor skill training is not adequate for modern surgery. This calls for new training methodologies which can increase the acquisition rate of sensorimotor skill. Haptic interventions offer one exciting possible avenue for enhancing surgical skills in a safe environment. Nevertheless, the best approach for implementing novel training methodologies involving haptic intervention within existing clinical training curricula has yet to be determined. This thesis set out to address this issue. In Chapter 2, the development of two novel tools which enable the implementation of bespoke visuohaptic environments within robust experimental protocols is described. Chapters 3 and 4 report the effects of intensive, long-term training on the acquisition of a compliance discrimination skill. The results indicate that active behaviour is intrinsically linked to compliance perception, and that long-term training can help to improve the ability of detecting compliance differences. Chapter 5 explores the effects of error augmentation and parameter space exploration on the learning of a complex novel task. The results indicate that error augmentation can help improve learning rate, and that physical workspace exploration may be a driver for motor learning. This research is a first step towards the design of objective haptic intervention strategies to help support the rapid acquisition of sensorimotor skill. The work has applications in clinical settings such as surgical training, dentistry and physical rehabilitation, as well as other areas such as sport