A Mathematical Model of the Pneumatic Force Sensor for Robot-assisted Surgery

Restoring the sense of touch in robotic surgery is an emerging need several researchers tried to address. In this paper, we focused on the slave side proposing a pneumatic sensor to estimate contact forces occurring during the interaction between surgical instruments and anatomical areas. It consists of a tiny pneumatic balloon, which, after being inflated, appears near the tip of the instrument during the measurement phase only. This paper presents a mathematical method relating the intensity of the contact force to the variation of pressure inside the balloon. The latter was modeled as a spherical elastic membrane, whose behavior during contact was characterized taking into account both the deformation of the membrane and the compression of the contained gas. Geometrical considerations combined with an energetic approach allowed us to compute the force of interest. The effectiveness of our sensing device has been confirmed by experimental results, based on comparison with a high-performance commercial force sensor

Design of active feedback for rehabilitation device

Sensor systems are an essential part of automated equipment. They are even more important in machines that come in contact with people, because they have a significant impact on safety. This paper describes the design of active feedback for rehabilitation device driven by pneumatic artificial muscles. Here are presented three methods for measuring the load of the robot. The first is a system composed of Force Sensitive Resistors (FSR) placed in the handle of the device. Two other methods are intended to measure the load of the actuator composed of artificial muscles. The principle of one method is to measure the difference in filling pressures of the muscles, second is based on strain measurement in the drive cables. The paper describes advantages and disadvantages of using each of these methods in a rehabilitation deviceEU; Operational Programme Research and Development; Measure 2.2 Transfer of knowledge and technology from research and development into practice; Research and development of intelligent nonconventional actuators based on artificial muscles", ITMS [26220220103]; Slovak Grant Agency VEGA [1/0911/14]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [L01303 (MSMT7778/2014)]; European Regional Development Fund under the project CEBIA-Tech [CZ.1.05/2.1.00/03.0089

Teleoperation of MRI-Compatible Robots with Hybrid Actuation and Haptic Feedback

Image guided surgery (IGS), which has been developing fast recently, benefits significantly from the superior accuracy of robots and magnetic resonance imaging (MRI) which is a great soft tissue imaging modality. Teleoperation is especially desired in the MRI because of the highly constrained space inside the closed-bore MRI and the lack of haptic feedback with the fully autonomous robotic systems. It also very well maintains the human in the loop that significantly enhances safety. This dissertation describes the development of teleoperation approaches and implementation on an example system for MRI with details of different key components. The dissertation firstly describes the general teleoperation architecture with modular software and hardware components. The MRI-compatible robot controller, driving technology as well as the robot navigation and control software are introduced. As a crucial step to determine the robot location inside the MRI, two methods of registration and tracking are discussed. The first method utilizes the existing Z shaped fiducial frame design but with a newly developed multi-image registration method which has higher accuracy with a smaller fiducial frame. The second method is a new fiducial design with a cylindrical shaped frame which is especially suitable for registration and tracking for needles. Alongside, a single-image based algorithm is developed to not only reach higher accuracy but also run faster. In addition, performance enhanced fiducial frame is also studied by integrating self-resonant coils. A surgical master-slave teleoperation system for the application of percutaneous interventional procedures under continuous MRI guidance is presented. The slave robot is a piezoelectric-actuated needle insertion robot with fiber optic force sensor integrated. The master robot is a pneumatic-driven haptic device which not only controls the position of the slave robot, but also renders the force associated with needle placement interventions to the surgeon. Both of master and slave robots mechanical design, kinematics, force sensing and feedback technologies are discussed. Force and position tracking results of the master-slave robot are demonstrated to validate the tracking performance of the integrated system. MRI compatibility is evaluated extensively. Teleoperated needle steering is also demonstrated under live MR imaging. A control system of a clinical grade MRI-compatible parallel 4-DOF surgical manipulator for minimally invasive in-bore prostate percutaneous interventions through the patient’s perineum is discussed in the end. The proposed manipulator takes advantage of four sliders actuated by piezoelectric motors and incremental rotary encoders, which are compatible with the MRI environment. Two generations of optical limit switches are designed to provide better safety features for real clinical use. The performance of both generations of the limit switch is tested. MRI guided accuracy and MRI-compatibility of whole robotic system is also evaluated. Two clinical prostate biopsy cases have been conducted with this assistive robot

Design, Development, and Evaluation of a Teleoperated Master-Slave Surgical System for Breast Biopsy under Continuous MRI Guidance

The goal of this project is to design and develop a teleoperated master-slave surgical system that can potentially assist the physician in performing breast biopsy with a magnetic resonance imaging (MRI) compatible robotic system. MRI provides superior soft-tissue contrast compared to other imaging modalities such as computed tomography or ultrasound and is used for both diagnostic and therapeutic procedures. The strong magnetic field and the limited space inside the MRI bore, however, restrict direct means of breast biopsy while performing real-time imaging. Therefore, current breast biopsy procedures employ a blind targeting approach based on magnetic resonance (MR) images obtained a priori. Due to possible patient involuntary motion or inaccurate insertion through the registration grid, such approach could lead to tool tip positioning errors thereby affecting diagnostic accuracy and leading to a long and painful process, if repeated procedures are required. Hence, it is desired to develop the aforementioned teleoperation system to take advantages of real-time MR imaging and avoid multiple biopsy needle insertions, improving the procedure accuracy as well as reducing the sampling errors. The design, implementation, and evaluation of the teleoperation system is presented in this dissertation. A MRI-compatible slave robot is implemented, which consists of a 1 degree of freedom (DOF) needle driver, a 3-DOF parallel mechanism, and a 2-DOF X-Y stage. This slave robot is actuated with pneumatic cylinders through long transmission lines except the 1-DOF needle driver is actuated with a piezo motor. Pneumatic actuation through long transmission lines is then investigated using proportional pressure valves and controllers based on sliding mode control are presented. A dedicated master robot is also developed, and the kinematic map between the master and the slave robot is established. The two robots are integrated into a teleoperation system and a graphical user interface is developed to provide visual feedback to the physician. MRI experiment shows that the slave robot is MRI-compatible, and the ex vivo test shows over 85%success rate in targeting with the MRI-compatible robotic system. The success in performing in vivo animal experiments further confirm the potential of further developing the proposed robotic system for clinical applications

Multi-fingered haptic palpation utilizing granular jamming stiffness feedback actuators

This paper describes a multi-fingered haptic palpation method using stiffness feedback actuators for simulating tissue palpation procedures in traditional and in robot-assisted minimally invasive surgery. Soft tissue stiffness is simulated by changing the stiffness property of the actuator during palpation. For the first time, granular jamming and pneumatic air actuation are combined to realize stiffness modulation. The stiffness feedback actuator is validated by stiffness measurements in indentation tests and through stiffness discrimination based on a user study. According to the indentation test results, the introduction of a pneumatic chamber to granular jamming can amplify the stiffness variation range and reduce hysteresis of the actuator. The advantage of multi-fingered palpation using the proposed actuators is proven by the comparison of the results of the stiffness discrimination performance using two-fingered (sensitivity: 82.2%, specificity: 88.9%, positive predicative value: 80.0%, accuracy: 85.4%, time: 4.84 s) and single-fingered (sensitivity: 76.4%, specificity: 85.7%, positive predicative value: 75.3%, accuracy: 81.8%, time: 7.48 s) stiffness feedback

Robotic simulators for tissue examination training with multimodal sensory feedback

Tissue examination by hand remains an essential technique in clinical practice. The effective application depends on skills in sensorimotor coordination, mainly involving haptic, visual, and auditory feedback. The skills clinicians have to learn can be as subtle as regulating finger pressure with breathing, choosing palpation action, monitoring involuntary facial and vocal expressions in response to palpation, and using pain expressions both as a source of information and as a constraint on physical examination. Patient simulators can provide a safe learning platform to novice physicians before trying real patients. This paper reviews state-of-the-art medical simulators for the training for the first time with a consideration of providing multimodal feedback to learn as many manual examination techniques as possible. The study summarizes current advances in tissue examination training devices simulating different medical conditions and providing different types of feedback modalities. Opportunities with the development of pain expression, tissue modeling, actuation, and sensing are also analyzed to support the future design of effective tissue examination simulators

Novel soft bending actuator based power augmentation hand exoskeleton controlled by human intention

This article presents the development of a soft material power augmentation wearable robot using novel bending soft artificial muscles. This soft exoskeleton was developed as a human hand power augmentation system for healthy or partially hand disabled individuals. The proposed prototype serves healthy manual workers by decreasing the muscular effort needed for grasping objects. Furthermore, it is a power augmentation wearable robot for partially hand disabled or post-stroke patients, supporting and augmenting the fingers’ grasping force with minimum muscular effort in most everyday activities. This wearable robot can fit any adult hand size without the need for any mechanical system changes or calibration. Novel bending soft actuators are developed to actuate this power augmentation device. The performance of these actuators has been experimentally assessed. A geometrical kinematic analysis and mathematical output force model have been developed for the novel actuators. The performance of this mathematical model has been proven experimentally with promising results. The control system of this exoskeleton is created by hybridization between cascaded position and force closed loop intelligent controllers. The cascaded position controller is designed for the bending actuators to follow the fingers in their bending movements. The force controller is developed to control the grasping force augmentation. The operation of the control system with the exoskeleton has been experimentally validated. EMG signals were monitored during the experiments to determine that the proposed exoskeleton system decreased the muscular efforts of the wearer

Soft Robot-Assisted Minimally Invasive Surgery and Interventions: Advances and Outlook

Since the emergence of soft robotics around two decades ago, research interest in the field has escalated at a pace. It is fuelled by the industry's appreciation of the wide range of soft materials available that can be used to create highly dexterous robots with adaptability characteristics far beyond that which can be achieved with rigid component devices. The ability, inherent in soft robots, to compliantly adapt to the environment, has significantly sparked interest from the surgical robotics community. This article provides an in-depth overview of recent progress and outlines the remaining challenges in the development of soft robotics for minimally invasive surgery

Scalability study for robotic hand platform

The goal of this thesis project was to determine the lower limit of scale for the RIT robotic grasping hand. This was accomplished using a combination of computer simulation and experimental studies. A force analysis was conducted to determine the size of air muscles required to achieve appropriate contact forces at a smaller scale. Input variables, such as the actuation force and tendon return force, were determined experimentally. A dynamic computer model of the hand system was then created using Recurdyn. This was used to predict the contact (grasping) force of the fingers at full-scale, half-scale, and quarter-scale. Correlation between the computer model and physical testing was achieved for both a life-size and half-scale finger assembly. To further demonstrate the scalability of the hand design, both half and quarter-scale robotic hand rapid prototype assemblies were built using 3D printing techniques. This thesis work identified the point where further miniaturization would require a change in the manufacturing process to micro-fabrication. Several techniques were compared as potential methods for making a production intent quarter-scale robotic hand. Investment casting, Swiss machining, and Selective Laser Sintering were the manufacturing techniques considered. A quarter-scale robotic hand tested the limits of each technology. Below this scale, micro-machining would be required. The break point for the current actuation method, air muscles, was also explored. Below the quarter-scale, an alternative actuation method would also be required. Electroactive Polymers were discussed as an option for the micro-scale. In summary, a dynamic model of the RIT robotic grasping hand was created and validated as scalable at full and half-scales. The model was then used to predict finger contact forces at the quarter-scale. The quarter-scale was identified as the break point in terms of the current RIT robotic grasping hand based on both manufacturing and actuation. A novel, prototype quarter-scale robotic hand assembly was successfully built by an additive manufacturing process, a high resolution 3D printer. However, further miniaturization would require alternate manufacturing techniques and actuation mechanisms

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