Design and Modeling of a Sub-2 mm Steerable Neuroendoscopic Grasping Tool

Minimally invasive procedures, such as endoscopic third ventriculostomy (ETV), benefit from the increased dexterity and safety that surgical continuum robots can bring. However, due to their natural compliance, new compatible end-effectors, such as graspers or scissors, must be developed and their actuation must be considered when developing the robotic structures in which they are housed due to the inherent coupling that will be introduced. In this paper, we integrate a tendon-driven meso-scale grasper, with a closed configuration diameter of 1.69 mm, into a 2 degree-of-freedom (DoF) tendon-driven neurosurgical robot with an outer diameter of less than 2 mm. Furthermore, the kinematics of the grasper is validated and an analysis of the coupling between the grasper and the robotic joints is conducted in order to evaluate the design performance.

A Modular 3-Degrees-of-Freedom Force Sensor for Robot-Assisted Minimally Invasive Surgery Research

Effective force modulation during tissue manipulation is important for ensuring safe, robot-assisted, minimally invasive surgery (RMIS). Strict requirements for in vivo applications have led to prior sensor designs that trade off ease of manufacture and integration against force measurement accuracy along the tool axis. Due to this trade-off, there are no commercial, off-the-shelf, 3-degrees-of-freedom (3DoF) force sensors for RMIS available to researchers. This makes it challenging to develop new approaches to indirect sensing and haptic feedback for bimanual telesurgical manipulation. We present a modular 3DoF force sensor that integrates easily with an existing RMIS tool. We achieve this by relaxing biocompatibility and sterilizability requirements and by using commercial load cells and common electromechanical fabrication techniques. The sensor has a range of ±5 N axially and ±3 N laterally with errors of below 0.15 N and maximum errors below 11% of the sensing range in all directions. During telemanipulation, a pair of jaw-mounted sensors achieved average errors below 0.15 N in all directions. It achieved an average grip force error of 0.156 N. The sensor is for bimanual haptic feedback and robotic force control in delicate tissue telemanipulation. As an open-source design, the sensors can be adapted to suit other non-RMIS robotic applications.

Force sensing in robot-assisted keyhole endoscopy: A systematic survey

Instrument–tissue interaction forces in minimally invasive surgery (MIS) provide valuable information that can be used to provide haptic perception, monitor tissue trauma, develop training guidelines, and evaluate the skill level of novice and expert surgeons. Force and tactile sensing is lost in many robot-assisted surgery (RAS) systems. Therefore, many researchers have focused on recovering this information through sensing systems and estimation algorithms. This article provides a comprehensive systematic review of the current force sensing research aimed at RAS and, more generally, keyhole endoscopy, in which instruments enter the body through small incisions. Articles published between January 2011 and May 2020 are considered, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The literature search resulted in 110 papers on different force estimation algorithms and sensing technologies, sensor design specifications, and fabrication techniques.

A decade retrospective of medical robotics research from 2010 to 2020

[Figure: see text].

Artificial Intelligence Surgery: How Do We Get to Autonomous Actions in Surgery?

Most surgeons are skeptical as to the feasibility of autonomous actions in surgery. Interestingly, many examples of autonomous actions already exist and have been around for years. Since the beginning of this millennium, the field of artificial intelligence (AI) has grown exponentially with the development of machine learning (ML), deep learning (DL), computer vision (CV) and natural language processing (NLP). All of these facets of AI will be fundamental to the development of more autonomous actions in surgery, unfortunately, only a limited number of surgeons have or seek expertise in this rapidly evolving field. As opposed to AI in medicine, AI surgery (AIS) involves autonomous movements. Fortuitously, as the field of robotics in surgery has improved, more surgeons are becoming interested in technology and the potential of autonomous actions in procedures such as interventional radiology, endoscopy and surgery. The lack of haptics, or the sensation of touch, has hindered the wider adoption of robotics by many surgeons; however, now that the true potential of robotics can be comprehended, the embracing of AI by the surgical community is more important than ever before. Although current complete surgical systems are mainly only examples of tele-manipulation, for surgeons to get to more autonomously functioning robots, haptics is perhaps not the most important aspect. If the goal is for robots to ultimately become more and more independent, perhaps research should not focus on the concept of haptics as it is perceived by humans, and the focus should be on haptics as it is perceived by robots/computers. This article will discuss aspects of ML, DL, CV and NLP as they pertain to the modern practice of surgery, with a focus on current AI issues and advances that will enable us to get to more autonomous actions in surgery. Ultimately, there may be a paradigm shift that needs to occur in the surgical community as more surgeons with expertise in AI may be needed to fully unlock the potential of AIS in a safe, efficacious and timely manner.

Surgical audio information as base for haptic feedback in robotic-assisted procedures

This work aims to demonstrate the feasibility that haptic information can be acquired from a da Vinci robotic tool using audio sensing according to sensor placement requirements in a real clinical scenario. For that, two potential audio sensor locations were studied using an experimental setup for performing, in a repeatable way, interactions of a da Vinci forceps with three different tissues. The obtained audio signals were assessed in terms of their resulting signal-to-noise-ratio (SNR) and their capability to distinguish between different tissues. A spectral energy distribution analysis using Discrete Wavelet Transformation was performed to extract signal signatures from the tested tissues. Results show that a high SNR was obtained in most of the audio recordings acquired from both studied positions. Additionally, evident spectral energy-related patterns could be extracted from the audio signals allowing us to distinguish between different palpated tissues.

Motion Control and External Force Estimation of a Pneumatically Driven Multi-DOF Robotic Forceps

Robotic forceps with a rigid-link joint mechanism is orthodox for current robotic-assisted surgery systems. However, external force estimation without force sensors during operations is difficult for such electrically driven forceps. This work introduces a pneumatically driven multi-DOF (DOF: degree of freedom) forceps using a rigid-link mechanism with less interference of the wire drive between joints and realizes external force estimation by utilizing high back-drivability of pneumatic cylinders. We developed a position controller with dynamic compensation of the mechanical friction, in which the rotational angles of the three movable joints of the forceps are independently controlled. Moreover, we designed an external force observer in the position controller by applying the disturbance observer scheme. The results of the performance evaluation experiments are as follows. First, in the joint position control experiments, smooth and stable controllability is confirmed for sinusoidal reference inputs with the mean absolute errors of less than 2°. The resolution of the joint position control is approximately 1° for the response of step increasing reference inputs, which is acceptable for laparoscopic surgery. Second, the external force observer can correctly estimate the translational and the grasping forces with less than 20% errors of the maximum output forces. The practical sensitivities of the external force estimation are better than 0.5 N for translational forces and 0.2 N for grasping forces. The achieved performance of the developed forceps can be applicable for interactive force control in some particular surgical tasks such as suturing, ligation, organ traction and exclusion.

Engineering approaches for characterizing soft tissue mechanical properties: A review

From cancer diagnosis to detailed characterization of arterial wall biomechanics, the elastic property of tissues is widely studied as an early sign of disease onset. The fibrous structural features of tissues are a direct measure of its health and functionality. Alterations in the structural features of tissues are often manifested as local stiffening and are early signs for diagnosing a disease. These elastic properties are measured ex vivo in conventional mechanical testing regimes, however, the heterogeneous microstructure of tissues can be accurately resolved over relatively smaller length scales with enhanced spatial resolution using techniques such as micro-indentation, microelectromechanical (MEMS) based cantilever sensors and optical catheters which also facilitate in vivo assessment of mechanical properties. In this review, we describe several probing strategies (qualitative and quantitative) based on the spatial scale of mechanical assessment and also discuss the potential use of machine learning techniques to compute the mechanical properties of soft tissues. This work details state of the art advancement in probing strategies, associated challenges toward quantitative characterization of tissue biomechanics both from an engineering and clinical standpoint.

Modular Optic Force Sensor for a Surgical Device Using a Fabry–Perot Interferometer

The ability to sense force in surgery is in high demand in many applications such asforce feedback in surgical robots and remote palpation (e.g., tumor detection in endoscopic surgery).In addition, recording and analyzing surgical data is of substantial value in terms of evidence-basedmedicine. However, force sensing in surgery remains challenging because of the specific requirementsof surgical instruments, namely, they must be small, bio-compatible, sterilizable, and tolerant tonoise. In this study, we propose a modular optic force sensor using a Fabry–Perot interferometer thatcan be used on surgical devices. The the proposed sensor can be implemented like a strain gauge,which is widely used in industrial applications but not compatible with surgery. The proposed sensorincludes two key elements, a fiber-optic pressure sensor using a Fabry–Perot interferometer thatwas previously developed by one of the authors and a structure that includes a carbide pin thatcontacts the pressure sensor along the long axis. These two elements are fixed in a guide channelfabricated in a 3 × 2 × 0.5 mm sensor housing. The experimental results are promising, revealinga linear relationship between the output and the applied load while showing a linear temperaturecharacteristic that suggests temperature compensation will be needed in use.

Improved surgical instruments without coupled motion used in minimally invasive surgery

BACKGROUND

Unlike a manual surgical instrument, a surgical instrument used in robot-assisted minimally invasive surgery (MIS) is configured with a wrist to improve flexibility in surgical operation. However, this configuration has a shortcoming that leads to coupled motion between the wrist and end-effector.

METHODS

Three methods are presented to eliminate the coupled motion between the wrist and end-effector. The three methods are compared via the decoupled motion characteristic, and the third method is applied to design four surgical instruments. Several experiments are done to validate the effectiveness of these surgical instruments.

RESULTS

These improved surgical instruments create decoupled motion. The results of experiments on the removal of gall bladder and kidney are excellent, which validates the effectiveness of decoupled surgical instruments.

CONCLUSIONS

Improved surgical instruments without coupled motion are developed and have a promising clinical application in MIS.

Design and Evaluation of FBG-Based Tension Sensor in Laparoscope Surgical Robots

Due to the narrow space and a harsh chemical environment in the sterilization processes for the end-effector of surgical robots, it is difficult to install and integrate suitable sensors for the purpose of effective and precise force control. This paper presents an innovative tension sensor for estimation of grasping force in our laparoscope surgical robot. The proposed sensor measures the tension of cable using fiber gratings (FBGs) which are pasted in the grooves on the inclined cantilevers of the sensor. By exploiting the stain measurement characteristics of FBGs, the small deformation of the inclined cantilevers caused by the cable tension can be measured. The working principle and the sensor model are analyzed. Based on the sensor model, the dimensions of the sensor are designed and optimized. A dedicated experimental setup is established to calibrate and test the sensor. The results of experiments for estimation the grasping force validate the sensor.

Three-dimensional nonlinear force-sensing method based on double microgrippers with E-type vertical elastomer for minimally invasive robotic surgery

This paper presents a new type of forceps that consist of two microgrippers with the capability of direct force sensing, which enables grasping and manipulating forces at the tip of surgical instrument for minimally invasive robotic surgery. For the prototype design of the forceps, a double E-type vertical elastomer with four strain beams is presented, whose force-sensing principle is expounded. Thus, the forceps with the elastomer can be considered a compliant component, which provides tiny displacements that allow large strain, and the overall diameter is 10 mm. The sizes of the elastomer and forceps are successively determined by analyzing the relationship of several parameters and strain. Then, the linearity analysis of strain beams determines the positions to apply gauges for sensing. The two-dimensional force decoupling models for a single microgripper are proposed based on piecewise analytical polynomials of the strain difference and employed to develop a new three-dimensional force nonlinear decoupling algorithm based on double microgrippers, which realizes single-axial grasping and three-axial pulling forces. Finally, the required force-sensing performance of the proposed method is successfully verified in theory using finite-element simulations.

Grasper having tactile sensing function using acoustic reflection for laparoscopic surgery

PURPOSE

In current minimally invasive surgery techniques, the tactile information available to the surgeon is limited. Improving tactile sensation could enhance the operability of surgical instruments. Considering surgical applications, requirements such as having electrical safety, a simple structure, and sterilization capability should be considered. The current study sought to develop a grasper that can measure grasping force at the tip, based on a previously proposed tactile sensing method using acoustic reflection. This method can satisfy the requirements for surgical applications because it has no electrical element within the part that is inserted into the patient's body.

METHODS

We integrated our acoustic tactile sensing method into a conventional grasping forceps instrument. We designed the instrument so that acoustic cavities within a grasping arm and a fork sleeve were connected by a small cavity in a pivoting joint. In this design, when the angle between the two grasping arms changes during grasping, the total length and local curvature of the acoustic cavity remain unchanged. Thus, the grasping force can be measured regardless of the orientation of the grasping arm.

RESULTS

We developed a prototype sensorized grasper based on our proposed design. Fundamental tests revealed that sensor output increased with increasing contact force applied to the grasping arm, and the angle of the grasping arm did not significantly affect the sensor output. Moreover, the results of a grasping test, in which objects with different softness characteristics were held by the grasper, revealed that the grasping force could be appropriately adjusted to handle different objects on the basis of sensor output.

CONCLUSIONS

Experimental results demonstrated that the prototype grasper can measure grasping force, enabling safe and stable grasping.

DEVELOPMENT OF A SIX-DIMENSIONAL SENSOR FOR MINIMALLY INVASIVE ROBOTIC SURGERY

In minimally invasive robotic surgery (MIRS), the force/torque which occurred between instruments and organs cannot be accessed by surgeon. This paper presents development of a six-dimensional sensor based on double-hole parallel crossing beam, which can be integrated into instruments of MIRS. The size of sensor is 9.8 mm (diameter) × 6 mm (height). The structure of the sensor can acquire the force signals directly. The decoupling mechanism of the sensor was analyzed. The result of the finite element analysis (FEA) showed that the maximum coupling error was 3.8%. The machining error of the sensor was also investigated, and it was feasible for numerical control (NC) machine tools to manufacture the components of the sensor. The experimental calibration and soft tissue experiment indicated that the developed sensor can measure the force/torque loaded on the instrument and can be used to obtain the force feedback in the application of teleoperation surgical robot.