Differences in grip forces among various robotic instruments and da Vinci surgical platforms

Perceived comfort and tool usability during robot-assisted and traditional laparoscopic surgery: a survey study

It is known that over half of previously surveyed surgeons performing Robot-Assisted Laparoscopic Surgery (RALS) and three-quarters of those performing Traditional Laparoscopic Surgery (TLS) experience intraoperative pain. This survey study aimed to expand upon the ongoing impact of that pain as well as perceived tool usability associated with TLS and RALS, for which considerably less documentation exists. A survey regarding the presence and impact, either immediate or ongoing, of intraoperative pain and Likert scale questions regarding tool usability was administered to TLS and RALS surgeons on the European Association for Endoscopic Surgery (EAES) mailing list. Prevalence statistics as well as trends based on biological sex and glove size were obtained from the 323 responses. Most respondents were right-handed European males (83-88%) with a medium glove size (55.8%). Moderate or severe shoulder symptoms were experienced by one-third of TLS surgeons. Twenty-one percent of RALS surgeons experienced neck symptoms that impacted their concentration. Small-handed surgeons experienced wrist symptoms significantly more frequently than large-handed surgeons, regardless of modality. RALS was associated with a significantly more optimal back and wrist posture compared to TLS. TLS surgeons reported increased ease with applying and moderating force while operating. These results suggest that intraoperative pain may be severe enough in many cases to interfere with surgeon concentration, negatively impacting patient care. Continuing to understand the relationship between tool usability and comfort is crucial in guaranteeing the health and well-being of both surgeons and patients.

Design, Analysis and Experimental Validation of a Novel 7-Degrees of Freedom Instrument for Laparoscopic Surgeries

Laparoscopic surgery is widely used for treating intra-abdominal conditions involving the gallbladder, pancreas, liver, intestines and reproductive organs. Conventional laparoscopy instruments used in manual surgeries usually have straight shafts and four degrees of freedom (DOF) plus grasping. However, these are insufficient for the complete rotation of the instrument tip. This makes it challenging to access difficult-to-reach organs inside the abdomen during the surgeries. A few robotic instruments available in the market have higher maneuverability but are expensive. Instruments incorporating cable-based mechanisms require replacement after a few sterilization cycles. This paper describes a novel, reusable and affordable multi-DOF laparoscopy instrument that provides two additional DOF: (a) wrist articulation about one axis (wristed yaw) and (b) rotation of the jaw after articulation (jaw roll). The wrist can articulate up to 45° and also roll after articulation. The additional degrees of freedom enable better maneuverability, functionality and reach than conventional laparoscopy instruments. Further, the new instrument employs only rigid links, providing better strength and minimal loss of function after multiple sterilizations. The complete design of the novel instrument, followed by its kinematic analysis and force calculations are explained in this paper, concluding with its manufacture and experimental validation.

Encouraging and Detecting Preferential Incipient Slip for Use in Slip Prevention in Robot-Assisted Surgery

Robotic surgical platforms have helped to improve minimally invasive surgery; however, limitations in their force feedback and force control can result in undesirable tissue trauma or tissue slip events. In this paper, we investigate a sensing method for the early detection of slip events when grasping soft tissues, which would allow surgical robots to take mitigating action to prevent tissue slip and maintain stable grasp control while minimising the applied gripping force, reducing the probability of trauma. The developed sensing concept utilises a curved grasper face to create areas of high and low normal, and thus frictional, force. In the areas of low normal force, there is a higher probability that the grasper face will slip against the tissue. If the grasper face is separated into a series of independent movable islands, then by tracking their displacement it will be possible to identify when the areas of low normal force first start to slip while the remainder of the tissue is still held securely. The system was evaluated through the simulated grasping and retraction of tissue under conditions representative of surgical practice using silicone tissue simulants and porcine liver samples. It was able to successfully detect slip before gross slip occurred with a 100% and 77% success rate for the tissue simulant and porcine liver samples, respectively. This research demonstrates the efficacy of this sensing method and the associated sensor system for detecting the occurrence of tissue slip events during surgical grasping and retraction.

Reducing retraction forces with tactile feedback during robotic total mesorectal excision in a porcine model

Excessive tissue-instrument interaction forces during robotic surgery have the potential for causing iatrogenic tissue damages. The current in vivo study seeks to assess whether tactile feedback could reduce intraoperative tissue-instrument interaction forces during robotic-assisted total mesorectal excision. Five subjects, including three experts and two novices, used the da Vinci robot to perform total mesorectum excision in four pigs. The grip force in the left arm, used for retraction, and the pushing force in the right arm, used for blunt pelvic dissection around the rectum, were recorded. Tissue-instrument interaction forces were compared between trials done with and without tactile feedback. The mean force exerted on the tissue was consistently higher in the retracting arm than the dissecting arm (3.72 ± 1.19 vs 0.32 ± 0.36 N, p < 0.01). Tactile feedback brought about significant reductions in average retraction forces (3.69 ± 1.08 N vs 4.16 ± 1.12 N, p = 0.02), but dissection forces appeared unaffected (0.43 ± 0.42 vs 0.37 ± 0.28 N, p = 0.71). No significant differences were found between retraction and dissection forces exerted by novice and expert robotic surgeons. This in vivo animal study demonstrated the efficacy of tactile feedback in reducing retraction forces during total mesorectal excision. Further research is required to quantify the clinical impact of such force reduction.

Toward Mechanochromic Soft Material-Based Visual Feedback for Electronics-Free Surgical Effectors

A chromogenically reversible, mechanochromic pressure sensor is integrated into a mininvasive surgical grasper compatible with the da Vinci robotic surgical system. The sensorized effector, also featuring two soft-material jaws, encompasses a mechanochromic polymeric inset doped with functionalized spiropyran (SP) molecule, designed to activate mechanochromism at a chosen pressure and providing a reversible color change. Considering such tools are systematically in the visual field of the operator during surgery, color change of the mechanochromic effector can help avoid tissue damage. No electronics is required to control the devised visual feedback. SP-doping of polydimethylsiloxane (2.5:1 prepolymer/curing agent weight ratio) permits to modulate the mechanochromic activation pressure, with lower values around 1.17 MPa for a 2% wt. SP concentration, leading to a shorter chromogenic recovery time of 150 s at room temperature (25 °C) under green light illumination. Nearly three-times shorter recovery time is observed at body temperature (37 °C). To the best of knowledge, this study provides the first demonstration of mechanochromic materials in surgery, in particular to sensorize unpowered surgical effectors, by avoiding dramatic increases in tool complexity due to additional electronics, thus fostering their application. The proposed sensing strategy can be extended to further tools and scopes.

Design and implementation of a hand-held robot-assisted minimally invasive surgical device with enhanced intuitive manipulability and stable grip force

BACKGROUND

The conventional hand-held minimally invasive surgical devices commonly suffer from non-intuitive manipulability and restricted flexibility for operation.

METHODS

A hand-held surgical device with enhanced intuitive manipulability and stable grip force was proposed for minimally invasive surgery (MIS). The dexterous instrument and isomorphic handle were designed, and the cable transmission structure and model of the instrument were analysed. A modelling method for grip force pre-compensation was proposed to produce stable grip forces under different posture.

RESULTS

The prototype of the proposed MIS device was developed, and the related experiments were carried out. The maximum opening angle error was 1.2°. Compared with the non-compensation model, the variation of grip force reduced 8 times with the pre-compensation model. The animal vivo experiments verified the feasibility and practicability of the device.

CONCLUSIONS

The proposed hand-held device could provide intuitive manipulability and stable operation, which contributes to the performance improvement of the MIS.

Design and Evaluation of a Dexterous and Modular Hand-Held Surgical Robot for Minimally Invasive Surgery

Current surgical instruments with fewer degrees-of-freedom (DOF) for minimally invasive surgery (MIS) have limited capability to perform complicated and precise procedures, such as suturing and knot-tying. To address such a problem, a modular dexterous hand-held surgical robot with an ergonomic handle and 4DOF interchangeable instruments was developed. The kinematic arrangement of the instrument and that of the handle were designed to be the same. A compact roll-yaw-roll transmission was proposed applying cable-driven mechanism. Performance experiments were carried out to evaluate the effectiveness of the overall system. The measured grip forces of the robot ranged from 8.63 N to 19.18 N. The suturing performance score of the robot was significantly higher than that of the conventional instrument (28.8 ± 5.02 versus 17.2 ± 7.43, p = 0.041). The trajectory tracking test and animal experiment verified the accuracy and feasibility of the robot. The proposed robot could improve the surgical performance of MIS, providing various end-effectors and having an intuitive interface in the meantime.

Robotic-Assisted Transrectal Cholecystectomy in a Porcine Model

Background. With increasing experience and technological advancement in surgical instruments, surgeons have explored the feasibility of single-incision laparoscopic surgery and natural orifice transluminal endoscopic surgery (NOTES). These techniques aim to further reduce surgical trauma, but are not popular due to their inherent pitfalls including clashing of instruments, lack of counter traction, lengthy operating time, and so on. A novel surgical robotic system was designed to overcome the limitations of the existing technologies. Animal trials were conducted to demonstrate its feasibility in performing robotic-assisted transrectal cholecystectomy in a porcine model. Method. The Novel surgical robotic system is a high dexterity, single access port surgical robotic system that enables surgeons to carry out single-port surgical procedure or NOTES. The proposed system’s main features include the ability to perform intraabdominal and pelvic surgeries via natural orifices like the vagina or rectum. The system is equipped with multiple miniaturized (16 mm diameter) internally motorized robotic arms, each with a minimum of 7 degrees of freedom, a dual in vivo camera system, a cannula, and an external swivel system. Results. Robotic-assisted transrectal cholecystectomy was successfully performed in 3 adult male pigs. The estimated blood loss was <10 mL in all 3 cases. There were no intraoperative complications. The system provided good dexterity and clear vision. Conclusions. The trial demonstrated that the system can provide the surgeon a stable platform with adequate spacing for the transrectal insertion of robotic arms, 3-dimensional vision, and enhanced dexterity in performing NOTES cholecystectomy.

Conditions for reliable grip force and jaw angle estimation of da Vinci surgical tools

PURPOSE

This work presents an estimation technique as well as corresponding conditions which are necessary to produce an accurate estimate of grip force and jaw angle on a da Vinci surgical tool using back-end sensors alone.

METHODS

This work utilizes an artificial neural network as the regression estimator on a dataset acquired from custom hardware on the proximal and distal ends. Through a series of experiments, we test the effect of estimation accuracy due to change in operating frequency, using the opposite jaw, and using different tools. A case study is then presented comparing our estimation technique with direct measurements of material response curves on two synthetic tissue surrogates.

RESULTS

We establish the following criteria as necessary to produce an accurate estimate: operate within training frequency bounds, use the same side jaw, and use the same tool. Under these criteria, an average root mean square error of 1.04 mN m in grip force and 0.17 degrees in jaw angle is achieved. Additionally, applying these criteria in the case study resulted in direct measurements which fell within the 95% confidence bands of our estimation technique.

CONCLUSION

Our estimation technique, along with important training criteria, is presented herein to further improve the literature pertaining to grip force estimation. We propose the training criteria to begin establishing bounds on the applicability of estimation techniques used for grip force estimation for eventual translation into clinical practice.

Estimating Tool-Tissue Forces Using a 3-Degree-of-Freedom Robotic Surgical Tool

Robot-assisted minimally invasive surgery (MIS) has gained popularity due to its high dexterity and reduced invasiveness to the patient; however, due to the loss of direct touch of the surgical site, surgeons may be prone to exert larger forces and cause tissue damage. To quantify tool-tissue interaction forces, researchers have tried to attach different kinds of sensors on the surgical tools. This sensor attachment generally makes the tools bulky and/or unduly expensive and may hinder the normal function of the tools; it is also unlikely that these sensors can survive harsh sterilization processes. This paper investigates an alternative method by estimating tool-tissue interaction forces using driving motors' current, and validates this sensorless force estimation method on a 3-degree-of-freedom (DOF) robotic surgical grasper prototype. The results show that the performance of this method is acceptable with regard to latency and accuracy. With this tool-tissue interaction force estimation method, it is possible to implement force feedback on existing robotic surgical systems without any sensors. This may allow a haptic surgical robot which is compatible with existing sterilization methods and surgical procedures, so that the surgeon can obtain tool-tissue interaction forces in real time, thereby increasing surgical efficiency and safety.

Evaluating tactile feedback in robotic surgery for potential clinical application using an animal model

INTRODUCTION

The aims of this study were to evaluate (1) grasping forces with the application of a tactile feedback system in vivo and (2) the incidence of tissue damage incurred during robotic tissue manipulation. Robotic-assisted minimally invasive surgery has been shown to be beneficial in a variety of surgical specialties, particularly radical prostatectomy. This innovative surgical tool offers advantages over traditional laparoscopic techniques, such as improved wrist-like maneuverability, stereoscopic video displays, and scaling of surgical gestures to increase precision. A widely cited disadvantage associated with robotic systems is the absence of tactile feedback.

METHODS AND PROCEDURE

Nineteen subjects were categorized into two groups: 5 experts (six or more robotic cases) and 14 novices (five cases or less). The subjects used the da Vinci with integrated tactile feedback to run porcine bowel in the following conditions: (T1: deactivated tactile feedback; T2: activated tactile feedback; and T3: deactivated tactile feedback). The grasping force, incidence of tissue damage, and the correlation of grasping force and tissue damage were analyzed. Tissue damage was evaluated both grossly and histologically by a pathologist blinded to the sample.

RESULTS

Tactile feedback resulted in significantly decreased grasping forces for both experts and novices (P < 0.001 in both conditions). The overall incidence of tissue damage was significantly decreased in all subjects (P < 0.001). A statistically significant correlation was found between grasping forces and incidence of tissue damage (P = 0.008). The decreased forces and tissue damage were retained through the third trial when the system was deactivated (P > 0.05 in all subjects).

CONCLUSION

The in vivo application of integrated tactile feedback in the robotic system demonstrates significantly reduced grasping forces, resulting in significantly less tissue damage. This tactile feedback system may improve surgical outcomes and broaden the use of robotic-assisted minimally invasive surgery.

Pneumatic-type surgical robot end-effector for laparoscopic surgical-operation-by-wire

BACKGROUND

Although minimally invasive surgery (MIS) affords several advantages compared to conventional open surgery, robotic MIS systems still have many limitations. One of the limitations is the non-uniform gripping force due to mechanical strings of the existing systems. To overcome this limitation, a surgical instrument with a pneumatic gripping system consisting of a compressor, catheter balloon, micro motor, and other parts is developed.

METHOD

This study aims to implement a surgical instrument with a pneumatic gripping system and pitching/yawing joints using micro motors and without mechanical strings based on the surgical-operation-by-wire (SOBW) concept. A 6-axis external arm for increasing degrees of freedom (DOFs) is integrated with the surgical instrument using LabVIEW® for laparoscopic procedures. The gripping force is measured over a wide range of pressures and compared with the simulated ideal step function. Furthermore, a kinematic analysis is conducted. To validate and evaluate the system's clinical applicability, a simple peg task experiment and workspace identification experiment are performed with five novice volunteers using the fundamentals of laparoscopic surgery (FLS) board kit. The master interface of the proposed system employs the hands-on-throttle-and-stick (HOTAS) controller used in aerospace engineering. To develop an improved HOTAS (iHOTAS) controller, 6-axis force/torque sensor was integrated in the special housing.

RESULTS

The mean gripping force (after 1,000 repetitions) at a pressure of 0.3 MPa was measured to be 5.8 N. The reaction time was found to be 0.4 s, which is almost real-time. All novice volunteers could complete the simple peg task within a mean time of 176 s, and none of them exceeded the 300 s cut-off time. The system's workspace was calculated to be 11,157.0 cm3.

CONCLUSIONS

The proposed pneumatic gripping system provides a force consistent with that of other robotic MIS systems. It provides near real-time control. It is more durable than the existing other surgical robot systems. Its workspace is sufficient for clinical surgery. Therefore, the proposed system is expected to be widely used for laparoscopic robotic surgery. This research using iHOTAS will be applied to the tactile force feedback system for surgeon's safe operation.

Experience related factors compensate for haptic loss in robot-assisted laparoscopic surgery

BACKGROUND AND PURPOSE

Surgeons anecdotally report awareness of nontactile sensory cues that compensate for absent haptic feedback in robot-assisted surgery. This study investigates this poorly understood adaptive process by evaluating frequency of in vivo suture damage.

PATIENTS AND METHODS

Consecutive cases of children undergoing robot-assisted dismembered pyeloplasty were examined. Suture damage was defined as incomplete (i.e., fraying) or complete (i.e., broken) loss of thread integrity and prospectively recorded with clinical data. Suture technique, size, and robotic instruments used for suturing were subjected to post hoc analysis. Statistical analysis was undertaken using appropriate nonparametric tests.

RESULTS

Overall frequency of suture damage was 2.6% among 1135 sutures used in 52 patients. The mean number of sutures used for cases in this series was 22 (standard deviation±6). There was a significant inverse trend between surgeon experience and suture damage frequency (P=0.014), implying that greater surgeon experience was associated with less suture damage. The impact of experience on suture damage was most apparent when comparing the earliest quartile subgroup (Q1) with the later three quartile subgroups (Q2-Q4) (P<0.001). Plateau of suture damage frequency was seen after approximately 28 cases. Continuous sutures had significantly higher damage frequency compared with interrupted sutures (P=0.022). Significantly higher frequency of suture damage was seen with cases in which forceps instruments were used for suturing compared with paired needle drivers (1.4% vs 7.1%, P<0.001). All events of inadvertent tissue injury involved damage to exposed edges of the renal pelvis (n=5).

CONCLUSIONS

Suture damage is likely to be encountered during the learning curve of robot-assisted surgery but decreases with surgeon experience. Preferential use of larger suture size, interrupted sutures, and paired needle driver instruments may help to minimize suture damage. Experience-related perceptual skills that compensate for haptic loss are likely to be acquirable in a preclinical simulation environment.

How does a surgeon's brain buzz? An EEG coherence study on the interaction between humans and robot

Introduction

In humans, both primary and non-primary motor areas are involved in the control of voluntary movements. However, the dynamics of functional coupling among different motor areas have not been fully clarified yet. There is to date no research looking to the functional dynamics in the brain of surgeons working in laparoscopy compared with those trained and working in robotic surgery.

Experimental procedures

We enrolled 16 right-handed trained surgeons and assessed changes in intra- and inter-hemispheric EEG coherence with a 32-channels device during the same motor task with either a robotic or a laparoscopic approach. Estimates of auto and coherence spectra were calculated by a fast Fourier transform algorithm implemented on Matlab 5.3.

Results

We found increase of coherence in surgeons performing laparoscopy, especially in theta and lower alpha activity, in all experimental conditions (M1 vs. SMA, S1 vs. SMA, S1 vs. pre-SMA and M1 vs. S1; p < 0.001). Conversely, an increase in inter-hemispheric coherence in upper alpha and beta band was found in surgeons using the robotic procedure (right vs. left M1, right vs. left S1, right pre-SMA vs. left M1, left pre-SMA vs. right M1; p < 0.001).

Discussion

Our data provide a semi-quantitative evaluation of dynamics in functional coupling among different cortical areas in skilled surgeons performing laparoscopy or robotic surgery. These results suggest that motor and non-motor areas are differently activated and coordinated in surgeons performing the same task with different approaches. To the best of our knowledge, this is the first study that tried to assess semi-quantitative differences during the interaction between normal human brain and robotic devices.