Closed-loop control of soft continuum manipulators under tip follower actuation.

Continuum manipulators, inspired by nature, have drawn significant interest within the robotics community. They can facilitate motion within complex environments where traditional rigid robots may be ineffective, while maintaining a reasonable degree of precision. Soft continuum manipulators have emerged as a growing subfield of continuum robotics, with promise for applications requiring high compliance, including certain medical procedures. This has driven demand for new control schemes designed to precisely control these highly flexible manipulators, whose kinematics may be sensitive to external loads, such as gravity. This article presents one such approach, utilizing a rapidly computed kinematic model based on Cosserat rod theory, coupled with sensor feedback to facilitate closed-loop control, for a soft continuum manipulator under tip follower actuation and external loading. This approach is suited to soft manipulators undergoing quasi-static deployment, where actuators apply a follower wrench (i.e., one that is in a constant body frame direction regardless of robot configuration) anywhere along the continuum structure, as can be done in water-jet propulsion. In this article we apply the framework specifically to a tip actuated soft continuum manipulator. The proposed control scheme employs both actuator feedback and pose feedback. The actuator feedback is utilized to both regulate the follower load and to compensate for non-linearities of the actuation system that can introduce kinematic model error. Pose feedback is required to maintain accurate path following. Experimental results demonstrate successful path following with the closed-loop control scheme, with significant performance improvements gained through the use of sensor feedback when compared with the open-loop case.

The waterjet necrosectomy device for endoscopic management of pancreatic necrosis: design, development, and preclinical testing (with videos).

BACKGROUND AND AIMS: Endoscopic intervention has emerged as a first-line option for management of symptomatic pancreatic necrosis, yet endoscopic debridement is limited by the lack of dedicated endoscopic tools intended for this purpose. The objectives of this study were to design and build a prototype necrosectomy device compatible for use with a flexible endoscope and capable of selective tissue fragmentation, and to test the prototype in benchtop and porcine models. METHODS: A novel prototype, named the waterjet necrosectomy device (WAND), was designed and developed, consisting of a single-use disposable endoscopic waterjet instrument capable of waterjet selection and independent tip articulation while fitting through a 2.8-mm working channel of a standard adult upper GI endoscope. Benchtop, ex vivo, and in vivo (porcine) testing was performed in the initial stages of investigation. RESULTS: The WAND was capable of delivering a continuous waterjet force with a surface pressure of 0.72 bar at a flow rate of 0.37 L/minute. In phase 1 of testing, the WAND was able to achieve complete fragmentation of gelatin as a surrogate for pancreatic necrosis in benchtop testing. In phase 2 of testing, the WAND was able to achieve complete fragmentation of freshly explanted human pancreatic necrosis. In phase 3 of testing for safety in fresh necropsy swine, use of the WAND resulted in no significant tissue trauma, even when irrigation was applied at closer proximity and for more extended duration than would be anticipated in clinical use. CONCLUSION: The WAND prototype delivers irrigation capable of fragmenting necrotic debris ex vivo and avoiding trauma to healthy nontarget tissue. Planning is underway for first-in-human studies to assess the efficacy and safety of the WAND for endoscopic pancreatic necrosectomy.

A Compression Valve for Sanitary Control of Fluid-Driven Actuators.

With significant research focused on integrating robotics into medical devices, sanitary control of pressurizing fluids in a precise, accurate and customizable way is highly desirable. Current sanitary flow control methods include pinch valves which clamp the pressure line locally to restrict fluid flow; resulting in damage and variable flow characteristics over time. This paper presents a sanitary compression valve based on an eccentric clamping mechanism. The proposed valve distributes clamping forces over a larger area, thereby reducing the plastic deformation and associated influence on flow characteristic. Using the proposed valve, significant reductions in plastic deformation (up to 96%) and flow-rate error (up to 98%) were found, when compared with a standard pinch valve. Additionally, an optimization strategy presents a method for improving linearity and resolution over the working range to suit specific control applications. The valve efficacy has been evaluated through controlled testing of a water jet propelled low-cost endoscopic device. In this case, use of the optimized valve shows a reduction in the average orientation error and its variation, resulting in smoother movement of the endoscopic tip when compared to alternative wet and dry valve solutions. The presented valve offers a customizable solution for sanitary control of fluid driven actuators.

Sensitivity Ellipsoids for Force Control of Magnetic Robots with Localization Uncertainty.

The navigation of magnetic medical robots typically relies on localizing an actuated, intracorporeal, ferromagnetic body and back-computing a necessary field and gradient that would result in a desired wrench on the device. Uncertainty in this localization degrades the precision of force transmission. Reducing applied force uncertainty may enhance tasks such as in-vivo navigation of miniature robots, actuation of magnetically guided catheters, tissue palpation, as well as simply ensuring a bound on forces applied on sensitive tissue. In this paper, we analyzed the effects of localization noise on force uncertainty by using sensitivity ellipsoids of the magnetic force Jacobian and introduced an algorithm for uncertainty reduction. We validated the algorithm in both a simulation study and in a physical experiment. In simulation, we observed reductions in estimated force uncertainty by factors of up to 2.8 and 3.1 when using one and two actuating magnets, respectively. On a physical platform, we demonstrated a force uncertainty reduction by a factor of up to 2.5 as measured using an external sensor. Being the first consideration of force uncertainty resulting from noisy localization, this work provides a strategy for investigators to minimize uncertainty in magnetic force transmission.

Enhanced Real-Time Pose Estimation for Closed-Loop Robotic Manipulation of Magnetically Actuated Capsule Endoscopes.

Pose estimation methods for robotically guided magnetic actuation of capsule endoscopes have recently enabled trajectory following and automation of repetitive endoscopic maneuvers. However, these methods face significant challenges in their path to clinical adoption including the presence of regions of magnetic field singularity, where the accuracy of the system degrades, and the need for accurate initialization of the capsule's pose. In particular, the singularity problem exists for any pose estimation method that utilizes a single source of magnetic field if the method does not rely on the motion of the magnet to obtain multiple measurements from different vantage points. We analyze the workspace of such pose estimation methods with the use of the point-dipole magnetic field model and show that singular regions exist in areas where the capsule is nominally located during magnetic actuation. Since the dipole model can approximate most magnetic field sources, the problem discussed herein pertains to a wider set of pose estimation techniques. We then propose a novel hybrid approach employing static and time-varying magnetic field sources and show that this system has no regions of singularity. The proposed system was experimentally validated for accuracy, workspace size, update rate and performance in regions of magnetic singularity. The system performed as well or better than prior pose estimation methods without requiring accurate initialization and was robust to magnetic singularity. Experimental demonstration of closed-loop control of a tethered magnetic device utilizing the developed pose estimation technique is provided to ascertain its suitability for robotically guided capsule endoscopy. Hence, advances in closed-loop control and intelligent automation of magnetically actuated capsule endoscopes can be further pursued toward clinical realization by employing this pose estimation system.

Evaluation of a novel tablet application for improvement in colonoscopy training and mentoring (with video).

BACKGROUND AND AIMS: Endoscopic training can be challenging for the trainee and preceptor. Frustration can result from ineffective communication regarding areas of interest. Our team developed a novel tablet application for real-time mirroring of the colonoscopy examination that allows preceptors to make annotations directly on the viewing monitor. The potential for improvement in team proficiency and satisfaction is unknown. METHODS: The on-screen endoscopic image is mirrored to an Android tablet and permits real-time annotation directly on the in-room endoscopic image display. Preceptors can also "freeze-frame" an image and provide visual on-screen instruction (telestration). Trainees, precepted by a GI attending, were 1:1 randomized to perform colonoscopy on a training phantom using the application with traditional precepting or traditional precepting alone. Magnetized polyps (size < 5 mm) were placed in 1 of 5 preset location scenarios. Each trainee performed a total of 10 colonoscopies and completed each location scenario twice. During withdrawal, the trainee and the attending identified polyps. Outcome measures included number of polyps missed and participant satisfaction after each trial. RESULTS: Fifteen trainees (6 novice and 9 GI fellows) performed a total of 150 colonoscopies where 330 polyps in total were placed. Fellows missed fewer polyps using the tablet versus traditional precepting alone (4.2% vs 12.5%; P = .04). There was no significant difference in missed polyps for novices (12.5% vs 18.8%; P = .66). Overall, fellows missed fewer polyps when compared with novices regardless of the precepting method (P = .01). The attending and all trainees reported reduced stress with improved communication using the tablet. CONCLUSIONS: Fellows missed fewer polyps using the tablet when compared with traditional endoscopy precepting. All trainees reported reduced stress, quicker identification of polyps, and improved educational satisfaction using the tablet. Our application has the potential to improve trainee plus attending team lesion detection and to enhance the endoscopy training experience for both the trainee and attending preceptor.

Providing Hospitalized Patients With an Educational Booklet Increases the Quality of Colonoscopy Bowel Preparation.

BACKGROUND & AIMS: Inadequate bowel preparation is a problem frequently encountered by gastroenterologists who perform colonoscopies on hospitalized patients. A method is needed to increase the quality of bowel preparation in inpatients. An educational booklet has been shown to increase the overall quality of bowel preparation for outpatients. We performed a prospective study to evaluate the effects of an educational booklet on the quality of bowel preparation in a group of hospitalized patients. METHODS: We performed a randomized, single-blind, controlled trial of all inpatients at a tertiary care medical center scheduled for inpatient colonoscopy from October 2013 through March 2014. They were randomly assigned to groups that were (n = 45) or were not (controls, n = 40) given the booklet before bowel preparation the evening before their colonoscopy. All patients received a standard bowel preparation (clear liquid diet the day before the procedure, followed by split-dose GoLYTELY). At the colonoscopy, the Boston Bowel preparation scale (BBPS) was used to assess bowel preparation. The primary outcome measure was adequate bowel preparation (a total BBPS score ≥6 with all segment scores ≥2). Secondary outcomes assessed included total BBPS score, BBPS segment score, and a total BBPS score of 0. RESULTS: There were no differences between the groups in age, race, sex, body mass index, history of colonoscopy, history of polyps, or time of colonoscopy. Twenty-eight patients who received the booklet (62%) and 14 who did not (35%) had an adequate bowel preparation (P = .012). The number needed to treat to attain adequate bowel preparation was 4. After adjusting for age and history of prior colonoscopies, the odds of achieving an adequate bowel preparation and a higher total BBPS score after receipt of the booklet were 3.14 (95% confidence interval, 1.29-7.83) and 2.27 (95% confidence interval, 1.05-4.88), respectively. Three patients in the booklet group and 9 in the no-booklet group had a BBPS score of 0 (P = .036). The mean BBPS segment score was greater for the booklet group than the no-booklet group (right colon, P = .097; transverse colon, P = .023; left colon, P = .045). CONCLUSIONS: In a randomized controlled trial, we found that providing hospitalized patients with an educational booklet on colonoscopy preparation increases the odds of a quality bowel preparation more than 2-fold.

Video on Diet Before Outpatient Colonoscopy Does Not Improve Quality of Bowel Preparation: A Prospective, Randomized, Controlled Trial.

OBJECTIVES: Successful outpatient colonoscopy (CLS) depends on many factors including the quality of a patient's bowel preparation. Although education on consumption of the pre-CLS purgative can improve bowel preparation quality, no study has evaluated dietary education alone. We have created an educational video on pre-CLS dietary instructions to determine whether dietary education would improve outpatient bowel preparation quality. METHODS: A prospective randomized, blinded, controlled study of patients undergoing outpatient CLS was performed. All patients received a 4 l polyethylene glycol-based split-dose bowel preparation and standard institutional pre-procedure instructions. Patients were then randomly assigned to an intervention arm or to a no intervention arm. A 4-min educational video detailing clear liquid diet restriction was made available to patients in the intervention arm, whereas those randomized to no intervention did not have access to the video. Patients randomized to the video were provided with the YouTube video link 48-72 h before CLS. An attending endoscopist blinded to randomization performed the CLS. Bowel preparation quality was scored using the Boston Bowel Preparation Scale (BBPS). Adequate preparation was defined as a BBPS total score of ≥6 with all segment scores ≥2. Wilcoxon rank-sum and Pearson's χ2-tests were performed to assess differences between groups. RESULTS: Ninety-two patients were randomized (video: n=42; control: n=50) with 47 total video views being tallied. There were no demographic differences between groups. There was no statistically significant difference in adequate preparation between groups (video=74%; control=68%; P=0.54). CONCLUSIONS: The availability of a supplementary patient educational video on clear liquid diet alone was insufficient to improve bowel preparation quality when compared with standard pre-procedure instruction at our institution.

Emerging Issues and Future Developments in Capsule Endoscopy.

Capsule endoscopy (CE) has transformed from a research venture into a widely used clinical tool and the primary means for diagnosing small bowel pathology. These orally administered capsules traverse passively through the gastrointestinal tract via peristalsis and are used in the esophagus, stomach, small bowel, and colon. The primary focus of CE research in recent years has been enabling active CE manipulation and extension of the technology to therapeutic functionality; thus, widening the scope of the procedure. This review outlines clinical standards of the technology as well as recent advances in CE research. Clinical capsule applications are discussed with respect to each portion of the gastrointestinal tract. Promising research efforts are presented with an emphasis on enabling active capsule locomotion. The presented studies suggest, in particular, that the most viable solution for active capsule manipulation is actuation of a capsule via exterior permanent magnet held by a robot. Developing capsule procedures adhering to current healthcare standards, such as enabling a tool channel or irrigation in a therapeutic device, is a vital phase in the adaptation of CE in the clinical setting.

Controlled colonic insufflation by a remotely triggered capsule for improved mucosal visualization.

BACKGROUND AND STUDY AIMS: Capsule endoscopy is an attractive alternative to colorectal cancer screening by conventional colonoscopy, but is currently limited by compromised mucosal visibility because of the lack of safe, controlled colonic insufflation. We have therefore developed a novel system of untethered, wireless-controlled carbon dioxide (CO2) insufflation for use in colonic capsule endoscopy, which this study aims to assess in vivo. MATERIAL AND METHODS: This observational, nonsurvival, in vivo study used five Yorkshire-Landrace cross swine. A novel insufflation capsule was placed in the porcine colons, and we recorded volume of insufflation, time, force, visualization, and a pathologic assessment of the colon. RESULTS: The mean (standard deviation [SD]) diameter of insufflation was 32.1 (3.9) mm. The volume of CO2 produced successfully allowed complete endoscopic visualization of the mucosa and safe proximal passage of the endoscope. Pathologic examination demonstrated no evidence of trauma caused by the capsule. CONCLUSIONS: These results demonstrate the feasibility of a novel method of controlled colonic insufflation via an untethered capsule in vivo. This technological innovation addresses a critical need in colon capsule endoscopy.

Small-bowel endoscopy core curriculum.

This is one of a series of documents prepared by the ASGE Training Committee. This curriculum document contains recommendations for training, intended for use by endoscopy training directors, endoscopists involved in teaching endoscopy, and trainees in endoscopy. It was developed as an overview of techniques currently favored for the performance and training of small-bowel endoscopy and to serve as a guide to published references, videotapes, and other resources available to the trainer. By providing information to endoscopy trainers about the common practices used by experts in performing the technical aspects of the procedure, the ASGE hopes to improve the teaching and performance of small-bowel endoscopy.

Wireless Millimeter-Size Soft Climbing Robots with Omnidirectional Steerability on Tissue Surfaces.

Wirelessly actuated miniature soft robots actuated by magnetic fields that can overcome gravity by climbing soft and wet tissues are promising for accessing challenging enclosed and confined spaces with minimal invasion for targeted medical operation. However, existing designs lack the directional steerability to traverse complex terrains and perform agile medical operations. Here we propose a rod-shaped millimeter-size climbing robot that can be omnidirectionally steered with a steering angle up to 360 degrees during climbing beyond existing soft miniature robots. The design innovation includes the rod-shaped robot body, its special magnetization profile, and the spherical robot footpads, allowing directional bending of the body under external magnetic fields and out-of-plane motion of the body for delivery of medical patches. With further integrated bio-adhesives and microstructures on the footpads, we experimentally demonstrated inverted climbing of the robot on porcine gastrointestinal (GI) tract tissues and deployment of a medical patch for targeted drug delivery.

Robust endoscopic image mosaicking via fusion of multimodal estimation.

We propose an endoscopic image mosaicking algorithm that is robust to light conditioning changes, specular reflections, and feature-less scenes. These conditions are especially common in minimally invasive surgery where the light source moves with the camera to dynamically illuminate close range scenes. This makes it difficult for a single image registration method to robustly track camera motion and then generate consistent mosaics of the expanded surgical scene across different and heterogeneous environments. Instead of relying on one specialised feature extractor or image registration method, we propose to fuse different image registration algorithms according to their uncertainties, formulating the problem as affine pose graph optimisation. This allows to combine landmarks, dense intensity registration, and learning-based approaches in a single framework. To demonstrate our application we consider deep learning-based optical flow, hand-crafted features, and intensity-based registration, however, the framework is general and could take as input other sources of motion estimation, including other sensor modalities. We validate the performance of our approach on three datasets with very different characteristics to highlighting its generalisability, demonstrating the advantages of our proposed fusion framework. While each individual registration algorithm eventually fails drastically on certain surgical scenes, the fusion approach flexibly determines which algorithms to use and in which proportion to more robustly obtain consistent mosaics.