Colorectal cancer incidence has been steadily rising worldwide. Magnetic colonoscopes provide new approaches to conduct colon inspection and treatment. This paper presents a novel electromagnetically ...actuated soft-tethered colonoscope to achieve precise and stable orientation control. An inflated balloon is designed to eliminate the unpredictable disturbance of the floating tether. A 2OR Pseudo-Rigid-Body (PRB) model of the soft tether is developed to analyze the relationship between the tether deflection and applied force and torque. A closed-loop control framework is constructed with visual position feedback. Experiments are first conducted to validate the assumption of the PRB model and the efficacy of the magnetic field model. Then, trajectory tracking tasks and disturbance rejection tests are performed to validate the feasibility of the proposed solution and closed-loop control. Results show that the colonoscope can stably and accurately orient to the desired orientation with an absolute mean position error of less than 0.5 mm and an average velocity of 3.5 mm/s. The distal tip can quickly re-stabilize to the desired orientation even when a large disturbance exists.
Gastrointestinal (GI) tract related diseases are common and deadly. To avoid the diseases developing into an advanced stage, early inspection and intervention are crucial. However, existing ...inspection methods are either uncomfortable or lack of active steering. Therefore, it is necessary to investigate a locomotion method that is friendly to the GI tract. This paper proposed a novel soft snail robot targeted for active locomotion inside the GI tract. By studying the locomotion mechanism of gastropods, a snail robot propelled with longitudinal travelling wave was designed. The wave was generated by deflating and inflating a series of chambers. The snail robot could adhere to different surfaces, including the ex vivo porcine intestine, by the mucus underneath. Experiments were designed to study the performance of the proposed snail robot. Results show that, the soft snail robot could crawl over different substrates including hard substrate, soft substrate and biological tissue. The speed of the snail is affected by multiple factors, including the surface condition, wave frequency and the mucus concentration.
Magnetic field is regarded as a safe and efficient method for controlling minimally invasive medical robots remotely, and magnetic actuation system based on mobile electromagnetic coils are preferred ...due to the enlarged working space and fast response. Enhanced flexibility on coils' positions will further enable the system to deal with possible constraints inside the workspace, while design and control of such flexible systems remain challenging. In this work, a magnetic actuation system based on three mobile electromagnetic coils with decoupled movements is designed and the performance is demonstrated. The system consists of three 4-axis robotic arms that can adjust the relative positions of three mobile coils independently. The prototype of RoboMag is designed and able to program magnetic field at a required point inside a hemispherical space with a diameter of 152 mm. A method to drive the mobile-electromagnetic-coil-based systems with flexible movements is proposed. To begin with, a model of the robotic platform is built to place the coils to demanded position. A numerical model of a single coil is constructed and average error of magnetic field is reduced to 3.30% after calibration. Afterwards, a method based on coordinate transformation is proposed for the entire system to produce demanded magnetic torque and force at a required position. Experiments are conducted to demonstrate the system's capability on generating magnetic torque and force to actuate medical device analog.
Conventional colonoscopy using a flexible colono-scope remains two major limitations, including patient discomfort and nonintuitive manipulations for surgeons. To address these limitations, robotic ...colonoscopes have been developed to provide new approaches for conducting colon diagnosis and therapy. However, low autonomy level of most robotic colonoscopes leads to nonintuitive and difficult manipulations, which limits their applications in clinical practice. In this paper, we demonstrate semi-autonomous manipulations of an electro-magnetic actuated soft-tethered (EAST) colonoscope based on visual servo control, which aims to reduce the difficulties of colonoscope manipulation and lower the workload of surgeons. A visual servo controller is established with the magnetic actuation model and kinematic model of the tethered colono-scope. Two semi-autonomous manipulations, including region-of-interest automatic tracking and autonomous navigation with automatic polyp detection, are proposed based on visual servo control, with several image feature extraction methods developed. Experimental validation is conducted with a proof-of-concept EAST colonoscope prototype and a colon phantom. The results show that the system successfully performs visual servoing and semi-autonomous manipulations, which demon-strates the potential of applications in clinical practice.
Aim: Endoscopically‐placed, push‐type percutaneous endoscopic gastrostomies (PEG) have recently been made possible through the use of a gastropexy device. However, the safety and efficacy of the ...procedure in patients suffering from severe trismus or malignant obstruction due to head and neck cancers have rarely been reported. The aim of this study was thus to investigate the feasibility, safety and risk of endoscopic push‐type PEG in this group of patients.
Patients and Methods: Consecutive patients who were indicated for PEG and suffered from severe trismus or malignant obstruction due to head and neck cancers, precluding the introduction of a 9.8 mm oesophagogastroduodenoscope were included. Push‐type PEG was performed under endoscopic control with a 5‐mm endoscope and the loop fixture device.
Results: Eleven patients had push‐type PEG performed under conscious sedation. All procedures were successful, and minor complications occurred in one patient with a dislodged gastrostomy tube and another with wound infection. There were no mortalities or major morbidities related to the procedure.
Conclusions: Push‐type PEG with gastropexy inserted under endoscopic control by an ultrathin endoscope is a feasible alternative to open gastrostomy in patients with severe trismus or pharyngeal obstruction.
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