Carbon nanotube/glycerol embedded low cost flexible sensor for large deflection sensing of continuum manipulators

Large deflection sensing is highly crucial for proper positioning and control of continuum robots during robot assisted minimally invasive surgery. Existing techniques suffer from eletromagnetic noise susceptibility, harmful radiation exposure, limited range, bio-incompatibility and necessity of expensive instruments. In the present study, we propose a Multi-Walled Carbon Nano-Tube (MWCNT)/polyglycerol based low cost, flexible and biocompatible sensor which could allow safer, faster and accurate angular deflection measurement of continuum robots for biomedical applications. Experimental results demonstrate that the sensor is stretchable upto 100% , provides a gauge factor upto 11.65, have response time around 8 ms, durability of -0.14% for cyclic loading and unloading and show very small creep upto ±0.0008 ( ±2.88%). Furthermore, the sensor can measure continuum robot deflection upto ±150 o with a sensitivity of 666.67 ohms/degree, with a maximum error of 1.67% and maximum hysteresis of 1.41%. Thus, wide range, low cost, fast response, and biocompatibility justify the potential of the proposed sensor for large deflection sensing of continuum robots during robot assisted minimally invasive surgery.

Effect of Geometrical Shape on Axial Deformation of Soft Actuator

Soft actuators are the latest trend of research because of their light weight and ease of manufacturing and control. Soft actuators have expanded their fields and taken place in many applications where linear or angular deflection is required. Soft actuators are very useful in the applications where deflection is required with soft touch. Soft Actuators are highly compliant and adaptive to unknown environments. Because of these characteristics, soft actuators are very popular in the field of medical and in the applications where interaction with fragile structure is required. The soft actuators can give required responses mostly depends on their shape. Linear or angular deformation can be achieved by changing the geometrical shape of actuators. This paper presents the effect of geometrical shape on axial deformation of soft pneumatic actuator. Samples of soft actuators are selected with various shapes for finite element analysis. Results are obtained in form of axial and lateral deformation. An attempt is made to achieve good amount of axial deformation with very less or negligible lateral deformation by selecting appropriate shape. Based on the generated results, the shape is identified which gives desired results and more suitable among the selected nine samples. This sample can be useful in the application having space constraint in lateral direction.

Influence of Anisotropy Properties of as-Rolled CMn Plate on Welding Induced Distortion

Welding induced distortion remain persistent problems leading to the inferior on Product Quality. The study is to investigate on welding induced angular distortion due to effect of anisotropy properties of the As-rolled C-Mn plate. The outcome could enhance the minimum distortion while cutting the raw material on rolling direction for fabrication process. The Anisotropy properties of the base metal were analyzed with along and transverse to rolling direction through microstructure examination, hardness measurement and mechanical properties. Microstructure contains coarse grains of pearlite and ferrite in transverse to rolling, whereas fine grains along the rolling. Hardness was 80 and 84 HRB along and transverse to rolling respectively. A weld bead was laid on the plate’s substrate with along and transverse to the rolling and angular deflections were measured with a dial gauge indicator. Finite element analysis (FEA) was carried out to evaluate the angular deflection on both the rolling. From the experimental results, the anisotropy properties of the as-rolled plate had influenced on angular deflection and indicating with good agreement with FEA.

Speckle reduction in ultrasound endoscopy using refraction based elevational angular compounding

Endoscopic ultrasonography (EUS) is a safe, real-time diagnostic and therapeutic tool. Speckle noise, inherent to ultrasonography, degrades the diagnostic precision of EUS. Elevational angular compounding (EAC) can provide real-time speckle noise reduction; however, EAC has never been applied to EUS because current implementations require costly and bulky arrays and are incompatible with the tight spatial constraints of hollow organs. Here we develop a radial implementation of a refraction-based elevational angular compounding technique (REACT) for EUS and demonstrate for the first time spatial compounding in a radial endoscopy. The proposed implementation was investigated in cylindrical phantoms and demonstrated superior suppression of ultrasound speckle noise and up to a two-fold improvement in signal- and contrast- ratios, compared to standard image processing techniques and averaging. The effect of elevational angular deflection on image fidelity was further investigated in a phantom with lymph node-like structures to determine the optimum elevational angular width for high speckle reduction efficiency while maintaining image fidelity. This study introduces REACT as a potential compact and low-cost solution to impart current radial echo-endoscopes with spatial compounding, which could enable accurate identification and precise sizing of lymph nodes in staging of gastrointestinal tract cancers.

Optimization for a Flexure Hinge Using an Effective Hybrid Approach of Fuzzy Logic and Moth-Flame Optimization Algorithm

Flexure hinge is a critical element in a positioner of a nanoindentation tester. To effectively work, a suitable flexure hinge should simultaneously meet multiple objectives, including rotation axis shift, safety factor, and angular deflection. The main aim of this article was to illustrate a hybrid method of the Taguchi method, fuzzy logic, response surface method, and Moth-flame optimization algorithm to solve the design optimization of a flexure hinge in order to enhance the three quality characteristics of the flexure hinge. Firstly, four common flexure hinges are compared together to seek the best suitable one. Secondly, numerical experiments are gathered via the Taguchi-based detasFlex software. Thirdly, three objective functions are transferred into signal to noises in order to eliminate the unit differences. Later on, fuzzy modeling is proposed to interpolate these three objective functions into one integrated objective function. An integrated regression equation is built using the response surface method. Finally, the flexure hinge is optimized by the Moth-flame optimization algorithm. The results found that the rotation axis shift is 10.944∗10−5 mm, the high safety factor is 2.993, and the angular deflection is 52.0058∗10−3 rad. The verifications are in a suitable agreement with the forecasted results. An analysis of variance and sensitivity analysis are also performed to identify the effects and meaningful contributions of input variables on the integrated objective function. In addition, employing the Wilcoxon signed rank test and the Friedman test, the results find that the proficiency of the proposed method has more benefits than the ASO algorithm and the GA. The results of this research provide a beneficial approach for conducting complicated multiobjective optimal problems.

Cartesian Aerial Manipulator with Compliant Arm

This paper presents an aerial manipulation robot consisting of a hexa-rotor equipped with a 2-DOF (degree of freedom) Cartesian base (XY–axes) that supports a 1-DOF compliant joint arm that integrates a gripper and an elastic linear force sensor. The proposed kinematic configuration improves the positioning accuracy of the end effector with respect to robotic arms with revolute joints, where each coordinate of the Cartesian position depends on all the joint angles. The Cartesian base reduces the inertia of the manipulator and the energy consumption since it does not need to lift its own weight. Consequently, the required torque is lower and, thus, the weight of the actuators. The linear and angular deflection sensors of the arm allow the estimation, monitoring and control of the interaction wrenches exerted in two axes (XZ) at the end effector. The kinematic and dynamic models are derived and compared with respect to a revolute-joint arm, proposing a force-position control scheme for the aerial robot. A battery counterweight mechanism is also incorporated in the X–axis linear guide to partially compensate for the motion of the manipulator. Experimental results indoors and outdoors show the performance of the robot, including object grasping and retrieval, contact force control, and force monitoring in grabbing situations.

COMPUTER MODELING IN MSC ADAMS/VIEW AS PART OF A MODERN APPROACH TO THE DESIGN OF MECHANICAL SYSTEMS OF ROBOTS

The presented paper deals with the use of computer simulation in the design of a robot model with 4 degrees of freedom of movement. The MSC Adams program is used in the computer simulation, and the use of the Matlab program is also shown. The robot's mechanism is an open kinematic chain. During kinematic analysis, attention is paid to solving the direct problem of kinematics in MSC Adams and in Matlab. The result of the solution is the calculated trajectory of the movement of the selected point of the end effector. The trajectory is shown in graphical form. In Matlab, the magnitude of the position vector of the effector point is calculated as a function of time at the selected course of angular deflection in individual kinematic pairs at constant angular velocities in individual joints of the robot.

Stochastics of pipeline vibrations under dynamic interna

Рассматриваются колебания заполненного жидкостью трубопровода относительно горизонтальной оси, опирающегося на две опоры - одна из которых неподвижна, другая может смещаться в горизонтальном направлении. Начальное движение трубы характеризуется её изгибным отклонением в вертикальной плоскости, угловым во вращательном движении вокруг горизонтальной оси и гидравлическим ударом, при действии которого внутреннее давление на стенки трубы приобретает вид δ -толчков. Исходная система уравнений колебаний трубопровода приводится к уравнению Дуффинга. В переменных «действие-угол» получена граница стохастичности, которая отделяет детерминированную область решения от стохастической. Получено диффузионное уравнение типа Фоккера-Планка-Колмогорова, решение которого определяет функцию плотности вероятности, с помощью которой можно находить случайные параметры колебаний трубы для оценки её движения. Vibrations of a liquid-filled pipeline relative to the horizontal axis are considered. The pipe is supported by two supports - a movable and a fixed one. The initial movement of the pipe is characterized by is bending, angular deflection and hydraulic shok, after which the internal pressure on the pipe walls takes the form of δ -shoks. The system of equations for pipeline vibrations is reduced to the Duffing equation. A stochasticity boundary is obtained that divides the deterministic domain of the solution from the stochastic one. The Fokker-Plank-Kolmogorov diffusion equation is obtained, which makes it possible to determine the standard deviation of the bending vibrations of the pipe.

Design, Fabrication, and Testing of a Flexible Three-Dimensional Printed Percutaneous Needle with Embedded Actuators

Percutaneous needle procedures have replaced open surgeries in cancer treatments to perform the tasks with minimal invasiveness to the tissue. Precise placement of the needle at target positions in cancer diagnostic (e.g., breast biopsy) or therapeutic (e.g., prostate brachytherapy) procedures governs the success of such procedures. Also, in many applications it is desired to steer the needle away from critical organs or anatomical obstacles towards the target. This work introduces a three-dimensional (3D) printed surgical needle with embedded actuators for improved flexibility and manipulation inside the tissue towards the target. The needle is manipulated via a programmed portable motorized control unit. Performance evaluation experiments in air and in a tissue phantom showed an average angular deflection of 11 degrees towards each actuator. The needle's capability to reach the target, avoiding obstacles has also been shown. The controllable 3D deflection of the needle is expected to assist in breast cancer lumpectomy for multiple extractions of tissue samples or in prostate brachytherapy via a curvilinear approach. The needle can be eventually used in trajectory tracking and to improve targeting accuracy.

Cyclic Fatigue, Torsional Resistance, and Angular Deflection of Two Heat-Treated Files: M-Wire Versus New F-Wire Technology

The cyclic fatigue, torsional resistance, and angular deflection of a new Fire-Wire rotary file (CricENDO) were compared. A total of 20 files of each type were tested. Cyclic fatigue testing was performed for each group (n = 10) by measuring the number of cycles to fracture (NCF) in an artificial stainless-steel canal (60° angle of curvature, with a 6-mm radius) for each group. The torque and angle of rotation at the failure of each group (n = 10) were measured according to ISO 3630-1. The fractured surfaces were examined using scanning electron microscopy. Statistical analysis was carried out utilizing Student’s t-test at a significance level set at 5%. The Fire-Wire CricENDO rotary files were associated with a significantly higher number of cycles to fracture and time to failure (in seconds) compared to the M-Wire Protaper Next (p < 0.05). A significantly higher angular deflection to fracture was observed for CricENDO compared to Protaper Next (p < 0.05). The new Fire-Wire CricENDO rotary files exhibit higher cyclic fatigue resistance and angle of rotation to fracture than M-Wire Protaper Next. Without warning, file fracture may occur as a result of cyclic fatigue, torsional stress, or a combined effect of both. CricENDO rotary files may be an effective alternative in curved root canals as they exhibited elevated cyclic and torsional resistance. It will be helpful in eliminating one of the reasons for file fracture during the root canal treatment.