Precise Maneuvers Research Articles

Charged aerodynamics: Ionospheric plasma drag on objects in low-Earth orbit

Objects in Low-Earth Orbit (LEO) experience a range of environmental conditions that influence their trajectories. Aside from gravitational effects and solar radiation pressure, drag due to the residual background atmosphere is conventionally viewed as the primary perturbing factor. The ionosphere is an additional background environment composed of charged particles that is well-known to result in spacecraft charging, and in the worst case, cause arcing or unwanted electrostatic discharges. While the ionospheric plasma density is typically an order of magnitude (or more) lower than the atmospheric neutral gas density, electrostatic charging can lead to the formation of plasma sheath and wake structures around an object that artificially increase its effective collecting area. Direct charged particle collection and indirect charged particle deflection gives rise to a drag force that can exceed that due to atmospheric neutral gas alone at some altitudes and charging potentials. Here, we present a model accounting for charged particle flow effects (i.e. charged aerodynamics) around objects in LEO, and validate this model with previous particle-in-cell simulations and experiments. Using atmospheric properties from the Mass Spectrometer and Incoherent Scatter radar (MSIS) model and ionospheric properties from the International Reference Ionosphere (IRI), we show that plasma-induced drag in LEO can be significant and may have important orbit prediction implications for space domain awareness and space traffic management. Through differential spacecraft biasing, ionospheric plasma drag can also be used as a propellantless and “solid-state” mechanism to achieve in-orbit mobility for precision maneuvers, formation flying, deorbiting, and even partial attitude control.

Precisely Navigated Biobot Swarms of Bacteria Magnetospirillum magneticum for Water Decontamination.

Hybrid biological robots (biobots) prepared from living cells are at the forefront of micro-/nanomotor research due to their biocompatibility and versatility toward multiple applications. However, their precise maneuverability is essential for practical applications. Magnetotactic bacteria are hybrid biobots that produce magnetosome magnetite crystals, which are more stable than synthesized magnetite and can orient along the direction of earth's magnetic field. Herein, we used Magnetospirillum magneticum strain AMB-1 (M. magneticum AMB-1) for the effective removal of chlorpyrifos (an organophosphate pesticide) in various aqueous solutions by naturally binding with organic matter. Precision control of M. magneticum AMB-1 was achieved by applying a magnetic field. Under a programed clockwise magnetic field, M. magneticum AMB-1 exhibit swarm behavior and move in a circular direction. Consequently, we foresee that M. magneticum AMB-1 can be applied in various environments to remove and retrieve pollutants by directional control magnetic actuation.

Robust dynamic control algorithm for uncertain powered wheelchairs based on sliding neural network approach

<abstract><p>The dynamic model of mobile wheelchair technology requires developing and implementing an intelligent control system to improve protection, increasing performance efficiency, and creating precise maneuvering in indoor and outdoor spaces. This work aims to design a robust tracking control algorithm based on a reference model for operating the kinematic model of powered wheelchairs under the variation of system parameters and unknown disturbance signals. The control algorithm was implemented using the pole placement method in combination with the sliding mode control (PP-SMC) approach. The design also adopted a neural network approach to eliminate system uncertainties from perturbations. The designed method utilized the sinewave signal as an essential input signal to the reference model. The stability of a closed-loop control system was achieved by adopting the Goa reaching law. The performance of the proposed tracking control system was evaluated in three scenarios under different conditions. These included assessing the tracking under normal operation conditions, considering the tracking performance by changing the dynamic system's parameters and evaluating the control system in the presence of uncertainties and external disturbances. The findings demonstrated that the proposed control method efficiently tracked the reference signal within a small error based on mean absolute error (MAE) measurements, where the range of MAE was between 0.08 and 0.12 in the presence of uncertainties or perturbations.</p></abstract>

New Concept of External and Independent Next-to-the-Scope Intraluminal Grasping Device (EINTS).

Background: Interventional endoscopic procedures require complex manipulations and precise maneuvering of end-effectors. One focus in research on improved endoscopic instrument function was based on surgical experience to gain additional traction. The idea has emerged using assisting instruments by applying external tools next-to-the endoscope to follow surgical concepts. The aim of this study is the assessment of flexible endoscopic grasping instruments regarding their function and working-radius introducing the concept of an intraluminal "next-to the-scope" endoscopic grasper. Methods: In this study endoscopic graspers are evaluated (1:through-the-scope-grasper, TTSG; 2:additional-working-channel-system AWC-S;3:external-independent-next-to-the-scope-grasper EINTS-G) regarding their working-radius, grasping abilities, maneuverability and the ability to expose tissue with varying angulation. Results: The working radius of the tools attached or within the endoscope (TTS-G and AWC-S) benefit from the steering abilities of the scope reaching 180-210 degrees in retroflexion; EINTS-G is limited to 110-degrees. The robust EINTS-grasper has the advantage of stronger grip for grasping and pulling force, which enables manipulation of larger objects. The independent maneuverability during ESD-dissection provides better tissue-exposure by changing the traction-angulation. Conclusion: The working radius of tools attached to the endoscope benefit from scope- steering. The EINTS-grasper has the advantage of stronger grasping force and pulling within the GI-tract and independent maneuverability enables improved tissue-exposure. WC200.

Applying a rigid curved video laryngoscope in laryngeal microsurgery of patients with difficult laryngeal exposure

Objective:To test the feasibility of a rigid curved video laryngoscope in laryngeal microsurgery of patients with difficult laryngeal exposure. Methods:Thirteen patients with difficult laryngeal exposure underwent microlayngeal surgery using a new-design rigid curved video laryngoscope. The clinical data were collected and analyzed. Results:In all of the 13 patients with difficult laryngeal exposure,the fully exposure rate of glottis was 100% using a new-design rigid curved laryngoscope.But only 7 precise surgeries using our rigid curved instruments were completed successfully. Conclusion:Rigid curved laryngoscope is a useful tool to in treating patients with difficult laryngeal exposure in microlaryngeal surgery. Satisfactory glottis exposure, magnified surgical field and precise maneuver of the lesions could be achieved. But manipulation of this tool is challenging, which warrants further investigation．.

Effects of carbon, graphite, and graphene as propellant dopants in a laser-electric hybrid acceleration system

With the combination of laser ablation and electromagnetic acceleration, the laser–electric hybrid thruster is now perceived as an advanced propulsion system to support the precise maneuvering of microsatellites. To improve the performance of a laser–electric hybrid acceleration thruster, we used carbon, graphite, and graphene as dopants to modify the polymeric propellant fed into it. The impulse bit, consumed mass, discharge success rate, specific impulse, momentum coupling coefficient, and efficiency were measured and analyzed. Results showed that these three dopants led to higher values of impulse bit, specific impulse, discharge success rate, efficiency, and momentum coupling coefficient. The samples doped with carbon and graphene yielded better performances than those doped with graphite. Furthermore, the propellant sample made of 5% graphene and 95% polytetrafluoroethylene yielded the highest impulse bit of 394.7 μN·s, largest specific impulse of 1012.05 s, highest momentum coupling coefficient of 16.21 N/MW, and maximal efficiency of 8.21%. Furthermore, we compared the performances of the doped samples at different filling ratios and different operations. It was found that 5% was the optimal doping ratio for the dopants of carbon and graphene, and a higher discharge width could effectively improve the performances of the carbon-doped and graphene-doped samples.

Can minimally invasive surgical techniques reduce the incidence of postoperative adhesions?

<br><b>Introduction:</b> Postoperative intra-abdominal adhesions are a clinical condition that may develop after any abdominal surgery and constitute the leading cause of mechanical small bowel obstructions.</br> <br><b>Aim:</b> This study investigates factors which influence the formation of postoperative adhesion and evaluates the efficiency of applying minimally invasive surgical techniques in reducing adhesion.</br> <br><b>Material and methods:</b> Patients who underwent surgery to diagnose obstructive ileus in our clinic between January 2015 and January 2020 were analyzed retrospectively. Demographic data of the patients, operation details time between the operations and history of hospitalizations, postoperative mortality and morbidity, as well as the severity of complications were recorded. The patients included in the study were divided into groups according to the surgical technique applied in the first operation (laparoscopy/ laparotomy), the abdominal incision line (upper/lower/total), and the etiology of the primarily operated lesion (benign/malignant).</br> <br><b>Results:</b> One hundred eighteen (118) patients were included in the study. The mean age of patients was 61.2 ± 10.8 (39-82) years. Age, ileus history, time to the onset of ileus, length of hospital stay and the number of complications were shorter in the laparoscopy group as compared to the laparotomy group and the difference was found to be statistically significant. In addition, when patients were categorized according to the abdominal incision line, fewer hospitalizations and more frequent postoperative complications due to ileus were observed in the sub-umbilical incision group (p < 0.05).</br> <br><b>Conclusions:</b> Postoperative adhesion formation is currently one of the clinical conditions which pose a challenge to both the patient and the clinician due to its incidence and recurrence. However, adhesion formation can be reduced by applying minimally invasive surgical methods, especially laparoscopic surgery and precise maneuvers during surgery.</br&gt.

Plasmonic-magnetic nanorobots for SARS-CoV-2 RNA detection through electronic readout

The coronavirus disease 2019 (COVID‐19) has prompted an urgent demand for nanotechnological solutions towards the global healthcare crisis, particularly in the field of diagnostics, vaccines, and therapeutics. As an emerging tool for nanoscience and technology, micro/nanorobots have demonstrated advanced performances, such as self-propelling, precise maneuverability, and remote actuation, thus hold great potential to provide breakthroughs in the COVID-19 pandemic. Here we show a plasmonic-magnetic nanorobot-based simple and efficient COVID-19 detection assay through an electronic readout signal. The nanorobots consist of Fe3O4 backbone and the outer surface of Ag, that rationally designed to perform magnetic-powered propulsion and navigation, concomitantly the probe nucleic acids transport and release upon the hybridization which can be quantified with the differential pulse voltammetry (DPV) technique. The magnetically actuated nanorobots swarming enables enhanced micromixing and active targeting, thereby promoting binding kinetics. Experimental results verified the enhanced sensing efficiency, with nanomolar detection limit and high selectivity. Further testing with extracted SARS-CoV-2 viral RNA samples validated the clinical applicability of the proposed assay. This strategy is versatile to extend targeting various nucleic acids, thus it could be a promising detection tool for other emerging pathogens, environmental toxins, and forensic analytes.

곡률 변화에 따른 코안다 와류 고리 추진기의 유동 해석

The vortex ring thruster (VRT) is a propulsion system mimicking the propulsive technique of Mollusca, such as squids and jellyfish. VRT’s acknowledged advantages include low noise generation, delicate attitude control, and precise maneuverability. However, due to the low propulsion efficiency, its application is limited to low-speed unmanned underwater vehicle (UUV) only. In the present study, the propulsion performance evaluation of Coanda vortex ring thruster (CoVoRT) with different curvature was performed to examine the application of CoVoRT. The flows around the typical VRT and CoVoRT were analyzed using SNUFOAM, which was open-source toolkit CFD code based on the OpenFOAM. For computational validation, the CFD results for the flow around VRT were compared with the previous simulations and experimental results. Then propulsion performance of VRT and CoVoRT was compared in terms of the PPEI, and the vortex ring formation process. The results showed that CoVoRT

Shrimp Robot Mechanism

The Shrimp rover is highly suitable for planetary exploration missions because of its unconventional wheel order, in-built passive adaptability and good ability to climb obstacles. It is a spatial multi-body system and a multi-variable, multi-parameter coupled non-linear system. Thus, kinematic and dynamic analyses for such systems are complex and time consuming. Long-range robotic missions for Martian exploration imply a high degree of autonomy. The most advanced locomotion concepts are based on wheels or caterpillars (e.g. Sojourner, NASA or Nanokhod, ESA). These rovers have clear advantages regarding power efficiency and complexity if compared with walking robots. However, they still have quite limited climbing abilities. Typically they can only overcome obstacle smaller than their wheel size. In this paper we present Shrimp, an innovative long range rover architecture with 6 motorized wheels. Using a rhombus configuration, the rover has a steering wheel in both, the front and the rear, and two wheels arranged on a bogie on each side. The front wheel has a spring suspension to guarantee optimal ground contact of all wheels at any time. The steering of the rover is realized by synchronizing the steering of the front and rear wheel and the speed difference of the bogie wheels. This allows for high precision maneuvers and even turning on the spot with minimum slip. The use of parallel articulations for the front wheel and the bogies enables to set a virtual centre of rotation at the level of the wheel axis while maintaining a high ground clearance. This insures maximum stability and climbing abilities even for relatively low friction coefficients between the wheel and the ground. This rover is able to passively overcome unstructured obstacles of up to two times its wheel diameter. With this high mobility, this architecture is the perfect candidate for long range planetary missions.

Topographic and Landcover Influence on Lower Atmospheric Profiles Measured by Small Unoccupied Aerial Systems (sUAS)

Small unoccupied aerial systems (sUASs) are increasingly being used for field data collection and remote sensing purposes. Their ease of use, ability to carry sensors, low cost, and precise maneuverability and navigation make them a versatile tool for a field researcher. Procedures and instrumentation for sUASs are largely undefined, especially for atmospheric and hydrologic applications. The sUAS’s ability to collect atmospheric data for characterizing land–atmosphere interactions was examined at three distinct locations: Costa Rican rainforest, mountainous terrain in Georgia, USA, and land surfaces surrounding a lake in Florida, USA. This study aims to give further insight on rapid, sub-hourly changes in the planetary boundary layer and how land development alters land–atmosphere interactions. The methodology of using an sUAS for land–atmospheric remote sensing and data collection was developed and refined by considering sUAS wind downdraft influence and executing systematic flight patterns throughout the day. The sUAS was successful in gathering temperature and dew point data, including rapid variations due to changing weather conditions, at high spatial and temporal resolution over various land types, including water, forest, mountainous terrain, agriculture, and impermeable human-made surfaces. The procedure produced reliably consistent vertical profiles over small domains in space and time, validating the general approach. These findings suggest a healthy ability to diagnose land surface atmospheric interactions that influence the dynamic nature of the near-surface boundary layer.

Dual Ultrasound and Photoacoustic Tracking of Magnetically Driven Micromotors: From In Vitro to In Vivo.

The fast evolution of medical micro- and nanorobots in the endeavor to perform non-invasive medical operations in living organisms has boosted the use of diverse medical imaging techniques in the last years. Among those techniques, photoacoustic imaging (PAI), considered a functional technique, has shown to be promising for the visualization of micromotors in deep tissue with high spatiotemporal resolution as it possesses the molecular specificity of optical methods and the penetration depth of ultrasound. However, the precise maneuvering and function's control of medical micromotors, in particular in living organisms, require both anatomical and functional imaging feedback. Therefore, herein, the use of high-frequency ultrasound and PAI is reported to obtain anatomical and molecular information, respectively, of magnetically-driven micromotors in vitro and under ex vivo tissues. Furthermore, the steerability of the micromotors is demonstrated by the action of an external magnetic field into the uterus and bladder of living mice in real-time, being able to discriminate the micromotors' signal from one of the endogenous chromophores by multispectral analysis. Finally, the successful loading and release of a model cargo by the micromotors toward non-invasive in vivo medical interventions is demonstrated.

Pareto Effect of LMI for Ship Propulsion

The aim of this study was to analyze the dynamics of a multidimensional object based on the Pareto curve for the Linear Matrix Inequalities (LMI) controller. The study was carried out based on an available “Blue Lady” training vessel model controller with the use of a MATLAB and Simulink simulation package. Research was focused on optimising both the energy to be used when manoeuvring and the ship’s dynamics. Analysis was combined with the application of H2/H∞ norms finding the Pareto optimal solution for mixed norms used at the γ∞ parameter. Observations for a multidimensional ship model proved that it is possible to optimize the system, using principles of the Pareto curve, to reduce energy consumption in steering-propulsion systems while performing precise manoeuvres in ports correctly. Parameter values, received from observations of operation of individual steering-propulsion systems, proved to be reasonable.

Automatic orbital docking with tumbling target using sliding mode control

The present study aimed to propose translational and rotational control of a chaser spacecraft in the close vicinity docking phase with a target subjected to external disturbances. For this purpose, two sliding mode controls (SMC) are developed to coordinate the relative position and attitude of two spacecraft. The chaser is guided to the tumbling target by the relative position control, approaching in the direction of the target docking port. At the same moment, the relative attitude control coordinates the chaser attitude so that it can be aligned with the target orientation. These control systems regulate the relative translational and rotational velocities to be zero when two spacecraft are docking. The robustness of the closed-loop system in the presence of external disturbances, measurement noises and uncertainties is guaranteed by analyzing and calculating the control gains via the Lyapunov function. The simulations in different scenarios indicated the effectiveness of the controller scheme and precise maneuver regarding the accuracy of docking conditions.

Development of Non Expensive Technologies for Precise Maneuvering of Completely Autonomous Unmanned Aerial Vehicles.

In this paper, solutions for precise maneuvering of an autonomous small (e.g., 350-class) Unmanned Aerial Vehicles (UAVs) are designed and implemented from smart modifications of non expensive mass market technologies. The considered class of vehicles suffers from light load, and, therefore, only a limited amount of sensors and computing devices can be installed on-board. Then, to make the prototype capable of moving autonomously along a fixed trajectory, a “cyber-pilot”, able on demand to replace the human operator, has been implemented on an embedded control board. This cyber-pilot overrides the commands thanks to a custom hardware signal mixer. The drone is able to localize itself in the environment without ground assistance by using a camera possibly mounted on a 3 Degrees Of Freedom (DOF) gimbal suspension. A computer vision system elaborates the video stream pointing out land markers with known absolute position and orientation. This information is fused with accelerations from a 6-DOF Inertial Measurement Unit (IMU) to generate a “virtual sensor” which provides refined estimates of the pose, the absolute position, the speed and the angular velocities of the drone. Due to the importance of this sensor, several fusion strategies have been investigated. The resulting data are, finally, fed to a control algorithm featuring a number of uncoupled digital PID controllers which work to bring to zero the displacement from the desired trajectory.

Technical details of the abdominal part during full robotic-assisted minimally invasive esophagectomy.

The full robotic-assisted minimally invasive esophagectomy (RAMIE) is an upcoming approach in the treatment of esophageal and junctional cancer. Potential benefits are seen in angulated precise maneuvers in the abdominal part as well as in the thoracic part, but due to the novelty of this approach the optimal setting of the trocars, the instruments and the operating setting is still under debate. Hereafter, we present a technical description of the 'Mainz technique' of the abdominal part of RAMIE carried out as Ivor Lewis procedure. Postoperative complication rate and duration of the abdominal part of 100 consecutive patients from University Medical Center in Mainz are illustrated. In addition, the abdominal phase of the full RAMIE is discussed in general.

Securing Fixed Orthodontic Components With Vinyl Polysiloxane for Ease During Orthognathic Surgery

Unease from brackets, archwires, and ligature ties during orthognathic surgery makes oral and maxillofacial surgeons to distract from their work field, which in turn makes precise maneuvering and fixation of the jaws challenging. The present article describes a simple, useful clinical tip which eliminates the above problem by covering the fixed orthodontic components using vinyl polysiloxane impression material (putty).

Assessment of the Steering Precision of a Hydrographic USV along Sounding Profiles Using a High-Precision GNSS RTK Receiver Supported Autopilot

Unmanned Surface Vehicles (USV) are increasingly used to perform numerous tasks connected with measurements in inland waters and seas. One of such target applications is hydrography, where traditional (manned) bathymetric measurements are increasingly often realized by unmanned surface vehicles. This pertains especially to restricted or hardly navigable waters, in which execution of hydrographic surveys with the use of USVs requires precise maneuvering. Bathymetric measurements should be realized in a way that makes it possible to determine the waterbody’s depth as precisely as possible, and this requires high-precision in navigating along planned sounding profiles. This paper presents research that aimed to determine the accuracy of unmanned surface vehicle steering in autonomous mode (with a Proportional-Integral-Derivative (PID) controller) along planned hydrographic profiles. During the measurements, a high-precision Global Navigation Satellite System (GNSS) Real Time Kinematic (RTK) positioning system based on a GNSS reference station network (positioning accuracy: 1–2 cm, p = 0.95) and a magnetic compass with the stability of course maintenance of 1°–3° Root Mean Square (RMS) were used. For the purpose of evaluating the accuracy of the vessel’s path following along sounding profiles, the cross track error (XTE) measure, i.e., the distance between an USV’s position and the hydrographic profile, calculated transversely to the course, was proposed. The tests were compared with earlier measurements taken by other unmanned surface vehicles, which followed the exact same profiles with the use of much simpler and low-cost multi-GNSS receiver (positioning accuracy: 2–2.5 m or better, p = 0.50), supported with a Fluxgate magnetic compass with a high course measurement accuracy of 0.3° (p = 0.50 at 30 m/s). The research has shown that despite the considerable difference in the positioning accuracy of both devices and incomparably different costs of both solutions, the authors proved that the use of the GNSS RTK positioning system, as opposed to a multi-GNSS system supported with a Fluxgate magnetic compass, influences the precision of USV following sounding profiles to an insignificant extent.

Feasibility analysis of using the hp-adaptive Radau pseudospectral method for minimum-effort collision-free docking operations of AUV

This paper continues the previous effort on the development of a trajectory generation platform that assures minimum-control expenditure and collision-free manoeuvre of a torpedo-shaped autonomous underwater vehicle (AUV) into a funnel-shaped stationary docking station (DS). The earlier-developed guidance system was based on the Inverse Dynamics in the Virtual Domain (IDVD) method accounting for AUV’s dynamics and producing a smooth trackable trajectory, thus guaranteeing safe arrival to DS. The optimality of the real-time generated solutions has been assessed via comparing them with the Legendre–Gauss–Lobatto pseudo-spectral (PS) method solutions that could only be obtained off-line. This paper explores a possibility of employing a more advanced hp-adaptive Radau (hp-AR) PS method for the same Hamiltonian two-point boundary-value problem. The considered approach explicitly encapsulates all realistic vehicular and environmental constraints such as the AUV’s dynamics, ocean current disturbances, no-fly zones, and DS pose while minimizing the vehicle’s controls expenditure and permitting precise manoeuvring into DS. The performance evaluation of the hp-AR PS based optimization routine is carried out through extensive software-in-the-loop simulations. For completeness, computational effectiveness and solution optimality of the trajectory generator engine based on the hp-AR method is compared with two other well-known PS methods based on Legendre and Chebyshev polynomial approximation. The results of this study show the superb performance of the hp-AR method-based trajectory generator among all other PS methods and a possibility of using it along with IDVD in the real-time implementation.

Design and development of autonomous robotic fish for object detection and tracking

In this article, an autonomous robotic fish is designed for underwater operations like object detection and tracking along with collision avoidance. The computer-aided design model for prototype robotic fish is designed using the Solid Works® software to export an stereolithography (STL) file to MakerBot, a 3D printer, to manufacture the parts of robotic fish using polylactic acid thermoplastic polymer. The precise maneuverability of the robotic fish is achieved by the propulsion of a caudal fin. The oscillation of the caudal fin is controlled by a servomotor. A combination of visual and ultrasonic sensors is used to track the position and distance of the desired object with respect to the fish and also to avoid the obstacles. The robotic fish has the ability to detect an object up to a distance of 90 cm at normal exposure conditions. A computational fluid dynamics analysis is conducted to analyze the fluid hydrodynamics (flow rate of water and pressure) around the hull of a robotic fish and the drag force acting on it. A series of experimental results have shown the effectiveness of the designed underwater robotic fish.