Roll Orientation Research Articles

Adaptive backstepping and sliding mode control of a quadrotor

This article proposes a simple robust adaptive control architecture with minimum parameter estimation laws for trajectory tracking of a quadrotor subjected to parametric variations and environmental disturbances. This simple control architecture aims to achieve highly accurate, robust, and fast trajectory tracking of the quadrotor in a short time with low computational cost. Firstly, the quadrotor model is divided into altitude, attitude, and position subsystems for which appropriate control methods are designed without prior knowledge of the upper bound of external disturbances. A simple adaptive fractional-order sliding mode control (AFSMC) is designed to enhance the tracking of the altitude subsystem and estimate the upper bound of the disturbances. Then, a simple adaptive backstepping control (ABC) is developed for the horizontal position to generate the required roll and pitch orientations. The adaptation laws not only estimate the upper bound of the disturbances but also adjust the controller gains thereby enhancing the robustness of the ABC. A nonsingular fast terminal sliding mode control (NFTSMC) is incorporated with a finite-time disturbance observer (FDO) to accurately suppress the disturbances, and follow the target rotation angles within a short finite-time. Simulation results showed that the compounded control structure ensures accurate, fast, and robust tracking. The AFSMC can achieve the desired altitude with a settling time of 0.31 s and root mean square error (RMSE) of 0.0454 m. The ABC can attain the target horizontal position coordinates with a settling time of (0.47 s, 0.47 s) and RMSE of (0.0370 m, 0.0518 s). The NFTSMC-FDO can achieve the desired attitude angles with a settling time of (0.11 s, 0.13 s, 0.52 s) and RMSE of (0.0098 rad, 0.0092 rad, 0.0935 rad). Performance comparisons with existing control methods in terms of settling time and RMSE demonstrated that the proposed control architecture is superior.

Influence of scene aspect ratio and depth cues on verticality perception bias.

Perceiving verticality is crucial for accurate spatial orientation. Previous research has revealed that tilted scenes can bias verticality perception. Verticality perception bias can be represented as the sum of multiple periodic functions that play a role in the perception of visual orientation, where the specific factors affecting each periodicity remain uncertain. This study investigated the influence of the width and depth of an indoor scene on each periodic component of the bias. The participants were presented with an indoor scene showing a rectangular checkerboard room (Experiment 1), a rectangular aperture on the wall (Experiment 2), or a rectangular dotted room (Experiment 3), with various aspect ratios. The stimuli were presented with roll orientations ranging from 90° clockwise to 90° counterclockwise. The participants were asked to report their subjective visual vertical (SVV) perceptions. The contributions of 45°, 90°, and 180° periodicities to the SVV error were assessed by the weighted vector sum model. In Experiment 1, the periodic components of the SVV error increased with the aspect ratio. In Experiments 2 and 3, only the 90° component increased with the aspect ratio. These findings suggest that extended transverse surfaces may modulate the periodic components of verticality perception.

Fiber optic sensor embedded in robotic systems for 3-D orientation assessment using polymer fiber

The present work is considered to installed sensor system to the robotics system. The structure of 3-D rotational sensor is based on polymer fiber, where two fibers are twisted to couple the light. Twisted fibers are kept in a bending shape after twisting and installed on the robot where three scenarios are carried out. The bending radius variation leads to the bending loss in the first fiber, and the loss is being coupled in the second fiber. Robot's orientation causes the change in the macro-bend radius of the sensor. Our proposed sensor analyzes the robot's orientation where the robot is moved in the full rotational cycle from 0° to 360° in both clock and anti-clockwise rotation directions. Furthermore, the robot is also rotated at different speeds to analyze the dynamic response and also analyzed for simultaneous response of roll, pitch, and yaw's orientation. The results indicate that the proposed sensor of present work is a timely response with the robot moments. The simple structure and flexible 3-D rotational sensor structure pave to easily integrate into the robotics system.

Aero-Propulsive Characterization of a Flight Vehicle with Two Side-Jets

Numerical simulations were carried out to study the aero-propulsive characteristics of a flight vehicle using in-house developed Reynolds Averaged Navier-Stokes code CERANS. The analyses involved subsonic external flow with inclined supersonic dual sustainer jets at various angles of attack, roll orientations and side slip. The control characteristics of the configuration are evaluated for the flow with and without sustainer jets. Numerical simulations indicated that the jet plume exhausting out of the scarf sustainer nozzle grazed and clung to the airframe for a considerable downstream distance causing serious damage to the airframe. This numerical study led to an important design change of the sustainer nozzle shape from ‘scarf’ to ‘conical’ which alleviated plume interference problem with the airframe.

A novel method for testing accuracy of bite registration using intraoral scanners.

The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners. Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch. The average maximum error in interocclusal registration exceeded 50 μm. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 μm or more. The models with acrylic teeth exhibited higher errors. A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

ELDOC - Design of Electric Dolly Camera for Video Recording Using the Omni-Direction Wheel

The dolly camera has function as a regulator of camera movement in making video productions such as films. The movement system on the dolly camera uses the thrust of humans and the running track rail for its movement. The process of preparing the dolly camera also requires a long process, such as assembling the dolly camera and then installing the track, etc. In this case study, we conducted research that designed an electric vehicle to carry a camera but with a simple way of working such as moving without rails and can be controlled with a mobile android. We named this robot vehicle ELDOC: Electric Dolly Camera which uses a four Omni-direction wheels system in the flexibility of direction and motion for taking videos and pictures. Contributions to the design of ELDOC in addition to the multimedia/cinematography field can also be used in the medical field as a monitoring tool for patient activities in isolation or ICU room with a mobile android from different rooms. In the results of the process running on the motor, we take error data from the calculation speed and measurement speed, wherein the duty circle is 19.60%, 38.50%, 58.8%, 78.66%, and the average error is 0,08. The stability level of the ELDOC when carrying the camera is stable but has vibrations or oscillations. The results of the data orientation (gyroscope) show the total average of the three samples Y (Roll) orientation is 0.6°/s and X (Pitch) orientation is 0.18°/s.

Experimental approach to calculate the moments of inertia of a hexacopter unmanned aerial vehicle

Moments of inertia define the amount of torque needed to rotate an object at a defined angular acceleration around a given axis. With the limited information available for multi-rotor unmanned aerial vehicles (UAVs), this paper sets out to experimentally determine the moments of inertia of a hexarotor UAV with a mounted payload. The moments of inertia are calculated in three rotational axes using pendulum and torsion tests. The pendulum test is performed to verify the test setup by experimentally determining a parameter which is already known: gravity. In pitch and yaw orientations gravity could be experimentally calculated to within 1.33% and 1.22% respectively. Unfortunately, this was not the case in the roll orientation, indicating that the test setup in that orientation needs to be adjusted. The torsion test is then performed to determine the period which is used to calculate the moments of inertia. Ultimately, these calculated moments of inertia will be used in simulation from which a flight controller can be designed.

Development of a patient-specific immobilisation facemask for radiation therapy using additive manufacturing, pressure sensors and topology optimisation

PurposeRadiotherapy relies on the delivery of radiation to cancer cells with millimetre accuracy, and immobilisation of patients is essential to minimise unwanted damage to surrounding healthy cells due to patient movement. Traditional thermoformed face masks can be uncomfortable and stressful for patients and may not be accurately fitted. The purpose of this study was to use 3D scanning and additive manufacturing to digitise this workflow and improve patient comfort and treatment outcomes.Design/methodology/approachThe head of a volunteer was scanned using an Artec Leo optical scanner (Artec, Luxembourg) and ANSYS (Ansys, Canonsburg, USA) software was used to make two 3D models of the mask: one with a nose bridge and one open as would be used with optical surface guidance. Data based on measurements from ten pressure sensors around the face was used to perform topology optimisation, with the best designs 3D printed using fused deposition modelling (FDM) and tested on the volunteer with embedded pressure sensors.FindingsThe two facemasks proved to be significantly different in terms of restricting head movement inside the masks. The optimised mask with a nose bridge effectively restricted head movement in roll and yaw orientations and exhibited minimal deformation as compared to the open mask design and the thermoformed mask.Originality/valueThe proposed workflow allows customisation of masks for radiotherapy immobilisation using additive manufacturing and topology optimisation based on collected pressure sensor data. In the future, sensors could be embedded in masks to provide real-time feedback to clinicians during treatment.

Deep cold rolling of single crystal nickel-based superalloy CMSX-4

Nickel-based superalloys used in the aerospace industry are regularly subjected to high temperature and stress cycles. In order to extend component life, many components are subjected to a cold work process during manufacturing. One such technique is deep cold rolling, a highly controllable process which utilises a roller ball to impart cold work and deep compressive residual stress into a surface. In this study, local misorientation analysis of electron backscattered diffraction data has been used to quantify the surface cold worked layers in single crystal samples of the superalloy CMSX-4®, deep cold rolled with different pressures, ball diameters and roll orientations. As expected, it was found that greater pressure and ball diameter both increased the cold work depth, with pressure also affecting the amount of cold work per depth. Different roll orientations produced very similar distributions of cold work. In comparison with mechanical shot peening, another surface hardening technique, deep cold rolling is shown to produce a much deeper layer of relatively low cold work.

A Complete Digital Workflow for Planning, Simulation, and Evaluation in Orthognathic Surgery.

The purpose of this study was to develop a complete digital workflow for planning, simulation, and evaluation for orthognathic surgery based on 3D digital natural head position reproduction, a cloud-based collaboration platform, and 3D landmark-based evaluation. We included 24 patients who underwent bimaxillary orthognathic surgery. Surgeons and engineers could share the massive image data immediately and conveniently and collaborate closely in surgical planning and simulation using a cloud-based platform. The digital surgical splint could be optimized for a specific patient before or after the physical fabrication of 3D printing splints through close collaboration. The surgical accuracy was evaluated comprehensively via the translational (linear) and rotational (angular) discrepancies between identical 3D landmarks on the simulation and postoperative computed tomography (CT) models. The means of the absolute linear discrepancy at eight tooth landmarks were 0.61 ± 0.55, 0.86 ± 0.68, and 1.00 ± 0.79 mm in left–right, advance–setback, and impaction–elongation directions, respectively, and 1.67 mm in the root mean square direction. The linear discrepancy in the left–right direction was significantly different from the other two directions as shown by analysis of variance (ANOVA, p < 0.05). The means of the absolute angular discrepancies were 1.43 ± 1.06°, 0.50 ± 0.31°, and 0.58 ± 0.41° in the pitch, roll, and yaw orientations, respectively. The angular discrepancy in the pitch orientation was significantly different from the other two orientations (ANOVA, p < 0.05). The complete digital workflow that we developed for orthognathic patients provides efficient and streamlined procedures for orthognathic surgery and shows high surgical accuracy with efficient image data sharing and close collaboration.

Does somatosensory feedback from the plantar foot sole contribute to verticality perception?

Aim of the study In upright standing, the human foot sole is the only point of contact with the ground conveying information about the pressure distribution under the feet. We examined how the altered somatosensory input from the plantar foot receptors, when standing on a soft surface, affects the subjective estimation of the earth vertical in different sensory contexts. Materials and methods Twelve (12) healthy young females (mean age: 21.8 ± 2.4 years) adjusted the orientation of a visual line (35 × 1.5 cm) representing the roll orientation of a hand-held (attached on a 24.9 × 4 cm cylinder) or head-attached electromagnetic tracking sensor (Nest of Birds, Ascension Technologies Inc., VT. USA, 60 Hz) under two visual conditions (eyes open, eyes closed) while standing on a soft or firm surface. The mean absolute (accuracy) and variable (precision) error in the verticality estimate was depicted in the sensor’s roll deviation from the gravitational vertical. Results The accuracy and the precision of the estimate decreased in the absence of vision, while standing on the soft surface and when the estimate was provided by an active hand rather than head rotation. The surface effect was significant only in the absence of vision and when the estimate was provided by the hand. Conclusions The contribution of the plantar foot mechanoreceptors to gravity perception is sensory context dependent. Perception of the earth vertical is more accurate when estimated by active head rotation due to the integration of the vestibular and neck proprioceptive afferents.

Pristine PSP/WISPR Observations of the Circumsolar Dust Ring near Venus's Orbit

Abstract The Parker Solar Probe mission (PSP) has completed seven orbits around the Sun. The Wide-field Imager for Solar Probe (WISPR) on PSP consists of two visible light heliospheric imagers, which together image the interplanetary medium between 13.°5 and 108° elongation. The PSP/WISPR nominal science observing window occurs during the solar encounters, which take place when the spacecraft (S/C) is within 0.25 au from the Sun. During Orbit 3, an extended science campaign took place while PSP transited between 0.5 and 0.25 au (during both inbound and outbound orbit segments). PSP mission operations implemented a variety of 180° S/C rolls about the S/C-Sun pointing axis during the extended science window. The vantage of the PSP location, combined with the different S/C roll orientations, allowed us to unveil a circumsolar dust density enhancement associated with Venus’s orbit. Specifically, we observed an excess brightness band of about 1% at its center over the brightness of the background zodiacal light in all PSP/WISPR images obtained during the extended campaign. We explain this brightness band as due to an increase in the density of the circumsolar dust orbiting the Sun close to the Venusian orbit. The projected latitudinal extent of the ring is estimated at about 0.043 au ± 0.004 au, exhibiting an average density enhancement of the order of 10%. Here, we report and characterize the first comprehensive, pristine observations of the plane-of-sky projection of the dust ring in almost its full 360° longitudinal extension.

Orientation of marine atmospheric rolls in a SAR imagery using wavelet transform: A case study over Bay of Bengal

An objective wavelet based algorithm has been developed to find the orientation of rolls in Synthetic Aperture Radar (SAR) imagery using Radar Imaging Satellite (RISAT-1) data. The orientation of rolls plays a very crucial role for the estimation of ocean surface wind direction. It also affects the shape and size of a tropical cyclone. In this manuscript, SAR image was decomposed using Haar Wavelet Transform (HWT) and optimal thresholding was done to delineate the direction of propagating rolls. The roll features were found oriented in the range 26°–31° from the along track direction. These features are very useful to retrieve wind direction and hence the vector wind observation over the ocean surface.

Estimasi Sudut Orientasi Rigid Body Dengan Menggunakan Sensor IMU (Inertial Measurement Unit) Dan Magnetometer

One of the instruments that can be used today for navigation is the IMU (Inertial Measurement Unit) sensor which consists of an accelerometer sensor, gyroscope, and an additional magnetometer. The three sensors are useful for determining the orientation angle. However, the presence of high enough noise in the three-output data can cause the orientation angle to be inaccurate. This study aims to determine the roll, pitch and yaw orientation more accurately using a Kalman filter. This filter is used because it has a lightweight computation and can reduce noise significantly. The results of this study show that the orientation angle calculated using the Kalman filter is close to the actual orientation angle with an accuracy of 99.2% for roll, 99.5% for pitch, and 98.6% for yaw.

Prolonged Static Whole-Body Roll-Tilt and Optokinetic Stimulation Significantly Bias the Subjective Postural Vertical in Healthy Human Subjects.

Background: Prolonged static whole-body roll-tilt has been shown to bias estimates of the direction of gravity when assessed by static paradigms such as the subjective visual vertical and the subjective haptic vertical.Objective: We hypothesized that these shifts are paradigm-independent and thus predicted a post-tilt bias as well for self-adjustments along perceived vertical (subjective postural vertical, SPV). Likewise, rotatory optokinetic stimuli, which have been shown to shift the SPV when presented at the time of adjustments, may have an lasting effect on the SPV, predicting a shift in the perceived direction of gravity in the direction of the optokinetic rotatory stimulation.Methods: Self-adjustments along perceived vertical by use of a motorized turntable were recorded at baseline and after 5 min of static whole-body roll-tilt (orientation = ±90°, adaptation period) in 10 healthy human subjects. During adaptation subjects were either in darkness (no OKN stimulation) or were presented a full-field rotatory optokinetic stimulus (velocity = ±60°/s). Statistical analysis of adjustment errors for the different conditions was performed using a generalized linear model.Results: After 5 min of static whole-body roll-tilt in darkness, we observed significant (p < 0.001) shifts in the SPV averaging −2.8° (adaptation position: −90°) and 3.1° (+90°), respectively. Adding an optokinetic rotatory stimulus resulted in an additional, significant shift of SPV adjustments toward the direction of the previously presented optokinetic rotation (optokinetic clockwise rotation: 1.4°, p = 0.034; optokinetic counter-clockwise rotation: −1.3°, p = 0.037). Trial-to-trial variability of turntable adjustments was not significantly affected by adaptation.Conclusions: Prolonged static roll-tilt results in a significant post-tilt bias of the perceived direction of gravity when assessed by the SPV, confirming previous findings from other vision-dependent and vision-independent paradigms. This finding emphasizes the impact of recent whole-body roll orientations relative to gravity. Such adaptational shifts in verticality estimates may be explained in the context of Bayesian optimal observer theory with a bias of prior knowledge (i.e., expectation biased by experience). Our findings also have clinical implications, as the observed post-tilt bias may contribute to postural instability when standing up in the morning with an increasing risk for falls and fall-related injuries in humans with preexisting balance disorders.

A gravity-based three-dimensional compass in the mouse brain

Gravity sensing provides a robust verticality signal for three-dimensional navigation. Head direction cells in the mammalian limbic system implement an allocentric neuronal compass. Here we show that head-direction cells in the rodent thalamus, retrosplenial cortex and cingulum fiber bundle are tuned to conjunctive combinations of azimuth and tilt, i.e. pitch or roll. Pitch and roll orientation tuning is anchored to gravity and independent of visual landmarks. When the head tilts, azimuth tuning is affixed to the head-horizontal plane, but also uses gravity to remain anchored to the allocentric bearings in the earth-horizontal plane. Collectively, these results demonstrate that a three-dimensional, gravity-based, neural compass is likely a ubiquitous property of mammalian species, including ground-dwelling animals.

On the absence or presence of 3D tuned head direction cells in rats: a review and rebuttal.

A major question in the field of spatial cognition is how animals represent three-dimensional (3D) space. Different results have been obtained across various species and may depend on whether the species inhabits a 3D environment or is terrestrial (land dwelling). The head direction (HD) cell system is an attractive candidate to study in terms of 3D representations. HD cells fire as a function of the animal's directional heading in the horizontal plane, independent of the animal's location and on-going behavior. Another issue concerns whether HD cells are tuned in 3D space or tuned to the 2D horizontal plane. Shinder and Taube (Shinder ME, Taube JS. J Neurophysiol 121: 4-37, 2019) addressed this issue by manipulating a rat's orientation in 3D space while monitoring responses from classic HD cells in the rat anterodorsal thalamus. They reported that HD cells did not display conjunctive firing with pitch or roll orientations. Direction-specific firing was primarily derived from horizontal semicircular canal information and that the gravity vector played an important role in influencing the cell's firing rate and its preferred firing direction. Laurens and Angelaki (Laurens J, Angelaki DE. J Neurophysiol 122: 1274-1287, 2019) challenged this view by performing a mathematical analysis on the Shinder and Taube data and concluded that they would not have seen 3D tuning based on their experimental approach. We provide a historical review of these issues followed by a summary of the experiments, which includes additional analyses. We then define what it means for a HD cell to be tuned in 3D and finish by rebutting the reanalyses performed by Laurens and Angelaki.

&lt;p&gt;Microscope Integrated Intraoperative Optical Coherence Tomography-Guided DMEK in Corneas with Poor Visualization&lt;/p&gt;

PurposeTo assess the utility of microscope-integrated intraoperative optical coherence tomography (Mi-OCT) for performing Descemet membrane endothelial keratoplasty (DMEK) in corneas with poor visualization.MethodsIt is a prospective interventional case series that included 25 consecutive cases of corneal decompensation with poor visualization that underwent Mi-OCT-guided DMEK at a tertiary eye care centre. The main outcome measures were graft attachment on day 3 and requirement for re-bubbling.ResultsThe etiology for corneal decompensation was pseudophakic bullous keratopathy (n=17), Fuchs endothelial corneal dystrophy (n=4), failed graft (n=2), iridocorneal endothelial syndrome (n=1) and failed Descemet stripping automated endothelial keratoplasty (n=1). Complete graft attachment was noted in 72% of cases. Graft detachment was noted in 16% of cases which required re-bubbling. No intervention was done for shallow peripheral detachment (n=2) and peripheral Descemet membrane (DM) fold (n=1). All grafts were attached at six-months follow-up. The mean corrected distance visual acuity and central corneal thickness improved from 1.4 ± 0.5 logMAR and 799.6 ± 110.9 µm at baseline to 0.3 ± 0.3 logMAR and 536.28 ± 11.44 um at six months. Mi-OCT was helpful in visualizing areas of peripheral anterior synechiae, missing DM, retained DM tags after descemetorhexis, DMEK roll configuration and orientation in the injector and anterior chamber, interface fluid and peripheral folds in the DMEK graft.ConclusionMi-OCT helps in identification of the anatomy and dynamics of the host DM, DM roll and anterior chamber in cases with poor visualization and is a useful tool while performing DMEK in such cases.

Orientation of Cone-Beam Computed Tomography Image: Pursuit of Perfect Orientation Plane in Three Dimensions—A Retrospective Cross-Sectional Study

Abstract Objective This study aimed to evaluate the reproducibility of nine reference planes used in orientation of as-received cone-beam computed tomography (CBCT) images in all three dimensions. Materials and Methods The study was conducted on CBCT images of 15 adult subjects (mean age 21.2 ± 5.8 years). The anonymized CBCT images were oriented using five different methods created from nine reference planes by two experienced orthodontists. For each subject, pitch, yaw, and roll changes with five orientation methods were recorded twice by each observer. Statistical Analysis The inter- and intraobserver agreement was tested using intraclass correlation (ICC) and Bland–Altman plot. The intra- and interobserver error was analyzed using paired t-test. Analysis of variance and paired t-test were used to analyze the differences among the various pitch, roll, and yaw orientation planes. Results Inter- and intraobserver agreement (ICC, 0.9) was excellent for all the nine reference planes. The interobserver reliability showed statistically significant differences for four planes namely Frankfort horizontal plane constructed on right side (p = 0.014) and left side (p = 0.000), transorbital plane (p = 0.001), and midsagittal plane on top view (p = 0.036); however, the mean differences were clinically insignificant. Conclusion The landmark-based nine reference planes used in this study to orient CBCT images showed good reproducibility. Therefore, these reference planes can be used to orient CBCT images and can be incorporated into automated software.

Onset of Convection in an Inclined Anisotropic Porous Layer with Internal Heat Generation

The onset of convection in an inclined porous layer which is heated internally by a uniform distribution of heat sources is considered. We investigate the combined effects of inclination, anisotropy and internal heat generation on the linear instability of the basic parallel flow. When the Rayleigh number is sufficiently large, instability occurs and a convective motion is set up. It turns out that the preferred motion at convection onset depends quite strongly on the anisotropy ratio, ξ , and the inclination angle. When ξ &lt; 1 the preferred motion is in the form of longitudinal rolls for all inclinations. When ξ &gt; 1 transverse rolls are preferred for small inclinations but, at high inclinations, longitudinal rolls are preferred. At intermediate inclinations the preferred roll orientation varies smoothly between these two extremes.