Yaw Deviation Research Articles

Test-re-test reliability and dynamics of the Fukuda-Unterberger stepping test.

The Fukuda-stepping-test (FST), i.e., repetitive walking on the spot while blindfolded, has been proposed as a means to assess the integrity of the vestibular pathways. While its sensitivity to detect abnormalities in patients is limited, it may be useful in studying the physiology of the subjective-straight-ahead (SSA). Considering reported systematic shifts in SSA in humans, we hypothesize that such asymmetries arise from individual differences in the orientation/configuration of the macular organs and in central processing of vestibular input. We hypothesize that such asymmetries are stable over time in individual subjects. Alternatively, such asymmetries may arise from random noise in the sensory/motor systems involved, demonstrating low reproducibility over time. Twenty-four subjects walked on the spot over 60 s while blindfolded (n = 6 trials per subject). Using an inertial measurement unit (IMU) placed at the chest, angular deviations were recorded and compared to manually-measured final positions. Both static (direction, magnitude) and dynamic (time-to-onset of deviation, pattern of deviations) parameters were retrieved from the yaw slopes. Significant deviations were found in 15/24 participants for the manual measurements (leftwards = 8; rightwards = 7), whereas when using the IMU-sensor 13/24 participants showed significant shifts (leftwards = 9; rightwards = 4). There was a high correlation (0.98) between manually measured rotation angles (average absolute deviations = 58.0 deg ± 48.6 deg; intra-individual variability = 39 deg ± 24 deg) and sensor-based yaw slopes (1.00 deg/s ± 0.88 deg/s; 0.67 deg/s ± 0.41 deg/s). Relevant yaw deviation was detected 22.1 s ± 12.3 s (range = 5.6 s-59.2 s) after the onset of marching (no relevant yaw-deviation in 15/139 measurements), showing a mostly linear behavior over time. We observed significant inter-individual variability in task performance in the FST, reproducing findings from previous studies. With test-re-test reliability being moderate only, but at the same time observing a preference in the side of shifts in most trials and subjects, we conclude that likely both individually varying estimates of straight-ahead and random noise contribute to the pattern of angular deviations observed. Using an IMU-sensory based approach, additional dynamic parameters could be retrieved, emphasizing the value of such a quantitative approach over manual measurements. Such an approach may provide useful additional information to distinguish patients from healthy controls.

Trajectory Tracking of Autonomous Vehicle Using Clothoid Curve

This paper proposes a clothoid-curve-based trajectory tracking control method for autonomous vehicles to solve the problem of tracking errors caused by the discontinuous curvature of the control curve calculated by the pure pursuit tracking algorithm. Firstly, based on the Ackerman steering model, the motion model is constructed for vehicle trajectory tracking, Then, the position of the vehicle after the communication delay of the control system is predicted as the starting point of the clothoid control curve, and the optimization interval of the curve end point is determined. The clothoid control curves are calculated, and their parameters are verified by the vehicle motion and safety constraints, so as to obtain the optimal clothoid control curve satisfying the constraints. Finally, considering the servo system response delay time of the steering system, the steering angle target control value is obtained by previewing the curvature of the clothoid control curve. The field experiment is conducted on the test road, which consists of straight, right-angle turns and lane-change elements under three sets of speed limitations, and the test results show that the proposed clothoid-curve-based trajectory tracking control method greatly improved the tracking accuracy compared with the pure pursuit method; in particular, the yaw deviation is improved by more than 50%.

An equivalent source method for removal of attitude-induced responses in drone-towed magnetic scalar gradiometry data

SUMMARY Drone-towed scalar field gradiometry surveys conducted in windy conditions or under self-excited oscillations generate attitude-induced responses that can hinder the geological interpretation. Here, we present a gradiometric equivalent source method (GESM) to remove these attitude-induced responses by interpolating and continuing the measured gradiometry data to new idealized pseudo-sensor positions free of any attitude deviations. In addition, we present transverse horizontal difference (THD) data from a precisely positioned drone-towed horizontal gradiometry survey collected in Nautanen, northern Sweden. Analysing the Nautanen survey’s positional data revealed that the gradiometer system exhibited directional-dependent yaw deviations with periods of unpredictable attitude deviations. Based on synthetic THD data created using the Nautanen survey’s positional data, these deviations manifest as line-to-line striping and short-wavelength oscillations in the THD maps. Applying GESM to the synthetic THD data removes these attitude-induced THD responses with satisfactory accuracy compared to the true THD values. Furthermore, on the actual THD data collected in Nautanen, applying GESM improved the continuity of anomalies, significantly improving the interpretation of the data. The results suggest that including GESM in the data processing of drone-towed gradiometry surveys, given precise positional information via an onboard GNSS-IMU system, ensures high-quality geological interpretation even in windy conditions or in high-gradient areas.

Does Intraoperative Navigation Improve Implant Position Accuracy in Orbital Fracture Repair?

Purpose: Our aim was to determine if intraoperative navigation (ION) improved radiographic outcomes in patients undergoing delayed primary/secondary orbital reconstruction for inferomedial defects, as measured by volume restoration, enophthalmos correction, and positional accuracy of implants. Patients and Methods: A prospective quasiexperimental study was performed to compare two groups of patients requiring orbital reconstruction. Use of ION was the exposure evaluated. Outcome measures were (i) intraorbital volume and enophthalmos evaluated radiologically, (ii) implant position accuracy, and (iii) procedural duration. Data were analyzed statistically to compare variance between groups. Results: Forty patients (6 females and 34 males) were recruited into the study with a mean age of 27.3 years. The study group demonstrated a greater reduction of intraorbital volume (0.49 cu.cm; p = 0.02) and enophthalmos (0.72 mm; p = 0.001). Implant positioning was more accurate using ION, with less mediolateral (p = 0.006) and yaw (p = 0.04) deviations. Surgical time for implant positioning was shorter by 17 min, with navigation (p < 0.001). Conclusion: The use of ION demonstrated radiographic improvements in volume restoration, enophthalmos correction, as well as accuracy of implant positioning, in patients requiring delayed primary/secondary orbital reconstruction.

A novel use of 3D-printed template in vaginal HDR brachytherapy

PURPOSEThe High-Dose-Rate (HDR) vaginal cylinder treatment is typically designed using the initial CT, while the subsequent implants are verified using rudimentary methods (i.e., visual inspection, ruler measurements, etc.) and/or X-ray imaging. We are proposing the use of a 3D-printed individualized template that could provide simple and reproducible vaginal cylinder insertion. MATERIAL AND METHODSSix patients were included in the study with prescriptions of 6 Gy/fraction for 2 to 5 fractions (total 27 treatments). The first 1 to 2 treatments were delivered without the template and the rest with the CT-based 3D-printed templates. Cone beam CTs (CBCTs) were acquired to verify the cylinder placement for all treatments. D2cc of the bladder and rectum are recorded on both planning CT and the following on-treatment CBCTs. RESULTSBy using the templates, the tip position variation on average (±1 SD) reduced from 0.8±0.5 cm to 0.6±0.4 cm, and angular difference decreased from 5.3±3.5° to 4.7±2.4°. The pitch and yaw deviation are reduced from 0.9 ± 5.8° and 0.4±2.9° to 0.0±3.9° and -0.2±3.0°, respectively. The deviation of D2cc to bladder from the plan reduced from 6±4% to 5±3%, and rectum from 5±2% to 4±4%. CONCLUSIONThe 3D-printed patient-specific cylinder templates could potentially improve the geometrical reproducibility of cylinder treatments at no cost of additional imaging. The D2cc for the bladder and rectum are determined by the treatment length rather than their respective volumes.

Research on Yaw Deviation of Wind Turbine Based on Dynamic Time Warping

The yaw deviation is common in the process of wind turbine generation. Excessive wind deviation will cause a series of problems, such as the reduction of wind turbine generating efficiency, the wear of main shaft, gearbox failure. In this paper, a wind deviation detection algorithm based on dynamic time warping is proposed by using data in supervisory control and data acquisition (SCADA) of wind turbine. Through dynamic time warping (DTW), the wind speed is divided into three sections: ascending, descending and stationary. Then the wind speed is divided into three sections, and the wind deviation is obtained by fitting the function of wind angle and power. Compared with the traditional algorithm, the wind deviation detection algorithm proposed in this paper is more stable and accurate.

Numerical Simulation Study on the Effects of Course Keeping on the Roll Stability of Submarine Emergency Rising

A direct numerical simulation method based on Reynolds Average Navier–Stokes (RANS) equations is used to carry out numerical prediction studies of submarine emergency rising in this paper. Firstly, a numerical simulation of the nonpropelled model without rudder manipulating is accomplished as the basis of this study. The numerical prediction results are in good agreement with the experimental data, which proves the feasibility and accuracy of the direct numerical simulation method. Meanwhile, both model tests and numerical simulation results reveal the strong coupling effect between roll and yaw motions during the underwater ascending process. Based on the above observation and analysis, another two numerical simulations, whose grids are identical with the non-manipulation simulation, are conducted respectively under the condition of rudder steering, i.e., course keeping simulation and self-propulsion simulation. An optimized S surface controller based on conditional determination is designed to manipulate the rudders. As a result, the yaw angle of the latter two simulations is limited within the range of 0.2° and 0.8° respectively, proving the effectiveness of the S surface controller. Correspondingly, the maximum roll angle is reduced by 96% and 70% respectively, which demonstrates that the roll stability is significantly enhanced by improving the course keeping ability of the model. Moreover, it is also proven from the perspective of reverse verification that, the excessive yaw deviation is the root cause of emergency rising roll instability for the situation of incidence angle lower than 30°.

Experimental investigation on roll stability of blunt-nose submarine in buoyantly rising maneuvers

The roll stability of submarine buoyantly rising is investigated by means of kinematics model test in this paper. The physical model design, similarity criteria and experimental procedures are presented in detail for simulating emergency rising of the real submarine with similar properties. Experimental results reveal that the roll and yaw are strongly coupled and interacted. In addition, excessive roll occurs inevitably when underwater drift angle is larger than 5°. In other words, the yaw instability is the most key coupled factor of increasing drift angle as well as generating snap roll, which eventually aggravates the excessive roll. Furthermore, the rising sternplane angle is essential to pitch up nose because a larger pitch rate is conducive to maintain stable heading angle. In summary, by keeping yaw deviation as low as possible helps to limit the increase of drift angle, and further delay the onset of snap roll. Therefore, the excessive roll can be avoided through optimal control of initial speed, blown ballast longitudinal centroid and sternplane angle. The experimental results can provide manipulations recommendations for the emergency rising of the real submarine.

25-Influence of vestibular neurectomy on posture of the head and shoulder

Introduction The aim of this study was quantitative evaluation of vestibular head tilt in 3 D. Patients after vestibular neurectomy served as model of acute unilateral vestibular failure. Methods Real time measurement of head and shoulder posture was done in eleven patients who underwent vestibular neurectomy for vestibular Schwannoma. All patients were examined within two weeks. Angle deviations of the head in pitch, yaw and roll planes and deviation of the shoulders in yaw and roll planes were calculated. Results were compared with a control group of 130 healthy persons. Results There was significant head tilt in the roll plane towards operated ear. No correlation between head rotation in yaw and pitch planes was observed. Position of shoulders tended to compensate head rotation in six of eleven patients. Range of movements of head was increased. Conclusions Our study finds significant head tilt in roll towards weak labyrinth – part of vestibular ocular tilt reaction. Contrary to expectations, no systemic head rotation in yaw plane was found.

Guineafowl with a twist: asymmetric limb control in steady bipedal locomotion.

In avian bipeds performing steady locomotion, right and left limbs are typically assumed to act out of phase, but with little kinematic disparity. However, outwardly appearing steadiness may harbor previously unrecognized asymmetries. Here, we present marker-based XROMM data showing that guineafowl on a treadmill routinely yaw away from their direction of travel using asymmetrical limb kinematics. Variation is most strongly reflected at the hip joints, where patterns of femoral long-axis rotation closely correlate to degree of yaw divergence. As yaw deviations increase, hip long-axis rotation angles undergo larger excursions and shift from biphasic to monophasic patterns. At large yaw angles, the alternately striding limbs exhibit synchronous external and internal femoral rotations of substantial magnitude. Hip coordination patterns resembling those used during sidestep maneuvers allow birds to asymmetrically modulate their mediolateral limb trajectories and thereby advance using a range of body orientations.

无人机滑跑线性化建模与增益调节纠偏控制

As the three wheel taxiing stage of an Unmanned Aerial Vehicle (UAV) is the most vulnerable in whole flight process, this paper explores linear modeling and a gain scheduling control method of nose wheel steering turning for a tricycle-undercarriage UAV in taxiing on the ground. The force of three wheel taxiing of the UAV was analyzed, and its nonlinear mathematical model was established considering the effect of engine torque, thrust misalignment and ground angles. Then, the nonlinear model was linearized using small perturbation theory under reasonable assumptions, and the transfer function was deduced by using the nose wheel steering angle as a input and the yaw rate, yaw angle, and lateral deviation as outputs. The three gain scheduling control law through nose wheel steering turning was designed. Finally, the method was verified through a field taxiing test. The result shows that the most lateral position deviation is 0.3 m and the most yaw deviation is 4.5 under an initial yaw deviation of 3 and a lateral position deviation of 0.2 m during the process of taxiing from rest to the speed of 32 m/s. Moreover, the crosswind disturbance of not more than 4.6 m/s was inhibited. The control law designed by using the method above is robustness to the uncertain factors of the runway, tire cornering stiffness and tire deflection and has been applied to a practical UAV successfully.

Analysis of Pitch and Yaw Deviations Using an Aid-Pillow for the Head and Neck Cancer on the TomoTherapy

The aim of this study was to analysis of the pitch and yaw deviations with or without using an aid-pillow for the head and neck cancer on the TomoTherapy. A total of 14 head and neck patients were selected to without-group (n=7) and with-group (n=7). A total of 333 MVCT image sets used to evaluate the translational (lateral, longitudinal and vertical) and rotational adjustments (pitch, roll and yaw) with 153 and 180 MVCT image sets at without- and with-group, respectively. Deviations of without- and with-groups were 0.12o and 0.09 o , respectively at pitch. And, deviations without- and with-groups were 0.47 o and 0.17 o , respectively at yaw. In generally, with-group had reduced than without-group for the pitch and yaw deviations. Therefore, using an aid-pillow, it will able to increase the reproducibility of treatment for the head and neck cancer patients on the TomoTherapy.

Self-motion perception and vestibulo-ocular reflex during whole body yaw rotation in standing subjects: The role of head position and neck proprioception

Self-motion perception and vestibulo-ocular reflex (VOR) were studied during whole body yaw rotation in the dark at different static head positions. Rotations consisted of four cycles of symmetric sinusoidal and asymmetric oscillations. Self-motion perception was evaluated by measuring the ability of subjects to manually track a static remembered target. VOR was recorded separately and the slow phase eye position (SPEP) was computed. Three different head static yaw deviations (active and passive) relative to the trunk (0°, 45° to right and 45° to left) were examined. Active head deviations had a significant effect during asymmetric oscillation: the movement perception was enhanced when the head was kept turned toward the side of body rotation and decreased in the opposite direction. Conversely, passive head deviations had no effect on movement perception. Further, vibration (100 Hz) of the neck muscles splenius capitis and sternocleidomastoideus remarkably influenced perceived rotation during asymmetric oscillation. On the other hand, SPEP of VOR was modulated by active head deviation, but was not influenced by neck muscle vibration. Through its effects on motion perception and reflex gain, head position improved gaze stability and enhanced self-motion perception in the direction of the head deviation.

Age-related kinematic changes in late visual-cueing during obstacle circumvention

On a daily basis, we are challenged by common environmental obstacles (e.g. street posts) that require simple and often rapid modifications to our gait patterns to avoid collisions. Poor vision appears to be responsible for important reductions in postural stability during gait; and therefore, individuals with impaired vision, such as the elderly, may be at a greater risk of falling, especially under conditions where stepping avoidance strategies may be constrained by the environment. The purpose of the current study was to examine the body segment and eye-gaze reorientation strategy, role of base of support, as well as visual areas of interest attended to by healthy young (YA) and older adults (OA) when only given limited time, one stride, to prepare for an obstacle circumvention task. Six YA and six OA were asked to perform ten walking trials which required them to circumvent an obstacle in their travel path. Participants used one of two avoidance strategies, either lead leg crossing-over trail leg (narrow base of support) or lead leg stepping-out (wide base of support). Results indicate that base of support constraints did not affect segment reorientation sequence in either age group. The general segment reorientation sequence in YA was initiated by trunk yaw and head yaw, followed by gaze and finally, by M-L foot deviation. No trunk roll deviations were observed. In OA, the general segment reorientation sequence was the following: trunk yaw and trunk roll, gaze and finally, M-L foot deviation. No head yaw deviations were observed. Our findings suggest that YA utilized a foot placement strategy to perform the transient change in travel direction while OA relied on a hip strategy. In addition, YA spent more time gazing straight ahead at the obstacle and the wall, while OA spent more time looking at the ground. This strategy indicates that OA use a more cautious strategy to safely avoid the obstacle. Findings from the present work contribute further knowledge regarding locomotor adjustments during a common, and complex, everyday task in young and older adults.

A Vision-Based Automatic Landing Method for Fixed-Wing UAVs

In this paper, a vision-based landing system for small-size fixed-wing unmanned aerial vehicles (UAVs) is presented. Since a single GPS without a differential correction typically provide position accuracy of at most a few meters, an airplane equipped with a single GPS only is not guaranteed to land at a designated location with a sufficient accuracy. Therefore, a visual servoing algorithm is proposed to improve the accuracy of landing. In this scheme, the airplane is controlled to fly into the visual marker by directly feeding back the pitch and yaw deviation angles sensed by the forward-looking camera during the terminal landing phase. The visual marker is a monotone hemispherical airbag, which serves as the arresting device while providing a strong and yet passive visual cue for the vision system. The airbag is detected by using color- and moment-based target detection methods. The proposed idea was tested in a series of experiments using a blended wing-body airplane and proven to be viable for landing of small fixed-wing UAVs.

A model for insect locomotion in the horizontal plane: Feedforward activation of fast muscles, stability, and robustness

We develop a neuromechanical model for running insects that includes a simplified hexapedal leg geometry with agonist–antagonist muscle pairs actuating each leg joint. Restricting to dynamics in the horizontal plane and neglecting leg masses, we reduce the model to three degrees of freedom describing translational and yawing motions of the body. Muscles are driven by stylized action potentials characteristic of fast motoneurons, and modeled using an activation function and nonlinear length and shortening velocity dependence. Parameter values are based on measurements from depressor muscles and observations of kinematics and dynamics of the cockroach Blaberus discoidalis; in particular, motoneuronal inputs and muscle force levels are chosen to approximately achieve joint torques that are consistent with measured ground reaction forces. We show that the model has stable double-tripod gaits over the animal's speed range, that its dynamics at preferred speeds matches those observed, and that it maintains stable gaits, with low frequency yaw deviations, when subject to random perturbations in foot touchdown and lift-off timing and action potential input timing. We explain this in terms of the low-dimensional dynamics.

Evaluation of Lane Departure Warnings for Drowsy Drivers

Lane departure warning (LDW) is a driver warning system designed to reduce the number of unintended lane departures. We addressed warning effectiveness and customer acceptance when the unintended lane departures are the result of drowsy driving. Thirty-two adults who were sleep deprived for 23 hours participated in the study and drove Ford's VIRTTEX driving simulator. Four Human Machine Interfaces (HMI) for LDW were evaluated: Steering Wheel Torque, Rumble Strip Sound, Steering Wheel Vibration and Head Up Display. A yaw deviation technique was used to produce controlled lane departures in the first two hours of the drive while for the last 20 minutes driver-initiated lane departures were analyzed. The Steering Wheel Vibration HMI, accompanied by Steering Wheel Torque, was found to be the most effective HMI for LDW in a group of drowsy drivers, with faster reaction times and smaller lane excursions. The Vibration HMI was also perceived by the drowsy drivers to be acceptable and helpful.

Identification Method For Scale, Pitch And YawDeviations With Linear Measurements

This paper suggests a new method of identification for both translational and rotational deviations of a prismatic mobility with solely linear optics. A mathematic model is developed for laser interferometer measurements and a matrix identification system is built for calculating scale, pitch and yaw deviations of an X axis. The system is solved using the pseudo-inverse method. A sensitivity study of this solution, with regards to the system uncertainties, is achieved using a jacobian matrix. The benefits of t h s new method compared to angular optic measurements are given using analytical equations. Finally, experimental results are presented.

四輪操舵車両の車線自動追従制御の検討 : 横運動とヨー運動の理論的考察(機械力学,計測,自動制御)

This paper investigates the use of four-wheel-steering system for the control of vehicle, in the context of automatic lane-keeping. Four-wheel-steering system provides two independent control inputs which can much enhance handling and stability, thus it is expected that such system can also provide satisfactory lane-keeping performance. Here, lateral deviation of front and rear virtual points are proposed to be state variables in control system design procedure instead of lateral deviation at center of gravity and yaw deviation. As a result, decoupling of lateral and yaw motion control can be realized during lane-keeping maneuver. Finally, simulations in straight and curved lane-keeping are conducted to investigate the validity of the proposed control system.

The Perception Of The Visual Flow Field By Flying Locusts: A Behavioural And Neuronal Analysis

ABSTRACT Tethered locusts (Locusta migratoria’) were stimulated with an artificial flow field (FF) device, which produced the visual effect of forward motion (‘progressive flow field’) or backward motion (‘regressive flow field’). Progressive FFs (contrast frequencies, CF, of 2–10Hz and angular period of pattern, λ, of 33° or 42°) can initiate and maintain flight, even without frontal wind. Regressive FFs inhibit flight. The locusts adjust their wingbeat frequency (and thus probably their flight speed) in response to a gradually changing FF contrast frequency; they fly faster when the FF motion is faster and vice versa. Sudden decelerations of FF motion, however, are transiently counteracted by increases in wingbeat frequency. Rotational movements of the entire flow field device, simulating yaw and/or roll deviations during progressive flight, elicit compensatory steering responses of the head and abdomen. Corrective steering behaviour and simultaneously presented FF stimuli do not influence each other. A descending interneurone (FFDN1) is described which reports the progressive visual FF. It receives input from both compound eyes, prefers FFs on the ventral retina, and responds over the range of contrast frequencies of 1–20 Hz. Its response is tonic and adapts only weakly to maintained FF stimuli. It follows changing FF velocities but tends to counteract sudden decelerations. In addition, FFDN1 is excited by frontal and contralateral wind and inhibited by ipsilateral wind. It is also excited by the flight motor and sometimes by light-off at the ocelli. The neurone is generally insensitive to simulated roll and yaw deviations. Electrical stimulation of the cell can result in lifting of the abdomen, inhibition of dorsal neck muscle activity, and occasional flight muscle spikes. FFDN1 is probably a sister cell of the previously described DNM neurone, but the two could be one neurone with very variable responses. At least one further descending interneurone responding selectively to progressive flow fields, but with a different morphology, is present in the central nervous system. Additionally, two different thoracic intemeurones have been found with properties suggesting that they are postsynaptic to FFDNs and presynaptic to the flight circuitry. 5. The possible role of the visual flow field in the regulation of flight activity of locusts and other insects is discussed.