Pitch Plane Research Articles

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.

Unmanned air vehicles for targeting tasks

Unmanned aerial vehicle in surveillance and reconnaissance operations are well known with its flight operations confining to the lateral and longitudinal plane where the altitude is maintained constant. The objective in these operations is to have a wide field of view when camera is mounted underneath the aircraft. However, in obstacle detection algorithms as well as in weapon-target assignments by an unmanned combat air vehicle, the sensors such as cameras and radars are mounted along the X direction of the body fixed frame. The unmanned vehicles with such sensor locations are expected to offer obstacle-camera and weapon-target line-of-sight engagements. These operations by the unmanned vehicles are referred as targeting tasks. In this paper, a procedure to use unmanned vehicles as targeting systems in pitch plane is presented with respect to a fixed order controller at the inner loop. The remote pilot's inputs at the outer loop is disengaged and to mimic these inputs, various flight path angles are scheduled thus depicting autonomous characteristics. Illustrations to depict targeting tasks are provided.

Model Based Compensator Design for Pitch Plane Stability of a Farm Tractor with Implement

An agricultural tractor finds extensive application in agriculture and is used with various types of implements. When it is driven with an implement attached to its rear, on-road or on uneven terrain, it experiences excessive vibrations in the pitch plane, which results in front wheel lift-off as an extreme scenario. The objective of this paper is to minimize these vibrations caused due to road disturbances by automatically controlling the lifting and lowering of the implement with the help of a hydraulic actuator. Using a Linear Time Invariant (LTI) approximation, a model relating the current input and the force variation output on the implement was developed based on the analysis of frequency response and time response. The data used in this process were acquired from an experimental setup consisting of control valves, hydraulic actuator and hitch system. Since the lifting and lowering of the implement is controlled by separate solenoid valves, individual models were obtained for each of them. These models were the used to design a lag compensator in order to reduce the gain of the system in the desired frequency range while maintaining the control variable (current) within its design limits. Results showed that the designed lag compensator exhibited a positive performance by reducing the variation of force on the hitch point by 95.8% during lifting and 87.2% during lowering.

Problems of Group Pursuit of a Target in a Perturbed Environment

In this paper, we consider some game-theory problems of group pursuit of a target under perturbations. Here, the players are unmanned flight vehicles (FVs) whose mathematical models are given by transfer functions that describe a double-loop control system with an autopilot and certain settings to provide the necessary stability of flight. According to the separation principle, without loss of generality, solutions are considered in a pitch plane. In the case of an antagonistic game, the velocity of the target is higher than that of the pursuers. The problem is solved when one of the pursuers gets close enough to the target or when the target manages to evade the pursuers. The target tracking problem implies that a randomly-arranged FV group approaches the target and flights near it during a specified time period. The low-velocity target seeks to evade the pursuers as far as possible. Finally, in the path following problem, each FV needs to fly along the trajectory given by the motion of a corresponding reference target. In the process of problem solving, each FV implements a set of heuristic behavioral strategies in a perturbed environment by following the rules of pitch angle and velocity selection. In the experimental part of this paper, some situations typical for these problems are modeled.

Research on dynamic behaviors of wheel loaders with different layout of hydropneumatic suspension

The traditional wheel loader is built without any axle suspension and experiences severe vibration. Three different layouts of hydropneumatic suspension, namely, unconnected strut (UCS), interconnected in roll plane (IC-R) and interconnected in roll and pitch plane (IC-RP), are installed on the wheel loader to improve ride comfort. This study mainly focuses on the damping effect of different layouts of suspensions and investigates whether the suspensions will affect the driving and operation stability of the wheel loader. The multibody model of the wheel loader with hydropneumatic suspension is developed by RecurDyn in co-simulation with MATLAB/Simulink. Detailed analysis was performed as the wheel loader was traveling on a C-class road, turning on a flat road, and scooping and unloading crushed rocks. Results showed that (1) the three layouts of suspensions can greatly reduce the vector sum of weighted acceleration; (2) the UCS suspension affects both the driving and operation stability of the wheel loader, and the IC-R suspension affects the operation stability when the wheel loader scoops and unloads crushed rocks, (3) the IC-RP suspension with anti-roll and anti-pitch functions has little effect on the driving and operation stability of the wheel loader.

Gravitational and Somatosensory Influences on Control and Perception of Roll Balance

Blindfolded subjects used a joystick to orient themselves to the direction of balance in a device programmed to exhibit inverted pendulum behavior in the roll plane; they indicated with a trigger press when they were at that location. Our goal was to determine how otolith and somatosensory information about the gravitational vertical influenced the ability to locate the direction of balance. The subjects (N = 12) were tested in each of three orientations of the body roll plane: vertical (Upright), 45° back (45_Degree), and 90° back (Supine), which provided progressively less salient otolith and somatosensory information about roll orientation with regard to the direction of gravity. For each pitch plane, subjects were tested with three directions of balance: 0° (aligned with the gravitational vertical in the Upright condition) and 30° right or left. The mean achieved and indicated orientations for the Upright and 45_Degree conditions were significantly displaced away from the direction of balance in the direction of gravity, with indicated angles less displaced. In the Supine condition, the mean achieved and indicated angles were closer to the direction of balance, but their within-trial standard deviations were significantly larger than in the Upright and 45_Degree conditions, which did not differ. This greater variability resulted from the frequent side to side "drifting" behavior that was a characteristic feature of the Supine condition only. These findings indicate that in the absence of vision accurate dynamic orientation requires gravity dependent shear forces on the otolith organs and body surface.Panic AS, Panic H, DiZio P, Lackner JR. Gravitational and somatosensory influences on control and perception of roll balance. Aerosp Med Hum Perform. 2017; 88(11):993-999.

Droplet Bouncing and Breakup during Impact on a Microgrooved Surface.

We experimentally investigate the impact dynamics of a microliter water droplet on a hydrophobic microgrooved surface. The surface is fabricated using photolithography, and high-speed visualization is employed to record the time-varying droplet shapes in the transverse and longitudinal directions. The effect of the pitch of the grooved surface and Weber number on the droplet dynamics and impact outcome are studied. At low pitch and Weber number, the maximum droplet spreading is found to be greater in the longitudinal direction than the transverse direction to the grooves. The preferential spreading inversely scales with the pitch at a given Weber number. In this case, the outcome is no bouncing (NB); however, this changes at larger pitch or Weber number. Under these conditions, the following outcomes are obtained as a function of the pitch and Weber number: droplet completely bounces off the surface (CB), bouncing occurs with droplet breakup (BDB), or no bouncing because of a Cassie to Wenzel wetting transition (NBW). In BDB and NBW, the liquid partially or completely penetrates the grooves beneath the droplet as a result of the wetting transition. The former results in droplet breakup alongside bouncing, while the latter suppresses the bouncing. These outcomes are demarcated on the Weber number-dimensionless pitch plane, and the proposed regime map suggests the existence of a critical Weber number or pitch for the transition from one regime to the other. CB and BDB are quantified by plotting the coefficient of restitution of the bouncing droplet and the volume of the daughter droplet left on the surface, respectively. The critical Weber number needed for the transition from CB to BDB is estimated using an existing mathematical model and is compared with the measurements. The comparison is good and provides insights into the mechanism of liquid penetration into the grooves. The present results on microgrooved surfaces are compared with published results on micropillared surfaces in order to assess the water-repelling properties of the two surfaces.

Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input.

Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs). Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain) was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly, proprioceptive deprivation heavily destabilizes BVF, even when visual control is provided.

Evidence of dynamic visual acuity impairment in asymptomatic mixed martial arts fighters.

Aim:The purpose of this study was to determine the amount of visual acuity loss with head movement in actively training mixed martial arts (MMA) fighters.Methods:Vestibulo-ocular reflex function of 22 asymptomatic, male MMA fighters (age = 29.2 ± 5.1) was assessed by taking the difference between static visual acuity and the dynamic visual acuity test, in both yaw and pitch planes.Results:The mean static visual acuity testing logMAR was -0.173 (standard deviation [SD] = 0.114). Mean dynamic visual acuity test values decreased with head movement to 0.196 logMAR (SD = 0.103) in yaw; p < 0.001, and to 0.283 logMAR (SD = 0.133) in pitch; p < 0.001.Conclusion:MMA fighters had a decay, beyond normal ranges, in visual acuity during head movement. These decreases may suggest vestibulo-ocular reflex impairment and were unrelated to self-reported concussion history. These results should be cautiously interpreted since there was not a control group.

Nonlinear integrated guidance and control based on adaptive backstepping scheme

PurposeThe purpose of this paper is to design an adaptive nonlinear controller for a nonlinear system of integrated guidance and control.Design/methodology/approachA nonlinear integrated guidance and control approach is applied to a homing, tail-controlled air vehicle. Adaptive backstepping controller technique is used to deal with the problem, and the Lyapanov theory is used in the stability analysis of the nonlinear system. A nonlinear model of normal force coefficient is obtained from an existing nonlinear model of lift coefficient which was validated by open loop response. The simulation was performed in the pitch plane to prove the benefits of the proposed scheme; however, it can be readily extended to all the three axes.FindingsMonte Carlo simulations indicate that using nonlinear adaptive backstepping formulation meaningfully improves the performance of the system, while it ensures stability of a nonlinear system.Practical implicationsThe proposed method could be used to obtain better performance of hit to kill accuracy without the expense of control effort.Originality/valueA nonlinear adaptive backstepping controller for nonlinear aerodynamic air vehicle is designed and guaranteed to be stable which is a novel-based approach to the integrated guidance and control. This method makes noticeable performance improvement, and it can be used with hit to kill accuracy.

Analysis of Subjective Postural Vertical in Pitch Plane in Patients with Pusher Behavior

Analysis of Subjective Postural Vertical in Pitch Plane in Patients with Pusher Behavior

Vibro-tactile and auditory balance biofeedback changes muscle activity patterns: Possible implications for vestibularimplants.

The two different types of balance prostheses being developed, implants and vibro-tactile/auditory feedback prostheses, rely on different measures to prove efficacy (those based on vestibular ocular reflexes versus balance control, respectively). Here we provide evidence that examining muscle activity might provide a useful alternative for both. The muscle activity of 6 bilateral vestibular loss (BVL) and 7 age-matched healthy controls (HC) was examined while standing eyes closed on a foam support surface. Pelvis and upper trunk angular movements were recorded in the roll and pitch planes. Surface EMG was recorded from the lower leg, trunk and upper arm muscles. BVL subjects were first assessed without feedback of pelvis sway, then received training with combined vibro-tactile and auditory feedback, before being re-assessed with feedback. Feedback reduced the amplitudes of pelvis and shoulder sway to values of HC without feedback. Both the level of background EMG activity and the EMG area amplitudes changed when feedback was provided in a manner consistent with the reduced amplitude modulation of muscle synergies of HC. The results of this study indicate that changed muscle synergy amplitudes underlie improvements in sway achieved by BVL subjects. The concept of this investigation may provide a means to prove efficacy for different types of balance prostheses, including implants.

Unmanned Aerial Vehicle Flight Control Evaluations Under Sensor and Actuator Faults

Nonlinear aircraft controlled by its linearized model based controller will be asymptotically stable if its trajectories originating from various initial conditions are all contained in the stability region (or the region of attraction). In such a stable aircraft, suppose a sensor or an actuator fault occurs. Depending upon the fault size, the stability region is modified. As a result, the trajectories for a potential failure to contain in the modified stability region could lead to flight control degradation. In this paper, first, a stability margin is determined to separate an acceptable fault size from an unacceptable fault. Secondly, with an acceptable fault size, the aircraft will remain stable in distorted stability regions. In this paper, admissible control inputs which generate the perturbed trajectories in the distorted stability regions is presented for safe unmanned aerial vehicle flight control evaluations. A three degree of freedom aircraft in pitch plane is considered to illustrate the stability margins and control inputs that are safe to operate the damaged aircraft.

Sensor fusions for constant thrust aircraft navigation in pitch plane

Constant thrust aircraft navigation is an altitude hold mode in air transportation systems, air refueling systems, traffic alert and collision avoidance system and automatic dependent surveillance broadcast based collision avoidance, as well as in surveillance operations of unmanned aerial vehicles. In pitch plane, determination of the elevator input options available to maneuver the aircraft from its altitude hold mode using constant thrust is an important problem. Such inputs are useful to avoid time critical obstacles or collisions sensed in the horizontal plane. In this paper, it is shown that sensor fusions in feedback path are particularly attractive to generate such elevator inputs. Given the nonlinear aircraft’s linear time-invariant model based controllers at the inner loop, constant thrust aircraft navigation requires these controllers derived for sensor fusions. That is, in state feedback format, usually an identity matrix is considered for all state variables as measurements whereas in the present paper, particular combinations of the sensors in the feedback path are considered. A procedure to derive the stabilizing controllers that accommodates the sensor fusions is presented in partial pole placement framework. Then the nonlinear aircraft embedded with such controllers is simulated with capabilities to avoid the time critical obstacles. Examples by using a micro air vehicle model are illustrated.

A dual-axis single-proof-mass angular accelerometer for a vestibular prosthesis.

A dual-axis single-proof-mass angular accelerometer has been developed for a vestibular prosthesis. Designed to sense head rotations both in the yaw and the pitch planes, the output of the inertial sensor may be coded as amplitude or rate modulated biphasic current pulses to stimulate vestibular nerves. Fabricated with a high aspect ratio commercial process, a sensor with small form factor (1.4 mm × 0.8 mm) is achieved with a scale factor of 95.5 μV/rad/sec2 and 145.8 μV/rad/sec2 in the yaw and the pitch planes, respectively. Superior linear acceleration rejection was demonstrated for both rotating axis, and an overall power consumption of 296 μW was estimated including sensor and interface circuit.

Uncertainty and disturbance estimator based sliding mode control of an autonomous underwater vehicle

In this paper, a highly non-linear model of an autonomous underwater vehicle (AUV) with six degrees-of-freedom is linearized to yaw (horizontal) and pitch (vertical) planes under several working conditions. For controlling steering and diving planes, an uncertainty disturbance estimator based sliding mode control (UDE-SMC) scheme is proposed and designed separately as single-input single-output controllers for horizontal and vertical plane dynamics of an AUV system. The proposed UDE-SMC scheme is effective in compensating the uncertainties in the hydrodynamic parameters of the vehicle and rejecting unpredictable disturbances due to ocean currents. The UDE-SMC consists of an equivalent and estimated lumped uncertain terms to suppress the effect of external disturbances and parametric uncertainties acting on the vehicle dynamics. Numerical simulations were performed to validate the UDE-SMC.

Path integration in 3D from visual motion cues: A human fMRI study

While neural correlates of path integration on a yaw plane have been studied extensively, much less is known about path integration in three-dimensions (3D). Here we used fMRI during virtual navigation within tunnels in pseudo-3D. We found that the same visual motion stimuli are encoded differently in the brain depending on whether they represent displacements within the yaw plane or within the pitch plane. The yaw plane is more represented in the hippocampus while the pitch plane is more represented in the angular gyrus (AG) and in the posterior inferior temporal gyrus (pITG), known to be involved in 3D space encoding. In addition, a region in pITG, located just above the previous one, showed two different patterns with multi-voxel analysis, separately coding for the pitch and yaw planes. These results suggest that information encoded within pITG about the yaw plane may be exchanged with the hippocampus, while information about the pitch plane may be exchanged with the AG.

Nonlinear cooperative UAV maneuvers in pitch plane

Flight formations of unmanned aerial vehicles may require coordinated motion in pitch for such tasks as terrain tracking. They maintain a constant altitude over varying terrain elevations and may assist collision avoidance where an altitude change is needed rather than a lateral change. In these maneuvers, controller ability to adjust relative altitude positions (as attractions and repulsions) of the aircraft subject to stability constraints that ends up in a formation shape should be demonstrated. The ascent and descent flight control mode combinations of each unmanned aerial vehicle participating in the formation generally offer the attractions and repulsions. In this paper, centralized and decentralized controller abilities to develop a cooperative formation with flight control modes made of transients and steady states are presented by using two and more than two homogenous unmanned aerial vehicles. A challenge in presenting such a formation by using a centralized controller is its design itself. Generally, eigenstructure properties depict flight control mode variations. That is, variations in closed-loop poles offered by a structurally varying centralized controller compatible to its reconfigurable communication patterns are sufficient to capture the flight control mode options. Hence, a procedure to design such a controller using real parameters is presented.

Subjective body vertical: a promising diagnostic tool in idiopathic normal pressure hydrocephalus?

Postural instability is a frequent symptom of patients with idiopathic normal pressure hydrocephalus (iNPH), and might be due to the misperception of body verticality. The objective of this study was to assess the usefulness of the subjective body vertical (SBV) as a potential tool for diagnosing iNPH. Twenty patients with iNPH underwent tests of SBV in the pitch and roll planes before and after cerebrospinal fluid (CSF) drainage. Ten patients with other central gait disorders served as controls and also underwent tests for SBV. Before CSF drainage, patients with iNPH showed an impaired verticality perception in the pitch plane with a significant backward deviation of the SBV as compared to the control group (iNPH: mean±SD -3.7±3.6°; control group: -0.8±2.2°; t value=-2.30, p t-test=0.03). After CSF drainage, the SBV of the iNPH patients normalized for the pitch plane (-0.9±1.9°). There was a correlation between the backward deviation of the SBV and the ventricular enlargement of the frontal horns (Evan's index; r=-0.52; p Pearson=0.02). An even stronger correlation was found with the enlargement of the third ventricle (Thalamus index; r=-0.64; p Pearson=0.002). The new and clinically relevant finding of this study is that verticality perception of patients with iNPH is primarily impaired the pitch plane, and it improves after CSF drainage. This disturbance in pitch might be due to a bilateral central vestibular dysfunction of the thalamus. Determination of the SBV in pitch promises to increase diagnostic accuracy in the cases of suspected iNPH.

Verticality Perceptions Associate with Postural Control and Functionality in Stroke Patients.

Deficits of postural control and perceptions of verticality are disabling problems observed in stroke patients that have been recently correlated to each other. However, there is no evidence in the literature confirming this relationship with quantitative posturography analysis. Therefore, the objectives of the present study were to analyze the relationship between Subjective Postural Vertical (SPV) and Haptic Vertical (HV) with posturography and functionality in stroke patients. We included 45 stroke patients. The study protocol was composed by clinical interview, evaluation of SPV and HV in roll and pitch planes and posturography. Posturography was measured in the sitting and standing positions under the conditions: eyes open, stable surface (EOSS); eyes closed, stable surface (ECSS); eyes open, unstable surface (EOUS); and eyes closed, unstable surface (ECUS). The median PV in roll plane was 0.34° (-1.44° to 2.54°) and in pitch plane 0.36° (-2.72° to 2.45°). The median of HV in roll and pitch planes were -0.94° (-5.86° to 3.84°) and 3.56° (-0.68° to 8.36°), respectively. SPV in the roll plane was correlated with all posturagraphy parameters in sitting position in all conditions (r = 0.35 to 0.47; p < 0.006). There were moderate correlations with the verticality perceptions and all the functional scales. Linear regression model showed association between speed and SPV in the roll plane in the condition EOSS (R2 of 0.37; p = 0.005), in the condition ECSS (R2 of 0.13; p = 0.04) and in the condition EOUS (R2 of 0.22; p = 0.03). These results suggest that verticality perception is a relevant component of postural control and should be systematically evaluated, particularly in patients with abnormal postural control.