Reorientation Task Research Articles

Output feedback attitude control for rigid spacecraft under attitude constraints

<p style='text-indent:20px;'>An output feedback control law is proposed in this paper for spacecraft attitude reorientation task. Although attitude maneuver has been widely investigated and obtained significant results, it is still challenging when considering attitude pointing constraints and lacking the information of angular velocity. Firstly, potential function is introduced to tackle attitude pointing constraints. Then, by jointly designing sign function and potential function, the anti-unwinding performance can also be achieved. Furthermore, the relevant information of angular velocity is obtained by utilizing first-order passive filter with the attitude error quaternion. Moreover, by properly selecting candidate Lyapunov function, the feasibility of attitude constraints can be rigorously proved under the proposed control law, while the stability of the system can be guaranteed without signal of angular velocity and information of inertia matrix. A numerical example is carried out to demonstrate the effectiveness of the proposed method.</p>

Rescuing impaired cortical‐hippocampal interactions during sleep with 40Hz stimulation targeted to hippocampus in 3xTg‐AD/PVcre mice

AbstractBackgroundIn preclinical Alzheimer’s disease (AD), spatial learning and memory is impaired. We previously reported similar impairments in 6‐month 3xTg‐AD female mice on a virtual spatial reorientation task that requires learning to use landmarks for spatial orientation. Memory replay during sleep is critical for learning related plasticity, and hippocampal‐cortical dysfunction during sleep is a potential mechanism for memory impairments in AD. Consistent with this, we previously found that prior to emergence of significant pathology there were deficits in hippocampal‐parietal cortex (PC) coordination during sleep which predicted performance on the virtual spatial reorientation task. Gamma‐stimulation (40Hz) has been shown to clear AD pathology in mice, and improve functional connectivity in preclinical AD patients. Thus, we assessed hippocampal‐PC coordination in 6‐month female 3xTg‐AD/PVcre (4xTg) mice that were learning the same spatial reorientation task.MethodWe implanted a 16‐tetrode recording array targeting PC and hippocampus and an optical fiber aimed at hippocampus. Daily recording sessions of rest‐task‐rest commenced as mice learned to locate the unmarked reward zone. During the same surgery, cre‐dependent AAV was used to express channel rhodopsin 2 in hippocampal interneurons. This allowed for daily stimulation sessions after recording sessions, with either 40Hz or SHAM hippocampal stimulation. We assessed sleep quality metrics, and cortical spindles, and delta waves (DW) in PC during slow wave sleep. In hippocampus we assessed markers of memory replay (SWRs) during SWS.ResultAnimals with 40Hz entrainment showed increased REM sleep compared to SHAM animals. There was also a significant increase in SWR rate from pre‐ to post‐sleep, opposite a decrease in post‐sleep in SHAM mice; however, there was no difference in the absolute number or rate of DW or . Finally, in SHAM stimulated mice SWR‐DW temporal‐correlations were significantly reduced, similar to our previous findings in 3xTg‐AD mice; while in the 40Hz mice, this phase locking was rescued. .ConclusionThus, 40Hz stimulation of hippocampus may rescue learning and memory related functional interactions in the hippocampal‐PC network during sleep and as a consequence at least partially rescue impairments in spatial navigation.

Bureaucratic Poetics: Brian O’Nolan and the Irish Civil Service

This guest editorial introduces the topic of this special issue, ‘Brian O’Nolan and the Irish Civil Service,’ and sets out some key points on why the theme of bureaucracy should be considered more closely in O’Nolan criticism. At the same time, the editorial sketches out aspects of the current political and cultural context in which the issue approaches the bureaucrat as a topic of discussion. Calling to attention certain critical interventions on the question of how writers operate when they are concurrently state functionaries, the note sets the stage for O’Nolan to be re-considered as a ‘writer-official.’ Introducing the articles which make up the issue, the authors point towards how the contributors have taken on such a task of critical re-orientation. The note concludes with an appendix, which provides a detailed timeline of O’Nolan’s career in the Irish Civil Service.

Separation of geometric and featural information in children’s spatial representation: Evidence from a model selection task

Previous studies in spatial reorientation have found that young children rely mainly on geometric shapes for reorientation and sometimes ignore features in the environment. Theoretical interpretations of children’s reorientation performance are usually attributed to children’s spatial representation of their surrounding environments. The geometric module theory states that featural information is represented separately from geometric shape in young children’s reorientation, whereas the adaptive combination model depicts an integral representation. Reorientation tasks, however, require the recognition of a specific location, and thus how the whole environment is represented remains unknown. The current study, using a model selection task, explored young children’s representation of the whole surrounding environment. A total of 75 children aged 3–5 years participated in the study. In each trial, children observed a large enclosure and were then asked to choose the corresponding model from two small models. The geometric shapes of the enclosure (rectangle vs. rhombus) and the types of distractors (shape distraction vs. feature position distraction) varied. Results showed that all three age groups performed above the chance level in the shape distraction conditions. Children had more difficulty with the feature position distraction conditions than with the shape distraction conditions. When the distractor shared the feature but at an inappropriate position, children’s performance was significantly poorer, especially in the rhombic enclosure. The results provide evidence that young children may represent featural cues separately from geometric shapes.

Manipulation Planning for Object Re-Orientation Based on Semantic Segmentation Keypoint Detection.

In this paper, a manipulation planning method for object re-orientation based on semantic segmentation keypoint detection is proposed for robot manipulator which is able to detect and re-orientate the randomly placed objects to a specified position and pose. There are two main parts: (1) 3D keypoint detection system; and (2) manipulation planning system for object re-orientation. In the 3D keypoint detection system, an RGB-D camera is used to obtain the information of the environment and can generate 3D keypoints of the target object as inputs to represent its corresponding position and pose. This process simplifies the 3D model representation so that the manipulation planning for object re-orientation can be executed in a category-level manner by adding various training data of the object in the training phase. In addition, 3D suction points in both the object’s current and expected poses are also generated as the inputs of the next operation stage. During the next stage, Mask Region-Convolutional Neural Network (Mask R-CNN) algorithm is used for preliminary object detection and object image. The highest confidence index image is selected as the input of the semantic segmentation system in order to classify each pixel in the picture for the corresponding pack unit of the object. In addition, after using a convolutional neural network for semantic segmentation, the Conditional Random Fields (CRFs) method is used to perform several iterations to obtain a more accurate result of object recognition. When the target object is segmented into the pack units of image process, the center position of each pack unit can be obtained. Then, a normal vector of each pack unit’s center points is generated by the depth image information and pose of the object, which can be obtained by connecting the center points of each pack unit. In the manipulation planning system for object re-orientation, the pose of the object and the normal vector of each pack unit are first converted into the working coordinate system of the robot manipulator. Then, according to the current and expected pose of the object, the spherical linear interpolation (Slerp) algorithm is used to generate a series of movements in the workspace for object re-orientation on the robot manipulator. In addition, the pose of the object is adjusted on the z-axis of the object’s geodetic coordinate system based on the image features on the surface of the object, so that the pose of the placed object can approach the desired pose. Finally, a robot manipulator and a vacuum suction cup made by the laboratory are used to verify that the proposed system can indeed complete the planned task of object re-orientation.

Enabling Dynamic Behaviors With Aerodynamic Drag in Lightweight Tails

Many agile legged animals employ lightweight, furry tails to regulate orientation during running, leaping, and turning. Most robots attempting the same tasks either lack a tail or employ one with high inertia, which can induce impractical payload and energy costs. Inspired by nature's solution to this tradeoff, we explore the use of aerodynamic drag tails in reorientation tasks. In this article, we present a model of the aerodynamic drag and from this derive a metric that allows for direct comparison between aerodynamic and inertial tails. Motivated by this model, we construct a tail to maximize this effectiveness while minimizing inertia. We demonstrate the utility of this tail for two dynamic behaviors executed on a quadrupedal robot. First, in aerial reorientation the robot achieves a 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> rotation within one body length of fall at the same performance as an inertial tail but with just 37% of the normalized inertia. Second, the forward acceleration of the robot is improved by 12% despite increasing the system mass by 10% over a tailless version. These results show that aerodynamic drag can provide significant control authority for a robot while decreasing the payload and energy cost.

Impaired Hippocampal-Cortical Interactions during Sleep in a Mouse Model of Alzheimer’s Disease

Spatial learning is impaired in humans with preclinical Alzheimer's disease (AD). We reported similar impairments in 3xTg-AD mice learning a spatial reorientation task. Memory reactivation during sleep is critical for learning-related plasticity, and memory consolidation is correlated with hippocampal sharp wave ripple (SWR) density, cortical delta waves (DWs), cortical spindles, and the temporal coupling of these events-postulated as physiological substrates for memory consolidation. Further, hippocampal-cortical discoordination is prevalent in individuals with AD. Thus, we hypothesized that impaired memory consolidation mechanisms in hippocampal-cortical networks could account for spatial memory deficits. We assessed sleep architecture, SWR-DW dynamics, and memory reactivation in a mouse model of tauopathy and amyloidosis implanted with a recording array targeting isocortex and hippocampus. Mice underwent daily recording sessions of rest-task-rest while learning the spatial reorientation task. We assessed memory reactivation by matching activity patterns from the approach to the unmarked reward zone to patterns during slow-wave sleep (SWS). AD mice had more SWS, but reduced SWR density. The increased SWS compensated for reduced SWR density so there was no reduction in SWR number. In control mice, spindles were phase-coupled with DWs, and hippocampal SWR-cortical DW coupling was strengthened in post-task sleep and was correlated with performance on the spatial reorientation task the following day. However, in AD mice, SWR-DW and spindle-DW coupling were impaired. Thus, reduced SWR-DW coupling may cause impaired learning in AD, and spindle-DW coupling during short rest-task-rest sessions may serve as a biomarker for early AD-related changes in these brain dynamics.

The geometry as an eyed fish feels it in spontaneous and rewarded spatial reorientation tasks

Disoriented human beings and animals, the latter both sighted and blind, are able to use spatial geometric information (metric and sense properties) to guide their reorientation behaviour in a rectangular environment. Here we aimed to investigate reorientation spatial skills in three fish species (Danio rerio, Xenotoca eiseni, Carassius auratus) in an attempt to discover the possible involvement of extra-visual senses during geometric navigation. We observed the fish’s behaviour under different experimental procedures (spontaneous social cued task and rewarded exit task), providing them different temporal opportunities to experience the environmental shape (no experience, short and prolonged experience). Results showed that by using spontaneous social cued memory tasks, fishes were not able to take advantage of extra-visual senses to encode the spatial geometry, neither allowing them short time-periods of environmental exploration. Contrariwise, by using a reference memory procedure, during the rewarded exit tasks, thus providing a prolonged extra-visual experience, fishes solved the geometric task, showing also differences in terms of learning times among species.

Distinct and combined responses to environmental geometry and features in a working-memory reorientation task in rats and chicks

The original provocative formulation of the ‘geometric module’ hypothesis was based on a working-memory task in rats which suggested that spontaneous reorientation behavior is based solely on the environmental geometry and is impervious to featural cues. Here, we retested that claim by returning to a spontaneous navigation task with rats and domestic chicks, using a single prominent featural cue (a striped wall) within a rectangular arena. Experiments 1 and 2 tested the influence of geometry and features separately. In Experiment 1, we found that both rats and chicks used environmental geometry to compute locations in a plain rectangular arena. In Experiment 2, while chicks failed to spontaneously use a striped wall in a square arena, rats showed a modest influence of the featural cue as a local marker to the goal. The critical third experiment tested the striped wall inside the rectangular arena. We found that although chicks solely relied on geometry, rats navigated based on both environmental geometry and the featural cue. While our findings with rats are contrary to classic claims of an impervious geometric module, they are consistent with the hypothesis that navigation by boundaries and features may involve distinct underlying cognitive computations. We conclude by discussing the similarities and differences in feature-use across tasks and species.

Use of medial axis for reorientation by the Clark’s nutcracker (Nucifraga columbiana)

Many animals are challenged with the task of reorientation. Considerable research over the years has shown a diversity of species extract geometric information (e.g., distance and direction) from continuous surfaces or boundaries to reorient. How this information is extracted from the environment is less understood. Three encoding strategies that have received the most study are the use of principal axes, medial axis or local geometric cues. We used a modeling approach to investigate which of these three general strategies best fit the spatial search data of a highly-spatial corvid, the Clark’s nutcracker (Nucifraga columbiana). Individual nutcrackers were trained in a rectangular-shaped arena, and once accurately locating a hidden goal, received non-reinforced tests in an L-shaped arena. The specific shape of this arena allowed us to dissociate among the three general encoding strategies. Furthermore, we reanalyzed existing data from chicks, pigeons and humans using our modeling approach. Overall, we found the most support for the use of the medial axis, although we additionally found that pigeons and humans may have engaged in random guessing. As with our previous studies, we find no support for the use of principal axes.

Sex differences and the effect of instruction on reorientation abilities by humans.

This study examined whether differences in the amount of information provided to men and women, in the form of verbal instruction, influenced their encoding during a reorientation task. When a navigator needs to orient, featural (e.g., colour or texture) and geometry (e.g., metric information) are used to determine which direction to begin traveling. The current study used a spatial reorientation task to examine how men and women use featural and geometric cues and whether the content of the task's instructions influenced how these cues were used. Participants were trained to find a target location in a rectangular room with distinctive objects situated at each corner. Once the participants were accurately locating the target, various tests manipulating the spatial information were conducted. We found both men and women encoded the featural cues, and even though the features provided reliable information, participants generally showed an encoding of geometry. However, when participants were not provided with any information about the spatial aspects of the task in the instructions, they failed to encode geometry. We also found that women used distant featural cues as landmarks when the featural cue closest to the target was removed, whereas men did not. Yet, when the two types of cues were placed in conflict, both sexes weighed featural cues more heavily than geometric cues. The content of the task instructions also influenced how cues were relied upon in this conflict situation. Our results have important implications for our understanding of how spatial cues are used for reorientation.

Consistency of Spatial Representations in Rat Entorhinal Cortex Predicts Performance in a Reorientation Task

Goal-directed behavior can be affected by environmental geometry. A classic example is the rectangular arena reorientation task, where subjects commonly confuse opposite but geometrically identical corners [1]. Until recently, little was known about how environmental geometry shapes spatial representations in a neurobehavioral context [2] (although see [3]). In the present study, we asked: Under what circumstances does the internal cognitive map predict behavior? And when does it fail to do so? To this end, we developed a variant of the classical reorientation task that allows for investigation of temporal dynamics of reorientation. We recorded head-direction (HD) cells and grid cells in the medial entorhinal cortex (MEC) of rats before, during, and after performing the task. MEC cells showed a bimodal response of being either aligned or rotated, relative to the free-foraging open-field sessions. Alignment was remarkably stable between disorientations andindicative of corner choice as a function of current and past alignment of spatial representations. Accordingly, when the cells showed consistent andproperly aligned readout across multiple trials, behavioral choices were better predicted by HD and grid cell readout, with a probability of more than 70%. This was not the case when the cells did not show a stable consistent readout. Our findings indicate that entorhinal spatial representations predict corner choice, contingent on the stability and reliability of their readout. This work sets the stage for further studies on the link between the reliability of the neuronal signal and behavior, with implications for many brain systems in many organisms.

Angles no longer weigh in: The effect of geometric cue directness on reorientation.

Previous research in spatial reorientation, which only presented the target location in the corner, has found that adults weighed angles more than wall lengths. We proposed that in previous research, angular cues were available for direct use whereas length cues had to be associated with the left/right sense. We thus investigated whether the directness of cues rather than the cues themselves accounted for the previous findings in the reorientation task. Through navigating a virtual environment, 111 participants were trained to remember target locations in a parallelogram-shaped room and tested in varied versions of the training environment: (a) a reverse-parallelogram environment where angular information conflicted with wall length information, (b) a rhombic environment that preserved only angular information from the training environment, and (c) a rectangular environment that preserved only wall length information. We varied the directness of the two cues in the current study. In addition to the condition with target location in the corner, we included a condition that placed the target positions in the middle of the walls, making the length cues direct. The results revealed that angular information no longer received priority, especially in the wall condition. More interestingly, compared to the group trained with the target positions at walls, the group trained with target positions at corners weighted angular cues more heavily in conflict trials and performed less accurately using length cues in rectangular environments. The results suggest that human adults prefer to rely on direct cues more than indirect cues in the reorientation process. (PsycINFO Database Record

Geometry, landmarks and the cerebral hemispheres: 2D spatial reorientation in split-brain patients.

A right-hemispheric superiority in spatial encoding based on geometric cues has been largely documented in a variety of species, together with a left-hemispheric specialization for encoding based on landmarks. In humans, hemispheric asymmetries for spatial encoding have been little explored. In this study, we compared a patient with a complete callosal resection (D.D.C.) and a patient with a wide callosal resection saving the splenium (A.P.), with healthy participants. In two 2D versions of the 'reorientation task', participants were asked to find the target corner of a rectangle-shaped environment, by exploiting either geometric information alone or the combination of geometric and landmark information. In Experiment 1, the landmark consisted of a coloured side of the rectangle; in Experiment 2, this cue was replaced by a coloured disc located inside the rectangle. In both experiments, the rectangular shape ensured the geometric cue. D.D.C. was always unable to recall the target, whereas A.P. correctly solved the task when only the geometric information was available, without difference with respect to the controls. Importantly, the performance of A.P. did not differ from controls' when the right hemisphere was tested with the landmark cues (the task being carried out using the left hand), whereas when the left hemisphere was tested (right-hand session) his performance was worse than controls' with the coloured side of the space, but it was better than controls' with the coloured disc. The results are discussed comparing them with data collected on other species, and with theories of spatial processing.

Investigation of the Task of the Optimal Reorientation of a Spacecraft Orbit through a Limited or Impulse Jet Thrust, Orthogonal to the Plane of the Orbit. Part 2

Investigation of the Task of the Optimal Reorientation of a Spacecraft Orbit through a Limited or Impulse Jet Thrust, Orthogonal to the Plane of the Orbit. Part 2

Investigation of the Task of the Optimal Reorientation of a Spacecraft Orbit through a Limited or Impulse Jet Thrust, Orthogonal to the Plane of the Orbit. Part 1

Investigation of the Task of the Optimal Reorientation of a Spacecraft Orbit through a Limited or Impulse Jet Thrust, Orthogonal to the Plane of the Orbit. Part 1

The overlap between false belief and spatial reorientation in the temporo-parietal junction: The role of input modality and task

ABSTRACTNeuroimaging research has demonstrated that the temporo-parietal junction (TPJ) is activated when unexpected stimuli appear in spatial reorientation tasks as well as during thinking about the beliefs of other people triggered by verbal scenarios. While the role of potential common component processes subserved by the TPJ has been extensively studied to explain this common activation, the potential confounding role of input modality (spatial vs. verbal) has been largely ignored. To investigate the role of input modality apart from task processes, we developed a novel spatial false belief task based on moving shapes. We explored the overlap in TPJ activation across this novel task and traditional tasks of spatial reorientation (Posner) and verbal belief (False Belief vs. Photo stories). The results show substantial overlap across the same spatial input modality (both reorientation and false belief) as well as across the common task process (verbal and spatial belief), but no triple overlap. This suggests the potential for an overarching function of the TPJ, with some degree of specialization in different subregions due to modality, function and connectivity. The results are discussed with respect to recent theoretical models of the TPJ.

姿勢遷移途中のリリース動作を許容した平行グリッパによる対象部品の置き直し動作に関する研究

We introduce a novel motion strategy to reorient parts from the initial orientations toward desired orientations by a parallel gripper in a robotic assembly system. In the proposed strategy, a target part is grasped, picked up, made contact the workbench in a certain orientation, and then released so that it topples and eventually settles in a desired orientation on the workbench. This strategy is expected to improve the efficiency in reorientation tasks of parts compared to the conventional strategy. Toward motion planning of efficient reorientation of parts, in this paper, orientational transition of a part after releasing is analyzed, and the validity of the analysis is verified experimentally. The feasibility of reorientation of a part by the proposed strategy is also confirmed with experiments.

Развитие российской туристской отрасли в условиях импортозамещения

The tendencies of development of tourism in Russia in 2015 are examined in the article; predictions and possible vectors of evolution of tourism in Russia are presented. Statistics on external and internal tourism in Russia in the 1st quarter of 2015 is analyzed; development policy of internal tourism is considered and its results are characterized. Russian tourism is having some problems with the support of internal tourism now, so the examination of last tendencies and statistics about the tourist streams in Russia are really up-to-date. Thie research will provide the complex decision of the task of reorientation of tourist streams from external to internal.

Speed and accuracy of reorientation from a bird's eye view: Does the type of spatial information matter?

This set of studies examines accuracy and reaction times of human adults in a reorientation task when the spatial information available is manipulated. All experiments used within subjects designs in which participants saw figures containing different types of useful spatial information (Experiment 1: a landmark, a geometric cue, a landmark and a geometric cue, and no useful cue) or pairs of different cues (Experiment 2a: two landmarks, two geometric cues, and a landmark and a geometric cue together; Experiment 2b: two configurations of two landmarks, two geometric cues, and a landmark and a geometric cue together) on a computer screen and were asked to find a location on a rotated version of the figure following a short delay. In Experiment 1, participants were less accurate in the landmark condition and the conditions that included geometric elements were faster. In Experiments 2a and 2b, the conditions that included geometry were faster than the landmark only condition that had no geometry. The results are discussed in terms of theoretical accounts of the processing of featural and geometric sources of information.