Human Path Integration by Optic Flow

Path integration or 'dead reckoning' is the ability to keep track of relative position using self-motion signals that convey information about speed and direction of movement. Most animal species, including humans, exhibit some degree of path integration capability and neurophysiological studies have demonstrated that self-motion signals are sufficient to update internal representations of both position and orientation. In the present study, human subjects were required to monitor their position or orientation on the basis of unstructured optic flowfields. Trials were conducted at different speeds to examine the accuracy of path integration and rates of random error accumulation, and at two different head azimuths to prevent a confounding strategy of position updating based primarily on tracking changes in the angular declination of distant landmarks with respect to the horizon. Participants integrated the speed of visual motion to update accurately a representation of their position and orientation within the environment. Consistent with the characteristics of real-world path integration, errors accumulated linearly with the magnitude of position and orientation estimation. We conclude that coherent optic flowfields provide a sufficient basis for humans to keep track of their position and orientation relative to remembered landmarks.     

欠驱动余度机械臂的非完整冗余特征研究

欠驱动技术在航天领域有重要应用价值。针对空间机器人系统,研究了欠驱动冗余度机械臂的"非完整冗余"特征和无碰撞路径最优运动规划方法。这种系统对于给定的机械臂末端位姿,其冗余特征不便通过传统意义上的运动学"自运动"来刻画,但是因机构自由度数大于工作空间维数,系统的冗余特征可通过动力学水平的控制体现出来。基于李雅普诺夫方法,提出一种欠驱动冗余度机械臂的无碰撞路径最优规划方法,揭示了这种机器人系统的"非完整冗余"特征,通过平面3连杆机械臂进行了仿真。     

激光雷达动态成像几何畸变的缩略修正法

针对激光雷达动态成像的畸变问题，系统地给出了相对静止成像映射变换模型、动态成像映射变换模型、完整的逐点修正法表达式。为了解决实时获取目标信息与复杂的修正运算之间的矛盾，给出了缩略修正法及其误差分析结果，此结果可作为设计与选择雷达陀螺平台的工程依据。     

Man in space.

Today, more than 20 years after the first in the world man's space walk, soviet cosmonautics gained large experience of extravehicular activity (EVA). Space suits of high reliability, onboard facilities for passing through the airlock, sets of special tools and technological rigging, as well as procedures for carrying out various EVA's were developed. In the course of the Salyut-7 space station orbital operation the EVA's have become regular. The author of the report as the participant of the EVA's considers the main steps of man activities in space and analyzes specific problems arised in performing such activities.     

传爆药柱参数选择方法研究

进行了传爆药柱参数选择方法研究。针对研制的不同阶段,结合界面可靠性要求,提出可靠性设计、可靠性验证及可靠性评估3个参数优化程序。以柱形爆炸器传爆药柱设计为实例,说明此套传爆药柱参数选择方法是可行的。     

通信卫星系统潜在故障识别与应对方法

针对新一代高集成度、高复杂度通信卫星系统应用背景，以通信卫星平台长寿命、高可靠设计需求为牵引，提出一种基于系统理论事故模型与过程（STAMP）的系统级潜在故障识别与分析方法，在总体设计早期即提出对卫星平台各分系统的可靠性设计需求。以某地球同步轨道（GEO）通信卫星为例介绍该方法，通过构建系统控制逻辑架构自上至下地分析潜在的不安全控制过程，通过检查控制与反馈回路的各环节确定故障发生场景，提出对控制过程的约束条件以消除或降低故障发生的可能，最终形成有针对性的分系统可靠性设计需求。     

Motion sickness susceptibility during rotation at 30 rpm in free-fall parabolic flight

Free fall per se whether in parabolic or orbital flight may be regarded as a "partial" motion environment with respect to eliciting motion sickness, requiring an additional component to render this environment "complete" or stressful. Parabolic flight in toto falls in the category of a "complete" motion environment in that some persons became motion sick with head fixed and eyes closed. In the present experiment we selected subjects who were symptom free or nearly symptom free in the KC-135 with head fixed. All tests were conducted with the subject rotating at 30 rpm in a rotating litter chair, and comparisons were made between head-fixed and head-moving conditions (right-left) in the free-fall phase of parabolic flight and under simulated free-fall phases in the laboratory. With head fixed most subjects were insusceptible; with head moving left-right susceptibility was slightly higher in the laboratory than aloft. An additional comparison was made correlating susceptibility in the free-fall phases of parabolic flight with susceptibility to experimental motion sickness in Skylab. In both situations cross-coupled angular accelerations were generated by executing head and body movements out of the plane of rotation. In parabolic flight 9 of 15 subjects reached an endpoint just short of frank motion sickness. In the Skylab workshop all eight of the astronauts tested were symptom free at the end of the test. The explanation for the difference in susceptibility rests in two factors: (1) Basic susceptibility in free fall is lower than on the ground, and (2) in Skylab the astronauts who needed to adapt had achieved this goal prior to the first test on Mission-Day 8.     

Learning to Reach to Locations Encoded from Imaging Displays

We examined the use of hand gestures while people solved spatial reasoning problem in which they had to infer motion from static diagrams (mental animation problems). In Experiment 1, participants were asked to think aloud while solving mental animation problems. They gestured on more than 90% of problems, and most gestures expressed information about the component motions that was not stated in words. Two further experiments examined whether the gestures functioned in the mechanical inference process, or whether they merely served functions of expressing or communicating the results of this process. In these experiments, we examined the effects of instructions to think aloud, restricting participants' hand motions, and secondary tasks on mental animation performance. Although participants who were instructed to think aloud gestured more than control groups, some gestures occurred even in control conditions. A concurrent spatial tapping task impaired performance on mechanical reasoning, whereas a simple tapping task and restricting hand motions did not. These results indicate that gestures are a natural way of expressing the results of mental animation processes and suggest that spatial working memory and premotor representations are involved in mental animation. They provide no direct evidence that gestures are functional in the thought process itself, but do not rule out a role for overt gestures in this type of spatial thinking.     

Artificial gravity--head movements during short-radius centrifugation: influence of cognitive effects

Short-radius centrifugation is a potential countermeasure against the effects of prolonged weightlessness. Head movements in a rotating environment, however, induce serious side effects: inappropriate vestibular ocular reflexes (VOR), body-tilt illusions and motion sickness induced by cross-coupled accelerations on a rotating platform. These are well predicted by a semicircular canal model. The present study investigates cognitive effects on the inappropriate VOR and the illusory sensations experienced by subjects rotating on a short-radius centrifuge (SRC). Subjects (N=19) were placed supine on a rotating horizontal bed with their head at the center of rotation. To investigate the extent to which they could control their sensations voluntarily, subjects were asked alternatively to "fight" (i.e. to try to resist and suppress) those sensations, or to "go" with (i.e. try to enhance or, at least, acquiesce in) them. The only significant effect on the VOR of this cognitive intervention was to diminish the time constant characterizing the decay of the nystagmus in subjects who had performed the "go" (rather than the "fight") trials. However, illusory sensations, as measured by reported subjective intensities, were significantly less intense during the "fight" than during the "go" trials. These measurements also verified an asymmetry in illusory sensation known from earlier experiments: the illusory sensations are greater when the head is rotated from right ear down (RED) to nose up (NU) posture than from NU to RED. The subjects habituated, modestly, to the rotation between their first and second sequences of trials, but showed no better (or worse) suppression of illusory sensations thereafter. No significant difference in habituation was observed between the "fight" and "go" trials.     

In Memoriam: Herbert L. Pick,Jr. (1930–2012)

ABSTRACT

Fictive motion in language (as in “the ridge went north”) is claimed to reflect the attention focus of the observer on the extension and spatial layout of an entity. This paper investigates fictive motion in alpine narratives, which describe the experience of moving in a very specifically structured space. We examine space properties that are highlighted through fictive motion in this specific context and describe how they go beyond spatial extension. We further report the communicative motivation behind the use of fictive motion, ranging from conveying the sense of place to encoding the full spatial footprint of a motion event.     

Personal growth following long-duration spaceflight

IntroductionSalutogenesis and posttraumatic growth represent personal growth and improved functioning as a result of experiencing major challenging events. These developments are not simply resilience (a return to a baseline level of well-being), but positive change in such characteristics as self-understanding, relations with others, personal values, and life goals. Space agencies and space psychologists, primarily concerned with deleterious effects and their countermeasures, have not paid much attention to such beneficial long-term aftereffects of spaceflight.PurposeTo document what changes veterans of the Soviet/Russian space program report as a consequence of their experiences.MethodTwenty retired male cosmonauts Mir and/or ISS cosmonauts filled out relevant self-report questionnaires. Results: Although there was little change in the relative rankings of a list of values, the scale showed an overall increase in the rated importance of all personal values, although only the increase in Self-Direction reached statistical significance. Responses to one of two post-space growth questionnaires based on the Post-Traumatic Growth Inventory (PTGI) were compared to the means of two comparison groups: 152 first-time mothers, and 926 respondents who had experienced various forms of trauma. The cosmonauts reported higher scores on the dimension of New Possibilities when compared to the new mothers and the traumatized group, and higher scores on Personal Strength and Overall PTG compared to the latter. Respondents who had spent more than a year in space, and those who flew on both Mir and ISS, were the most likely to report positive change in the domain Appreciation of Life. The other post-space career questionnaire reflected major changes in Perceptions of the Earth and of Space, and increases on a number of other dimensions, including New Possibilities and Changes in Daily Life, with positive scores that significantly exceeded the original report.DiscussionIt appears that cosmonauts do experience various aspects of positive personal growth following their space flights. As long-duration missions are (and will remain) the norm, it is important for the space agencies and the voyagers themselves to develop a better understanding and possible enhancement of this phenomenon.     

Dynamics and chaos control of asymmetric gyrostat satellites

The motion of a free gyrostat consisting of a platform with a triaxial ellipsoid of inertia and a rotor with a slight asymmetry with respect to the axis of rotation is considered. Dimensionless equations of motion for a system with perturbations caused by the small asymmetries of the rotor are written in Andoyer-Deprit variables. These perturbations result in a chaotic layer in the separatrix vicinity. Heteroclinic and homoclinic trajectories are written in analytical form for gyrostats with different ratios of their moments of inertia. These trajectories are used to construct a modified Melnikov function, and to produce control that eliminates separatrix chaos. The Poincare sections and Melnikov function are constructed via numerical modeling that demonstrates the effectiveness of control.     

Suited crewmember productivity

Analysis of the extravehicular activity (EVA) sortie experience gained in the former Soviet Union and physiologic hygienic aspect of space suit design and development shows that crewmember productivity is related to the following main factors: -space suit microclimate (gas composition, pressure and temperature); -limitation of motion activity and perception, imposed by the space suit; -good crewmember training in the ground training program; -level of crewmember general physical performance capabilities in connection with mission duration and intervals between sorties; -individual EVA experience (with accumulation) at which workmanship improves, while metabolism, physical and emotional stress decreases; -concrete EVA duration and work rate; -EVA bioengineering, including selection of tools, work station, EVA technology and mechanization.