Effect of transported mass and constant force on times for ballistic and visually-controlled movements

Abstract

A series of experiments are reported in which the effects of transferred mass and resistive/assistive forces were investigated for both ballistic and visually-controlled movements. The first experiment involved the transfer of mass in the horizontal plane so that only inertia] forces were present. This was followed by experiments in which movements were made with a purely resistive or assistive force, without the presence of increased inertia. Finally the effects of transferring mass in the vertical direction were investigated, where resistive/assistive forces were present due to gravity, as well as increased inertia force due to the transferred mass. Both theoretical and empirical models are presented for each of these cases. It was found that, for both ballistic and visually-controlled movements, the data were well accounted for simply by a component of added time proportional to the transferred mass or the magnitude of the constant force. This result is in agreement with the procedure used in some predetermined motion time systems.     

Underwater ballistic movement

A mathematical model is developed for ballistic arm movements in an underwater environment. Characteristics of the arm moving in water, the ‘induced’ moment of inertia and drag coefficient, are found from experiments on an artificial arm. These data, along with the mathematical model, are used to predict underwater movement times from experimental data for movement times in air.

Experiments on two groups of subjects, in both air and water environments, show that the model yields a good prediction of ballistic movement times in an underwater environment.     

Sequential ballistic movement

Studies of sequential ballistic movements showed that strong interaction occurs between components of a complex movement task. Within an individual component of the motion, a good predictor of movement time was the square root of the movement amplitude. There was a statistically significant influence of the preceding amplitude on the movement time, apart from the first component where the movement time was dependent on the immediate subsequent movement amplitude. Models for movement times are proposed for the different components of sequential movements.     

The use of ballistic movement as an additional method to assess performance of computer mice

This study investigates an additional method for independently evaluating performance of speed and accuracy of computer mice, based on five parameters of the initial submovement when aiming at a target. This first submovement is known to be carried out in a ballistic manner and hence the Fitts-type aiming movement may be studied by means of the established relationships for ballistic movement. To test the ballistic movement method, eight participants used four different computer mice to execute ballistic movements and Fitts-type aiming movements. Regression tests showed that the Fitts movement time was well correlated with the time and stopping-variable error of ballistic movement, implying that measuring ballistic movement parameters can predict the performance of Fitts-type aiming movements. More importantly, the use of ballistic movement method allows independent assessments of the speed and accuracy, providing additional information for input devices assessment and designs.Relevance to industryThe study illustrates the close correspondence between input device evaluation using the proposed ballistic movement method and Fitts' law. The ballistic movement method allows independent measures of speed and four types of accuracy, which should benefit input devices assessment and designs.     

Geometrical conditions for ballistic and visually controlled movements

The ballistic movement is defined as a rapid voluntary movement which is motor programmed and in which visual feedback for path correction is not possible. A discrete ballistic movement is of short movement duration (less than about 200 msec) with a triphasic pattern in the electromyograph (EMG) for muscle activity and has an acceleration pattern which approximates a sinusoidal waveform. When the Index of Difficulty for such a movement is less than 3·0, the movement time is found to be related to the square root of the movement amplitude. The occurrence of ballistic movement is determined by the combined factors of Fitts' Index of Difficulty and movement amplitude.     

Dynamical approach to ballistic transport in graphene

The process of the coherent creation of particle–hole excitations by an electric field in graphene is quantitatively described beyond linear response. We calculate the evolution of the current density and the number of pairs in the ballistic regime using the tight binding model. While for small electric fields the I–V curve is linear characterized by the universal minimal resistivity σ=π/2(e²/h), for larger fields, after a certain time interval, the linear regime crosses over to a quadratic one and finally at larger times Bloch oscillations set in.     

Eye movement prediction by oculomotor plant Kalman filter with brainstem control

Our work addresses one of the core issues related to Human Computer Interaction （HCI） systems that use eye gaze as an input. This issue is the sensor, transmission and other delays that exist in any eye tracker-based system, reducing its performance. A delay effect can be compensated by an accurate prediction of the eye movement trajectories. This paper introduces a mathematical model of the human eye that uses anatomical properties of the Human Visual System to predict eye movement trajectories. The eye mathematical model is transformed into a Kalman filter form to provide continuous eye position signal prediction during all eye movement types. The model presented in this paper uses brainstem control properties employed during transitions between fast （saccade） and slow （fixations, pursuit） eye movements. Results presented in this paper indicate that the proposed eye model in a Kalman filter form improves the accuracy of eye movement prediction and is capable of a real-time performance. In addition to the HCI systems with the direct eye gaze input, the proposed eye model can be immediately applied for a bit-rate/computational reduction in real-time gaze-contingent systems     

未爆弹在机场道面下的侵彻弹道研究

研究未爆弹对机场道面的侵彻（侵彻深度、侵彻轨迹以及未爆弹在机场道面下的状态等）以及侵彻过程中可能产生的状况,是殉爆系统能够顺利隧进到未爆弹有效殉爆范围内的关键。影响未爆弹侵彻弹道的因素非常多,且其中一些无法精确知道,导致侵彻弹道有很大的差异。在分析经验计算公式的基础上,对侵彻深度经验公式进行了分析与比较。     

弹道导弹的雷达探测系统仿真

该文根据弹道理论建立了雷则弹道导弹的仿真模型,并对雷达跟踪的导弹弹道数据进行了处理,预报了它的落点范围,并与理论落点进行比较,给出了落点精度。仿真结果表明：雷达对导弹的探测数据经过一数据处理,所得到的落点比较精确。     

Seated leg/foot ballistic and visually-controlled movements

An experiment with 52 participants investigated the relationship between movement time of the leg/foot for seated persons when moving in the transverse and sagittal planes. Four amplitudes of movement and 11 values of Fitts' Index of Difficulty (ID) were used to determine conditions under which ballistic movements could be made along with the need for visual control at higher ID values. Vision of the foot was available in all movements. As with arm movements (Gan and Hoffmann, 1988) there was a critical ID value below which it was possible to use ballistic movements and where movement times were approximately linear with the square-root of movement amplitudes. Above these ID values, Fitts' law applied, with gradients dependent on the amplitude of movement, suggesting that the muscle torque applied to the leg varied with movement amplitude. The critical ID varied with the amplitude of movement as previously found for arm movements.Relevance to industryThere is increasing use of the foot/leg for input to various controlling devices. Consequently it is necessary to have detailed information on the capacity of the leg/foot system to provide accurate input to a machine via a control pedal or other device. The present research provides such information over a wide range of control sizes and spacings.     

基于平方根求积卡尔曼滤波器的弹道目标跟踪

针对再入阶段的弹道目标跟踪问题,提出运用平方根求积卡尔曼滤波器(SRQKF)估计目标的状态.所提出的算法是求积卡尔曼滤波(QKF)算法的平方根实现.该算法传播了目标状态的均值和协方差的平方根,确保了协方差矩阵的对称性和半正定性,改进了数值精度和稳定性,但其计算复杂性稍有增加.仿真实验表明,所提出算法的估计精度优于QKF算法和扩展卡尔曼滤波(EKF)算法,是一种很有效的非线性滤波方法.     

Directional communication with movement prediction in mobile wireless sensor networks

By introducing mobility to some or all the nodes in a wireless sensor network (WSN), WSN can enhance its capability and flexibility to support multiple missions. In mobile wireless sensor networks, mobile nodes collect data and send data to a sink station. When the sink station employs directional antennas to send and receive data, its communication capability can increase. Using directional antennas implies the transmitters must know the direction or location of the receiver. It is necessary to predict a mobile receiver’s movement to keep the transmitter’s antenna pointing to the right direction. A mobility prediction algorithm is proposed in this paper, which is based on the knowledge extracted from real vehicles traces. The validation experiments indicate that the prediction accuracy rate of the algorithm is 96.5 % and the communication using directional antenna with movement prediction saves about 92.6 % energy consumption with a suitable beam-width and shakehand interval.     

Using eye movement data to infer human behavioral intentions

Behavior-directed intentions can be revealed by certain biological signals that precede behaviors. This study used eye movement data to infer human behavioral intentions. Participants were asked to view pictures while operating under different intentions, which necessitated cognitive search and affective appraisal. Intentions regarding the pictures were non-specific or specific, specific intentions were cognitive or affective, and affective intentions were to evaluate either the positive or negative emotions expressed by the individuals depicted. The affective task group made more fixations and had a larger average pupil size than the cognitive task group. The positive appreciation group made more and shorter fixations, on average, than the negative appreciation group. However, support vector machine algorithms revealed low classification accuracy. This was due to large inter-individual variance and psychological factors underlying intentions. We demonstrated improvement in classification accuracy using individual repeated measures data, which helped infer participants’ self-selected intentions.     

Effects of path angle changes on the times for ballistic and visually-controlled two-component arm movements

Although several Predetermined Motion time Systems mention the effects of change of path angle during a movement, there does not appear to be any experimental evidence for the quoted effects. Here we report effects of angle changes between zero and 180° during the movement, with and without an intervening target at the end of the first component of the movement. The effects are variable: with ballistic movements without an intervening target there is an increase of MT with path angle change; when there is an intervening target the MT of the first component decreases with change of path angle, while that of the second component increases, so that the total movement time is independent of the change in path angle. When the movements are made under visual control, with no intervening target, MT increases with change of path angle, whereas when there is an intervening target, there is no effect of change of path angle, either on the first or second component of the movement. Thus the occurrence of movement time increments is dependent on the form of motor control and the way in which the path angle change occurs.     

Influence of different types of the internal system of the ballistic helmet shell on the thermal insulation measured by a manikin headform

The head is a part of the body whose temperature influences not only physiological parameters of the whole body but also the perception of a thermal environment and psychomotor parameters of a human. For this reason, it is important to prevent the head from overheating and to use head covers which render it possible to release heat from head surface to the environment.     

Verification of models for ballistic movement time and endpoint variability

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices.

Practitioner summary: This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.     

Eye movement as a mediator of the relationships among time pressure,feedback, and learning performance

The goal of this study is to examine the effects of time pressure and feedback on learning performance, as mediated by eye movement. Time pressure is one of main causes of human error in the workplace. Providing participants with feedback about their performance before task completion has been shown to reduce human error in diverse domains. Since both time pressure and feedback induce motivation, which is closely related to attention, we measured participants' eye movements to trace their attention and information acquisition coupled with a visual display. Time-to-deadline (long and short) and the presence of feedback were the independent factors used while measuring participants’ performance and eye movements as they learned new information about the subject of project management and answered multiple-choice questions via self-paced online learning systems. Using structural equation modeling, we found a mediating effect of eye movement on the relationships among time-to-deadline, feedback, and learning performance. Insufficient time-to-deadline accelerated the number of fixations on the screen, which resulted in longer task completion times and increased correct rates for participants learning about project management. The models in this study suggest the possibility of predicting performance from eye movement under time-to-deadline and feedback conditions. The structural equation model in the study can be applied to online and remote learning systems, in which time management is one of the main challenges for individual learners.     

Evaluating camouflage design using eye movement data

This study investigates the characteristics of eye movements during a camouflaged target search task. Camouflaged targets were randomly presented on two natural landscapes. The performance of each camouflage design was assessed by target detection hit rate, detection time, number of fixations on display, first saccade amplitude to target, number of fixations on target, fixation duration on target, and subjective ratings of search task difficulty. The results showed that the camouflage patterns could significantly affect the eye-movement behavior, especially first saccade amplitude and fixation duration, and the findings could be used to increase the sensitivity of the camouflage assessment. We hypothesized that the assessment could be made with regard to the differences in detectability and discriminability of the camouflage patterns. These could explain less efficient search behavior in eye movements. Overall, data obtained from eye movements can be used to significantly enhance the interpretation of the effects of different camouflage design.