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Man-Machine Systems, IEEE Transactions on

Popular Articles (December 2014)

Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
  • 1. Resolved Motion Rate Control of Manipulators and Human Prostheses

    Page(s): 47 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1587 KB)  

    The kinematics of remote manipulators and human prostheses is analyzed for the purpose of deriving resolved motion rate control. That is, the operator is enabled to call for the desired hand motion directly along axes relevant to the task environment. The approach suggests solutions to problems of coordination, motion under task constraints, and appreciation of forces encountered by the controlled hand. View full abstract»

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  • 2. AI in CAI: An Artificial-Intelligence Approach to Computer-Assisted Instruction

    Page(s): 190 - 202
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    The main purpose of the research reported here is to show that a new and more powerful type of computer-assisted instruction (CAI), based on extensive application of artificial-intelligence (AI) techniques, is feasible, and to demonstrate some of its major capabilities. A set of computer programs was written and given the name SCHOLAR. Due to its complexity, only the conception and educational aspects of this system (including an actual on-line protocol) are presented in this paper. In what may be called conventional ad hoc-frame-oriented (AFO) CAI, the data base consists of many "frames" of specific pieces of text, questions, and anticipated answers entered in advance by the teacher. By contrast, an information-structure-oriented (ISO) CAI system is based on the utilization of an information network of facts, concepts, and procedures; it can generate text, questions, and corresponding answers. Because an ISO CAI system can also utilize its information network to answer questions formulated by the student, a mixed-initiative dialogue between student and computer is possible with questions and answers from both sides. View full abstract»

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  • 3. Human factors research in motor vehicle occupant restraint systems

    Page(s): 88 - 89
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    The US national program in highway and motor vehicle safety has provided a new stimulus to human factors research by agencies of the Federal Government. As early as 1957, McFarland and Moore described areas of application of this discipline in a series of articles entitled, "Human Factors in Highway Safety". An important area included in their list was the protection of occupants of a motor vehicle from injury during a crash. This paper will describe some results of human factors research in motor vehicle occupant restraint systems by the Office of Vehicle Systems Research in the National Bureau of Standards. View full abstract»

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  • 4. Tactile Television - Mechanical and Electrical Image Projection

    Page(s): 65 - 71
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    The feasibility of communicating pictorial information through the skin has been demonstrated. A tactile television system has permitted blind subjects to determine the position, size, shape, and orientation of visible objects and to track moving targets. The system comprises 1) a vidicon camera utilizing a zoom lens, 2) a digital switching matrix to sequentially connect each element of the photocathode surface through a single video amplifier and signal conditioner to each of the 3) 400 tactile stimulators in a 20 × 20 matrix in contact with a 10-inch square of skin. This image-projector matrix impresses on the skin a two-dimensional vibrating facsimile of either the silhouette or the outline of a visible object. The single-channel swept system exhibits inherent economies when a great number of picture elements is to be processed. Since the fovea of the human eye subserving the central two degrees of detailed vision is comprised of cone cells in a matrix about 200 receptors across, the present 20-line system permits picture transmission with a linear resolution about one-tenth that of the fovea, and has proved adequate for the recognition of human faces. Calculations indicate that the input capacity of the skin of the trunk should compare favorably with that of the fovea. We have determined the electrical-stimulus parameters for painless stimulation of the sensation of mechanical vibration with small electrodes in a closely spaced matrix. View full abstract»

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  • 5. Braille, the Language, Its Machine Translation and Display

    Page(s): 96 - 100
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    The manufacture of Braille textbooks has, in the past, been accomplished in two ways. The first is the large-scale production, utilizing zinc plate embossing presses. The second is hand production, done by a large number of dedicated volunteers. This paper outlines the trend in the last few years toward automatic Braille production and describes the development of a low-cost Braille translation and embossing system at the Research Laboratory of Electronics, Massachusetts Institute of Technology. Criteria are given for the generation of input to an automatic system along with techniques for increasing the cost effectiveness of Braille manufacture. View full abstract»

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  • 6. Kinesthetic Sensing for the EMG Controlled "Boston Arm"

    Page(s): 110 - 115
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    The contribution of a novel cutaneous display of elbow angle to an amputee's ability to position an EMG-controlled externally powered elbow prosthesis was objectively evaluated. Comparisons were made between the amputee's positional control of his conventional mechanical cable-operated elbow and the EMG "Boston Arm"l elbow, with and without angle feedback, in REACHING tasks with vision occluded in all cases and with and without auditory occlusion. MATCHING tasks compared his ability to position the EMG limb to conform with the flexion of his normal (contralateral) elbow. Computer reduction of almost 9000 individual trials and analysis of variance indicated that for the EMG limb the tactile feedback with sound occluded reduced errors by 50 percent. Terminal device load did not significantly affect positioningperformance due to the force proprioception built into the Boston Arm. In comparison with the standard mechanical prosthesis, the EMG limb with feedback achieves virtually identical kinesthetic performance. The display is completely compatible with the EMG control, causes no discomfort to the wearer, and is not significantly degraded by the environmental conditions of the limb socket. View full abstract»

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  • 7. An Electrotactile Display

    Page(s): 72 - 79
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    An explorable electrotactile display has been constructed and tested. A thus far neglected sensation was identified and has been shown to be more useful than the more common electrotactile sensations. Exploration of the surface of the electrotactile display elicits a sensation describable as texture. Experiments have indicated that the intensity of this texture sensation is due primarily to the peak applied voltage rather than to current density as is the case for the classical electrotactile sensation. For subjects employing the texture sensation, experimental results are given for approximate thresholds and for the effect of electrode area on these thresholds. A boundary-localization measurement is offered as a measure of the usefulness of the display for textured-area presentation, and form-separation measurements are given as a measure of usefulness for line-drawing presentations. A proposed model for the mechanism producing the texture sensation is offered as a guide for future experimentation and display-engineering development. View full abstract»

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  • 8. Optical-to-Tactile Image Conversion for the Blind

    Page(s): 58 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5232 KB)  

    This paper describes two optical-to-tactile imageconversion systems being developed for the blind. The first is a reading aid in which an area on the printed page about the size of a letterspace is translated into a corresponding vibratory tactile image. The tactile image is produced by a 24-by-6 array of pins driven by piezoelectric bimorphs. The array of 144 pins fits on the distal and a portion of the middle phalanges of one finger. The piezoelectric bimorphs cause the pins to impact the skin in a nonlinear manner. Precise measurements on this bimorph-finger system are given. These measurements also show that shades of "grey" can be displayed by sequentially varying the threshold level. Three experiments conducted with the reading aid involved measurement of legibility, reading rate, and the effect of field of view. Legibility in the 92-98 percent range was obtained at the design magnification. A reading rate of 50 words per minute was achieved with one subject after roughly 160 hours of practice. Three other subjects achieved reading rates of over 10 words per minute after about 40 hours of practice. Reading rate increased markedly as the number of columns in the array was varied from one to six. The second optical-to-tactile image-conversion system is merely an extension of the first to permit information to be acquired from the environment. In fact, ultimately only one system with two sets of optics, one appropriate for the printed page and one appropriate for environment sensing, would be used. View full abstract»

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  • 9. Character Legibility versus Resolution in Image Processing of Printed Matter

    Page(s): 66 - 71
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    In order to determine optimum resolution requirements for digital facsimile systems, a legibility study was conducted. The study was designed to measure the quality of output copy as a function of equipment parameters and copy parameters. The experimental equipment permitted systematic variations in horizontal and vertical resolution, scan direction, and simulated transmission noise; the test documents prepared included uppercase and lowercase characters of several sizes. During the course of the overall study, more than 300 subjects read the facsimile output copies; approximately 750 000 responses were accumulated and analyzed. The data are summarized by showing the spatial resolutions required to maintain 97.5 percent legibility for varying character sizes. Measurements were also made on secondary parameters, indicating slight differences in legibility due to scan direction, and a decrease in legibility when type was lowercase rather than uppercase. The decrease in legibility was also measured for a model of channel errors that assumes the use of run-length compression coding. Some of the results of this study can be generalized to other display systems. View full abstract»

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  • 10. Neurophysiological Basis of a Tactile Vision-Substitution System

    Page(s): 108 - 110
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    The instrumentation produced and the results obtained with the tactile vision-substitution system (TVSS) developed in our laboratories have been described by Collins [1] and White [2]. With the TVSS, the information from a TV camera is carried to the brain by means of the tactile receptors in the skin of the back and their neural pathways. Such information produces subjective impressions in blind subjects that are analogous to the subjective impressions produced by the visual input in normal sighted people. Some of the neural mechanisms underlying the systems design and the results obtained with the TVSS are noted. View full abstract»

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  • 11. SIMON - A Simple Instructional Monitor

    Page(s): 174 - 180
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    An instructional monitor is a program that tries to detect, diagnose, and possibly help overcome a student's learning difficulties in the course of solving a problem or performing a task. In one approach to building an instructional monitor, the student uses a special task- or problem-oriented language expressly designed around some particular class of problems. Correspondingly, the diagnostic programs in this special-purpose type of monitor system often utilize information that is specific to the kind of problem being studied. The SIMON system represents a different approach. The student addresses SIMON in an easy and very general programming language rather than a special task language. Using SIMON, students construct programs for systems or processes that can represent vastly different situations from mathematics, biology, physics, engineering, or elsewhere. The student tests his program against a "true" program provided to SIMON by an instructor. At the student's request, SIMON tests his program against its "true" model to determine if it works. If not, SIMON points out cases where the program fails and, if requested, informs the student which variables he has chosen that are inappropriate to the process. View full abstract»

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  • 12. A Neuromuscular Actuation System Model

    Page(s): 61 - 71
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    Recently, both high quality physiological data and human-operator-describing function data of low variability and large dynamic range have become available. These data lead to control engineering descriptions for neuromuscular actuation systems that are compatible with the available data and that provide insight into the overall human control structure (e.g., the types of feedback systems used for various inputs). In this paper, some of these physiological and human-operator data are briefly reviewed, and a simple neuromuscular actuation system model is presented. The physiological data of interest include recent anatomical and physiological data for the muscle spindle and input-output studies of the muscle. These data indicate that simple linear models can describe the basic behavior of these two elements in tracking tasks. This paper contains two key developments: 1) the variation in system parameters as a function of average muscle tension or operating point; and 2) the role of the muscle spindle both as an equalization element and in its effects on muscle tone or average tension. The simplest neuromuscular model suggested by and compatible with the data is one in which muscle spindles provide four functions in one entity: 1) the feedback of limb position; 2) lead/lag series equalization; 3) the source of at least one command signal to the system; and 4) a signal for adjustment of the spindle gain, equalization, and steady-state spindle output which produces the average muscle tension. View full abstract»

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  • 13. A Relatively High-Resolution Reading Aid for the Blind

    Page(s): 1 - 9
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    Many direct-translation reading aids for the blind have been built in the past, employing an auditory output consisting of a combination of tones indicating the black regions in a vertical slice through a letter space, or a tactile output consisting of a raised or vibrating image of the letter shapes. Maximum reading rates obtained by the majority of subjects with these reading aids have been less than 10 correct words per minute, and the cause of this limitation has not been well understood. By analyzing the spatial spectral content of letter patterns, we show here that most of these reading aids have violated the well-known sampling theorem. It is suggested that this may be a significant factor in the observed reading-rate limitation. The design of a reading aid is described based on the conclusions from this analysis of the sampling process, and on recent results from tactile research. With this reading aid a hand-held probe images a vertical section of a letter space onto a 24 × 6 array of photosensors, and the probe is manually moved horizontally across the line of print. The signal from each photosensor controls a tactile stimulator in a corresponding array of 144 stimulators, which are placed on a single finger. In preliminary reading tests with this device, four subjects have all read at rates greater than 10 correct words per minute, and two of the subjects have read at rates greater than 20 correct words per minute. View full abstract»

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  • 14. Model of the Adaptive Behavior of the Human Operator in Response to a Sudden Change in the Control Situation

    Page(s): 72 - 80
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    An adaptive model is presented to describe the behavior of the human operator in response to sudden changes in plant dynamics and transient disturbances. The plant simulated for tracking experiments is approximately second-order and has rate and attitude feedback augmentation for increased stability. The failure of the rate sensor and/or the attitude sensor results in a sudden transition in the order and gain of the effective plant dynamics. These failures may be accompanied by hard-over transient conditions in either the rate or attitude sensors. The adaptive model suggested has a variable structure, contains mode switching based on pattern recognition as evidence, and incorporates the decision-control logic required for successful adaptation to failures. The model in effect attempts to mimic the control strategy or algorithm used by a trained operator. View full abstract»

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  • 15. Some Comparisons between Touch and Hearing

    Page(s): 28 - 35
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    The skin can be used for sound localization with accuracy nearly as good as that for hearing. However, auditory sound localization is based on the utilization of both intensive-difference and temporal-difference cues while cutaneous sound localization is based almost entirely on the utilization of only intensive-difference cues. Furthermore, the time interval necessary for resolving two temporally separated pulses was found to be 2.0 ms for binaural and monaural stimulation and, at best, 10 ms for stimulation of the skin. The superior temporal acuity of the ears over the skin was again demonstrated by the finding that pairs of auditory pulses separated by less than 30 ms were perceived as more separated in time than pairs of cutaneous stimuli separated by the same time interval. A series of experiments was conducted to measure inhibitory interaction between touch and hearing. When absolute thresholds were measured by a tracking method in which the subject was free to vary his judgment criterion, auditory stimulation by a click was found to increase tactile thresholds for mechanical pulses by as much as 5.0 dB. Intense tactile pulses slightly increased the auditory click threshold. Subsequent experiments using signal-detection methodology revealed that auditory-tactile masking is caused by a slight reduction in stimulus detectability accompanied by a corresponding increase in the subject's criterion. View full abstract»

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  • 16. Computer-Assisted Fingerprint Encoding and Classification

    Page(s): 156 - 160
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    A proposed man-machine system for encoding fingerprint ridge characteristics is described. The fundamental concept underlying the proposed system is to use an operator to recognize the ridge characteristics and to impart to a computer the ability to manipulate and compare the digitized locations and directions of these characteristics for single-fingerprint classification. The proposed system and encoding schemes were simulated using a RAND tablet and an IBM 1800 computer. Sample input prints were encoded and stored on a magnetic tape. Experimental results on human factors and multiple-impression file searches illustrate the feasibility of computer-assisted fingerprint encoding and classification. View full abstract»

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  • 17. A Describing Function Analysis of Tracking Performance Using Two Tactile Displays

    Page(s): 92 - 101
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    A display consisting of two vibrators attached to the body was tested using three different error signal-to-vibration amplitude transformations. In addition, a novel ripple display consisting of seven sequentially activated air-jet stimulators was tested on a compensatory tracking task. For both displays the range of gains and body locations were determined by both describing-function and error-power analyses. The results showed that the two-vibrator display was equally effective on all five body areas tested, but that the ripple display produced best tracking performance only when widely spaced or situated on an anatomical landmark. The best ripple display, however, was better than the best vibrator display and provided tracking performance nearly equivalent to visual displays. It was found that the ripple display was not enhanced by apparent motion but produced equivalent operator time delays shorter than those measured with visual displays. View full abstract»

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  • 18. Variable Perception Time in Car Following and Its Effect on Model Stability

    Page(s): 149 - 156
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    The functional variation of perception time T in car following is studied for the purpose of introducing a variable time delay into a previously proposed nonlinear model. The basic hypothesis is that the ratio of a just noticeable difference in visual angle (¿¿) to the visual angle (¿) is a constant. This hypothesis leads to a model in which perception time T is proportional to relative spacing and inversely proportional to relative speed. Experimental results agree very closely with the model for negative relative speeds between 3 and 18 ft/s. A second-order approximation is used to explain behavior for relative speeds of less than 3 ft/s in absolute value. This second-order approximation also agrees well with data taken previously with relative acceleration varying between 1 and 4.7 ft/s2 and initial relative speed between ¿ 1.9 and 2.9 ft/s. A brief discussion of "ideal" following distance b is presented to clarify the stability analysis. The introduction of a variable time delay and ideal following distance into the proposed car-following model changes the size of the minimum asymptotic stability region but not the basic properties of the model. The word "asymptotic" is used in the dynamic stability sense as in the classical control theory literature, not in the sense of platoon stability. View full abstract»

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  • 19. Information Transmission by Phantom Sensations

    Page(s): 85 - 91
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    A sensory-aids display system that transmits information to its user through the location of a vibratory sensation on the skin has been developed. The sensation location is controlled by use of the phantom-sensation phenomenon. The development of the display included the determination of sensory and mechanical characteristics of the skin. The system was evaluated as a kinesthetic feedback display from the elbow prostheses for above-elbow amputees. View full abstract»

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  • 20. A Survey of the Mechanical Characteristics of Skin and Tissue in Response to Vibratory Stimulation

    Page(s): 79 - 84
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    The possibility that the mechanical characteristics of skin and tissues may influence physiological and psychophysical measurements of tactile sensitivity is considered. A survey of selected literature indicating how certain mechanical characteristics of skin and tissue vary as a function of changes in variables known to influence physiological and psychophysical measurements of the tactile system is presented. Finally, certain physiological and psychophysical studies in which the physical properties of the area stimulated may have influenced the results are mentioned. View full abstract»

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  • 21. Theory of Manual Vehicular Control

    Page(s): 257 - 291
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    The analytical basis of manual vehicular control theory is a combination of feedback systems analysis and mathematical models for human operators engaged in control tasks. Simplified representations for the operator-system combination are provided by the 'crossover model', which is described in detail. The system dynamics and average performance of the crossover model system are developed. With these as bases, case studies are presented to illustrate the types of result which can be obtained from application of the operator-vehicle control theory. Two aircraft control examples illustrate the use of the theory and its empirical correlates to estimate operator dynamic characteristics, system performance, pilot ratings, pilot commentary, design implications, and some experimental guidelines. A driver automobile example is presented to illustrate the use of the theory in structuring the key guidance and control features of the driver's visual field. A comprehensive bibliography of operator-vehicle system analysis applications is also provided. View full abstract»

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  • 22. Aiding the Decision Maker - A Decision Process Model

    Page(s): 204 - 218
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    Despite an increasing capability for automating various tasks there continues to be a requirement for man to serve as the decision element in many complex systems. The complexity and far-reaching consequences of many decisions impels a concern for improving decision-making perforrnance in man-machine systems. In this paper current knowledge regarding human decision behaviour and methods for aiding this behaviour are briefly reviewed. A tentative, conceptual model of an idealized process of decision making is presented. This model, which is based on both empirical and theoretical research, contains three phases. These are (1) problem recognition, (2) problem diagnosis, and (3) action selection. The model is intended primarily to provide a guide to system designers in structuring decision tasks and a framework for organizing knowledge about decision-making behaviour. View full abstract»

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  • 23. The Use of Multi-Man System Trainers

    Page(s): 194 - 203
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    Current training practices in the use of U.S. Naval weapon system trainers (WST) do not reflect some fundamental principles of learning. In the use of such devices for refresher training, fleet personnel seek only to 'practice' behaviours as they would when training at sea under operational conditions. Thus, training is, for the most part, unplanned, unstructured, and the benefits of using the device are less than optimum. A utilization guide for an ASW (anti-submarine warfare) trainer is described, setting forth four principles for effective, tactical team training. (i) Training objectives should be specified across the fuill range of device capability; (ii) each exercise should be structured and controlled with respect to the-objectives; (iii) progression through the training programme should be according to levels of difficulty; (iv) exercise sequencing should be based on measured trainee performance. View full abstract»

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  • 24. Display Design: Principles and Procedures

    Page(s): 181 - 193
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    The history of research on display design is described briefly and the general problems of real/artificial displays and new/stored information are discussed with particular emphasis on compatibility The main discussion centres on the advantages and limitations of the three general approaches to display design: use of checklists, use of formal procedures and use of behaviour theory. A checklist for display design is provided and the other procedures are illustrated by case studies. View full abstract»

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  • 25. An Evaluation of a Pilot Model Based on Kalman Filtering and Optimal Control

    Page(s): 108 - 117
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    A pilot model based on Kalman filtering and optimal control is given which, because of its structure, provides for estimation of the plant state variables, the forcing functions, the time delay, and the neuromuscular lag. The inverse filter and control problem is considered where the noise and cost function parameters yield a frequency response which is in close agreement with that found experimentally. A good correspondence with sine-wave tracking is shown including "eyes closed" tracking. View full abstract»

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  • 26. A Model for Human Controller Remnant

    Page(s): 101 - 108
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    A model for human controller remnant is postulated in which remnant is considered to arise from an equivalent observation noise vector whose components are linearly independent white noise processes. Extensive analysis of data obtained from simple manual control systems verifies that this model structure holds over a wide range of input amplitudes and bandwidths, vehicle dynamics, and display locations. When the display is viewed foveally, the component noise processes are proportional to the variances of the displayed quantities. This constant of proportionality is independent of input parameters and of vehicle dynamics. View full abstract»

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  • 27. An Application of Measurement Methods to Improve the Quantitative Nature of Pilot Rating Scales

    Page(s): 81 - 92
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    Although various forms of pilot rating scales have been widely used, they have at the same time been criticized increasingly for supposed deficiencies. Thus, contemporary scale problems include wording ambiguity, the dual mission character of some scales, and a lack of information about the quantitative character of the scale continuum. In an attempt to quantize rating scales, a semantic experiment was conducted that allowed psychological measurement techniques to be applied to scale the wording used in rating scales. The results of the application of the method of successive intervals indicate that contemporary scale data can be averaged directly with little error if a reliable estimate of the mean is available. However, the number of samples necessary to obtain a reliable estimate depends on the rating itself, and increases as the rating becomes worse, so that the design of an experiment would need to depend on the outcome of the same experiment. The problem could be avoided by constructing a scale based on the successive interval scale values, where variability along the scale is constant. View full abstract»

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  • 28. Stretch Receptor Models I - Single-Efferent Single-Afferent Innervation

    Page(s): 17 - 27
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    Two lumped parameter models of muscle stretch receptors are described quantitatively on the basis of experimental data from crustacean, amphibian, and mammalian muscle spindles. These models have single-efferent (input) and single-afferent (output) innervation. It is shown that these simple mechanical models can account for many of the behavioral characteristics exhibited by muscle spindle, but are inadequate for a complete model. These inadequacies are discussed. The two models are shown to be sufficiently similar in their transient and steady-state responses to be physiologically equivalent from a systems viewpoint. View full abstract»

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  • 29. The Human as an Optimal Controller and Information Processor

    Page(s): 9 - 17
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    A mathematical model of the instrument-monitoring behavior of the human operator is developed. The model is based on the assumption that the operator behaves as an optimal controller and information processor, subject to his inherent physical limitations. The resulting model depends explicitly on the control task and the control actions. Provision is made for the ability to obtain information from the peripheral visual field. There are no restrictions on signal coupling. The specific characteristics of the operator's visual sampling behavior are predicted by solving a nonlinear, deterministic optimization problem. A two-axis compensatory tracking example is investigated, and the results exhibit the general characteristics expected of a human operator performing a similar task. View full abstract»

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  • 30. Human Information Processing Rates during Certain Multiaxis Tracking Tasks with a Concurrent Auditory Task

    Page(s): 129 - 138
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    A series of experiments was conducted to determine the information processing rates of several subjects performing one- and two-axis compensatory tracking tasks with a secondary auditory task. The experimental variables were the order of controlled element dynamics, the forcing function, and the addition of a secondary task. Human information processing rates decreased slightly on each tracking channel with the addition of the second tracking channel or the secondary auditory task. Other than this effect, the information processing rates were additive until a limit in the total information processing rate was reached. This limit was related to the order of the controlled element. View full abstract»

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  • 31. An Analysis of Pilot Adaptation in a Simulated Multiloop VTOL Hovering Task

    Page(s): 110 - 120
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    Human pilot adaptation in a simulated multiloop VTOL hovering task was investigated with a series-loop-closure model. Using the model equations, the pilot-model adaptable parameters were computed from rms hovering performance data measured in flight simulator experiments for a variety of VTOL aircraft configurations. Variations in the aircraft configurations affected both the aircraft's dynamic characteristics and its response to simulated turbulence. The pilot's pitch-loop adaptation generally correlated with the frequency-domain characteristics of the pitch response to turbulence and the pitch response to control inputs. The results of the study show no specific low-frequency attitude gain requirements that must be satisfied by the pilot for the attitude disturbance and dynamic characteristics considered. The influence of the aircraft position-loop characteristics on pilot pitch-loop adaptation was important only for configurations that had small attitude disturbances. For these cases the requirements for position-loop control apparently determined the minimum acceptable pitch-loop crossover frequency. Results also show that the pilot preferred to adjust pitch-loop gain by changing control-stick sensitivity (aircraft gain) rather than by changing his internal gain. View full abstract»

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  • 32. Measurement of Pilot Describing Functions from Flight Test Data with an Example from Gemini X

    Page(s): 49 - 55
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    It is well known that there is an error in identifying the pilot describing function from routine flight test records because the pilot's output noise is correlated with the input error signal. This paper shows that this identification error can be reduced in the computer processing by shifting the input signal an amount equivalent to the pilot's time delay. This technique for reducing the identification error is analyzed with theory and is demonstrated with the identification of a simulated pilot model. This technique is also applied to flight test records obtained from the retrofire phase of the Gemini X mission. View full abstract»

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  • 33. Stochastic Modeling of Human Learning Behavior

    Page(s): 36 - 46
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    A stochastic model of human learning behavior in a manual control task is described. Regulation of the state of a double integral plant to minimize the integrated absolute error is the operator's task. Subjects given this task were instructed to drive the process from an initial state to the null state using a two-position relay controller and a visual display. A subject is conceptualized in the model as a sequential data-processing system. A sensor, a decision maker, and an effector are the three serially connected components making up the system. Each element requires a finite time to either process or transmit information, and thus a delay is incurred between the reception of the visual stimulus and the execution of a motor response. Response decisions are based on the a priori estimate of the probability that the control polarity should be switched, given the current state of the plant. Patterns in the resultant phase trajectory are used as evidence by the decision maker to revise the prior estimate with an algorithm according to Bayes' theorem. Behavior of this model is compared with subject behavior in the motor skill experiment, and the model's characterization of the time-varying random nature of human learning is brought out by this comparison. Also discussed are the applications of the concept of this model to other manual control tasks. View full abstract»

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  • 34. A Physiologically Based Model of Neuromuscular System Dynamics

    Page(s): 21 - 23
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    A model of the neuromuscular system based on the physiology of muscle is described. All elements of the model have been discussed in earlier literature but certain new implications are considered here. View full abstract»

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  • 35. The Surge Model of the Well-Trained Human Operator in Simple Manual Control

    Page(s): 2 - 9
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    A new model of the human operator, termed the surge model, is developed. It is dual mode, containing a linearized constant coefficient model and an optimum second-order controller model. The equations describing its performance are written in the time domain. When the absolute values of the system error and of the first error derivative are less than certain specified bounds, the linear constant coefficient model is employed; and when the absolute values of the system error and of the first error derivative exceed these bounds, the optimum second-order controller model is employed. The surge model accurately predicts actual human operator performance in situations where the present widely used constant coefficient models yield unrealistic results, namely, when the signal being tracked contains discontinuous as well as continuous components, of either a random or a predictable nature. An Applied Dynamics 256 analog computer and a Control Data 3600 digital computer were employed, respectively, to simulate a real-time tracking problem and to solve the surge model equations characterizing the tracking task. Results presented in graphical form clearly indicate the superiority of the surge model in simulating tracking situations where discontinuities may occur. View full abstract»

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