Henk G. Stassen

Pilot's perception in the control of aircraft motions

For proper manual aircraft control, the pilot has to perceive the motion state of the aircraft. In this perception process both the visual and the vestibular systems play an important role. To understand this perception process and its impact on a pilots control behavior a descriptive model was developed. The single-channel information-processor model was applied as the basic structure of the final model. Three groups of experiments were performed to refine the model structure and to define the majority of the model parameters. The model has been evaluated by measuring the control behavior in tracking tasks.

Internal representation, internal model, human performance model and mental workload

Abstract In supervising complex industrial processes, the human supervisor has to reach a certain performance while not exceeding the mental capacity he is willing to spend. A well-designed Human-Machine Interface, HUMIF, will help the supervisor to achieve these goals. A well-proven method of designing systems, particularly HUMIF, is to model system behavior, thus modeling human performance and mental load. This paper reviews the literature in the field of human-machine systems, with special emphases on human operator models and mental load measures. The review is presented in terms of Rasmussens three level model and integrates the various articles in some well-defined concepts. An attempt is made to elucidate what can be expected of modeling techniques with reference to HUMIF design.

The Internal Model Concept: An Application to Modeling Human Control of Large Ships

Many human operator studies have used successfully the concept that the human operator performs his task on the basis of certain knowledge about the system to be controlled, called the internal model. In this paper, the literature on manual control will be reviewed briefly with attention focused on the use of the internal model concept. To illustrate the applicability of the internal model concept in the field of man-machine systems, an application is given in the human control of large ships. A model to describe the helmsmans behavior in steering a supertanker, and the influence on his behavior of additional displays such as a rate of turn indicator will be described.

A field evaluation of arm prostheses for unilateral amputees

A post-clinical investigation has been carried out among 42 unilateral amputees who lost their hand due to an accident. The investigation was directed at two main topics of interest. Firstly the amputee, the problems he has to cope with, and the role the prosthesis plays in his life; and secondly the prosthesis, its use and its potential benefits and burdens. The group of amputees consisted of above-elbow and below-elbow amputees. Body powered as well as myoelectric prostheses were represented in the group. Most of the information was obtained during a two-day home visit where a semi-structured interview was conducted, and where a number of daily life activities were observed. The information thus obtained has led to a number of conclusions and recommendations with respect to the rehabilitation of this category of amputees, and with respect to the design criteria of protheses for unilateral amputees.

Theoretical problems in man-machine systems and their experimental validation

Abstract This survey paper focusses on the main theoretical issues in todays man-machine systems research and applications. The following problem areas are discussed: (1) modelling human performance and mental workload, with identifying the state of the art as well as major methodological difficulties; (2) task allocation and decision support, with a human-centred perspective on cooperative problem solving, integrated automation, and distributed decision making in teams; (3) man-machine interfaces, with outlining some presentation and dialogue issues; (4) design problems, with stressing the need of early active participation of man-machine-systems specialists and the usefulness of guidelines; and, finally, (5) evaluation and experimental validation, with covering laboratory and field evaluations, with covering laboratory and field evaluations, experimental design and validation, as well as model-driven experimentation. The importance of man-machine-systems contributions to the design of better technical systems and their user acceptability is emphasised.

Rasmussen’s model of human behavior in laparoscopy training

Aims: Compared to aviation, where virtual reality (VR) training has been standardized and simulators have proven their benefits, the objectives, needs, and means of VR training in minimally invasive surgery (MIS) still have to be established. The aim of the study presented is to introduce Rasmussen’s model of human behavior as a practical framework for the definition of the training objectives, needs, and means in MIS. Methods: Rasmussen distinguishes three levels of human behavior: skill-, rule-, and knowledge-based behaviour. The training needs of a laparoscopic novice can be determined by identifying the specific skill-, rule-, and knowledge-based behavior that is required for performing safe laparoscopy. Future objectives of VR laparoscopy trainers should address all three levels of behavior. Results: Although most commercially available simulators for laparoscopy aim at training skill-based behavior, especially the training of knowledge-based behavior during complications in surgery will improve safety levels. However, the cost and complexity of a training means increases when the training objectives proceed from the training of skill-based behavior to the training of complex knowledge-based behavior. Conclusion: In aviation, human behavior models have been used successfully to integrate the training of skill-, rule-, and knowledge-based behavior in a full flight simulator. Understanding surgeon behavior is one of the first steps towards a future full-scale laparoscopy simulator.

Theoretical background and conceptual solution for depth perception and eye-hand coordination problems in laparoscopic surgery

SummaryThe indirect method of observation and manipulation in laparoscopic surgery complicates the surgeons depth perception and impairs his/her eye-hand coordination. Depth perception problems are due to misfits in accommodation and convergence, absence of shadows in endoscopic camera pictures and absence of stereo-vision and movement parallax. Eye-hand coordination problems are caused by the distant location of the monitor and by the fact that the surgeons hand movements are rotated, mirrored and amplified when they appear on the monitor. These effects are very confusing, especially for trainee laparoscopic surgeons and require a long and intensive training period to overcome. This paper gives a theoretical background of the depth perception and eye-hand coordination problems. A technical concept of an endoscope positioning system is described that compensates misorientations by using a flexible 90° endoscope. Movement parallax is achieved using a motorised endoscope positioner controlled by the surge...

Analysis of verbal communication during teaching in the operating room and the potentials for surgical training.

BackgroundVerbal communication in the operating room during surgical procedures affects team performance, reflects individual skills, and is related to the complexity of the operation process. During the procedural training of surgeons (residents), feedback and guidance is given through verbal communication. A classification method based on structural analysis of the contents was developed to analyze verbal communication. This study aimed to evaluate whether a classification method for the contents of verbal communication in the operating room could provide insight into the teaching processes.MethodsEight laparoscopic cholecystectomies were videotaped. Two entire cholecystectomies and the dissection phase of six additional procedures were analyzed by categorization of the communication in terms of type (4 categories: commanding, explaining, questioning, and miscellaneous) and content (9 categories: operation method, location, direction, instrument handling, visualization, anatomy and pathology, general, private, undefinable). The operation was divided into six phases: start, dissection, clipping, separating, control, closing.ResultsClassification of the communication during two entire procedures showed that each phase of the operation was dominated by different kinds of communication. A high percentage of explaining anatomy and pathology was found throughout the whole procedure except for the control and closing phases. In the dissection phases, 60% of verbal communication concerned explaining. These explaining communication events were divided as follows: 27% operation method, 19% anatomy and pathology, 25% location (positioning of the instrument–tissue interaction), 15% direction (direction of tissue manipulation), 11% instrument handling, and 3% other nonclassified instructions.ConclusionThe proposed classification method is feasible for analyzing verbal communication during surgical procedures. Communication content objectively reflects the interaction between surgeon and resident. This information can potentially be used to specify training needs, and may contribute to the evaluation of different training methods.

Telemanipulation and telepresence

Abstract Telemanipulation is studied by many disciplines; however, this is generally done independently. This paper is intended to contribute to the integration of these disciplines by bridging the gap between the control engineers in the man-machine systems field, the computer scientists in the field of human-computer interaction, and the biomedical researchers in the field of severely bodily disabled persons. Three major problems in telemanipulation are recognised, i.e. the lack of tactile and touch information, the lack of information for depth perception since visual displays only generate 2D data, and the existing time-delay in the human operator - telemanipulator - control loop. For control theory the importance of the Internal Model for obtaining optimal filtering and control is highlighted, and for perception theory the choice for the so-called “ecological approach” is explained. Control theory and perception theory both point to the importance of an increase in feedback modalities, for instance by pointing to the importance of proprioceptive feedback for 3D perception, and by designing two-handed controls that pay attention to the asymmetry in the effectivities of both hands. It is argued that a combination of proprioceptive feedback and 3D perception is needed for good telemanipulation, and for telepresence. Also, a short note on compensation methods using predictive displays is given. Finally, the traditional approach will be compared with the ecological approach.

Does virtual reality training make sense in interventional radiology? Training skill-, rule- and knowledge-based behavior.

To be able to meet the fast-growing demands of interventional radiology and endovascular therapy, many more interventional radiologists have to be trained in procedures that are becoming more complex. Until recently, fellows obtained their first basic skills training during diagnostic angiography procedures. This traditional method of training is disappearing because other diagnostic methods became available which raises the question “How can our future interventional radiologists be trained?” Training on animals, bench models (skill boxes) and virtual reality (VR) training has been suggested as a solution for this problem [1–5]. In many countries, animal experiments have been confronted with a growing resistance because animals are too expensive to be used as a full-scale training tool. With the use of bench models, objective assessment of performance is difficult to obtain. Training on simulators does not have these problems and seems therefore to be a good alternative. However, the effectiveness and efficiency of VR trainers in interventional radiology (IR) have not yet been addressed. In aviation, human behavior models have been implemented to develop and to evaluate new training methods [6, 7]. These models are useful for specifying the objectives, needs and means of training methods [8–10]. This paper introduces Rasmussen’s model of human behavior and applies it to IR. This model will be used to discuss the capabilities and limitations of current VR for IR training in relation to the training needs.