Multiple human tracking in high-density crowds

In this paper, we introduce a fully automatic algorithm to detect and track multiple humans in high-density crowds in the presence of extreme occlusion. Typical approaches such as background modeling and body part-based pedestrian detection fail when most of the scene is in motion and most body parts of most of the pedestrians are occluded. To overcome this problem, we integrate human detection and tracking into a single framework and introduce a confirmation-by-classification method for tracking that associates detections with tracks, tracks humans through occlusions, and eliminates false positive tracks. We use a Viola and Jones AdaBoost detection cascade, a particle filter for tracking, and color histograms for appearance modeling. To further reduce false detections due to dense features and shadows, we introduce a method for estimation and utilization of a 3D head plane that reduces false positives while preserving high detection rates. The algorithm learns the head plane from observations of human heads incrementally, without any a priori extrinsic camera calibration information, and only begins to utilize the head plane once confidence in the parameter estimates is sufficiently high. In an experimental evaluation, we show that confirmation-by-classification and head plane estimation together enable the construction of an excellent pedestrian tracker for dense crowds.     

Kinematic analysis of 3SPS+1PS bionic parallel test platform for hip joint simulator based on unit quaternion

As a novel parallel hip joint simulator, the 3SPS+1PS bionic parallel test platform with 4 degrees of freedom including three rotations and one translation is proposed. SPS denotes the spherical-prismatic-spherical leg and PS denotes the prismatic-spherical leg where only the prismatic joint is actuated and hence underlined. By means of the unit quaternion method, the formulae for solving the inverse/forward displacement, the inverse/forward velocity and the inverse/forward acceleration kinematics are derived. Using the unit quaternion to represent the position and orientation of a moving platform, singularities caused by Euler angles can be avoided. Combining the topological structure characteristics of the 3SPS+1PS bionic parallel test platform and letting the three-dimensional (3-D) motion of a human hip joint as its output movement, the displacement trajectories of three active legs are constructed based on the inverse displacement kinematics. The forward kinematic tests whose data are recorded by a 3-D orientation capture system are carried out on the developed parallel hip joint simulator. Moreover, the results of the forward kinematic tests prove that the 3SPS+1PS bionic parallel test platform can approximately represent human hip joint motion and provide more reliable experimental data for hip joint prostheses in clinical application.     

Alarm-initiated activities: an analysis of alarm handlingby operators using text-based alarm systems in supervisory control systems

Alarms constitute a significant aspect of the operator-system interface in human supervisory control tasks: they have the potential to display information that is of critical importance to overall system safety and integrity. This paper considers the trend toward the use of visual display terminals for the presentation of alarms, specifically in the use of scrolling text displays. It is suggested that this form of information display may not best serve all aspects of alarm handling. To illustrate why this is so, an analysis of human alarm handling activities is presented. The focus on text-based displays and annunciators allows the authors to concentrate on a number of problems associated with the alarm design using a specific medium. From this discussion, the alarm initiated activities model is developed. By considering the activities that people engage in when dealing with alarms, an insight is offered into the information requirements that can be used to inform the design of alarm systems.     

Book reviews

Abstract

Industrial robots often operate at high speed, with unpredictable motion patterns and erratic idle times. Serious injuries and deaths have occurred due to operator misperception of these robot design and performance characteristics. The main objective of the research project was to study human perceptual aspects of hazardous robotics workstations. Two laboratory experiments were designed to investigate workers' perceptions of two industrial robots with different physical configurations and performance capabilities. Twenty-four subjects participated in the study. All subjects were chosen from local industries, and had had considerable exposure to robots and other automated equipment in their working experience. Experiment 1 investigated the maximum speed of robot arm motions that workers, who were experienced with operation of industrial robots, judged to be ‘safe’ for monitoring tasks. It was found that the selection of safe speed depends on the size of the robot and the speed with which the robot begins its operation. Speeds of less than 51 cm/s and 63cm/s for large and small robots, respectively, were perceived as safe, i.e., ones that did not result in workers feeling uneasy or endangered when working in close proximity to the robot and monitoring its actions. Experiment 2 investigated the minimum value of robot idle time (inactivity) perceived by industrial workers as system malfunction, and an indication of the ‘safe-to-approach’ condition. It was found that idle times of 41 s and 28 s or less for the small and large robots, respectively, were perceived by workers to be a result of system malfunction. About 20% of the workers waited only 10 s or less before deciding that the robot had stopped because of system malfunction. The idle times were affected by the subjects' prior exposure to a simulated robot accident. Further interpretations of the results and suggestions for operational limitations of robot systems are discussed.     

Ergonomics and human factors: the paradigms for science,engineering, design,technology and management of human-compatible systems

This paper provides a theoretical perspective on human factors and ergonomics (HFE), defined as a unique and independent discipline that focuses on the nature of human-artefact interactions, viewed from the unified perspective of the science, engineering, design, technology and management of human-compatible systems. Such systems include a variety of natural and artificial products, processes and living environments. The distinguishing features of the contemporary HFE discipline and profession are discussed and a concept of ergonomics literacy is proposed. An axiomatic approach to ergonomics design and a universal measure of system-human incompatibility are also introduced. It is concluded that the main focus of the HFE discipline in the 21st century will be the design and management of systems that satisfy human compatibility requirements.     

Human and program factors affecting the maintenance of programs with deployed design patterns

Context

Practitioners may use design patterns to organize program code. Various empirical studies have investigated the effects of pattern deployment and work experience on the effectiveness and efficiency of program maintenance. However, results from these studies are not all consistent. Moreover, these studies have not considered some interesting factors, such as a maintainer’s prior exposure to the program under maintenance.

Objective

This paper aims at identifying what factors may contribute to the productivity of maintainers in the context of making correct software changes when they work on programs with deployed design patterns.

Method

We performed an empirical study involving 118 human subjects with three change tasks on a medium-sized program to explore the possible effects of a suite of six human and program factors on the productivity of maintainers, measured by the time taken to produce a correctly revised program in a course-based setting. The factors we studied include the deployment of design patterns and the presence of pattern-unaware solutions, as well as the maintainer’s prior exposure to design patterns, the subject program and the programming language, and prior work experience.

Results

Among the factors under examination, we find that the deployment of design patterns, prior exposure to the program and the presence of pattern-unaware solutions are strongly correlated with the time taken to correctly complete maintenance tasks. We also report some interesting observations from the experiment.

Conclusion

A new factor, namely, the presence of pattern-unaware solutions, contributes to the efficient completion of maintenance tasks of programs with deployed design patterns. Moreover, we conclude from the study that neither prior exposure to design patterns nor prior exposure to the programming language is supported by sufficient evidences to be significant factors, whereas the subjects’ exposure to the program under maintenance is notably more important.     

The smooth (tractor) operator: insights of knowledge engineering

The design of and training for complex systems requires in-depth understanding of task demands imposed on users. In this project, we used the knowledge engineering approach (Bowles et al., 2004) to assess the task of mowing in a citrus grove. Knowledge engineering is divided into four phases: (1) Establish goals. We defined specific goals based on the stakeholders involved. The main goal was to identify operator demands to support improvement of the system. (2) Create a working model of the system. We reviewed product literature, analyzed the system, and conducted expert interviews. (3) Extract knowledge. We interviewed tractor operators to understand their knowledge base. (4) Structure knowledge. We analyzed and organized operator knowledge to inform project goals. We categorized the information and developed diagrams to display the knowledge effectively. This project illustrates the benefits of knowledge engineering as a qualitative research method to inform technology design and training.     

The implications of cross-regional differences for the design of In-vehicle Information Systems: a comparison of Australian and Chinese drivers

The increasing global distribution of automobiles necessitates that the design of In-vehicle Information Systems (IVIS) is appropriate for the regions to which they are being exported. Differences between regions such as culture, environment and traffic context can influence the needs, usability and acceptance of IVIS. This paper describes two studies aimed at identifying regional differences in IVIS design needs and preferences across drivers from Australia and China to determine the impact of any differences on IVIS design. Using a questionnaire and interaction clinics, the influence of cultural values and driving patterns on drivers' preferences for, and comprehension of, surface- and interaction-level aspects of IVIS interfaces was explored. Similarities and differences were found between the two regional groups in terms of preferences for IVIS input control types and labels and in the comprehension of IVIS functions. Specifically, Chinese drivers preferred symbols and Chinese characters over English words and were less successful (compared to Australians) at comprehending English abbreviations, particularly for complex IVIS functions. Implications in terms of the current trend to introduce Western-styled interfaces into other regions with little or no adaptation are discussed.     

Significance of the dimensional view for visualizing relevant aspects of a production system in a co-operative planning process

Pictorial visualization is expected to facilitate communication between industrial professionals when planning working environments and production systems. This hypothesis was investigated by studying how 24 participants including managers, supervisors, machine operators, and occupational health and safety officials, judged three types of computer animated visualization varying in dimensional view (scale and scope of a production line):shop floor view/survey of shop floor; production unit view/semi-survey of production unit; and workplace view/close-up of workplace, in relation to a set of planning issues. The participants participated in a controlled 2-day planning workshop, redesigning a fictitious manufacturing process by means of computer graphics, and then responded to a questionnaire. It can be concluded that shop floor view as well as production unit view are significant for survey planning issues, while all 3-dimensional views are significant for close-up planning issues. Analogously, all dimensional views are significant for technocentric planning issues, whereas only the workplace view is valuable for anthropocentric planning issues.