The Onset Threshold of Cybersickness in Constant and Accelerating Optical Flow

This study investigated the principal translational or rotational axis that evokes the most severe cybersickness by detecting constant velocity and acceleration thresholds on the onset of cybersickness. This human subject experiment with 16 participants used a 3D particle field with movement directions (lateral, vertical, yaw, or pitch) and motion profiles (constant velocity or constant acceleration). The results showed that the threshold of pitch optical flow was suggestively lower than that of the yaw, and the vertical threshold was significantly lower than the lateral. Still, there was no effect of scene movement on the level of cybersickness. In four trials, the threshold increased from the first to the second trial, but the rest remained the same as the second one. However, the level of cybersickness increased significantly between the trials on the same day. The disorientation-related symptoms occurred on the first trial day diminished before the second trial day, but the oculomotor-related symptoms accumulated over the days. Although there were no correlations between the threshold and total cybersickness severity, participants with a lower threshold experienced severe nausea. The experimental findings can be applied in designing motion profiles to reduce cybersickness by controlling the optical flow in virtual reality.

Dimensions of Similarity Used to Identify Products As Sources of Analogy

This paper presents a human-subject experiment exploring the dimensions of product similarity that designers use to detect a product as a source of analogy during designing another. In the study, fifty voluntary participants are presented with a target product that is to be designed, and five other source products that are similar to the design task in various dimensions such as function, structure, or working principle. The designers are then asked to identify the products that they consider to be useful sources of analogy for designing the target, and to write in plain English why they considered so. These comments are analyzed using a protocol to reveal the dimensions of similarity between the target and the source product that inspired them to select the source. The data comprises of 2,440 total dimension instances among the participants. The results show that the identification of products as sources of analogy is driven by at least six dimensions: working principle, structure, human interaction, function, energy flows, and material flows. Among these, working principle, structure, and human interaction are more dominant than function, which was previously believed to be the sole driver of analogy.

Comparison Between Position and Rate Control Using a Foot Interface

There has been a recent increase in research related to supernumerary robotic arms. A challenge with supernumerary robotic arms is how to operate them effectively. One solution is to use the foot to teleoperate the arm. That frees the person to use their arms for other tasks. However, unlike hand interfaces, it is not known how to create effective foot control for robotic teleoperation. This paper presents an experiment to compare position and rate control methods for foot interfaces. A foot interface is presented that can be used for both position and rate control. A human subject experiment uses 2D positioning tasks to evaluate the effectiveness of each control method. These same tasks are tested with a hand interface to provide a baseline for comparison. Results show that, similar to the hand, position control performs faster than rate control when using the foot.

Coordinated Rate Control of a Hydraulic Excavator Using Traditional Joystick Hardware

This paper presents a novel user interface (UI) for coordinated rate control (CRC) of an excavator end effector using traditional hardware. Coordinated control of an excavator end effector alleviates the cognitive load created by nonlinear arm dynamics on the excavator operator, allowing the operator to perform tasks more quickly and with fewer errors. A human subject experiment demonstrates the feasibility of excavator CRC using the traditional twin joystick setup, and compares operator performance between a CRC UI and traditional excavator UI. Performance of the CRC UI was statically equivalent to the performance of the traditional UI. When asked to self-report UI preference: 26 participants stated they preferred the CRC UI, 6 preferred the traditional UI, and 14 had no preference. Although the current iteration of the CRC UI offered no measurable performance improvements, a remapping of the CRC joystick inputs to the end effector motion could make the CRC UI more intuitive, lead to better performance metrics, and make hydraulic excavators safer, more efficient, and easier to use.

Combining Head-Mounted and Projector-Based Displays for Surgical Training

We introduce and present preliminary results for a hybrid display system combining head-mounted and projector-based displays. Our work is motivated by a surgical training application where it is necessary to simultaneously provide both a highfidelity view of a central close-up task (the surgery) and visual awareness of objects and events in the surrounding environment. In this article, we motivate the use of a hybrid display system, discuss previous work, describe a prototype along with methods for geometric calibration, and present results from a controlled human subject experiment. This article is an invited resubmission of work presented at IEEE Virtual Reality 2003. The article has been updated and expanded to include (among other things) additional related work and more details about the calibration process.

Chest-lung statics: a realistic analog for student laboratory.

A mechanical analog of the human lung-chest wall system was developed in Fribourg and Geneva Universities, Switzerland, to help students understand chest-lung statics. The equipment comprises a lung bellows, with upper airway connected to a three-way manifold, and a transparent chest whose lower part is another bellows that can be mobilized manually. Two water manometers measure intrapulmonary and intrathoracic pressures. The pressure-volume relationships of the lung-chest wall analog, which are essentially determined by the diameters of the bellows and the strains imposed by steel coils, closely parallel those of the human respiratory system. The chest can be opened to demonstrate pneumothorax. A first, guided manipulation of the model at the physiology laboratory provides excellent preparation for--or useful complement to--a human subject experiment on chest-lung statics. Unguided, further use of the model provides an opportunity for students to teach each other. Since the model is used, mean score on chest-lung statics at the practical examination is as good as that on other, more easy subjects.