Presence: Teleoperators and Virtual Environments

Hilsenrat, Marcos; Reiner, Miriam

doi: 10.1162/pres.18.6.413pmid: N/A

Unaware haptic perception is often inferred but rarely demonstrated empirically. In this paper we present evidence for the effects of unaware haptic stimuli on users' motor interaction with virtual objects. Using a 3D hapto-visual virtual reality, we ran a texture-difference recognition test in which subjects glided a pen-like stylus along a virtual surface with varying roughness. We found that subjects were not aware of changes in texture roughness below a threshold limit, yet the normal force they applied changed. Subjects did not recognize on a cognitive level changes in the sensory cues, but behaved as if they did. These results suggest that performance can be affected through subliminal cues. Based on results from visual perception studies, we also tested the impact of context background conditions on the perception of unaware cues. We measured the threshold of awareness to changes in texture for several reference stimuli. We found that indeed, as in visual perception, this threshold for discriminating between the roughness of surfaces increases when the texture gets smoother, that is, sensitivity changes as a function of the background context. The implications of this work are mainly in the design of VR, especially for the remote manipulation of objects.

Hilsenrat, Marcos; Reiner, Miriam

doi: 10.1162/pres.18.6.413pmid: N/A

Unaware haptic perception is often inferred but rarely demonstrated empirically. In this paper we present evidence for the effects of unaware haptic stimuli on users' motor interaction with virtual objects. Using a 3D hapto-visual virtual reality, we ran a texture-difference recognition test in which subjects glided a pen-like stylus along a virtual surface with varying roughness. We found that subjects were not aware of changes in texture roughness below a threshold limit, yet the normal force they applied changed. Subjects did not recognize on a cognitive level changes in the sensory cues, but behaved as if they did. These results suggest that performance can be affected through subliminal cues. Based on results from visual perception studies, we also tested the impact of context background conditions on the perception of unaware cues. We measured the threshold of awareness to changes in texture for several reference stimuli. We found that indeed, as in visual perception, this threshold for discriminating between the roughness of surfaces increases when the texture gets smoother, that is, sensitivity changes as a function of the background context. The implications of this work are mainly in the design of VR, especially for the remote manipulation of objects.

Bullion, Conrad; Gurocak, Hakan

doi: 10.1162/pres.18.6.421pmid: N/A

Most existing haptic gloves are complicated user interfaces with remotely located actuators. More compact and simpler haptic gloves would greatly increase our ability to interact with virtual worlds in a more natural way. This research explored the design of a compact force feedback glove using a new finger mechanism and magnetorheological (MR) brakes as passive actuators that oppose human finger motion. The mechanism allowed for a reduction of the number of actuators and application of distributed forces at the bottom surface of user's fingers when an object was grasped in a virtual environment. The MR brakes incorporated a serpentine flux path that led to a small brake with high torque output and the elimination of remote actuation. Force analysis of the mechanism, grasping force experiments, and virtual pick-and-place experiments were done. The glove reduced task completion time by 61% and could support up to 17 N fingertip force along with 11.9 N and 18.7 N middle and proximal digit forces.

Bullion, Conrad; Gurocak, Hakan

doi: 10.1162/pres.18.6.421pmid: N/A

Most existing haptic gloves are complicated user interfaces with remotely located actuators. More compact and simpler haptic gloves would greatly increase our ability to interact with virtual worlds in a more natural way. This research explored the design of a compact force feedback glove using a new finger mechanism and magnetorheological (MR) brakes as passive actuators that oppose human finger motion. The mechanism allowed for a reduction of the number of actuators and application of distributed forces at the bottom surface of user's fingers when an object was grasped in a virtual environment. The MR brakes incorporated a serpentine flux path that led to a small brake with high torque output and the elimination of remote actuation. Force analysis of the mechanism, grasping force experiments, and virtual pick-and-place experiments were done. The glove reduced task completion time by 61% and could support up to 17 N fingertip force along with 11.9 N and 18.7 N middle and proximal digit forces.

Harris, Helen; Bailenson, Jeremy N; Nielsen, Alexia; Yee, Nick

doi: 10.1162/pres.18.6.434pmid: N/A

The current study tracked 80 participants who spent an average of six hours per week in Second Life over six consecutive weeks. Objective measures of movement and chat were automatically collected in real time when participants logged in to Second Life. Data regarding the number of groups and friends was self-reported through online questionnaires on a weekly basis. Results demonstrated that although the social networks of users continued to broaden over the course of the study, users became less inclined to explore regions, decreased their use of high-energy actions such as flying or running, and chatted less. We discuss implications for theories of virtual social interaction as well as the use of Second Life as a social science research platform.

Harris, Helen; Bailenson, Jeremy N; Nielsen, Alexia; Yee, Nick

doi: 10.1162/pres.18.6.434pmid: N/A

The current study tracked 80 participants who spent an average of six hours per week in Second Life over six consecutive weeks. Objective measures of movement and chat were automatically collected in real time when participants logged in to Second Life. Data regarding the number of groups and friends was self-reported through online questionnaires on a weekly basis. Results demonstrated that although the social networks of users continued to broaden over the course of the study, users became less inclined to explore regions, decreased their use of high-energy actions such as flying or running, and chatted less. We discuss implications for theories of virtual social interaction as well as the use of Second Life as a social science research platform.

Huegel, Joel C; Celik, Ozkan; Israr, Ali; O'Malley, Marcia K

doi: 10.1162/pres.18.6.449pmid: N/A

This paper introduces and validates quantitative performance measures for a rhythmic target-hitting task. These performance measures are derived from a detailed analysis of human performance during a month-long training experiment where participants learned to operate a 2-DOF haptic interface in a virtual environment to execute a manual control task. The motivation for the analysis presented in this paper is to determine measures of participant performance that capture the key skills of the task. This analysis of performance indicates that two quantitative measures—trajectory error and input frequency—capture the key skills of the target-hitting task, as the results show a strong correlation between the performance measures and the task objective of maximizing target hits. The performance trends were further explored by grouping the participants based on expertise and examining trends during training in terms of these measures. In future work, these measures will be used as inputs to a haptic guidance scheme that adjusts its control gains based on a real-time assessment of human performance of the task. Such guidance schemes will be incorporated into virtual training environments for humans to develop manual skills for domains such as surgery, physical therapy, and sports.

Huegel, Joel C; Celik, Ozkan; Israr, Ali; O'Malley, Marcia K

doi: 10.1162/pres.18.6.449pmid: N/A

This paper introduces and validates quantitative performance measures for a rhythmic target-hitting task. These performance measures are derived from a detailed analysis of human performance during a month-long training experiment where participants learned to operate a 2-DOF haptic interface in a virtual environment to execute a manual control task. The motivation for the analysis presented in this paper is to determine measures of participant performance that capture the key skills of the task. This analysis of performance indicates that two quantitative measures—trajectory error and input frequency—capture the key skills of the target-hitting task, as the results show a strong correlation between the performance measures and the task objective of maximizing target hits. The performance trends were further explored by grouping the participants based on expertise and examining trends during training in terms of these measures. In future work, these measures will be used as inputs to a haptic guidance scheme that adjusts its control gains based on a real-time assessment of human performance of the task. Such guidance schemes will be incorporated into virtual training environments for humans to develop manual skills for domains such as surgery, physical therapy, and sports.

Prendinger, Helmut; Brandherm, Boris; Ullrich, Sebastian

doi: 10.1162/pres.18.6.468pmid: N/A

This paper describes a simulation framework for sensor-based systems based on Second Life, a popular virtual 3D multi-user online world. With this platform, the components of sensor-based systems can be mapped to, or represented by, virtual devices and objects. The intuitive user interface of Second Life (SL) and its comprehensive visualization capability support evaluation tasks of ubiquitous computing applications. Developers, as avatars, can directly control and manipulate virtual devices. In this way, different settings of sensor-based systems can be tested, and interactively improved. A bidirectional interface between sensor-based systems and Second Life has been implemented to demonstrate Second Life as a testbed for an RFID-based positioning system.

Prendinger, Helmut; Brandherm, Boris; Ullrich, Sebastian

doi: 10.1162/pres.18.6.468pmid: N/A

This paper describes a simulation framework for sensor-based systems based on Second Life, a popular virtual 3D multi-user online world. With this platform, the components of sensor-based systems can be mapped to, or represented by, virtual devices and objects. The intuitive user interface of Second Life (SL) and its comprehensive visualization capability support evaluation tasks of ubiquitous computing applications. Developers, as avatars, can directly control and manipulate virtual devices. In this way, different settings of sensor-based systems can be tested, and interactively improved. A bidirectional interface between sensor-based systems and Second Life has been implemented to demonstrate Second Life as a testbed for an RFID-based positioning system.