Operators' Accessibility Studies using Virtual Reality

International audienceThe development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator's feedback to assess the feasibility of accessibility or maintenance processes. Virtual reality (VR) provides tools to optimize such integration. In 2010, the CEA IRFM decided to upgrade its design tools, by using VR during the life cycle (from design to operation) of a fusion component. The VR platform is intensively used in the design and assembly studies of WEST components. In particular, feasibility of the assembly scenario is assessed by the operators involving in the real assembly work. To study this aspect, the use of static manikins is quite frequent in the industry. However, more complex studies, like the feasibility of assembly and maintenance tasks in complex and very confined environments, require enhanced features such as dynamic and biomechanically realistic virtual humans. We also study the contribution of tactile feedback to improve physical presence and interaction in the virtual environment (VE), which is very important for the validation of a given task's feasibility and the ergonomic evaluation of the posture and gesture of the operator. In particular, we show that adapted behavior in respect to physical elements of the VE can be obtained using a dynamic co-localized representation of the subject's body and a pseudo-haptic tactile feedback. In this paper, we present integration studies involving operators and recent advances in the assessment of maintenance feasibility

An Empirical Evaluation On Vibrotactile Feedback For Wristband System

With the rapid development of mobile computing, wearable wrist-worn is becoming more and more popular. But the current vibrotactile feedback patterns of most wrist-worn devices are too simple to enable effective interaction in nonvisual scenarios. In this paper, we propose the wristband system with four vibrating motors placed in different positions in the wristband, providing multiple vibration patterns to transmit multi-semantic information for users in eyes-free scenarios. However, we just applied five vibrotactile patterns in experiments (positional up and down, horizontal diagonal, clockwise circular, and total vibration) after contrastive analyzing nine patterns in a pilot experiment. The two experiments with the same 12 participants perform the same experimental process in lab and outdoors. According to the experimental results, users can effectively distinguish the five patterns both in lab and outside, with approximately 90% accuracy (except clockwise circular vibration of outside experiment), proving these five vibration patterns can be used to output multi-semantic information. The system can be applied to eyes-free interaction scenarios for wrist-worn devices.Comment: 10 pages

Vibrotactile pattern recognition on the torso : effects of concurrent activities

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 25).Vibrotactile displays have been created to aid vision or hearing through the sense of touch. These displays communicate with the user to provide information. The focus of this thesis was to determine how concurrent activity affects vibrotactile signal recognition. An overall accuracy recognition rate of 90% or greater was desired from each of the signals in the each of the tasks. The first experiment asked subjects to wear the tactile display and walk while responding to signals. The results indicated that most of the subjects were able to recognize the patterns. The overall mean correct response rate was 92% and then when the subjects were asked to jog, they correctly identified the patterns 91% of the time. After determining the success rates from the first experiment, a second set of subjects were asked to concentrate on an internet game while responding to signals. The data from this experiment had an overall mean correct response rate of 93%. The results from this experiment further indicate that subjects can still receive communications while participating in other activities. The results also lead to specific conclusions about the patterns used and their ability to be identified with concurrent activity where some patterns are more easily received than others. By understanding how these patterns are recognized by humans, we can better develop patterns to communicate through tactile devices.by Christa M. Margossian.S.B

Wearable Vibrotactile Interface Using Phantom Tactile Sensation for Human-Robot Interaction

We present a wearable vibrotactile feedback device consisting of four linear resonant actuators (LRAs) that are able to generate virtual stimuli, known as phantom tactile sensation, for human-robot interaction. Using an energy model, we can control the location and intensity of the virtual stimuli independently. The device consists of mostly 3D-printed rigid and flexible components and uses commercially available haptic drivers for actuation. The actuators have a rated frequency of 175 Hz which is close to the highest skin sensitivity regarding vibrations (150 to 300 Hz). Our experiment was conducted with a prototype consisting of two bracelets applied to the forearm and upper arm of six participants. Eight possible circumferential angles were stimulated, of which four originated from real actuators and four were generated by virtual stimuli. The responses given by the participants showed a nearly linear relationship within ±10° for the responded angle against the presented stimulus angle. These results show that phantom tactile sensation allows for an increase of spatial resolution to design vibrotactile interfaces for human-robot interaction with fewer actuators

Vibrotactile pattern recognition on the torso with one and two dimensional displays

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 27-28).This research focused on the evaluation of a tactile display that is used for navigation and communication. In the first experiment, a four by four array of vibrating motors (tactors) was mounted on the torso while the subject wore an Interceptor Body Armor (IBA) vest. Subjects were required to identify which of eight patterns was presented. The results indicated that subjects could recognize the patterns presented with perfect accuracy, which indicates that wearing heavy body armor over the display does not affect the ability to perceive tactile inputs. A second set of experiments involved a one-dimension tactile array of eight tactors worn around the waist. The results indicated that the subjects could recognize the six circumferential patterns presented with an accuracy of 98-100% correct. A further experiment confirmed that the linear tactile display could be used to provide cues about the location of an event in the environment. These experiments showed that identification of the vibrotactile patterns was slightly superior on the two-dimension tactile array on the torso as compared to the one-dimension tactile array around the waist.(cont.) When subjects were required to identify the location of an individual vibrating motor using the one-dimensional array they achieved an accuracy of 94-100% correct. This suggests that a linear tactile array can be used to present navigational cues.by Amy R. Lam.S.B

Making Undergraduate Labs Challenging and Useful

Learning through laboratory work is critical in high quality science education. Traditional engineering labs are useful but not challenging. However, when the same labs are repeated every year, and students know the results, it is questionable how much is really learned. Students may copy the results from last year’s labs, making it difficult for instructors to evaluate their work. To address this problem, the Mechanical Engineering Experimentation and Laboratory II class was revised. A new lab designed to be challenging and useful by using a current research topic to guide it. The class taught in new class environment with state-of-the-art facilities. Students learn instrumentation in a way that forces them to think about the problem, develop a method to measure a phenomenon, and draw conclusions about the results. The tangible connection to research motivates students. It takes professors more time to create these labs. However, since the results fold directly into their research objectives, i.e., gathering data needed for publications, the approach ultimately becomes an efficient use of time. It is fairly common for professors to ignore undergraduate labs, but this paper shows that with a little bit of effort, these labs can provide a significant learning experience for students. Based on the survey, more than 90% of students agree that the new lab help them to develop defining problem, designing experiment, analyzing, concluding, and reporting skills. More than 70% of students agree that they learn new measurement equipment for the new lab. Also, 91% of students would recommend other students to take the new lab. Moreover, this paper shows that the results from the lab lead to the manuscript which has submitted to a journal.&nbsp

AN ANALYSIS OF STATIC, DYNAMIC, AND APPARENT MOTION VIBROTACTILE STIMULI

The sense of touch is uniquely suited for displaying certain types of information, such as navigation instructions and high-level messaging. As part of a line of research in developing a vibrotactile communication system to support person-to-person tactile messaging over a network, the present study examines the effectiveness and efficiency of three different vibrotactile signal presentation methods for communicating a spatial pattern. In an evaluation study, participants identified static (one or multiple locations vibrating at once), non-overlapping dynamic sequences of presentations, and saltatory presentations which induce the “apparent motion” tactile illusion; each at increasing levels of signal complexity and presentation duration. The equipment used for the interface devices consists of two Engineering Acoustics, Inc. solenoid tactor systems and a computer interface developed in C++. The results of the study suggest that both response time and accuracy are strongly dependent on the complexity of the signal and the presentation method utilized, with static and saltatory presentations outperforming dynamic presentations. With more complex signals, the relative benefit of saltatory presentations appears to increase. These results have implications for the design of tactile display signals of varying degrees of complexity, and will inform the continued development of the CHIAD (Creative Haptic Interaction At-a-Distance) system