Proper integration of sensory cues facilitates 3D user interaction within virtual environments (VEs). Studies on multi-sensory integration of visual and haptic cues revealed that the integration follows maximum likelihood estimation (MLE). Little effort focuses however on integrating force and vibrotactile cues-two sub-categorical cues of the haptic modality. Hence, this paper presents an investigation on MLE's suitability for integrating these sub-categorical cues. Within a stereoscopic VE, human users performed a 3D interactive task of navigating a flying drone along a high-voltage transmission line in an inaccessible region and identifying defects on the line. The users had to identify defects via individual force or vibrotactile cues, and their combinations in colocated and dislocated settings. The co-located setting provided both cues on the right hand of the users; whereas the dislocated setting delivered the force and vibrotactile cues on the right hand and forearm of the users, respectively. Task performance of the users, such as completion time and accuracy, was assessed under each cue and setting. The presence of the vibrotactile cue promoted a better performance than the force cue alone. This was in agreement with the role of tactile cues in sensing surface properties, herein setting a baseline for using MLE. The task performance under the co-located setting indicated certain degrees of combining those under the individual cues. In contrast, the performance under the dislocated setting was alike that under the individual vibrotactile cue. These observations imply an inconclusiveness of MLE to integrate both cues in a co-located setting for 3D user interaction.

4 CONCLUSION AND FUTURE WORK This work revealed that the compass pattern yields better performance of navigation than the pushing pattern. This indicates a potential of using the compass pattern to facilitate navigation in VEs. Future work includes the refinement of the compass pattern for reducing cybersickness.

Multi-user collaborative virtual environments (VEs) need strategies of conflict resolution to handle simultaneous interaction with shared objects. Current strategies are first-comefirst-serve (FCFS) and predefined static priority of each user. These strategies cannot provide each user with a perceived equal opportunity of interaction and often lead to perceived unfairness to abandon collaboration. To offer an equal opportunity, we created a dynamic priority (DP) strategy and compared the strategy with the FCFS strategy based upon subjective perception of multiple users. Visual or haptic (pertinent to the sense of touch) cues assisted each user to perceive his/her gaining of interaction. We observed that the DP strategy yielded significantly an equal opportunity of interaction. The haptic cue offered lower variations in perceiving the equality than the visual cue under the DP strategy. These observations imply a potential application of the DP strategy in a VE, where various experts require equal opportunities in collaboration. Keywords-conflict resolution; multi-user collaborative virtual environments; dynamic priority strategy; human perceptionI.

Software architecture evaluation has a crucial role in the life cycle of software intensive systems. In this paper we propose an approach to empower a software architecture evaluation method called the Architecture tradeoff Analysis Method (ATAM). Our approach is highly focused on the effective reusability of software architecture knowledge. We propose two ontologies focusing on the role of Attribute-Based Architectural styles (ABAS) in software architecture development and analysis. We show the effectiveness of our approach by presenting three case studies.

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. This is an author-deposited version published in: https://sam.ensam.eu Handle ID Abstract-In a three-dimensional (3D) virtual environment (VE), proper collaboration between vibrotactile and force cuestwo cues of the haptic modality -is important to facilitate task performance of human users.Many studies report that collaborations between multi-sensory cues follow maximum likelihood estimation (MLE). However, an existing work finds that MLE yields a mean and an amplitude mismatches when interpreting the collaboration between the vibrotactile and force cues. We thus proposed mean-shifted MLE and conducted a human study to investigate the mismatches. For the study, we created a VE to replicate the visual scene, the 3D interactive task, and the cues from the existing work. Our participants were biased to rely on the vibrotactile cue for their tasks, departing from unbiased reliance on both cues in the existing work. Assessments of task completion time and task accuracy validated the replication. We found that based on task accuracy MLE explained the cue collaboration to certain degrees, agreed with the existing work. Mean-shifted MLE remedied the mean mismatch, but maintained the amplitude mismatch. Further examinations revealed that the collaboration between both cues may not be entirely additive. This sheds an insight for proper modeling of the collaboration between the vibrotactile and force cues to aid interactive tasks in VEs.