Alexis Paljic

A methodology to assess the acceptability of human-robot collaboration using virtual reality

Robots are becoming more and more present in our everyday life: they are already used for domestic tasks, for companionship activities, and soon they will be used to assist humans and collaborate with them in their work. Human-robot collaboration has already been studied in the industry, for ergonomics and efficiency purposes, but more from a safety than from an acceptability point of view. In this work, we focused on how people perceive robots in a collaboration task and we proposed to use virtual reality as a simulation environment to test different parameters, by making users collaborate with virtual robots. A simple use case was implemented to compare different robot appearances and different robot movements. Questionnaires and physiological measures were used to assess the acceptability level of each condition with a user study. The results showed that the perception of robot movements depended on robot appearance and that a more anthropomorphic robot, both in its appearance and movements, was not necessarily better accepted by the users in a collaboration task. Finally, this preliminary use case was also the opportunity to guarantee the relevance of using such a methodology --- based on virtual reality, questionnaires and physiological measures --- for future studies.

Assessing the acceptability of human-robot co-presence on assembly lines: A comparison between actual situations and their virtual reality counterparts

This paper focuses on the acceptability of human-robot collaboration in industrial environments. A use case was designed in which an operator and a robot had to work side-by-side on automotive assembly lines, with different levels of co-presence. This use case was implemented both in a physical and in a virtual situation using virtual reality. A user study was conducted with operators from the automotive industry. The operators were asked to assess the acceptability to work side-by-side with the robot through questionnaires, and physiological measures (heart rate and skin conductance) were taken during the user study. The results showed that working close to the robot imposed more constraints on the operators and required them to adapt to the robot. Moreover, an increase in skin conductance level was observed after working close to the robot. Although no significant difference was found in the questionnaires results between the physical and virtual situations, the increase in physiological measures was significant only in the physical situation. This suggests that virtual reality may be a good tool to assess the acceptability of human-robot collaboration and draw preliminary results through questionnaires, but that physical experiments are still necessary to a complete study, especially when dealing with physiological measures.

User-defined gestural interaction: A study on gesture memorization

In this paper we study the memorization of user created gestures for 3DUI. Wide public applications mostly use standardized gestures for interactions with simple contents. This work is motivated by two application cases for which a standardized approach is not possible and thus user specific or dedicated interfaces are needed. The first one is applications for people with limited sensory-motor abilities for whom generic interaction methods may not be adapted. The second one is creative arts applications, for which gesture freedom is part of the creative process. In this work, users are asked to create gestures for a set of tasks, in a specific phase, prior to using the system. We propose a user study to explore the question of gesture memorization. Gestures are recorded and recognized with a Hidden Markov Model. Results show that it seems difficult to recall more than two abstract gestures. Affordances strongly improve memorization whereas the use of colocalization has no significant effect.

Determining the Important Subjective Criteria in the Perception of Human-Like Robot Movements Using Virtual Reality

This paper deals with the design and the evaluation of human-like robot movements. Three criteria were proposed and evaluated regarding their impact on the human-likeness of the robot movements: The inertia of the base, the inertia of the end-effector and the velocity profile. A specific tool was designed to generate different levels of anthropomorphism according to these three parameters. An industrial use case was designed to compare several robot movements. This use case was implemented with a virtual robot arm in a virtual environment, using virtual reality. A user study was conducted to determine what were the important criteria in the perception of human-like robot movements and what were their correlations with other notions such as safety and preference. The results showed that inertia on the end-effector was of most importance for a movement to be perceived as human-like and nonaggressive, and that those characteristics helped the users feel safer, less stressed and more willing to work with the robot.

Experiments on shape perception in stereoscopic displays

Stereoscopic displays are increasingly used for computer-aided design. The aim is to make virtual prototypes to avoid building real ones, so that time, money and raw materials are saved. But do we really know whether virtual displays render the objects in a realistic way to potential users? In this study, we have performed several experiments in which we compare two virtual shapes to their equivalent in the real world, each of these aiming at a specific issue by a comparison: First, we performed some perception tests to evaluate the importance of head tracking to evaluate if it is better to concentrate our efforts on stereoscopic vision; Second, we have studied the effects of interpupillary distance; Third, we studied the effects of the position of the main object in comparison with the screen. Two different tests are used, the first one using a well-known shape (a sphere) and the second one using an irregular shape but with almost the same colour and dimension. These two tests allow us to determine if symmetry is important in their perception. We show that head tracking has a more important effect on shape perception than stereoscopic vision, especially on depth perception because the subject is able to move around the scene. The study also shows that an object between the subject and the screen is perceived better than an object which is on the screen, even if the latter is better for the eye strain.

A study of image exposure for the stereoscopic visualization of sparkling materials

This work is performed as part of the perceptual validation stage in the stereoscopic visualization of computer- generated (CG) images of materials (typically car paints) containing sparkling metallic flakes. The perceived material aspect is closely linked to the flake density, depth, and sparkling; in turn, our perception of an image of said materials is strongly dependent on the image exposure, that is, the amount of light entering the sensor during the imaging process. Indeed, a high exposure may over saturate the image, reducing discrimination amongst high-luminance flakes, affecting the perceived depth; on the other hand, a low exposure may reduce image contrast, merging low-luminance flakes with the background, and reducing perceived flake density and sparkling. In order to choose the right exposure for each CG image, we have performed a user study where we presented observers with a series of stereoscopic photographs of plates, taken at different exposures with a radiometrically color-calibrated camera ,5 and asked them to assess each photographs similarity to a physical reference. We expect these results to help us find a correlation between optical settings and visual perception regarding the aforementioned parameters, which we could then use in the rendering process to obtain the desired material aspect.

Stereoscopy for visual simulation of materials of complex appearance

The present work studies the role of stereoscopy on perceived surface aspect of computer generated complex materials. The objective is to investigate if, and how, the additional information conveyed by the binocular vision affects the observer judgment on the evaluation of flake density in an effect paint simulation. We have set up a heuristic flake model with a Voronoi: modelization of flakes. The model was implemented in our rendering engine using global illumination, ray tracing, with an off axis-frustum method for the calculation of stereo images. We conducted a user study based on a flake density discrimination task to determine perception thresholds (JNDs). Results show that stereoscopy slightly improves density perception. We propose an analysis methodology based on granulometry. This allows for a discussion of the results on the basis of scales of observation.

An evaluation of rendering and interactive methods for volumetric data exploration in virtual reality environments

In this paper we evaluate one interaction method and four display techniques for exploring volumetric datasets in virtual reality immersive environments. We propose an approach based on the display of a subset of the volumetric data, as isosurfaces, and an interactive manipulation of the isosurfaces to allow the user to look for local feature in the datasets. We also studied the influence of four different rendering techniques for isosurface rendering in a virtual reality system. The study is based on a search and point task in a 3D temperature field. User precision, task completion time and user movement were evaluated during the test. The study allowed to choose the most suitable rendering mode for isosurface representation, and provided guidelines for data exploration tasks in immersive environments.

A Consensual and Non-ambiguous Set of Gestures to Interact with UAV in Infantrymen

In the context of using an Unmanned Aerial Vehicle (UAV) in hostile environments, gestures allow to free the operator of bulky control interfaces. Since a navigation plan is defined before the mission, only a few commands have to be activated during the mission. This allows a gestural symbolic interaction that maps commands to a set of gestures. Nevertheless, as gestures are not universal, this asks the question of choosing the proper gestures that are easy to learn memorize and perform. We propose a four step methodology for eliciting a gestural vocabulary, and apply it to this use case. The methodology consists of 4 steps: (1) collecting gestures through user creativity sessions, (2) extracting candidate gestures to build a catalogue, (3) electing the gesture vocabulary and (3) evaluating the non-ambiguity of it. We then discuss the relevance of the GV.

Physically based image synthesis of materials : a methodology towards the visual comparison of physical vs. virtual samples

The assessment of images of complex materials on an absolute scale is difficult for a human observer. Comparing physical and virtual samples side-by-side simplifies the task by introducing a reference. The goal of this article is to study the influence of image exposure on the perception of realism on images of paint materials containing sparkling metallic flakes. We use a radiometrically calibrated DSLR camera to acquire high resolution raw photographs of our physical samples which provide us with radiometric information from the samples. This is combined with the data obtained from the calibration of a stereoscopic display and shutter glasses to transform the raw photographs into images that can be shown by the display, controlling the colorimetric output signal. This ensures that we can transform our data back and forth between a radiometric and a colorimetric representation, minimizing the loss of information throughout the chain of acquisition and visualization. In this article we propose a paired comparison scenario that improves the results from our previous work, focusing on three main aspects: stereoscopy, exposure time, and dynamic range. Our results show that observers consider stereoscopy as the most important factor of the three for judging the similarity of these images to the reference, followed by exposure time and dynamic range, which supports our claims from previous research.