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Section: New Results

Natural Interaction with Robotics Systems

Human Characterization

Participants : François Charpillet, Abdallah Dib, Xuan Son Nguyen, Vincent Thomas.

We collaborate on this subject with Olivier Buffet and Alain Dutech from Inria Nancy - Grand Est, Arsène Fansi Tchango and Fabien Flacher from Thales ThereSIS, and Alain Filbois from SED Inria Nancy - Grand Est.

Multi-Camera Tracking in Partially Observable Environment

In collaboration with Thales ThereSIS - SE&SIM Team (Synthetic Environment & Simulation), we focus on the problem of following the trajectories of several persons with the help of several controllable cameras. This is a difficult problem since the set of cameras cannot simultaneously cover the whole environment, since some persons can be hidden by obstacles or by other persons, and since the behavior of each person is governed by internal variables which can only be inferred (such as his motivation or his hunger).

The approach we are working on is based on (1) the HMM (Hidden Markov Models) formalism to represent the state of the system (the persons and their internal states), (2) a simulator provided and developed by Thales ThereSIS, and (3) particle filtering approaches based on this simulator. Since activity and location depend on each other, we adopt a Simultaneous Tracking and Activity Recognition approach.

After having shown that it was possible to use a complex behavioral simulator to infer the behavior of complex individuals (motivation, possession, ...) even in case of long periods of occlusions [40] , we investigated how to propose a factored particle filter (with one distribution per target) for efficiently tracking multiple targets simultaneously. To that end, we use a Joint Probabilistic Data Association Filter with a particular model of dynamics that largely decouples the evolution of several targets, and turns out to be very natural to apply. We proposed to use a small number of “representatives” of each target to determine and consider only effective interactions among targets.

This work has been published in Arsène Fansi Tchango's PhD thesis which has been defended in December [7] .

Human Posture Recognition

Human pose estimation in realistic world conditions raises multiple challenges such as foreground extraction, background update and occlusion by scene objects. Most of existing approaches were demonstrated in controlled environments. In this work, we propose a framework to improve the performance of existing tracking methods to cope with these problems. To this end, a robust and scalable framework is provided composed of three main stages. In the first one, a probabilistic occupancy grid updated with a Hidden Markov Model used to maintain an up-to-date background and to extract moving persons. The second stage uses component labelling to identify and track persons in the scene. The last stage uses a hierarchical particle filter to estimate the body pose for each moving person. Occlusions are handled by querying the occupancy grid to identify hidden body parts so that they can be discarded from the pose estimation process. We provide a parallel implementation that runs on CPU and GPU at 4 frames per second. We also validate the approach on our own dataset that consists of synchronized motion capture with a single RGB-D camera data of a person performing actions in challenging situations with severe occlusions generated by scene objects. We make this dataset available online (http://www0.cs.ucl.ac.uk/staff/M.Firman/RGBDdatasets/ ).

Social Robotics

Participants : Amine Boumaza, Serena Ivaldi.

We collaborate on this subject with Yann Boniface from Loria, Alain Dutech from Inria Nancy - Grand Est and Nicolas Rougier from the Mnemosyne team (Inria Bordeaux - Sud-Ouest).

PsyPhINe: Cogito Ergo Es

PsyPhINe is an interdisciplinary and exploratory project (see 9.1.2 ) between philosophers, psychologists and computer scientists. The goal of the project is related to cognition and behavior. Cognition is a set of processes that are difficult to unite in a general definition. The project aims to explore the idea of assignments of intelligence or intentionality, assuming that our intersubjectivity and our natural tendency to anthropomorphize play a central role: we project onto others parts of our own cognition. To test these hypotheses, our aim is to design a “non-verbal” Turing Test, which satisfies the definitions of our various fields (psychology, philosophy, neuroscience and computer science), using a robotic prototype. Some of the questions that we aim to answer are: is it possible to give the illusion of cognition and/or intelligence through such a technical device? How elaborate must be the control algorithms or “behaviors” of such a device so as to fool test subjects? How many degrees of freedom must it have?

Preliminary experiments with human subjects conducted this past year on a simple device helped to design an experimental protocol and test simple hypotheses which set the ground for the full fledged non verbal Turing Test. This project was funded under a PEPS Mirabelle grant (see 9.1.2 ) which helped build a robotic device with many degrees of freedom to perform further experiments. We also organized an inter-disciplinary workshop gathering top researchers from philosophy, anthropology, psychology and computer science to discuss and exchange on our methodology (see ).

Multimodal Object Learning During Human-Robot Interaction

Robots working in evolving human environments need the ability to continuously learn to recognize new objects. Ideally, they should act as humans do, by observing their environment and interacting with objects, without specific supervision. However, if object recognition simply relies on visual input, then it may fail during human-robot interaction, because of the superposition of human and body parts. A multimodal approach was then proposed in [15] , where visual input from cameras was combined with the robot proprioceptive information, in order to classify objects, robot, and human body parts. We proposed a developmental learning approach that enables a robot to progressively learn appearances of objects in a social environment: first only through observation, then through active object manipulation. We focused on incremental, continuous, and unsupervised learning that does not require prior knowledge about the environment or the robot. In the first phase of the proposed method, we analyse the visual space and detect proto-objects as units of attention that are learned and recognized as possible physical entities. The appearance of each entity is represented as a multi-view model based on complementary visual features. In the second phase, entities are classified into three categories: parts of the body of the robot, parts of a human partner, and manipulable objects. The categorization approach is based on mutual information between the visual and proprioceptive data, and on motion behaviour of entities. The ability to categorize entities is then used during interactive object exploration to improve the previously acquired objects models. The proposed system was implemented and evaluated with an iCub and a Meka robot learning 20 objects. The system was able to recognize objects with 88.5% success rate and create coherent representation models that are further improved by learning during human-robot interaction.

Robot Functional and Social Acceptance

To investigate the functional and social acceptance of a humanoid robot, we carried out an experimental study with 56 adult participants and the iCub robot. Trust in the robot has been considered as a main indicator of acceptance in decision-making tasks characterized by perceptual uncertainty (e.g., evaluating the weight of two objects) and socio-cognitive uncertainty (e.g., evaluating which is the most suitable item in a specific context), and measured by the participants’ conformation to the iCub’s answers to specific questions. In particular, we were interested in understanding whether specific (i) user-related features (i.e., desire for control), (ii) robot-related features (i.e., attitude towards social influence of robots), and (iii) context-related features (i.e., collaborative vs. competitive scenario), may influence their trust towards the iCub robot. We found that participants conformed more to the iCub’s answers when their decisions were about functional issues than when they were about social issues. Moreover, the few participants conforming to the iCub’s answers for social issues also conformed less for functional issues. Trust in the robot’s functional savvy does not thus seem to be a pre-requisite for trust in its social savvy. Finally, desire for control, attitude towards social influence of robots and type of interaction scenario did not influence the trust in iCub. Results are also discussed with relation to methodology of HRI research in a currently submitted paper (http://arxiv.org/abs/1510.03678 [cs.RO] ). This work follows the research on engagement with social robots that was previously published [10] .

Relation Between Extroversion and Negative Attitude Towards Robot

Estimating the engagement is critical for human - robot interaction. Engagement measures typically rely on the dynamics of the social signals exchanged by the partners, especially speech and gaze. However, the dynamics of these signals is likely to be influenced by individual and social factors, such as personality traits, as it is well documented that they critically influence how two humans interact with each other. We assess the influence of two factors, namely extroversion and negative attitude toward robots, on speech and gaze during a cooperative task, where a human must physically manipulate a robot to assemble an object [23] . We evaluate if the score of extroversion and negative attitude towards robots co-variate with the duration and frequency of gaze and speech cues. The experiments were carried out with the humanoid robot iCub and 56 adult participants. We found that the more people are extrovert, the more and longer they tend to talk with the robot; and the more people have a negative attitude towards robots, the less they will look at the robot face and the more they will look at the robot hands where the assembly and the contacts occur. Our results confirm and provide evidence that the engagement models classically used in human-robot interaction should take into account attitudes and personality traits.