Jean-Louis Ferrier

Multi-modal virtual environments for education with haptic and olfactory feedback

It has been suggested that immersive virtual reality (VR) technology allows knowledge-building experiences and in this way provides an alternative educational process. Important key features of constructivist educational computer-based environments for science teaching and learning, include interaction, size, transduction and reification. Indeed, multi-sensory VR technology suits very well the needs of sciences that require a higher level of visualization and interaction. Haptics that refers to physical interactions with virtual environments (VEs) may be coupled with other sensory modalities such as vision and audition but are hardly ever associated with other feedback channels, such as olfactory feedback. A survey of theory and existing VEs including haptic or olfactory feedback, especially in the field of education is provided. Our multi-modal human-scale VE VIREPSE (virtual reality platform for simulation and experimentation) that provides haptic interaction using a string-based interface called SPIDAR (space interface device for artificial reality), olfactory and auditory feedbacks is described. An application that allows students experiencing the abstract concept of the Bohr atomic model and the quantization of the energy levels has been developed. Different configurations that support interaction, size and reification through the use of immersive and multi-modal (visual, haptic, auditory and olfactory) feedback are proposed for further evaluation. Haptic interaction is achieved using different techniques ranging from desktop pseudo-haptic feedback to human-scale haptic interaction. Olfactory information is provided using different fan-based olfactory displays (ODs). Significance of developing such multi-modal VEs for education is discussed.

RTIL-system: a Real-Time Interactive L-system for 3D interactions with virtual plants

The L-system is a rewriting process based on formal grammar and is used to generate 3D, dynamic structures such as virtual plants and fractal graphics. In previous works, we highlighted that existing L-system software applications and programs are limited, either in terms of human interaction or in terms of modelling. In particular, few of them allow the user to interact with virtual plants during their growth. Our own L-system engine was developed and called the real-time interactive L-system (RTIL-system). The RTIL-system covers most important L-system extensions such as parametric and context-sensitive features. Furthermore, real-time interactions with the user and the environment with respect to L-system formalism are available. This paper presents an RTIL-system focusing on human interaction, the Partial Interactive Derivation (PID) concept and further progress by the extension of PID to context-sensitive rules. To illustrate the potential of the RTIL-system, the effect of various interactive tasks such as sub-axis additions, pruning and bending on the subsequent dynamic development of virtual plants is described.

Search for Period-2 Cycles in a Class of Hybrid Dynamical Systems with Autonomous Switchings. Application to a Thermal Device

Abstract Our purpose is to complete the analysis of a class of hybrid dynamical systems with autonomous switchings generated by a hysteresis phenomenon. Because we yet have found limit period-1 cycles in paper (Quemard et al, 2005b) and because we deal with nonlinear equations systems, the question of the existence of more than one solution for them and so of the existence of cycles with more than one period is rather natural. Equations system for period-2 cycles is determined and a notion of stability is studied. A realistic application to a thermostat with anticipative resistance comes to illustrate theoretical results.

New Augmented Reality Techniques for Product Design: The Flip-Flop Menu

This paper presents two bimanual augmented reality (AR) interaction techniques for product design. The first technique allows the user to visualize 3D virtual object in his/her non-dominant hand while being able to map different textures on it using his/her dominant hand. The second technique is based on nine fiducial markers placed on a desk in front of the user. Two experiments were carried out using the second technique to compare four different markers arrangements and four viewing conditions. In these experiments, subjects were instructed to perform nine actions such as rotate the object, apply a texture on it, etc. Results of the first experiment revealed that a V-shape configuration was the best. Results of the second experiment revealed that camera placed behind the user was the more efficient condition.

Supervisory Control for Synchronized and Colored Petri Nets Under Static and Dynamic Constraints

Abstract In the framework of Ramadge and Wonham, a supervisor is synthesized using automata and languages. In order to reduce the model and supervisor dimensions, Petri net formalism has been used first by Krogh and Holloway. This contribution is also based on Petri nets. All the steps in the design of the feedback control law are presented. Starting from a synchronized and colored Petri net model of the plant, and including gradually the specifications of the required behavior, the supervisor is expressed finally. Illustrative examples are provided.

DES Control Under Constraints by Colored Petri Nets

Abstract Based on the concepts of supervisory control initiated by Ramadge and Wonham, this paper presents an original methodology for the determination of a supervisor. This contribution is based on Petri Nets - and not on automata and languages - in order to reduce the model and supervisor dimensions. All the steps in the design of the control law, starting from the modeling of the Discrete Event System to the integration of the control to this model, including the specifications of the required behavior and the design of the supervisor, are presented. Illustrative examples are provided.