Just-in-time control of time-varying discrete event dynamic systems in (max,+) algebra

We deal with timed event graphs whose holding times associated with places are variable. Defining a first-in-first-out functioning rule, we show that such graphs can be linearly described in (max,+) algebra. Moreover, this linear representation allows extending the just-in-time control synthesis existing for timed event graphs with constant holding times. An example is proposed in order to illustrate how the approach can be applied as a just-in-time strategy for production lines

Synthesis of greatest linear feedback for timed-event graphs in dioid

This paper deals with the synthesis of greatest linear causal feedback for discrete-event systems whose behavior is described in dioid. Such a feedback delays as far as possible the input of the system while keeping the same transfer relation between the input and the output. When a feedback exists in the system, the authors show how to compute a greater one without decreasing the system\u27s performance

Model reference control for timed event graphs in dioids

This paper deals with feedback controller synthesis for timed event graphs in dioids. We discuss here the existence and the computation of a controller which leads to a closed-loop system whose behavior is as close as possible to the one of a given reference model and which delays as much as possible the input of tokens inside the (controlled) system. The synthesis presented here is mainly based on residuation theory results and some Kleene star properties

Human-Scale Virtual Environment for Product Design: Effect of Sensory Substitution

This paper presents a human-scale virtual environment (VE) with haptic feedback along with two experiments performed in the context of product design. The user interacts with a virtual mock-up using a large-scale bimanual string-based haptic interface called SPIDAR (Space Interface Device for Artificial Reality). An original self-calibration methodis proposed. A vibro-tactile glove was developed and integrated to the SPIDAR to provide tactile cues to the operator. The purpose of the first experiment was: (1) to examine the effect of tactile feedback in a task involving reach-and-touch of different parts of a digital mock-up, and (2) to investigate the use of sensory substitution in such tasks. The second experiment aimed to investigate the effect of visual and auditory feedback in a car-light maintenance task. Results of the first experiment indicate that the users could easily and quickly access and finely touch the different parts of the digital mock-up when sensory feedback (either visual, auditory, or tactile) was present. Results of the of the second experiment show that visual and auditory feedbacks improve average placement accuracy by about 54 % and 60% respectively compared to the open loop case.

A 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

Augmented Reality Interaction Techniques : Design and Evaluation of the Flip-Flop Menu

We present the evaluation of a bimanual augmented reality (AR) interaction technique, and focus on the effect on viewpoint and image reversal on human performance The interaction technique (called flip-flop) allows theuser to interact with a 3D object model by using a V-shaped AR menu placed on a desk in front of her/him. The menu is made of two complementary submenus. Both submenus (master and slave) are made of four Artag fiducial markers. The functionalities of the slave submenu are the following : (1) increase/decrease the size or rotate/stop the 3D object, (2) apply a color (one over four) or (3) a 2D texture (one over four) on the 3D object and (4) apply predefined material parameters. Each event is triggered by a masking of a Artag marker by the the user’s right or left hand. 40 participants were instructed to perform actions such as rotate the object, apply a texture or a color on it, etc. The results revealed some difficulties due to the inversion of the image on the screen. Finally, although the proposed interaction technique is currently used for product design, it may also be applied to other fields such as edutainment, cognitive/motor rehabilitation, etc. Moreover, other tasks than the ones tested in the experiment may be archived using the menu