Jacques Marsot

Virtual hands and virtual reality multimodal platform to design safer industrial systems

To face with the competitiveness in product design, industrials come up with the solution to use virtual reality (VR) techniques. Coupled with a dynamic simulation, those techniques lead to natural user interactions with virtual environments (VE). Our research focuses on how to model the hands of the operator because they allow him to interact with the environment. In this paper, we address the problem of VR applications to design for a better integration of safety and health requirements. After reviewing the industrial applications using VR, we present our virtual hands which are coupled with a virtual press-brake by using a system of motion capture and a force feedback device. Thus, the operator can interact in real-time with the VE. Our simulation tool is also interfaced to a product model that allows configuring the machine itself. As a result, we are able to estimate the risk level of this machine tool.

Integration of Ergonomics Into Hand Tool Design: Principle and Presentation of an Example

The development of ergonomic tools responds to health protection needs on the part of workers, especially the work related musculoskeletal disorders of the upper limbs and to the development of ergonomic tools to take into account the needs of the factories. Only an ergonomic design process can enable tool manufacturers to meet these requirements. Three factors are involved: integration of ergonomics into the design process, definition of the different ergonomic stages involved, and finally knowledge of the different factors involved in hand tool design. This document examines these 3 elements in more detail and presents briefly a project of research whose main purpose is to integrate ergonomic criteria into a design process.

Dynamic digital human models for ergonomic analysis based on humanoid robotics techniques

Digital human models can be used for biomechanical risk factors assessment of a workstation and work activity design for which there is no physical equipment that can be tested using actual human postures and forces. Yet, using digital human model software packages is usually complex and time-consuming. A challenging aim therefore consists in developing an easy-to-use digital human model capable of computing dynamic, realistic movements and internal characteristics in quasi-real time, based on a simple description of future work tasks, in order to achieve reliable ergonomics assessments of various work task scenarios. We developed such a dynamic digital human model, which is automatically controlled in force and acceleration and inspired by human motor control and based on robotics and physics simulation. In our simulation framework, the digital human model motion was controlled by real-world Newtonian physical and mechanical laws. We also simulated and assessed experimental insert-fitting activities according to the occupational repetitive actions (OCRA) ergonomic index. Simulation led to satisfactory results: experimental and simulated ergonomics evaluations were consistent, and both joint torques and digital human model movements were realistic and coherent with human-like behaviours and performances.

Dynamical indexation of risk in a virtual work environment

When applying safety integration principles, work equipment designers are required to imagine future operating situations and assess a priori associated risk levels. Virtual reality techniques contribute partly to achieving this objective. Based on a feasibility study, this paper discusses the contribution of a dynamic risk-indexing tool applied in conjunction with these techniques. Following a brief reminder of the problem, this paper describes firstly the concepts underlying a generic model permitting a work situation risk index to be estimated. We then introduce the method retained for validating these virtual reality simulations. This focuses on the possibility of reproducing a reference activity through simulation. In spite of differences between the same task performed under real and virtual conditions, examples of industrial machinery is used to illustrate how risk indexing enables the designer to better assess the relevance of his choices and thus to act retrospectively on his design.

Virtual Hands for Risk Prevention Integration in Human-Computer Interactions

The development of virtual reality offers new possibilities to better simulate and understand the human/system interactions. The current challenge is to take into account the human being in order to generalize the use of ergonomics in the design stage. We propose to improve the simulation of the interactions between man and machine by estimating the risk level of the working situation. After reviewing the previous work, we present our virtual physically-based hands which are coupled with a virtual press-brake by using a motion capture system. Thus, the operator can interact in real-time with the virtual environment. By integrating a dynamic risk index, we can also estimate the degree of hazard of the current working situation

Safety of Manufacturing Equipment: Methodology Based on a Work Situation Model and Need Functional Analysis

The aim of “integrated prevention” is to conduct a preliminary risk analysis in order to achieve a lower level of risk in the design of future work equipment. Despite the many safety documents that exist, many companies, particularly SME/SMIs, do not yet apply these safe design principles. Integration of safety in the design process is mainly based on the individual knowledge or experience of the designers and is not conducted in any formalized way. In order to answer to this problem, this paper presents a methodology to involve engaging stakeholders in dynamic dialogue and a framework so that they may together define the information necessary for implementing safe design principles during the functional specification. The proposed methodology has been validated to industrial case.

Caractérisation en conception générale et détaillée du niveau de risque d'un équipement de travail

Ces travaux s’integrent dans le cadre d’une these realisee au sein du laboratoire « mixte » INRS - ENSAM.

Safety Level of Acrobatic Work: A Probabilistic Study.

Acrobatic work constitutes an activity during which individuals intervene on buildings, cliffs, towers, and so forth, through the use of mountaineering or speleological techniques. The most dangerous situations occur particularly when ascending a rope with ascenders or roping with a descender. Any free fall or false manoeuvre will result in a strong shock on the belaying system that may cause its rupture. The fatal accident rate (FAR) of a given occupation is defined as the average number of fatal accidents per 108 hrs of exposure to a given hazard. In this study it is assumed that the FAR is proportional to the average number of fall-initiating events, η, per worker and per hour of exposure to the fall hazard. η is estimated to be between 10-3 and 3 × 10-3. The maximum values of the rupture probability of the securing systems are calculated for the FAR of acrobatic work to be smaller than the FAR of the three most dangerous activity groups of the construction industry in France. These values allow the varying ranges of the parameters that influence this rupture probability to be determined.