Operators' Accessibility Studies using Virtual Reality

International audienceThe development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator's feedback to assess the feasibility of accessibility or maintenance processes. Virtual reality (VR) provides tools to optimize such integration. In 2010, the CEA IRFM decided to upgrade its design tools, by using VR during the life cycle (from design to operation) of a fusion component. The VR platform is intensively used in the design and assembly studies of WEST components. In particular, feasibility of the assembly scenario is assessed by the operators involving in the real assembly work. To study this aspect, the use of static manikins is quite frequent in the industry. However, more complex studies, like the feasibility of assembly and maintenance tasks in complex and very confined environments, require enhanced features such as dynamic and biomechanically realistic virtual humans. We also study the contribution of tactile feedback to improve physical presence and interaction in the virtual environment (VE), which is very important for the validation of a given task's feasibility and the ergonomic evaluation of the posture and gesture of the operator. In particular, we show that adapted behavior in respect to physical elements of the VE can be obtained using a dynamic co-localized representation of the subject's body and a pseudo-haptic tactile feedback. In this paper, we present integration studies involving operators and recent advances in the assessment of maintenance feasibility

Multi-physics modeling and Au-Ni/Rh coating assessment for ITER ion cyclotron resonance heating radio-frequency sliding contacts

ITER is a large scale fusion experimental device under construction in Cadarache (France) intended to prove the viability of fusion as an energy source. Ion Cyclotron Resonance Heating (ICRH) system is one of the three heating systems which will supply total heating power of 20 MW (40-55 MHz) up to one hour of operation. Radio-Frequency (RF) contacts are integrated within the antennas for assembly and operation considerations, which will face extremely harsh service conditions, including neutron irradiation, heavy electrical loads (RF current reaches up to 2 kA with a linear current density of 4.8 kA/m) and high thermal loads. Based on the thermal analysis, the contact resistance is expected to be lower than 7 mΩ to keep the maximum temperature on the louvers lower than 250°C. Few weeks of vacuum (~10 -5 Pa) baking at 250°C for outgassing is expected before each plasma experimental campaign, under which the RF contact materials' mechanical properties change and diffusion phenomena between different materials are inevitable. CuCrZr and 316L are proper base materials for ITER RF contact louvers and conductors respectively. In order to improve the RF contact's wear and corrosion resistivity as well as to reduce the contact resistance, Au-Ni and Rh functional layers could be electroplated on CuCrZr and 316L accordingly. The application of the Au-Ni/Rh coating pairs is assessed through the thermal ageing and diffusion tests. Wear and electrical contact performances of the Au-Ni/Rh pairs are deeply studied on a dedicated tribometer operated at ITER relevant conditions

Multifunctional tribometer development and performance study of CuCrZr-316L material pair for ITER application

Radio-Frequency (RF) contacts are key components on the International Thermonuclear Experimental Reactor (ITER) Ion Cyclotron Resonance Heating (ICRH) antenna, and these components are facing big challenges such as 2 kA operation current load and intensive sliding under up to 250 °C in high vacuum. Stainless steel (SS) 316L and CuCrZr are most likely to be applied as base materials for the conductor and the RF contacts louvers. To evaluate the performance of the selected materials, their electrical and tribological behaviors have to be studied. A multifunctional tribometer which can mimic the ITER ICRH RF contacts' relevant working conditions was designed and built in CEA. The contact resistance (Rc) and coefficient of friction (CoF) of CuCrZr-316L pair were researched on this tribometer

Development of a New Backdrivable Actuator for Haptic Interfaces and Collaborative Robots

Industrial robots are most often position controlled and insensitive to external forces. In many robotic applications, however, such as teleoperation, haptics for virtual reality, and collaborative robotics, a close cooperation between humans and robots is required. For such applications, force sensing and control capabilities are required for stable interactions with the operator and environment. The robots must also be backdrivable, i.e., the robot must be able to follow user’s induced movements with the least possible resistance. High force efficiency is also desirable. These requirements are different from the design drivers of traditional industrial robots and call for specific actuators and reducers. Many such devices were proposed in the literature. However, they suffer from several drawbacks, offering either a limited reduction ratio or being complex and bulky. This paper introduces a novel solution to this problem. A new differential cable drive reducer is presented. It is backdrivable, has a high efficiency, and a potentially infinite reduction ratio. A prototype actuator using such a reducer has been developed and integrated on a test bench. The experimental characterization of its performance confirms its theoretical advantages

Spatialized Vibrotactile Feedback Improves Goal-Directed Movements in Cluttered Virtual Environments

International audienceSpatial awareness in virtual reality (VR) is a dominant research topic. It plays an essential role in the assessment of human operators' behavior in simulated tasks, notably for the evaluation of the feasibility of manual maintenance tasks in cluttered industrial settings. In such contexts, it is decisive to evaluate the spatial and temporal correspondence between the operator's movement kinematics and that of his/her virtual avatar in the virtual environment (VE). Often, in a cluttered VE, direct kinesthetic (force) feedback is limited or absent. We tested whether vibrotactile (cutaneous) feedback would increase visuo-proprioceptive consistency, spatial awareness, and thus the validity of VR studies, by augmenting the perception of the operator's contact(s) with virtual objects. We present experimental results obtained using a head-mounted display (HMD) during a goal-directed task in a cluttered VE. Results suggest the contribution of spatialized vibrotactile feedback to visuo-proprioceptive consistency

Spatialized Vibrotactile Feedback Contributes to Goal-Directed Movements in Cluttered Virtual Environments

12th IEEE Symposium on 3D User Interfaces (3DUI), Los Angeles, CA, MAR 18-19, 2017International audienceIn virtual reality (VR), spatial awareness is a dominant research topic. It plays an essential role in the assessment of human operators' behavior within virtual environments (VE), notably for the evaluation of the feasibility of manual maintenance tasks in cluttered industrial settings. In such contexts, it is decisive to evaluate the spatial and temporal correspondence between the operator's movement kinematics and that of his/her virtual avatar in the virtual environment. Often, in a cluttered VE, direct kinesthetic (force) feedback is limited or absent. We tested whether vibrotactile (cutaneous) feedback would increase visuo-proprioceptive consistency, spatial awareness, and thus the validity of VR studies, by augmenting the perception of the operator's contact(s) with virtual objects. We present preliminary experimental results, obtained using a head-mounted display (HMD) during a goal-directed task in a cluttered VE. Data suggest that spatialized vibrotactile feedback contributes to visuo-proprioceptive consistency

Operators' accessibility studies for assembly and maintenance scenarios using virtual reality

29th Symposium on Fusion Technology (SOFT), Prague, CZECH REPUBLIC, SEP 05-09, 2016International audienceThe development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator's feedback to assess the feasibility of accessibility or maintenance processes. Virtual reality (VR) provides tools to optimize such integration. In 2010, the CEA IRFM decided to upgrade its design tools, by using VR during the life cycle (from design to operations) of a fusion component. The VR platform is intensively used in the design and assembly studies of WEST components. In particular, feasibility of the assembly scenario is assessed by the operators involving in the real assembly work. To study this aspect, the use of static manikins is quite frequent in the industry. However, more complex studies, like the feasibility of assembly and maintenance tasks in complex and very confined environments, require enhanced features such as dynamic and biomechanically realistic virtual humans. We also study the contribution of tactile feedback to improve physical presence and interaction in the virtual environment (VE), which is very important for the validation of a given task's feasibility and the ergonomic evaluation of the posture and gesture of the operator. In particular, we show that adapted behavior in respect to physical elements of the VE can be obtained using a dynamic co-localized representation of the subject's body and a pseudo-haptic tactile feedback. In this paper, we present integration studies involving operators and recent advances in the assessment of maintenance feasibility. (C) 2017 Elsevier B.V. All rights reserved

Use of virtual reality for optimizing the life cycle of a fusion component

International audienceEfficient development of a complex system such as a fusion component needs a stringent integration of standard and new constraints. For example, compared to the previous fusion experimental devices, remote handling (RH) and safety requirements are in ITER key parameters which must be integrated since the earliest design. For optimizing such integration studies, CEA, IRFM decided in 2010 to implement the use of virtual reality (VR) tools during the life cycle (from design to operation) of a fusion component. This paper describes a first feedback of such use for fusion engineering purposes. After a short overview of the CEA, IRFM VR platform capabilities, three main uses will be described: design review, simulation of remote handling and hands-on operations, with man in the loop. The Design review mode was intensively used within the framework of a fruitful collaboration with ITER design Integration Team. This mode, fully compatible with CAD software, enables scale one data visualization with stereoscopic rendering. It improves the efficiency in detecting inconsistencies inside models and machine sub-system design optimization needs. Several accessibility cases of major Safety Important Components (SIC-1) were studied giving important requirements to the design at an early stage. CEA, IRFM, in close collaboration with expertise of CEA, LIST for VR simulation software, applies VR technologies for designing RH maintenance scenario for ITER Test Blanket System (TBS) and Ion cyclotron Resonance Heating (ICRH) Port Plugs. RH compatibility studies using VR pointed out major design drivers while helping to propose credible solution. VR platform is intensively used in the design of WEST (Tungsten (W) Environment Steady-state Tokamak) components and assembly studies, providing important information about the feasibility of assembly processes, optimization of physical mock-ups and ergonomic posture and gestures of operator. Finally, new perspectives, as the integration of safety constraints (dose calculation) will be described, demonstrating the powerful of VR tools at different stages of the component lifecycle

Transfer of nuclear maintenance skills from virtual environments to reality - Toward a methodological guide

Financement ANRTNuclear maintenance operations require several types of cognitive and motor skills that can be trained in immersive environments. However, there is a lack of normalized methodological approaches to classify tasks and guide them for a potential transposition to immersive training. This paper proposes a methodological approach to classify nuclear maintenance tasks based on their complexity and the potential transfer of training obtainable from each type of immersion techniques and their related interactions.This proposed methodology provides a novel approach to compare various immersive technologies and interactions in a normalized way for a same industrial task.This paper aims at serving as a base for a methodological guide dedicated to the transposition of nuclear maintenance skills learned in immersive environments to real environment setups and proposes two future use cases based on this methodological approach