J.P. Friconneau

ABLE, an innovative transparent exoskeleton for the upper-limb

This paper presents ABLE, an innovative exoskeleton for the upper limb currently under development at CEA-LIST Interactive Robotics Unit. Its distinctive high performance mechanical transmissions - screw and cable patented arrangement - and its integrated architecture makes it the very first of its category. The first 4 axis model is described here but more complete models are already planned: a 7 axis model as well as portable versions. Its back-drivable, high efficiency, low inertia actuators provide a high capacity (around 40 N continuous effort at the hand) and allow hybrid force-position control without requiring any force sensor. Its first application is currently a research program in rehabilitation (BRAHMA project) and professional use is already in view. Assistance tasks for disabled persons (carrying a bottle) are also typical tasks to be performed by ABLE as well as intuitive telerobotics, haptic device for VR, and sport training, etc. Furthermore, its versatility and simple design allow industrial versions to become soon available.

Development of a long reach articulated manipulator for ITER in vessel inspection under vacuum and temperature

This project takes place in the EFDA Remote Handling (RH) activities for the fusion reactor International Thermonuclear Experimental Reactor (ITER). The aim of the R&D program is to demonstrate the feasibility of in-vessel RH intervention by a long reach, limited payload manipulator which penetrates the first wall using the six IVVS penetrations. Potential activities for this device include close inspection of the plasma facing surfaces and leak detection. The work includes the design, manufacture and testing of a demonstrator articulated manipulator called the In-Vessel Penetrator (IVP). The first part of this work concerned the analysis of the requirements and resulted in the development of the conceptual design of the overall manipulator, comprising a 5 module, 11 d.o.f robot based on a parallelogram structure. A scale one mock up of a representative segment was manufactured and tested. In parallel, a feasibility study of the IVP operation was made and provided recommendations to modify the design for intervention under vacuum and temperature. Some technologies were selected and analysed to determine their suitability to the IVP application and items identified for further validation. This paper presents the whole robot concept, the results of the test campaign on the prototype demonstrator and the vacuum and temperature technologies study.

Technology and control for hydraulic manipulators

Abstract Hydraulic manipulators are candidate for fusion reactor maintenance. Their main advantages are their large payload with respect to volume and mass, their reliability and their robustness. However, due to their force control limitations, they are disqualified for precise manipulation and are dangerous for the environment and themselves in case of unexpected collision. CEA, in collaboration with CYBERNETIX and IFREMER has developed the advanced hydraulic robot MAESTRO. Force and hybrid control has been developed in order to avoid the previous problems. Using “pressure” control servo-valve instead of the standard “flow” control servo-valve (standard configuration of the MAESTRO) makes a real simplification of the control loop. No more pressure sensors are needed for monitoring the hydraulic joint in force control mode and using this kind of valves makes big safety improvements. The French company IN-LHC, designed and manufactured a prototype of servo-valve that fits the performances and space constraints of the Maestro arm. A characterisation of this new product was made on a mock-up and a set of these prototypes integrated in the Maestro slave-arm. A comparison between the two actuating technologies was made and showed that the performances of the pressure servo-valves make it applicable to general application.

Demonstration of an ITER relevant remote handling equipment for Tokamak close inspection

This work concerns the development of an ITER relevant advanced robotic systems for fusion reactor. The feasibility demonstration will be performed on the thermonuclear experimental Tokamak: Tore Supra, located in Cadarache facilities. The manipulator developed by the interactive robotics unit of CEA-LIST will be used for close inspection intervention tasks in a Tokamak. The robot must meet severe specifications: small diameter, long reach with a 9.5 m cantilever length, high dexterity to move in a Torus shape environment and able to carry a 10 kg payload on its end effector. As the robot must be introduced without breaking the machine conditioning, it has to cope with the vacuum and temperature constraints: Ultra High Vacuum (10-6 Pa) and 120degC in use, 200degC during baking phase. This long reach multi-link carrier has 10 DOF (9 rotary joints and 1 prismatic joint). It is composed of 5 modules and a precise guiding and pushing system (the deployer) for a total weight of about 300 kg. The gravity effect in the manipulator is largely compensated by a special mechanical structure (the parallelogram) that helps reducing the size of the actuators. The severe operating conditions impose a selection of several vacuum and temperature technologies that have been tested, qualified or optimized to cope with the requirements.In September 2007, the Remote Handling Equipment deployment under atmospheric conditions in a real Tokamak environment (Tore Supra) enabled to qualify the entire prototype. The scenario has to be rehearsed under vacuum and temperature to achieve the complete feasibility demonstration of a Tokamak close inspection by means of a robotic equipment under real operating conditions. The demonstration is an important step in the project but further developments are or could be necessary to cope with 100% of the requirements toward a reliable industrial prototype. In particular, due to its size and weight, this large robot manipulator holds lots of elastic and geometric deformations. Thus its accuracy is a challenge. A mechanical model could be developed to take into consideration the flexibilities of the structure and by means of calibration, the model parameters could be identified and then integrated in a real time controller. Further advanced developments on the on line monitoring system are also necessary for operator assistance and fault detection.

Making hydraulic manipulators cleaner and safer: From oil to demineralized water hydraulics

This paper presents the developments carried out at CEA LIST to adapt the 6-DOF hydraulic manipulator Maestro to work with pure water instead of oil. Its elbow joint has been redesigned for water applications and a prototype of water hydraulic pressure servovalve has been manufactured. Both performances of the actuator and its pre-actuator are discussed. A model of the servovalve is proposed to identify its driving parameters and validate the next evolutions in its design, anticipating the second generation of prototypes.

Carrier and bore tools for 4 in. bent pipes

Following the ALARA principle, remote handling techniques are developed for ITER maintenance to prevent direct hands-on access on the vacuum vessel components and reduce the personal dose rate. Maintenance of the divertor cassettes will require cutting, welding and non-destructive testing of the water-cooling-pipes. Work performed under the EFDA work program aimed to demonstrate the feasibility to operate with bore tools by means of an innovative carrier concept and to study the associated mechanisms. This paper presents a carrier designed to navigate through 4 in. bent pipes and the results of the test campaigns on the prototypes.

Overview of Bore Tools Systems for divertor remote maintenance of ITER

Because of the radiation levels preventing direct, hands-on access to the machine components, maintenance work on ITER will eventually require the use of Remote Handling techniques. In particular, the replacement of components such as divertor and blanket modules will require the use of remote cutting, welding and Non Destructive Testing of water cooling pipes.