A vision-based vibration suppression scheme has previously been proposed to control the vibrational behaviour of long-reach arms operating in fusion reactors. In this paper we describe a new method to reconstruct the vibration using sinusoidal regression. This change makes the overall scheme more efficient since it enables the estimation of the tip oscillation whatever its origin may be. Both an exact solution and a simplified method are proposed to solve the regression problem. To limit the trade-off between good tracking capability and quality of the vibration reconstruction, these regression algorithms are performed over a variable-length sliding window. Consequently this paper also describes the change detection scheme used to automatically adjust the window length. Experimental results validate the proposed method.

In the field of comanipulation (i.e. a man and a robot sharing the same task), force amplification is an interesting function that can be achieved by using two force sensors. This technique is known in the literature but little attention has been paid so far to stability/passivity properties. We will explain how to deal with passivity based stability criteria, and point out performance limitations of such a control in case of noncollocated and bandwidth limited force sensors. Theoretical, as well as experimental results will be presented.

We focus on comanipulation, i.e. manipulation of an object simultaneously held by a robot and a human operator. In this domain, a major difficulty is raised by significant variations of human dynamics, which depend not only on the arm posture, but also on the muscular activity (muscular co-contraction) and more generally on the type of task being performed: fine positioning, gross and rapid movements, repeated movements, etc. An ideal comanipulation system should be able of adapting its behavior to the operator's functional intention, resulting in an intuitive assisting device. Toward this goal, we present in this paper first results of our research aimed at developing an instrumented handle mounted on a robot end-effector and held by an operator, that can be used for estimating the grasping force and for adapting the robot controller accordingly. We show first experimental evidences that changes in the grasping force drastically affect the robot controller performances. We thus propose a handle design and a gain scheduling strategy that result in a robot behavior adequate for any kind of grasps. This solution is successfully experimented with a 1 degree of freedom robot under largely variable comanipulation conditions, exhibiting a stable and efficiently adaptive behavior.

In this paper we present a vibration control scheme for a long-reach inspection arm in an environment as constrained as a fusion reactor. The ultra-high vacuum, the high operating temperature, the significant residual magnetic field and the nuclear activation in ITER will prevent from considering common on-the-shelf dynamics sensors. Therefore we propose to use the already developed rad-hardened viewing tool to feed an oscillation observer with visual information. In our approach the visual data are extracted from a totally unknown environment. Particular attention is paid to obtain a robust algorithm. Experimental results validate the proposed strategy.

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.

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.

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 (10-6Pa) 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.

This paper presents a new portable exoskeleton design for superior limbs by the CEA-LIST laboratories. The first model described here (4 axis) is designed to apply forces in 3 directions. The first application is foreseen as an assistance device to enable a disabled person to carry an object such as a teapot or water bottle. It is designed as a base for more complete systems. A partial realization of it is presented for the first time. The high potential of the actuators used both in terms of back drivability and force capacity, allows hybrid force-position control laws making it possible to cover a broad range of applications: rehabilitation, assistance, force feedback master arm for telerobotics, sport training, and a virtual reality workbench