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.

Thanks to recent advances in machine vision technology, vibration control of flexible manipulators using cameras have recently led to very promising results. However, in methods such as on-line sinusoidal regression, synchronization between the measured signal and the physical vibrational phenomenon is critical to properly damp vibrations. This paper comes back on the capture delay estimation as done in previous works and highlights the limitations of such a method. Then a new method using a synchronization sensor is proposed. Based on a cross-correlation technique, a novel algorithm for effective time delay estimation is derived. Experimental validation demonstrates that this method yields improved delay estimation which could be beneficial to the vibration damping.

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.