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The aim of this study was to design a multipole-electromagnet robotic platform named OctoRob. This platform provides a minimally invasive means for targeted therapeutic interventions in specific intraocular areas. OctoRob is capable of generating both appropriate magnetic fields and gradients. The main scientific objectives were: (i) To propose an optimal reconfigurable arrangement of electromagnets suitable for ophthalmic interventions. (ii) To model, design and implement a one-degree-of-freedom robotic arm connected with an electromagnet in order to optimize the generation of magnetic fields and gradients. (iii) To evaluate the magnetic performances of the OctoRob platform, including different tilted angles. The results show that OctoRob platform has great potential to be applied for ophthalmic surgery. [ABSTRACT FROM AUTHOR]

In the context of virtualized-reality-based telemicromanipulation, this paper presents a visual calibration technique for an optical microscope coupled to a charge-coupled device (CCD) camera. The accuracy and flexibility of the proposed automatic virtual calibration method, based on parallel single-plane properties, are outlined. In contrast to standard approaches, a 3-D virtual calibration pattern is constructed using the micromanipulator tip with subpixel-order localization in the image frame. The proposed procedure leads to a linear system whose solution provides directly both the intrinsic and extrinsic parameters of the geometrical model. Computer simulations and real data have been used to test the proposed technique, and promising results have been obtained. Based on the proposed calibration techniques, a 3-D virtual microenvironment of the workspace is reconstructed through the real-time imaging of two perpendicular optical microscopes. Our method provides a flexible, easy-to-use technical alternative to the classical techniques used in micromanipulation systems. Index Terms--Camera/microscope calibration, telemicromanipulation, virtual pattern, virtual reality.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.robot.2006.02.010 Byline: Moussa Boukhnifer, Antoine Ferreira Abstract: A wave-based bilateral controller for a micro-teleoperation system is presented for stability and transparency via a passivity approach. We showed that the application of wave variable formalism allows the passivity of the system in spite of external perturbations and environment uncertainties. While most of the existing wave-based approach assumes LTI and fixed time-delay, this paper extends the research domain to a scaled teleoperation system with variable time-delay, asymmetric gains in force and velocity variables or model uncertainties in the microenvironment. Based on the wave-based analysis of a time-varying system, a variable gain controller is proposed in order to guarantee the passivity of the system. Furthermore, in scaled teleoperation there exist positive gain matrices (scaling position and force factors) that preserve its passivity only if gain matrices are equal, which is hard to find in a real system. In case the equality condition is not satisfied, we introduced filter functions with a set of conditions for two operating cases: a structurally dominated system and a surface-dominated system. Finally, as the nonlinear nature of small scale environments with unknown dynamic passivity condition can not be satisfied, we analyzed the constraints inevitably occurring in a micro-teleoperation system and derived conditions between the parameters. The stability is analyzed based on the passivity of the resultant operator-telemanipulator-environment system. The experimental results show clearly that the proposed passivity conditions ensure stability and transparency performances against variable time-delays and scaling factors. Author Affiliation: Laboratoire Vision et Robotique, Universite d'Orleans-ENSI de Bourges, 10 bld Lahitolle, 18020, Bourges, France Article History: Received 22 March 2005; Revised 8 February 2006; Accepted 21 February 2006