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Based on sequencing data, norovirus (NoV) recombinants have been described, but no experimental evidence of recombination in NoVs has been documented. Using the murine norovirus (MNV) model, we investigated the occurrence of genetic recombination between two co-infecting wild-type MNV isolates in RAW cells. The design of a PCR-based genotyping tool allowed accurate discrimination between the parental genomes and the detection of a viable recombinant MNV (Rec MNV) in the progeny viruses. Genetic analysis of Rec MNV identified a homologous-recombination event located at the ORF1-ORF2 overlap. Rec MNV exhibited distinct growth curves and produced smaller plaques than the wild-type MNV in RAW cells. Here, we demonstrate experimentally that MNV undergoes homologous recombination at the previously described recombination hot spot for NoVs, suggesting that the MNV model might be suitable for in vitro studies of NoV recombination. Moreover, the results show that exchange of genetic material between NoVs can generate viruses with distinct biological properties from the parental viruses.

Traditional H ∞ design methods available in commercial softwares lead to controllers which present the same order as the model of the plant. Considering the high order of teleoperation systems, implementing such controllers may require the use of order-reduction methods. To avoid this extra step in the design, we propose to produce fixed-order controllers directly based on a full-order model of the system. In this paper, a zero-order (static output feedback) controller is designed for a teleoperation system. The design procedure, based on a cone complementary formulation is described and applied to a 22 nd -order model of the system. The resulting controller is implemented on a one degree of freedom teleoperation system. The experimental results obtained with this simple control structure validate the use of very low order control structures in the case of teleoperation systems with the extra advantage, with respect to conventional H ∞ design techniques, that the involved and time-consuming order reduction step is avoided.

In this paper, an experimental study of two control strategies for teleoperation is performed on a simple one degree-of-freedom (dof) mechanism made of two parallel arms. First, the so-called position-position scheme is implemented using controllers with an integrating action in order to achieve zero steady-state position error in contact free movement and the shortcomings of this approach are exhibited. Next they are overcome thanks to a force-position control scheme involving a controller switching mechanism so that the integrating action is only active in contact free motion. The so-called conditioning technique is used to avoid windup in the proposed control architecture (a multi-controller cascade scheme).

Trocars used in Minimally Invasive Surgery (MIS) are equipped with a sealing mechanism. During the motion of an instrument through a trocar, the sealing mechanism deforms itself. None of the friction models presented in the literature capture the macroscopical deformation of the seal mechanism. Therefore a specific hybrid model is developed to describe the movement of an instrument through a trocar. The only geometrical assumption of this model is the axial symmetry of the two bodies. It can thus be applied to all problems with the same symmetry. Two operating modes are distinguished, corresponding to the deformation of the sealing mechanism on the one hand, and to the sliding phase through the trocar on the other hand. The model is identified and validated using experimental data recorded on a dedicated test setup.

Flexible fluidic actuators present a lot of nice features regarding applications in the medical field and in the field of robotics. For example, they own a natural compliance and they can be very lightweight. Besides, an interesting measuring concept seems to be applicable to them: it is possible to determine and control the position of the actuator and the force it develops thanks to the measures of the fluid pressure and of the volume of supplied fluid. This means being able to determine and control the position of the actuator and the force it develops without displacement or force sensors. We validate experimentally this measuring concept in the case of a specific actuator and a method to model the behaviour of flexible fluidic actuators having one degree of freedom is proposed. Besides, the advantages and difficulties brought by this measuring concept are discussed.

International audience; In this paper the realization and implementation of a multi-controller scheme made of a finite set of linear multiple-input-multiple-output controllers, possibly having different state dimensions, is considered. The problem of bumpless switching between the active controller acting in closed-loop and another controller in the set of controllers waiting to take over the control loop is addressed. A non minimal parametrization of the set of controllers such that all controllers share the same state variables is presented, and it is shown that such a parametrization guarantees bumpless switching between any two controllers within the controller set