51 research outputs found

    Partial motion planning framework for reactive planning within dynamic environments

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    Abstract: This paper addresses the problem of motion planning in dynamic environments. As dynamic environments impose a real-time constraint, the planner has a limited time only to compute a motion. Given the intrinsic complexity of motion planning, computing a complete motion to the goal within the time available is, in many real-life situations, impossible to achieve. Partial Motion Planning (PMP) is the answer proposed in this paper to this problem. PMP calculates a motion until the time available is over. At each iteration step, PMP returns the best partial motion to the goal computed so far. Like reactive decision scheme, PMP faces a safety issue: what guarantee is there that the system will never end up in a critical situations yielding an inevitable collision? In this paper the safety issue relies upon the concept of Inevitable Collision States that account for both the system dynamics and the moving obstacles. By computing ICS-free partial motion, the system safety can be guaranteed. Application of PMP to the case of a car-like system in a dynamic environment is presented.

    A novel putative insect chitinase with multiple catalytic domains: hormonal regulation during metamorphosis

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    0264-6021 (Print) Journal Article Research Support, Non-U.S. Gov'tWe have used differential display to identify genes that are regulated by juvenile hormone in the epidermis of the beetle Tenebrio molitor. One of the genes encodes T. molitor chitinase 5 (TmChit5), a chitinase possessing an unusual structure. Sequence analysis of TmChit5 identified five 'chitinase units' of approx. 480 amino acids with similarity to chitinase family 18. These units are separated by less conserved regions containing putative PEST (rich in proline, glutamic acid, serine and threonine) sequences, putative chitin-binding domains and mucin domains. Northern-blot analysis identified a single transcript of approx. 9 kb, whose abundance correlated with that of 20-hydroxyecdysone during metamorphosis. Injection of pupae with 20-hydroxyecdysone alone, or in combination with cycloheximide, indicated that TmChit5 expression is directly induced by the hormone. Further experiments indicated that methoprene (a juvenile hormone analogue) indirectly induced TmChit5 mRNA expression. On the basis of the present results and previous studies, we propose a molecular mechanism for cuticle digestion during the moulting process

    Towards urban driverless vehicles

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    The paper addresses the problem of autonomous navigation of a car-like robot evolving in an urban environment. Such an environment exhibits an heterogeneous geometry and is cluttered with moving obstacles. Furthermore, in this context, motion safety is a critical issue. The proposed approach to the problem lies in the design of perception and planning modules that consider explicitely the dynamic nature of the vehicle and the environment while enforcing the safety constraint. The main contributions of this work are the development of such modules and they integration into a single application. Initial full scale experiments validating the approach are presented

    Integrating Perception and Planning for Autonomous Navigation of Urban Vehicles

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    The paper addresses the problem of autonomous navigation of a car-like robot evolving in an urban environment. Such an environment exhibits an heterogeneous geometry and is cluttered with moving obstacles. Furthermore, in this context, motion safety is a critical issue. The proposed approach to the problem lies in the coupling of two crucial robotic capabilities, namely perception and planning. The main contributions of this work are the development and integration of these modules into one single application, considering explicitly the constraints related to the environment and the system

    Characterization of a putative extracellular matrix protein from the beetle Tenebrio molitor: hormonal regulation during metamorphosis

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    0949-944X (Print) Journal Article Research Support, Non-U.S. Gov'tWe used differential display to isolate epidermis cDNAs corresponding to juvenile-hormone analog-regulated mRNA from the beetle Tenebrio molitor. One of them encodes a putative extracellular matrix (ECM) protein, named Tenebrin. Indeed, the deduced protein sequence contains ECM typical features like the presence of a signal peptide, internal repeats, a RGD tripeptide sequence motif known to bind integrins and von Willebrand factor type c domains involved in protein-protein interactions. Northern blot analysis reveals a single transcript of about 11 kb with an expression pattern correlated to 20-hydroxyecdysone fluctuations during metamorphosis. In vivo injections of exogenous 20-hydroxyecdysone alone or combined with cycloheximide show that Tenebrin expression is directly induced by this hormone. Methoprene (a juvenile hormone analog) application experiments show that Tenebrin expression is rapidly induced by this analog. This gene is still up-regulated in the presence of protein synthesis inhibitor but, in these conditions, the mRNA induction level is not maximal

    Towards urban driverless vehicles

    No full text
    The paper addresses the problem of autonomous navigation of a car-like robot evolving in an urban environment. Such an environment exhibits an heterogeneous geometry and is cluttered with moving obstacles. Furthermore, in this context, motion safety is a critical issue. The proposed approach to the problem lies in the design of perception and planning modules that consider explicitely the dynamic nature of the vehicle and the environment while enforcing the safety constraint. The main contributions of this work are the development of such modules and they integration into a single application. Initial full scale experiments validating the approach are presented
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