This paper describes development of a controllerfor bilateral robotic system for tele-echography with delayed communications. The system comprises two identical 6DOF robotic devices based on Stewart-Gough mechanisms, which were developed especially for the sake of the considered application. Controller design is facilitated by a symmetry of the teleoperation setup, in which the master and slave devices have identical geometry, actuation and measurement arrays. To further simplify the analysis, we treat coupling between degrees of freedom as exogenous disturbances and this allows us to split the control problem into six independent IDOF settings. The IDOF problems are addressed then using a novel approach to bilateral teleoperation control, based on a complete parameterization of feasible teleoperators. It allows to intuitively shape teleoperator performance while guaranteeing passivity and thus coupled stability of the system. The potential of the proposed control method is demonstrated with experimental results.

Abstract The goal of this study is to understand whether providing a search intermediary familiar with a problem domain and its topical structure would support a user's Web searching tasks, especially complicated tasks with multifaceted topics, and whether the order of searching tasks or system usage influences their successful completion. This study investigates the effect of two factors, the interaction mode and the display layout, on the three main measures of the user's Web searching behaviors: effectiveness, efficiency, and usability. Two interaction modes are compared, mediation via a domain‐specific document collection versus nonmediated search, and two display layouts, a combination of browsing‐supporting hierarchic display and ranked list of results versus the simple linear list of search results. The results are analyzed in the Flow theory point of view; they were analyzed by order of the tasks and system usage order. The findings of this study contribute to a better understanding of how the mediation system and/or the combined display support a Web information user.

This paper reports on and discusses a set of user experiments using the TREC 2003 Web interactive track protocol. The focus is on comparing humans and machine algorithms in terms of performance in a topic distillation task. We also investigated the effect of the search results layout in supporting the users' effort.We have demonstrated that machines can perform nearly as well as people on the topic distillation task. Given a system tailored to the task there is significant performance improvement and finally, given a presentation that supports the task, there is strong user satisfaction.

Query length in best-match information retrieval (IR) systems is well known to be positively related to effectiveness in the IR task, when measured in experimental, non-interactive environments. However, in operational, interactive IR systems, query length is quite typically very short, on the order of two to three words. We report on a study which tested the effectiveness of a particular query elicitation technique in increasing initial searcher query length, and which tested the effectiveness of queries elicited using this technique, and the relationship in general between query length and search effectiveness in interactive IR. Results show that the specific technique results in longer queries than a standard query elicitation technique, that this technique is indeed usable, that the technique results in increased user satisfaction with the search, and that query length is positively correlated with user satisfaction with the search.