Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

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    Robot Formations: Learning Minimum-Length Paths on Uneven Terrain
    (2000) Hristu, Dimitrios; ISR; CDCSS
    We discuss a prototypeproblem involving terrain exploration and learning by formations ofautonomous vehicles. We investigate an algorithm forcoordinating multiple robots whose task is to find the shortest pathbetween a fixed pair of start and target locations, without access toa "global" map containing those locations.

    Odometry information alone isnot sufficient for minimizing path length if the terrain is uneven orif it includes obstacles. We generalize existing results on a simplecontrol law, also known as "local pursuit," which is appropriate inthe context of formations and which requires limited interactionbetween vehicles.

    Our algorithm is iterative and converges to alocally optimal path. We include simulations and experimentsillustrating the performance of the proposed strategy.

    The research and scientific content in this material has been published in the IEEE Mediterranean Conference on Control and Automation, July 2000.
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    Generalized Inverses for Finite-Horizon Tracking
    (2000) Hristu, Dimitrios; ISR; CDCSS
    Control and communication issues aretraditionally "decoupled" in discussions of decision and controlproblems, as this simplifies the analysis and generally works well forclassical models. This fundamental assumption deserves re-examinationas control applications spread into new areas where system complexityis significant. Such areas include the coordinated control of aerialvehicles (UAVs), MEMS devices, multi-joint manipulators and othersettings where many systems must share the attention of adecision-maker. We consider a new class ofsampled-data systems (termed "computer-controlled systems") thatoffer the possibility of jointly optimizing between control andcommunication goals. Computer-controlled LTI systems can be viewed aslinear operators between appropriate inner-product spaces. Thegeneralized inverses of these operators are used to solve a class offinite-horizon tracking problems.

    This work was presented at the IEEE Conf. on Decision and Control, Dec. 1999.
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    Stabilization of LTI Systems with Communication Constraints
    (1999) Hristu, Dimitrios; ISR; CDCSS
    This work is directed towards exploring interactions ofcommunication and control in systems with communication constraints.Examples of such systems include groups of autonomousvehicles, MEMS arrays and systems whose sensors and actuators aredistributed across a network. We extend some recent results involvingthe stabilization of LTI systems under limited communication andaddress a class of feed-forward control problems for the systems ofinterest.