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Now showing 1 - 10 of 26
  • Publication
    Real-time Heart Model for Implantable Cardiac Device Validation and Verification
    (2010-01-20) Jiang, Zhihao; Pajic, Miroslav; Connolly, Allison T; Dixit, Sanjay; Mangharam, Rahul
    Designing bug-free medical device software is dif- ficult, especially in complex implantable devices that may be used in unanticipated contexts. Safety recalls of pacemakers and implantable cardioverter defibrillators due to firmware problems between 1990 and 2000 affected over 200,000 devices, comprising 41% of the devices recalled and are increasing in frequency. There is currently no formal methodology or open experimental platform to validate and verify the correct operation of medical device software. To this effect, a real-time Virtual Heart Model (VHM) has been developed to model the electrophysiological operation of the functioning (i.e. during normal sinus rhythm) and malfunctioning (i.e. during arrhythmia) heart. We present a methodology to extract timing properties of the heart to construct a timed-automata model. The platform exposes functional and formal interfaces for validation and verification of implantable cardiac devices. We demonstrate the VHM is capable of generating clinically-relevant response to intrinsic (i.e. premature stimuli) and external (i.e. artificial pacemaker) signals for a variety of common arrhythmias. By connecting the VHM with a pacemaker model, we are able to pace and synchronize the heart during the onset of irregular heart rhythms. The VHM has also been implemented on a hardware platform for closed-loop experimentation with existing and virtual medical devices. The VHM allows for exploratory electrophysiology studies for physicians to evaluate their diagnosis and determine the appropriate device therapy. This integrated functional and formal device design approach will potentially help expedite medical device certification for safer operation.
  • Publication
    Tail Assisted Dynamic Self Righting: Full Derivations
    (2012-07-01) Johnson, Aaron M; Libby, Tomas; Chang-Siu, Evan; Tomizuka, Masayoshi; Full, R J; Koditschek, Daniel E
    This technical report is a companion document to the CLAWAR 2012 paper of the same name, for which we explicitly write out a full derivation of the kinematics and dynamics. Please refer to that document for motivation, experimentation, and discussion.
  • Publication
    Joint Metering and Conflict Resolution in Air Traffic Control
    (2010-11-28) Le Ny, Jerome; Pappas, George J
    This paper describes a novel optimization-based approach to conflict resolution in air traffic control, based on geometric programming. The main advantage of the approach is that Geometric Programs (GPs) can also capture various metering directives issued by the traffic flow management level, in contrast to most recent methods focusing purely on aircraft separation issues. GPs can also account for some of the nonlinearities present in the formulations of conflict resolution problems, while incurring only a small penalty in computation time with respect to the fastest linear programming based approaches. Additional integer variables can be introduced to improve the quality of the obtained solutions and handle combinatorial choices, resulting in Mixed-Integer Geometric Programs (MIGPs). We present GPs and MIGPs to solve a variety of joint metering and separation scenarios, e.g. including miles-in-trail and minutes-in-trail restrictions through airspace fixes and boundaries. Simulation results demonstrate the efficiency of the approach.
  • Publication
    Technical Report on: Anchoring Sagittal Plane Templates in a Spatial Quadruped
    (2023-02-24) Greco, Timothy M; Koditschek, D. E.
    This technical report provides a more thorough treatment of the proofs and derivations in the authors' paper "Anchoring Sagittal Plane Templates in a Spatial Quadruped." The description of the anchoring controller is reproduced here without abridgement, and additional appendices provide a clearer account of the implementation details.
  • Publication
    Technical Report on: Towards Reactive Control of Simplified Legged Robotics Maneuvers
    (2017-10-24) Duperret, Jeff; Koditschek, D. E.
    This technical report provides proofs and calculations for the paper "Towards Reactive Control of Simplified Legged Robotics Maneuvers," as well as implementation notes and a discussion on robustness.
  • Publication
    Desert RHex Technical Report: Jornada and White Sands Trip
    (2014-11-01) Roberts, Sonia; Duperret, Jeff; Johnson, Aaron M.; van Pelt, Scott; Zobeck, Ted; Lancaster, Nick; Koditschek, Daniel E
    Researchers in a variety of fields, including aeolian science, biology, and environmental science, have already made use of stationary and mobile remote sensing equipment to increase their variety of data collection opportunities. However, due to mobility challenges, remote sensing opportunities relevant to desert environments and in particular dune fields have been limited to stationary equipment. We describe here an investigative trip to two well-studied experimental deserts in New Mexico with D-RHex, a mobile remote sensing platform oriented towards desert research. D-RHex is the latest iteration of the RHex family of robots, which are six-legged, biologically inspired, small (10kg) platforms with good mobility in a variety of rough terrains, including on inclines and over obstacles of higher than robot hip height. For more information: Kod*Lab
  • Publication
    Anytime Hierarchical Clustering
    (2014-04-13) Arslan, Omur; Koditschek, Daniel E
    We propose a new anytime hierarchical clustering method that iteratively transforms an arbitrary initial hierarchy on the configuration of measurements along a sequence of trees we prove for a fixed data set must terminate in a chain of nested partitions that satisfies a natural homogeneity requirement. Each recursive step re-edits the tree so as to improve a local measure of cluster homogeneity that is compatible with a number of commonly used (e.g., single, average, complete) linkage functions. As an alternative to the standard batch algorithms, we present numerical evidence to suggest that appropriate adaptations of this method can yield decentralized, scalable algorithms suitable for distributed/parallel computation of clustering hierarchies and online tracking of clustering trees applicable to large, dynamically changing databases and anomaly detection.
  • Publication
    Towards a method for obstacle porosity classification
    (2014-01-01) Roberts, Sonia F
  • Publication
    Report on the ICRA’22 Workshop on Lethal Autonomous Weapons
    (2022-12-01) Koditschek, Daniel E; Miracchi, Lisa J.; Hamilton, Jesse
  • Publication
    Technical Report on: Comparative Design, Scaling, and Control of Appendages for Inertial Reorientation
    (2016-09-01) Libby, Thomas; Johnson, Aaron; Chang-Siu, Evan; Full, R J; Koditschek, Daniel E.