373 research outputs found

    ‘YOUR LOVE IS LIKE BAD MEDICINE’: THE MEDICAL TRADITION OF LOVESICKNESS IN THE LEGENDS OF HIPPOCRATES AND ERASISTRATUS OF CEOS

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    The image of the lover physically afflicted by erƍs, with erratic pulse and fiery flushes under the skin, goes back at least as far as Sappho.  Ancient doctors like Galen and Oribasius of Pergamon saw the lovesick as a patient with a real disease in need of medicalintervention. In Western medieval medicine, the disease had various names, such as amor heroes and erotomania. This study defines lovesickness as erotomania, a psychosomatic illness with depressive symptoms caused by unrequited love, with its roots sometimes sought in a humoral imbalance of black bile, an excess of seminal fluid or in some inflammation of the brain. It traces this tradition to the anecdotes about the physicians Hippocrates and Erasistratus of Ceos on how they diagnosed and treated royal patients suffering from lovesickness. It is argued that these stories reflect real-life medical debates. The anecdotes suggest the cause of the disease to have been seen as psychic rather than purely physiological and somatic, calling for a therapy one might term psychological. They suggest the choice treatment for a patient suffering from sick unrequited love was to requite the demands of erƍs

    Manipulation Planning Using Environmental Contacts to Keep Objects Stable under External Forces

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    This paper addresses the problem of sequential manipulation planning to keep an object stable under changing external forces. Particularly, we focus on using object-environment contacts. We present a planning algorithm which can generate robot configurations and motions to intelligently use object-environment, as well as object-robot, contacts, to keep an object stable under forceful operations such as drilling and cutting. Given a sequence of external forces, the planner minimizes the number of different configurations used to keep the object stable. An important computational bottleneck in this algorithm is due to the static stability analysis of a large number of configurations. We propose a containment relationship between configurations, to prune the stability checking process

    A real-time web-based networked control system education platform

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    Networked control systems have recently experienced a surge in fundamental theoretical results ignited by numerous advantages of introducing shared multipurpose communication networks in control systems. Regarding developments on the practical side, however, a networked control system is still wanting when it comes to experimental platforms suitable for research and educational purposes, which contributes to most of networked control system theory being validated by means of numerical examples and simulations. This paper addresses this issue by presenting a low-cost real-time networked control system platform, based on custom hardware and software solutions that can be readily explored with the sole use of a web browser connected to the Internet. The technical decisions made during development represent a fundamentally novel take on networked control system experimental platforms that can potentially be reproduced by several universities. The platform provides the user with multiple controller and input reference options, network configurations, delay statistics, and even a downloadable file containing advanced experiment data. A survey conducted with students located over 1200 km away from the platform who used it during laboratory assignments highlight the system’s usability and interactivity, and supports the platform is suitable for educational purposes

    Robust Controller Design for Attitude Dynamics Subjected to Time-Delayed State Measurements

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    Attitude control and time-delay systems are well-developed fields in the control theory, but only a modicum of papers have explored control systems that fall within the intersection of the two. Indeed, combining kinematics and dynamics nonlinearities with sensor and actuator delays reinvigorates the original attitude control problem, typically leading to involved stability arguments based on nonlinear analysis techniques. This paper instead proposes solving the attitude stabilizer design problem by formulating it as a linear matrix inequality feasibility problem. The proposed approach simplifies the stability arguments, without loosing generality; the obtained conditions cope with the general case of rigid bodies that suffer from unknown, heterogeneous, time-varying state measurement delays, and have inertia uncertainties. This methodology is particularly well suited to resource-limited applications, because controllers can be designed offline using computationally efficient tools. Although simple, numerical evidence shows the stability criterion derived in this paper largely outperforms previous results

    Quaternion-based H∞ attitude tracking control of rigid bodies with time-varying delay in attitude measurements

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    The problem of attitude and angular velocity tracking in the presence of exogenous disturbances and where feedback measurements are subjected to unknown time-varying delays is addressed. Sufficient conditions which guarantee stability and disturbance attenuation performance in the H∞ sense are provided. Results are presented in the form of LMIs, which allow the conditions to be simply and efficiently computed. Using a simple quaternion-based linear state feedback controller and a feedforward term to compensate the nonlinearities of the system dynamics, simulation results illustrate that the control law is able to effectively track desired trajectories and reject disturbances even in the presence of large time-varying delays

    Planning for Muscular and Peripersonal-Space Comfort during Human-Robot Forceful Collaboration

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    This paper presents a planning algorithm designed to improve cooperative robot behavior concerning human comfort during forceful human-robot physical interaction. Particularly, we are interested in planning for object grasping and positioning ensuring not only stability against the exerted human force but also empowering the robot with capabilities to address and improve human experience and comfort. Herein, comfort is addressed as both the muscular activation level required to exert the cooperative task, and the human spatial perception during the interaction, namely, the peripersonal space. By maximizing both comfort criteria, the robotic system can plan for the task (ensuring grasp stability) and for the human (improving human comfort). We believe this to be a key element to achieve intuitive and fluid human-robot interaction in real applications. Real HRI drilling and cutting experiments illustrated the efficiency of the proposed planner in improving overall comfort and HRI experience without compromising grasp stability

    Dual quaternion-based bimodal global control for robust rigid body pose kinematic stabilization

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    A hybrid bimodal controller for rigid body pose stabilization within the group of unit norm dual-quaternions is proposed in this paper. Using two binary logic state variables, this hysteresis-based controller represents a middle term solution between the memoryless discontinuous controller and the fixed-width hysteretic one. The proposed strategy is novel within the dual-quaternions framework and addresses three common difficulties that appears in the literature of pose and attitude stabilization: global stability, robustness against chattering and against unwinding. The efficacy and performance of the proposed controller are illustrated with numerical examples

    Depth, Highness and DNR Degrees

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    A sequence is Bennett deep [5] if every recursive approximation of the Kolmogorov complexity of its initial segments from above satisfies that the difference between the approximation and the actual value of the Kolmogorov complexity of the initial segments dominates every constant function. We study for different lower bounds r of this difference between approximation and actual value of the initial segment complexity, which properties the corresponding r(n)-deep sets have. We prove that for r(n) = Δn, depth coincides with highness on the Turing degrees. For smaller choices of r, i.e., r is any recursive order function, we show that depth implies either highness or diagonally-non-recursiveness (DNR). In particular, for left-r.e. sets, order depth already implies highness. As a corollary, we obtain that weakly-useful sets are either high or DNR. We prove that not all deep sets are high by constructing a low order-deep set. Bennett's depth is defined using prefix-free Kolmogorov complexity. We show that if one replaces prefix-free by plain Kolmogorov complexity in Bennett's depth definition, one obtains a notion which no longer satisfies the slow growth law (which stipulates that no shallow set truth-table computes a deep set); however, under this notion, random sets are not deep (at the unbounded recursive order magnitude). We improve Bennett's result that recursive sets are shallow by proving all K-trivial sets are shallow; our result is close to optimal. For Bennett's depth, the magnitude of compression improvement has to be achieved almost everywhere on the set. Bennett observed that relaxing to infinitely often is meaningless because every recursive set is infinitely often deep. We propose an alternative infinitely often depth notion that doesn't suffer this limitation (called i.o. depth).We show that every hyperimmune degree contains a i.o. deep set of magnitude Δn, and construct a π01- class where every member is an i.o. deep set of magnitude Δn. We prove that every non-recursive, non-DNR hyperimmune-free set is i.o. deep of constant magnitude, and that every nonrecursive many-one degree contains such a set
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