Feedback Control of Impact Dynamics: the Bouncing Ball Revisited

peer reviewedWe study the the design of a tracking controller for the popular bouncing ball model: the continuous-time actuation of a table is used to control the impacts of the table with a bouncing ball. The proposed control law uses the impact times as the sole feedback information. We show that the acceleration of the table at impact plays no role in the stability analysis but is an important parameter for the robustness of the feedback system to model uncertainty, in particular to the uncertainty on the coefficient of restitution

Spatial and Timing Regulation of Upper-Limb Movements in Rhythmic Tasks

Rhythmic movement is vital to humans and a foundation of such activities as locomotion, handwriting, and repetitive tool use. The spatiotemporal regularity characterizing such movements reflects a level of automaticity and coordination that is believed to emerge from mutually inhibitory or other pattern generating neural networks in the central nervous system. Although many studies have provided descriptions of this regularity and have illuminated the types of sensory information that influence rhythmic behavior, an understanding of how the brain uses sensory feedback to regulate rhythmic behavior on a cycle-by-cycle basis has been elusive. This thesis utilizes the model task of paddle juggling, or vertical ball bouncing, to address how three types of feedback---visual, auditory, and haptic---contribute to spatial and temporal regulation of rhythmic upper-limb movements. We use a multi-level approach in accordance with the well-known dictum of Marr and Poggio. The crux of this thesis describes a method and suite of experiments to understand how the brain uses visual, audio, and haptic feedback to regulate spatial or timing regularity, and formulate acycle-by-cycle description of this control: to wit, the nature and algorithms of sensory-feedback guided regulation. Part I motivates our interest in this problem, by discussing the biological ``hardware'' that the nervous system putatively employs in these movements, and reviewing insights from previous studies of paddle juggling that suggest how the ``hardware'' may manifest itself in these behaviors. The central experimental approach of this thesis is to train participants to perform the paddle juggling task with spatiotemporal regularity (in other words, to achieve limit-cycle behavior), and then interrogate how the brain applies regulates closed-loop performance by perturbing task feedback. In Part II, we review the development of a novel hard-real-time virtual-reality juggling simulator that enabled precise spatial and temporal feedback perturbations. We then outline the central experimental approach, in which we perturb spatial feedback of the ball at apex phase (vision), and timing feedback of collision- (audio and haptic) and apex-phase events to understand spatial and timing regulation. Part III describes two experiments that yield the main research findings of this thesis. In Experiment 1, we use a sinusoidal-perturbation-based system identification approach to determine that spatial and timing feedback are used in two dissociable and complementary control processes: spatial error correction and temporal synchronization. In Experiment 2, a combination of sinusoidal and step perturbations is used to establish that these complementary processes obey different dynamics. Namely, spatial correction is a proportional-integral process based on a one-step memory of feedback, while temporal synchronization is a proportional process that is dependent only on the most recent feedback. We close in Part IV with a discussion of how insights and approaches from this thesis can lead to improved rehabilitation approaches and understanding of the physiological basis of rhythmic movement regulation

Nonprehensile Dynamic Manipulation: A Survey

Nonprehensile dynamic manipulation can be reason- ably considered as the most complex manipulation task. It might be argued that such a task is still rather far from being fully solved and applied in robotics. This survey tries to collect the results reached so far by the research community about planning and control in the nonprehensile dynamic manipulation domain. A discussion about current open issues is addressed as well

Modeling, analysis and control of robot-object nonsmooth underactuated Lagrangian systems: A tutorial overview and perspectives

International audienceSo-called robot-object Lagrangian systems consist of a class of nonsmooth underactuated complementarity Lagrangian systems, with a specific structure: an "object" and a "robot". Only the robot is actuated. The object dynamics can thus be controlled only through the action of the contact Lagrange multipliers, which represent the interaction forces between the robot and the object. Juggling, walking, running, hopping machines, robotic systems that manipulate objects, tapping, pushing systems, kinematic chains with joint clearance, crawling, climbing robots, some cable-driven manipulators, and some circuits with set-valued nonsmooth components, belong this class. This article aims at presenting their main features, then many application examples which belong to the robot-object class, then reviewing the main tools and control strategies which have been proposed in the Automatic Control and in the Robotics literature. Some comments and open issues conclude the article

Motion planning and control methods for nonprehensile manipulation and multi-contact locomotion tasks

Many existing works in the robotic literature deal with the problem of nonprehensile dynamic manipulation. However, a unified control framework does not exist so far. One of the ambitious goals of this Thesis is to contribute to identify planning and control frameworks solving classes of nonprehensile dynamic manipulation tasks, dealing with the non linearity of their dynamic models and, consequently, with the inherited design complexity. Besides, while passing through a number of connections between dynamic nonprehensile manipulation and legged locomotion, the Thesis presents novel methods for generating walking motions in multi-contact situations

A Poetics of Chaos: Schizoanalysis and Post modern American Fiction.

In "A Poetics of Chaos: Schizoanalysis and Postmodern American Fiction," I use theories from physics and psychoanalysis together to explore narrative structures in recent American fiction. Chaos theory, which emerged in mathematical and biological discourses in the 1960s, postulates the intrinsic instability and unpredictability of many natural and physical phenomena. Theorists like Bertalanffy, Mandelbrot and Lorenz produced a vocabulary to account for these pervasive systems. In assessing historical, economic and, indeed, literary systems, we may draw terms from chaotic inquiry: bifurcation, fractal, moebial, reiteration, complexity, butterfly effect, strange attractors, and sensitive dependence upon initial conditions. '"Chaotic narratives*" may explicitly deploy (Barth, Pynchon, Gibson) or inadvertently express (Coover, Ondaatje, Powers) the structural features of chaotic systems. Such writing is characterized by a diffusion of linear chronology, as well as ontological and narrative fracture, repetition and variation. Literary theorists N. Katherine Hayles, Joseph Conte, Hanjo Berressem and others have discussed how chaotic scientific and psycho-social systems are not only invoked in contemporary literature, but are themselves the structural and philosophical underpinnings of postmodern culture. My thesis builds upon chaotic-literary criticism by investigating the psychological implications of "chaotic narratives." Drawing from the anti-deterministic "schizoanalysis" of Gilles Deleuze and Felix Guattari, I explain how writings by Don DeLillo, Paul Auster, David Foster Wallace and Mark Z. Danielewski perform and reflect the "orderly disorder" of psychic development. I advance the term "psychochaotics*' to describe a theoretical approach that uses principles from chaos theory to reveal the psychodynamic systems in postmodern fiction

Abstraction of representation in live theater

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 151-158).Early in Tod Machover's opera Death and the Powers, the main character, Simon Powers, is subsumed into a technological environment of his own creation. The theatrical set comes alive in the form of robotic, visual, and sonic elements that allow the actor to extend his range and influence across the stage in unique and dynamic ways. The environment must compellingly assume the behavior and expression of the absent Simon. This thesis presents a new approach called Disembodied Performance that adapts ideas from affective psychology, cognitive science, and the theatrical tradition to create a framework for thinking about the translation of stage presence. An implementation of a system informed by this methodology is demonstrated. In order to distill the essence of this character, we recover performance parameters in real-time from physiological sensors, voice, and vision systems. This system allows the offstage actor to express emotion and interact with others onstage. The Disembodied Performance approach takes a new direction in augmented performance by employing a nonrepresentational abstraction of a human presence that fully translates a character into an environment. The technique and theory presented also have broad-reaching applications outside of theater for personal expression, telepresence, and storytelling.Peter Alexander Torpey.S.M