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Articles 1 - 7 of 7
Full-Text Articles in Engineering
Comparative Experiments With A New Adaptive Controller For Robot Arms, Louis L. Whitcomb, Daniel E. Koditschek, Alfred A. Rizzi
Comparative Experiments With A New Adaptive Controller For Robot Arms, Louis L. Whitcomb, Daniel E. Koditschek, Alfred A. Rizzi
Daniel E Koditschek
This paper presents a new model-based adaptive controller and proof of its global asymptotic stability with respect to the standard rigid-body model of robot-arm dynamics. Experimental data from a study of one new and several established globally asymptotically stable adaptive controllers on two very different robot arms 1) demonstrate the superior tracking performance afforded by the model-based algorithms over conventional PD control, 2) demonstrate and compare the superior performance of adaptive model-based algorithms over their nonadaptive counterparts, 3) reconcile several previous contrasting empirical studies, and 4) examine contexts that compromise their advantage.
X-Rhex: A Highly Mobile Hexapedal Robot For Sensorimotor Tasks, Kevin C. Galloway, Galen Clark Haynes, B. Deniz Ilhan, Aaron M. Johnson, Ryan Knopf, Goran A. Lynch, Benjamin N. Plotnick, Mackenzie White, Daniel E. Koditschek
X-Rhex: A Highly Mobile Hexapedal Robot For Sensorimotor Tasks, Kevin C. Galloway, Galen Clark Haynes, B. Deniz Ilhan, Aaron M. Johnson, Ryan Knopf, Goran A. Lynch, Benjamin N. Plotnick, Mackenzie White, Daniel E. Koditschek
Daniel E Koditschek
We report on the design and development of X-RHex, a hexapedal robot with a single actuator per leg, intended for real-world mobile applications. X-RHex is an updated version of the RHex platform, designed to offer substantial improvements in power, run-time, payload size, durability, and terrain negotiation, with a smaller physical volume and a comparable footprint and weight. Furthermore, X-RHex is designed to be easier to build and maintain by using a variety of commercial off-the-shelf (COTS) components for a majority of its internals. This document describes the X-RHex architecture and design, with a particular focus on the new ability of …
A Framework For The Coordination Of Legged Robot Gaits, Joel D. Weingarten, Richard E. Groff, Daniel E. Koditschek
A Framework For The Coordination Of Legged Robot Gaits, Joel D. Weingarten, Richard E. Groff, Daniel E. Koditschek
Daniel E Koditschek
This paper introduces a framework for representing, generating, and then tuning gaits of legged robots. We introduce a convenient parametrization of gait generators as dynamical systems possessing designer specified stable limit cycles over an appropriate torus. This parametrization affords a continuous selection of operation within a coordination design plane, inspired by biology, spanned by axes that determine the mix of "feedforward/feedback" and "centralized/decentralized" control. Tuning the gait generator parameters through repeated physical experiments with our robot hexapod, RHex, determines the appropriate operating point - the mix of feedback and degree of control decentralization - to achieve significantly increased performance relative …
Preliminary Analysis Of A Biologically Inspired 1-Dof "Clock" Stabilized Hopper, Haldun Komsuoglu, Daniel E. Koditschek
Preliminary Analysis Of A Biologically Inspired 1-Dof "Clock" Stabilized Hopper, Haldun Komsuoglu, Daniel E. Koditschek
Daniel E Koditschek
We investigate the stability of a one degree of freedom mechanical spring-mass system modulated by a feed-forward "clock" that stiffens and relaxes a Hooke's law potential force according to a periodic rhythm. At the present early stage of inquiry, we offer sufficient conditions for local asymptotic stability of an isolated periodic orbit when there is no feedback to the clock at all but some viscous friction in the mechanism. We conjecture that, absent feedback, a lossless mechanical system cannot exhibit an asymptotically stable limit cycle in response to such rhythmic excitation.
Disturbance Detection, Identification, And Recovery By Gait Transition In Legged Robots, Aaron M. Johnson, Galen Clark Haynes, Daniel E. Koditschek
Disturbance Detection, Identification, And Recovery By Gait Transition In Legged Robots, Aaron M. Johnson, Galen Clark Haynes, Daniel E. Koditschek
Daniel E Koditschek
We present a framework for detecting, identifying, and recovering within stride from faults and other leg contact disturbances encountered by a walking hexapedal robot. Detection is achieved by means of a software contactevent sensor with no additional sensing hardware beyond the commercial actuators’ standard shaft encoders. A simple finite state machine identifies disturbances as due either to an expected ground contact, a missing ground contact indicating leg fault, or an unexpected “wall” contact. Recovery proceeds as necessary by means of a recently developed topological gait transition coordinator. We demonstrate the efficacy of this system by presenting preliminary data arising from …
Sprawl Angle In Simplified Models Of Vertical Climbing: Implications For Robots And Roaches, Goran A. Lynch, Lawrence Rome, Daniel E. Koditschek
Sprawl Angle In Simplified Models Of Vertical Climbing: Implications For Robots And Roaches, Goran A. Lynch, Lawrence Rome, Daniel E. Koditschek
Daniel E Koditschek
Empirical data taken from fast climbing sprawled posture animals reveals the presence of strong lateral forces with significant pendulous swaying of the mass center trajectory in a manner captured by a recently proposed dynamical template. In this simulation study we explore the potential benefits of pendulous dynamical climbing in animals and in robots by examining the stability and power advantages of variously more and less sprawled limb morphologies when driven by conventional motors in contrast with animal-like muscles. For open loop models of gait generation inspired by the neural-deprived regimes of high stride-frequency animal climbing, our results corroborate earlier hypotheses …
A Brachiating Robot Controller, Jun Nakanishi, Toshio Fukuda, Daniel E. Koditschek
A Brachiating Robot Controller, Jun Nakanishi, Toshio Fukuda, Daniel E. Koditschek
Daniel E Koditschek
We report on our empirical studies of a new controller for a two-link brachiating robot. Motivated by the pendulum-like motion of an ape's brachiation, we encode this task as the output of a "target dynamical system." Numerical simulations indicate that the resulting controller solves a number of brachiation problems that we term the "ladder," "swing-up," and "rope" problems. Preliminary analysis provides some explanation for this success. The proposed controller is implemented on a physical system in our laboratory. The robot achieves behaviors including "swing locomotion" and "swing up" and is capable of continuous locomotion over several rungs of a ladder. …