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Publication Kod*fest: What is Robotics? The Koditschek Festschrift(University of Pennsylvania, 2023-05-22) Cowan, NoahOn Sunday, May 22, 2022, Kod*lab alumni, students, collaborators, and colleagues gathered to celebrate Dan Koditschek and Kod*lab’s research and culture in the academic tradition of Festschrift. Written remarks were prepared in advance of the daylong celebration. Entries were open to all invited, including those unable to attend. On the day, the agenda was full with 5 minute, 15 minute and 20 minute talks in person and over zoom. Here, we present the proceedings.Publication X-RHex: A Highly Mobile Hexapedal Robot for Sensorimotor Tasks(2010-11-04) Galloway, Kevin C; Haynes, Galen Clark; Ilhan, B. Deniz; Johnson, Aaron M; Knopf, Ryan; Lynch, Goran A; Plotnick, Benjamin N; White, Mackenzie; Koditschek, Daniel EWe 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 this robot to carry modular payloads as a laboratory on legs. X-RHex supports a variety of sensor suites on a small, mobile robotic platform intended for broad, general use in research, defense, and search and rescue applications. Comparisons with previous RHex platforms are presented throughout, with preliminary tests indicating that the locomotive capabilities of X-RHex can meet or exceed the previous platforms. With the additional payload capabilities of X-RHex, we claim it to be the first robot of its size to carry a fully programmable GPU for fast, parallel sensor processing.Publication Report on the ICRA’22 Workshop on Lethal Autonomous Weapons(2022-12-01) Koditschek, Daniel E; Miracchi, Lisa J.; Hamilton, JessePublication Technical Report on: Anchoring Sagittal Plane Templates in a Spatial Quadruped(2023-02-24) Greco, Timothy M; Koditschek, Daniel EThis 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 RHex Slips on Granular Media(2016-01-01) Roberts, Sonia F.; Koditschek, Dan E.RHex is one of very few legged robots being used for realworld rough-terrain locomotion applications. From its early days, RHex has been shown to locomote successfully over obstacles higher than its own hip height [1], and more recently, on sand [2] and sand dunes [3], [4] (see Figure 1). The commercial version of RHex made by Boston Dynamics has been demonstrated in a variety of difficult, natural terrains such as branches, culverts, and rocks, and has been shipped to Afghanistan, ostensibly for use in mine clearing in sandy environments [5]. Here, we discuss recent qualitative observations of an updated research version of RHex [6] slipping at the toes on two main types of difficult terrain: sand dunes and rubble piles. No lumped parameter (finite dimensional) formal model nor even a satisfactory computational model of RHexs locomotion on sand dunes or rubble piles currently exists. We briefly review the extent to which available physical theories describe legged locomotion on flat granular media and possible extensions to locomotion on sand dunes.Publication Extended Version of Stability of a Groucho-Style Bounding Run in the Sagittal Plane(2023-01-12) Duperret, Jeff; Koditschek, Daniel EThis paper develops a three degree-of-freedom sagittal-plane hybrid dynamical systems model of a Groucho-style bounding quadrupedal run. Simple within-stance controls using a modular architecture yield a closed form expression for a family of hybrid limit cycles that represent bounding behavior over a range of user-selected fore-aft speeds as a function of the model's kinematic and dynamical parameters. Controls acting on the hybrid transitions are structured so as to achieve a cascade composition of in-place bounding driving the fore-aft degree of freedom, thereby decoupling the linearized dynamics of an approximation to the stride map. Careful selection of the feedback channels used to implement these controls affords infinitesimal deadbeat stability which is relatively robust against parameter mismatch. Experiments with a physical quadruped reasonably closely match the bounding behavior predicted by the hybrid limit cycle and its stable linearized approximation.Publication Technical Report on: Comparative Design, Scaling, and Control of Appendages for Inertial Reorientation(2016-09-01) Libby, Thomas; Johnson, Aaron; Full, R J; Koditschek, Daniel E.; Chang-Siu, EvanPublication Technical Report on: Towards Reactive Control of Simplified Legged Robotics Maneuvers(2017-10-24) Duperret, Jeff; Koditschek, Daniel EThis 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 Parametric Jumping Dataset on the RHex Robot(2012-01-01) Johnson, Aaron M; Koditschek, Daniel EThis report presents the apex state achieved after performing a variety of jumps with the XRL robot. A full account of the behaviors and the theoretical basis is given in another paper, this document is intended to simply provide higher resolution copies of those figures, and present the results in numerical form.Publication Quadratic Lyapunov Functions for Mechanical Systems(1987-03-01) Koditschek, Daniel EThe “mechanical systems” define a large and important class of highly nonlinear dynamical equations which, for example, encompasses all robots. In this report it is shown that a strict Lyapunov Function suggested by the simplest examplar of the class - a one degree of freedom linear time invariant dynamical system - may be generalized over the entire class. The report lists a number of standard but useful consequences of this discovery. The analysis suggests that the input-output properties of the entire class of nonlinear systems share many characteristics in common with those of a second order, phase canonical, linear time invariant differential equation. 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