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Departmental Papers (ESE)

Legged robots

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Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

Sensor-Based Reactive Execution Of Symbolic Rearrangement Plans By A Legged Mobile Manipulator, Vasileios Vasilopoulos, T. Turner Topping, William Vega-Brown, Nicholas Roy, Daniel E. Koditschek Oct 2018

Sensor-Based Reactive Execution Of Symbolic Rearrangement Plans By A Legged Mobile Manipulator, Vasileios Vasilopoulos, T. Turner Topping, William Vega-Brown, Nicholas Roy, Daniel E. Koditschek

Departmental Papers (ESE)

We demonstrate the physical rearrangement of wheeled stools in a moderately cluttered indoor environment by a quadrupedal robot that autonomously achieves a user's desired configuration. The robot's behaviors are planned and executed by a three layer hierarchical architecture consisting of: an offline symbolic task and motion planner; a reactive layer that tracks the reference output of the deliberative layer and avoids unanticipated obstacles sensed online; and a gait layer that realizes the abstract unicycle commands from the reactive module through appropriately coordinated joint level torque feedback loops. This work also extends prior formal results about the reactive layer ...


Vertical Hopper Compositions For Preflexive And Feedback-Stabilized Quadrupedal Bounding, Pacing, Pronking, And Trotting, Avik De, Daniel E. Koditschek Jul 2018

Vertical Hopper Compositions For Preflexive And Feedback-Stabilized Quadrupedal Bounding, Pacing, Pronking, And Trotting, Avik De, Daniel E. Koditschek

Departmental Papers (ESE)

This paper applies an extension of classical averaging methods to hybrid dynamical systems, thereby achieving formally specified, physically effective and robust instances of all virtual bipedal gaits on a quadrupedal robot. Gait specification takes the form of a three parameter family of coupling rules mathematically shown to stabilize limit cycles in a low degree of freedom template: an abstracted pair of vertical hoppers whose relative phase locking encodes the desired physical leg patterns. These coupling rules produce the desired gaits when appropriately applied to the physical robot. The formal analysis reveals a distinct set of morphological regimes determined by the ...


Using The Art Practice Of Play To Communicate Legged Robotics Research Concepts, Diedra Krieger, Sonia F. Roberts Jan 2018

Using The Art Practice Of Play To Communicate Legged Robotics Research Concepts, Diedra Krieger, Sonia F. Roberts

Departmental Papers (ESE)

The art practice of play uses spontaneity and surprise to communicate meaningful content and inspire critical thinking (1-3). We describe three engineering education outreach efforts that use play to communicate legged robotics research concepts. In the first workshop, Penn engineering students were motivated to learn how to program a legged robot using the narrative of a “dance competition,” with the winning dances to be showcased at the Philadelphia Science Festival. In the second workshop, Philadelphia School District high school students used a poseably programmable legged robot to tell a story by performing a series of behaviors in a set of ...


Sensor-Based Legged Robot Homing Using Range-Only Target Localization, Vasileios Vasilopoulos, Omur Arslan, Avik De, Daniel E. Koditschek Dec 2017

Sensor-Based Legged Robot Homing Using Range-Only Target Localization, Vasileios Vasilopoulos, Omur Arslan, Avik De, Daniel E. Koditschek

Departmental Papers (ESE)

This paper demonstrates a fully sensor-based reactive homing behavior on a physical quadrupedal robot, using onboard sensors, in simple (convex obstacle-cluttered) unknown, GPS-denied environments. Its implementation is enabled by our empirical success in controlling the legged machine to approximate the (abstract) unicycle mechanics assumed by the navigation algorithm, and our proposed method of range-only target localization using particle filters.

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Modular Hopping And Running Via Parallel Composition, Avik De Nov 2017

Modular Hopping And Running Via Parallel Composition, Avik De

Departmental Papers (ESE)

Though multi-functional robot hardware has been created, the complexity in its functionality has been constrained by a lack of algorithms that appropriately manage flexible and autonomous reconfiguration of interconnections to physical and behavioral components.

Raibert pioneered a paradigm for the synthesis of planar hopping using a composition of ``parts'': controlled vertical hopping, controlled forward speed, and controlled body attitude. Such reduced degree-of-freedom compositions also seem to appear in running animals across several orders of magnitude of scale. Dynamical systems theory can offer a formal representation of such reductions in terms of ``anchored templates,'' respecting which Raibert's empirical synthesis (and ...