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

Systematizing Gibsonian Affordances In Robotics: An Empirical, Generative Approach Derived From Case Studies In Legged Locomotion, Sonia F. Roberts, Lisa J. Miracchi, Daniel E. Koditschek May 2019

Systematizing Gibsonian Affordances In Robotics: An Empirical, Generative Approach Derived From Case Studies In Legged Locomotion, Sonia F. Roberts, Lisa J. Miracchi, Daniel E. Koditschek

Departmental Papers (ESE)

A Gibsonian theory of affordances commits to direct perception and the mutuality of the agent-environment system. We argue that there already exists a research program in robotics which incorporates Gibsonian affordances. Controllers under this research program use information perceived directly from the environment with little or no further processing, and implicitly respect the indivisibility of the agentenvironment system. Research investigating the relationships between environmental and robot properties can be used to design reactive controllers that provably allow robots to take advantage of these affordances. We lay out key features of our empirical, generative Gibsonian approach and both show how it ...


Mechanical And Virtual Compliance For Robot Locomotion In A Compliant World, Sonia F. Roberts, Daniel E. Koditschek May 2019

Mechanical And Virtual Compliance For Robot Locomotion In A Compliant World, Sonia F. Roberts, Daniel E. Koditschek

Departmental Papers (ESE)

This abstract was accepted to the Robot Design and Customization workshop at ICRA 2019.

For more information: Kod*lab.


Mitigating Energy Loss In A Robot Hopping On A Physically Emulated Dissipative Substrate, Sonia F. Roberts, Daniel E. Koditschek May 2019

Mitigating Energy Loss In A Robot Hopping On A Physically Emulated Dissipative Substrate, Sonia F. Roberts, Daniel E. Koditschek

Departmental Papers (ESE)

We work with geoscientists studying erosion and desertification to improve the spatial and temporal resolution of their data collection over long transects in difficult realworld environments such as deserts. The Minitaur robot, which can run quickly over uneven terrain and use a single leg to measure relevant ground properties such as stiffness, is an attractive scout robot candidate for inclusion in a heterogeneous team in collaboration with a heavily geared, sensor-laden RHex. However, Minitaur is challenged by long-distance locomotion on sand dunes. Previous simulation results suggested that the energetic cost of transport can be mitigated by programming a virtual damping ...


Task-Based Control And Design Of A Bldc Actuator For Robotics, Avik De, Abriana Stewart-Height, Daniel E. Koditschek Jan 2019

Task-Based Control And Design Of A Bldc Actuator For Robotics, Avik De, Abriana Stewart-Height, Daniel E. Koditschek

Departmental Papers (ESE)

This paper proposes a new multi-input brushless DC motor current control policy aimed at robotics applications. The controller achieves empirical improvements in steady-state torque and power-production abilities relative to conventional controllers, while retaining similarly good torque-tracking and stability characteristics. Simulations show that non-conventional motor design optimizations whose feasibility is established by scaling model extrapolations from existing motor catalogues can vastly amplify the effectiveness of this new control-strategy.


Reactive Navigation In Partially Known Non-Convex Environments, Vasileios Vasilopoulos, Daniel E. Koditschek Dec 2018

Reactive Navigation In Partially Known Non-Convex Environments, Vasileios Vasilopoulos, Daniel E. Koditschek

Departmental Papers (ESE)

This paper presents a provably correct method for robot navigation in 2D environments cluttered with familiar but unexpected non-convex, star-shaped obstacles as well as completely unknown, convex obstacles. We presuppose a limited range onboard sensor, capable of recognizing, localizing and (leveraging ideas from constructive solid geometry) generating online from its catalogue of the familiar, non-convex shapes an implicit representation of each one. These representations underlie an online change of coordinates to a completely convex model planning space wherein a previously developed online construction yields a provably correct reactive controller that is pulled back to the physically sensed representation to generate ...


Reactive Velocity Control Reduces Energetic Cost Of Jumping With A Virtual Leg Spring On Simulated Granular Media, Sonia F. Roberts, Daniel E. Koditschek Nov 2018

Reactive Velocity Control Reduces Energetic Cost Of Jumping With A Virtual Leg Spring On Simulated Granular Media, Sonia F. Roberts, Daniel E. Koditschek

Departmental Papers (ESE)

Robots capable of dynamic locomotion behaviors and high-bandwidth sensing with their limbs have a high cost of transport, especially when locomoting over highly dissipative substrates such as sand. We formulate the problem of reducing the energetic cost of locomotion by a Minitaur robot on sand, reacting to robot state variables in the inertial world frame without modeling the ground online. Using a bulk-behavior model of high-velocity intrusions into dry granular media, we simulated single jumps by a one-legged hopper using a Raibert-style compression-extension virtual leg spring. We compose this controller with a controller that added damping to the leg spring ...


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 ...


Inertial Velocity And Attitude Estimation For Quadrotors: Supplementary Material, James B. Svacha Jr, Kartik Mohta, Michael Watterson, Giuseppe Loianno, Vijay Kumar Oct 2018

Inertial Velocity And Attitude Estimation For Quadrotors: Supplementary Material, James B. Svacha Jr, Kartik Mohta, Michael Watterson, Giuseppe Loianno, Vijay Kumar

Departmental Papers (ESE)

No abstract provided.


Analytically-Guided Design Of A Tailed Bipedal Hopping Robot, Abdulaziz Shamsah, Avik De, Daniel E. Koditschek Jul 2018

Analytically-Guided Design Of A Tailed Bipedal Hopping Robot, Abdulaziz Shamsah, Avik De, Daniel E. Koditschek

Departmental Papers (ESE)

We present the first fully spatial hopping gait of a 12 DoF tailed biped driven by only 4 actuators. The control of this physical machine is built up from parallel compositions of controllers for progressively higher DoF extensions of a simple 2 DoF, 1 actuator template. These template dynamics are still not themselves integrable, but a new hybrid averaging analysis yields a conjectured closed form representation of the approximate hopping limit cycle as a function of its physical and control parameters. The resulting insight into the role of the machine's kinematic and dynamical design choices affords a redesign leading ...


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 ...


Sensor-Based Reactive Navigation In Unknown Convex Sphere Worlds, Omur Arslan, Daniel E. Koditschek May 2018

Sensor-Based Reactive Navigation In Unknown Convex Sphere Worlds, Omur Arslan, Daniel E. Koditschek

Departmental Papers (ESE)

We construct a sensor-based feedback law that provably solves the real-time collision-free robot navigation problem in a compact convex Euclidean subset cluttered with unknown but sufficiently separated and strongly convex obstacles. Our algorithm introduces a novel use of separating hyperplanes for identifying the robot’s local obstacle-free convex neighborhood, affording a reactive (online-computed) continuous and piecewise smooth closed-loop vector field whose smooth flow brings almost all configurations in the robot’s free space to a designated goal location, with the guarantee of no collisions along the way. Specialized attention to planar navigable environments yields a necessary and sufficient condition on ...


Sensor-Based Reactive Symbolic Planning In Partially Known Environments, Vasileios Vasilopoulos, William Vega-Brown, Omur Arslan, Nicholas Roy, Daniel E. Koditschek May 2018

Sensor-Based Reactive Symbolic Planning In Partially Known Environments, Vasileios Vasilopoulos, William Vega-Brown, Omur Arslan, Nicholas Roy, Daniel E. Koditschek

Departmental Papers (ESE)

This paper considers the problem of completing assemblies of passive objects in nonconvex environments, cluttered with convex obstacles of unknown position, shape and size that satisfy a specific separation assumption. A differential drive robot equipped with a gripper and a LIDAR sensor, capable of perceiving its environment only locally, is used to position the passive objects in a desired configuration. The method combines the virtues of a deliberative planner generating high-level, symbolic commands, with the formal guarantees of convergence and obstacle avoidance of a reactive planner that requires little onboard computation and is used online. The validity of the proposed ...


On Balancing Event And Area Coverage In Mobile Sensor Networks, Hancheng Min May 2018

On Balancing Event And Area Coverage In Mobile Sensor Networks, Hancheng Min

Departmental Papers (ESE)

In practice, the mobile sensor networks have two important tasks: firstly, sensors should be able to locate themselves close to where major events are happening so that event tracking becomes possible; secondly, the sensor networks should also maintain a good area coverage over the environment in order to detect new events. Because these two tasks are usually conflicting with each other, a coverage control policy should be able to balance the event and area coverage of the environment. However, most existing work is to achieve either optimal event coverage or optimal area coverage over the environment. In this thesis, a ...


Nomadic Monument For Women In Robotics, Diedra Krieger, Gaby Alfaro, Joey Hartmann-Dow, Sonia F. Roberts Apr 2018

Nomadic Monument For Women In Robotics, Diedra Krieger, Gaby Alfaro, Joey Hartmann-Dow, Sonia F. Roberts

Departmental Papers (ESE)

We describe the Nomadic Monument for Women in Robotis (NMWR), a project celebrating women pioneers in robotics. NMWR is a 13’ semi-transparent geodesic dome with illustrations and descriptions of the women and their research on the inside faces of the triangles. Visitors can see rough outlines of the illustrations from the outside, but must enter the dome to learn about the women. As an immersive environment, the dome provides visitors not only a place to learn about inspiring women but also a space to feel that they are a member of this inspiring community.

The geodesic dome was introduced by ...


A Hybrid Dynamical Extension Of Averaging And Its Application To The Analysis Of Legged Gait Stability, Avik De, Samuel A. Burden, Daniel E. Koditschek Mar 2018

A Hybrid Dynamical Extension Of Averaging And Its Application To The Analysis Of Legged Gait Stability, Avik De, Samuel A. Burden, Daniel E. Koditschek

Departmental Papers (ESE)

We extend a smooth dynamical systems averaging technique to a class of hybrid systems with a limit cycle that is particularly relevant to the synthesis of stable legged gaits. After introducing a definition of hybrid averageability sufficient to recover the classical result, we illustrate its applicability by analysis of first a one-legged and then a two-legged hopping model. These abstract systems prepare the ground for the analysis of a significantly more complicated two legged model—a new template for quadrupedal running to be analyzed and implemented on a physical robot in a companion paper. We conclude with some rather more ...


Integration Of Local Geometry And Metric Information In Sampling-Based Motion Planning, Vincent Pacelli, Omur Arslan, Daniel E. Koditschek Feb 2018

Integration Of Local Geometry And Metric Information In Sampling-Based Motion Planning, Vincent Pacelli, Omur Arslan, Daniel E. Koditschek

Departmental Papers (ESE)

The efficiency of sampling-based motion planning algorithms is dependent on how well a steering procedure is capable of capturing both system dynamics and configuration space geometry to connect sample configurations. This paper considers how metrics describing local system dynamics may be combined with convex subsets of the free space to describe the local behavior of a steering function for sampling-based planners. Subsequently, a framework for using these subsets to extend the steering procedure to incorporate this information is introduced. To demonstrate our framework, three specific metrics are considered: the LQR cost-to-go function, a Gram matrix derived from system linearization, and ...


Voronoi-Based Coverage Control Of Pan/Tilt/Zoom Camera Networks, Omur Arslan, Hancheng Min, Daniel E. Koditschek Feb 2018

Voronoi-Based Coverage Control Of Pan/Tilt/Zoom Camera Networks, Omur Arslan, Hancheng Min, Daniel E. Koditschek

Departmental Papers (ESE)

A challenge of pan/tilt/zoom (PTZ) camera networks for efficient and flexible visual monitoring is automated active network reconfiguration in response to environmental stimuli. In this paper, given an event/activity distribution over a convex environment, we propose a new provably correct reactive coverage control algorithm for PTZ camera networks that continuously (re)configures camera orientations and zoom levels (i.e., angles of view) in order to locally maximize their total coverage quality. Our construction is based on careful modeling of visual sensing quality that is consistent with the physical nature of cameras, and we introduce a new notion ...


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 ...


A Dynamical System For Prioritizing And Coordinating Motivations, Paul Reverdy, Daniel E. Koditschek Jan 2018

A Dynamical System For Prioritizing And Coordinating Motivations, Paul Reverdy, Daniel E. Koditschek

Departmental Papers (ESE)

We develop a dynamical systems approach to prioritizing multiple tasks in the context of a mobile robot. We take navigation as our prototypical task, and use vector field planners derived from navigation functions to encode control policies that achieve each individual task. We associate a scalar quantity with each task, representing its current importance to the robot; this value evolves in time as the robot achieves tasks. In our framework, the robot uses as its control input a convex combination of the individual task vector fields. The weights of the convex combination evolve dynamically according to a decision model adapted ...


Towards Reactive Control Of Transitional Legged Robot Maneuvers, Jeff Duperret Dec 2017

Towards Reactive Control Of Transitional Legged Robot Maneuvers, Jeff Duperret

Departmental Papers (ESE)

We propose the idea of a discrete navigation problem – consisting of controlling the state of a discrete-time control system to reach a goal set while in the interim avoiding a set of obstacle states – to approximate a simplified class of transitional legged robotic tasks such as leaping which have no well established mathematical description that lends itself to synthesis. The control relation given in Theorem 1 is (assuming a task solution exists) necessary and sufficient to solve a discrete navigation problem in a minimum number of steps, and is well suited to computation when a legged system’s continuous-time within-stride ...


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.

For more information: Kod*lab


Joint Exploration Of Local Metrics And Geometry In Sampling-Based Planning, Vincent Pacelli Aug 2017

Joint Exploration Of Local Metrics And Geometry In Sampling-Based Planning, Vincent Pacelli

Departmental Papers (ESE)

This thesis addresses how the local geometry of the workspace around a system state can be combined with local metrics describing system dynamics to improve the connectivity of the graph produced by a sampling-based planner over a fixed number of configurations. This development is achieved through generalization of the concept of the local free space to inner products other than the Euclidean inner product. This new structure allows for naturally combining the local free space construction with a locally applicable metric. The combination of the local free space with two specific metrics is explored in this work. The first metric ...


Ground Robotic Measurement Of Aeolian Processes, Feifei Qian, Douglas J. Jerolmack, Nicholas Lancaster, George Nikolich, Paul B. Reverdy, Sonia F. Roberts, Thomas F. Shipley, Robert Scott Van Pelt, Ted M. Zobeck, Daniel E. Koditschek Aug 2017

Ground Robotic Measurement Of Aeolian Processes, Feifei Qian, Douglas J. Jerolmack, Nicholas Lancaster, George Nikolich, Paul B. Reverdy, Sonia F. Roberts, Thomas F. Shipley, Robert Scott Van Pelt, Ted M. Zobeck, Daniel E. Koditschek

Departmental Papers (ESE)

Models of aeolian processes rely on accurate measurements of the rates of sediment transport by wind, and careful evaluation of the environmental controls of these processes. Existing field approaches typically require intensive, event-based experiments involving dense arrays of instruments. These devices are often cumbersome and logistically difficult to set up and maintain, especially near steep or vegetated dune surfaces. Significant advances in instrumentation are needed to provide the datasets that are required to validate and improve mechanistic models of aeolian sediment transport. Recent advances in robotics show great promise for assisting and amplifying scientists’ efforts to increase the spatial and ...


Spatial Sampling Strategies With Multiple Scientific Frames Of Reference, Paul B. Reverdy, Thomas F. Shipley, Daniel E. Koditschek Jun 2017

Spatial Sampling Strategies With Multiple Scientific Frames Of Reference, Paul B. Reverdy, Thomas F. Shipley, Daniel E. Koditschek

Departmental Papers (ESE)

We study the spatial sampling strategies employed by field scientists studying aeolian processes, which are geophysical interactions between wind and terrain. As in geophysical field science in general, observations of aeolian processes are made and data gathered by carrying instruments to various locations and then deciding when and where to record a measurement. We focus on this decision-making process. Because sampling is physically laborious and time consuming, scientists often develop sampling plans in advance of deployment, i.e., employ an offline decision-making process. However, because of the unpredictable nature of field conditions, sampling strategies generally have to be updated online ...


Quasi-Static And Dynamic Mismatch For Door Opening And Stair Climbing With A Legged Robot, T. Turner Topping, Gavin Kenneally, Daniel E. Koditschek May 2017

Quasi-Static And Dynamic Mismatch For Door Opening And Stair Climbing With A Legged Robot, T. Turner Topping, Gavin Kenneally, Daniel E. Koditschek

Departmental Papers (ESE)

This paper contributes to quantifying the notion of robotic fitness by developing a set of necessary conditions that determine whether a small quadruped has the ability to open a class of doors or climb a class of stairs using only quasi-static maneuvers. After verifying that several such machines from the recent robotics literature are mismatched in this sense to the common human scale environment, we present empirical workarounds for the Minitaur quadrupedal platform that enable it to leap up, force the door handle and push through the door, as well as bound up the stairs, thereby accomplishing through dynamical maneuvers ...


Detecting Poisoning Attacks On Hierarchical Malware Classification Systems, Dan P. Guralnik, Bill Moran, Ali Pezeshki, Omur Arslan Mar 2017

Detecting Poisoning Attacks On Hierarchical Malware Classification Systems, Dan P. Guralnik, Bill Moran, Ali Pezeshki, Omur Arslan

Departmental Papers (ESE)

Anti-virus software based on unsupervised hierarchical clustering (HC) of malware samples has been shown to be vulnerable to poisoning attacks. In this kind of attack, a malicious player degrades anti-virus performance by submitting to the database samples specifically designed to collapse the classification hierarchy utilized by the anti-virus (and constructed through HC) or otherwise deform it in a way that would render it useless. Though each poisoning attack needs to be tailored to the particular HC scheme deployed, existing research seems to indicate that no particular HC method by itself is immune. We present results on applying a new notion ...


Discriminative Measures For Comparison Of Phylogenetic Trees, Omur Arslan, Dan P. Guralnik, Daniel E. Koditschek Jan 2017

Discriminative Measures For Comparison Of Phylogenetic Trees, Omur Arslan, Dan P. Guralnik, Daniel E. Koditschek

Departmental Papers (ESE)

In this paper we introduce and study three new measures for efficient discriminative comparison of phylogenetic trees. The NNI navigation dissimilarity $d_{nav}$ counts the steps along a “combing” of the Nearest Neighbor Interchange (NNI) graph of binary hierarchies, providing an efficient approximation to the (NP-hard) NNI distance in terms of “edit length”. At the same time, a closed form formula for $d_{nav}$ presents it as a weighted count of pairwise incompatibilities between clusters, lending it the character of an edge dissimilarity measure as well. A relaxation of this formula to a simple count yields another measure on all ...


Sensory Steering For Sampling-Based Motion Planning, Omur Arslan, Vincent Pacelli, Daniel E. Koditschek Jan 2017

Sensory Steering For Sampling-Based Motion Planning, Omur Arslan, Vincent Pacelli, Daniel E. Koditschek

Departmental Papers (ESE)

Sampling-based algorithms offer computationally efficient, practical solutions to the path finding problem in high-dimensional complex configuration spaces by approximately capturing the connectivity of the underlying space through a (dense) collection of sample configurations joined by simple local planners. In this paper, we address a long-standing bottleneck associated with the difficulty of finding paths through narrow passages. Whereas most prior work considers the narrow passage problem as a sampling issue (and the literature abounds with heuristic sampling strategies) very little attention has been paid to the design of new effective local planners. Here, we propose a novel sensory steering algorithm for ...


Comparative Design, Scaling, And Control Of Appendages For Inertial Reorientation, Thomas Libby, Aaron M Johnson, Evan Chang-Sui, R J. Full, Daniel E. Koditschek Dec 2016

Comparative Design, Scaling, And Control Of Appendages For Inertial Reorientation, Thomas Libby, Aaron M Johnson, Evan Chang-Sui, R J. Full, Daniel E. Koditschek

Departmental Papers (ESE)

This paper develops a comparative framework for the design of an actuated inertial appendage for planar reorientation. We define the Inertial Reorientation template, the simplest model of this behavior, and leverage its linear dynamics to reveal the design constraints linking a task with the body designs capable of completing it. As practicable inertial appendage designs lead to physical bodies that are generally more complex, we advance a notion of “anchoring” whereby a judicious choice of physical design in concert with an appropriate control policy yields a system whose closed loop dynamics are sufficiently captured by the template as to permit ...


Core Actuation Promotes Self-Manipulability On A Direct-Drive Quadrupedal Robot, Jeff Duperret, Benjamin Kramer, Daniel E. Koditschek Oct 2016

Core Actuation Promotes Self-Manipulability On A Direct-Drive Quadrupedal Robot, Jeff Duperret, Benjamin Kramer, Daniel E. Koditschek

Departmental Papers (ESE)

For direct-drive legged robots operating in unstructured environments, workspace volume and force generation are competing, scarce resources. In this paper we demonstrate that introducing geared core actuation (i.e., proximal to rather than distal from the mass center) increases workspace volume and can provide a disproportionate amount of work-producing force to the mass center without affecting leg linkage transparency. These effects are analytically quantifiable up to modest assumptions, and are demonstrated empirically on a spined quadruped performing a leap both on level ground and from an isolated foothold (an archetypal feature of unstructured terrain).