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Cooperative Air And Ground Survaillance, Ben Grocholsky, James Keller, Vijay Kumar, George J. Pappas Sep 2006

Cooperative Air And Ground Survaillance, Ben Grocholsky, James Keller, Vijay Kumar, George J. Pappas

Departmental Papers (MEAM)

Unmanned aerial vehicles (UAVs) can be used to cover large areas searching for targets. However, sensors on UAVs are typically limited in their accuracy of localization of targets on the ground. On the other hand, unmanned ground vehicles (UGVs) can be deployed to accurately locate ground targets, but they have the disadvantage of not being able to move rapidly or see through such obstacles as buildings or fences. In this article, we describe how we can exploit this synergy by creating a seamless network of UAVs and UGVs. The keys to this are our framework and algorithms for search and ...


Dynamic Rolling For A Modular Loop Robot, Jimmy Sastra, Sachin Chitta, Mark Yim Jul 2006

Dynamic Rolling For A Modular Loop Robot, Jimmy Sastra, Sachin Chitta, Mark Yim

Departmental Papers (MEAM)

Reconfigurable modular robots use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available to a modular robot for traversal of level ground. In this work, we analyze and implement a sensor-based feedback controller to achieve dynamic rolling for a 10 module loop robot. The controller exploits the dynamics of the system to build up momentum in each step by specifying a desired global shape for the robot at touchdown. Energy is input into the system both by raising the height of the center of mass of the robot and moving the ...


Improving Telerobotic Touch Via High-Frequency Acceleration Matching, Katherine J. Kuchenbecker, Günter Niemeyer Jun 2006

Improving Telerobotic Touch Via High-Frequency Acceleration Matching, Katherine J. Kuchenbecker, Günter Niemeyer

Departmental Papers (MEAM)

Humans rely on information-laden high-frequency accelerations in addition to quasi-static forces when interacting with objects via a handheld tool. Telerobotic systems have traditionally struggled to portray such contact transients due to closed-loop bandwidth and stability limitations, leaving remote objects feeling soft and undefined. This work seeks to maximize the user’s feel for the environment through the approach of acceleration matching; high-frequency fingertip accelerations are combined with standard low-frequency position feedback without requiring a secondary actuator on the master device. In this method, the natural dynamics of the master are identified offline using frequency-domain techniques, estimating the relationship between commanded ...


Elastic Instabilities Of Polymer Solutions In Cross-Channel Flow, Paulo E. Arratia, C. C. Thomas, J. Diorio, J. P. Gollub Apr 2006

Elastic Instabilities Of Polymer Solutions In Cross-Channel Flow, Paulo E. Arratia, C. C. Thomas, J. Diorio, J. P. Gollub

Departmental Papers (MEAM)

When polymer molecules pass near the hyperbolic point of a microchannel cross flow, they are strongly stretched. As the strain rate is varied at low Reynolds number ( < 10-2), tracer and particle-tracking experiments show that molecular stretching produces two flow instabilities: one in which the velocity field becomes strongly asymmetric, and a second in which it fluctuates nonperiodically in time. The flow is strongly perturbed even far from the region of instability, and this phenomenon can be used to produce mixing.


Modeling Induced Master Motion In Force-Reflecting Teleoperation, Katherine J. Kuchenbecker, Günter Niemeyer Jan 2006

Modeling Induced Master Motion In Force-Reflecting Teleoperation, Katherine J. Kuchenbecker, Günter Niemeyer

Departmental Papers (MEAM)

Providing the user with high-fidelity force feedback has persistently challenged the field of telerobotics. Interaction forces measured at the remote site and displayed to the user cause unintended master device motion. This movement is interpreted as a command for the slave robot and can drive the closed-loop system unstable. This paper builds on a recently proposed approach for achieving stable, high-gain force reflection via cancellation of the master mechanism’s induced motion. Such a strategy hinges on obtaining a good model of the master’s response to force feedback. Herein, we present a thorough modeling approach based on successive isolation ...


Evaluation Of Some Thermal Power Cycles For Use In Space, Jason Tarlecki, Noam Lior, Na Zhang Jan 2006

Evaluation Of Some Thermal Power Cycles For Use In Space, Jason Tarlecki, Noam Lior, Na Zhang

Departmental Papers (MEAM)

Production of power in space for terrestrial use is of great interest in view of the rapidly rising power demand and its environmental impacts. Space also offers a very low temperature, making it a perfect heat sink for power plants, thus offering much higher efficiencies. This paper focuses on the evaluation and analysis of thermal Brayton, Ericsson and Rankine power cycles operating at space conditions on several appropriate working fluids. 1. Under the examined conditions, the thermal efficiency of Brayton cycles reaches 63%, Ericsson 74%, and Rankine 85%. These efficiencies are significantly higher than those for the computed or real ...