Computer Engineering Commons^™

An Algorithm To Estimate Manipulator Dynamics Parameters, Pradeep K. Khosla, Takeo Kanade

Pradeep K Khosla

No abstract provided.

Choosing Sampling Rates For Robot Control, Pradeep K. Khosla

Pradeep K Khosla

No abstract provided.

Experimental Evaluation Of Nonlinear Feedback And Feedforward Control Schemes For Manipulators, Pradeep K. Khosla, Takeo Kanade

Pradeep K Khosla

No abstract provided.

Efficient Mapping Through Exploitation Of Spatial Dependencies, Yaron Rachlin, John M. Dolan, Pradeep K. Khosla

Pradeep K Khosla

Occupancy grid mapping algorithms assume that grid block values are independently distributed. However, most environments of interest contain spatial patterns that are better characterized by models that capture dependencies among grid blocks. To account for such dependencies, we model the environment as a pairwise Markov random field. We specify a belief propagation-based mapping algorithm that takes these dependencies into account when estimating a map. To demonstrate the potential benefits of this approach, we simulate a simple multirobot minefield mapping scenario. Minefields contain spatial dependencies since some landmine configurations are more likely than others, and since clutter, which causes false alarms, …

Optimal Sensor Placement For Cooperative Distributed Vision, Luis E. Navarro-Serment, John M. Dolan, Pradeep K. Khosla

Pradeep K Khosla

This paper describes a method for observing maneuvering targets using a group of mobile robots equipped with video cameras. These robots are part of a team of small-size (7x7x7 cm) robots configured from modular components that collaborate to accomplish a given task. The cameras seek to observe the target while facing it as much as possible from their respective viewpoints. This work considers the problem of scheduling and maneuvering the cameras based on the evaluation of their current positions in terms of how well can they maintain a frontal view of the target. We describe our approach, which distributes the …

Chimera Ii : A Real-Time Unix-Compatible Multiprocessor Operating System For Sensor-Based Control Applications, David B. Stewart, Donald Schmitz, Pradeep K. Khosla

Pradeep K Khosla

Abstract: "This paper describes the CHIMERA II multiprocessing operating system, which has been developed to provide the flexibility, performance, and UNIX-compatible interface needed for fast development and implementation of parallel real-time control code. The operating system is intended for sensor-based control applications such as robotics, process control, and manufacturing. The features of CHIMERA II include support for multiple general purpose CPUs; support for multiple special purpose processors and I/O devices; a UNIX-like environment, which supports most standard C system and library calls; standardized interrupt and exception handlers; and a user interface which serves as a terminal interface to the executing …

Two-Disk Motion Planning Strategy, Yangsheng Xu, Raju S. Mattikalli, Pradeep K. Khosla, Carnegie Mellon University.Engineering Design Research Center.

Pradeep K Khosla

Abstract: "This paper addresses the problem of planning the motion of a polygonal object through a set of planar obstacles. We propose a two-disk motion planning strategy to navigate the object within the free space between the obstacles from an initial location to a final location. This method makes use of the Medial Axis Transform (MAT) of the free space which can be generated efficiently using the method in [10]. We determine two minimal overlapping disks that fully enclose the moving object, and then constrain the centers of the two disks to move continuously along a path on the medial …

Crucial Factors Affecting Decentralized Multirobot Learning In An Object Manipulation Task, Poj Tangamchit, John M. Dolan, Pradeep K. Khosla

Pradeep K Khosla

Decentralized multirobot learning refers to the use of multiple learning entities to achieve the optimal solution for the overall robot system. We demonstrate that single-robot learning theory can be successfully used with multirobot systems, but with certain conditions. The success and the effectiveness of this method are potentially affected by various factors that we classify into two groups: the nature of the robots and the nature of the learning entities. Incorrect setup of these factors may lead to undesirable results. In this paper, we methodically test the effect of varying four common factors (reward scope, learning algorithms, diversity of robots, …

Adaptive Multi-Robot Wide-Area Exploration And Mapping, Kian Hsiang Low, John Dolan, Pradeep Khosla

Pradeep K Khosla

The exploration problem is a central issue in mobile robotics. A complete terrain coverage is not practical if the environment is large with only a few small hotspots. This paper presents an adaptive multi-robot exploration strategy that is novel in performing both wide-area coverage and hotspot sampling using non-myopic path planning. As a result, the environmental phenomena can be accurately mapped. It is based on a dynamic programming formulation, which we call the Multi-robot Adaptive Sampling Problem (MASP). A key feature of MASP is in covering the entire adaptivity spectrum, thus allowing strategies of varying adaptivity to be formed and …

Multi-Robot Path Planning By Predicting Structure In A Dynamic Environment, C. Spence Oliver, Mahesh Saptharishi, John M. Dolan, Ashitey Trebi-Ollennu, Pradeep K. Khosla

Pradeep K Khosla

Path planning for multiple mobile robots is complicated by the presence of a dynamic environment, in which obstacles and other robots are moving. Centralized approaches are too computationally intensive for real-time response. Decoupled approaches which perform individual preplanning, conflict resolution, and reactive obstacle avoidance for each robot, can be globally inefficient. We propose a novel mission coordination architecture, CPAD (Checkpoint/Priority/ Action Database), which performs path planning via checkpoint and dynamic priority assignment, using statistical estimates of the environment’s motion structure in order to make both preplanning and reactive behaviors more efficient. Simulation is used to validate and illustrate the approach.

Cyber-Atvs: Dynamic And Distributed Reconnaissance Using All-Terrain Ugvs, Alvaro Soto, Mahesh Saptharishi, Ashitey Trebi-Ollennu, John M. Dolan, Pradeep K. Khosla

Pradeep K Khosla

This paper describes our current effort to develop robotic vehicles for tactical distributed surveillance. Our research is focused on multi-agent collaboration, reconfigurable systems, efficient perception and sensor fusion, distributed command and control, and task decomposition. In particular, this paper describes the main features and capabilities of our All Terrain Vehicles (ATVs), concentrating on their autonomous navigation capabilities.

A Modified Reactive Control Framework For Cooperative Mobile Robots, J. Salido, John M. Dolan, J. Hampshire, Pradeep K. Khosla

Pradeep K Khosla

An important class of robotic applications potentially involves multiple, cooperating robots: security or military surveillance, rescue, mining, etc. One of the main challenges in this area is effective cooperative control: how does one determine and orchestrate individual robot behaviors which result in a desired group behavior? Cognitive (planning) approaches allow for explicit coordination between robots, but suffer from high computational demands and a need for a priori, detailed world models. Purely reactive approaches such as that of Brooks are efficient, but lack a mechanism for global control and learning. Neither approach by itself provides a formalism capable of a sufficiently …

Speech Enhancement Using Bayesian Estimators Of The Perceptually-Motivated Short-Time Spectral Amplitude (Stsa) With Chi Speech Priors, Marek B. Trawicki, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

In this paper, the authors propose new perceptually-motivated Weighted Euclidean (WE) and Weighted Cosh (WCOSH) estimators that utilize more appropriate Chi statistical models for the speech prior with Gaussian statistical models for the noise likelihood. Whereas the perceptually-motivated WE and WCOSH cost functions emphasized spectral valleys rather than spectral peaks (formants) and indirectly accounted for auditory masking effects, the incorporation of the Chi distribution statistical models demonstrated distinct improvement over the Rayleigh statistical models for the speech prior. The estimators incorporate both weighting law and shape parameters on the cost functions and distributions. Performance is evaluated in terms of the …

Maine Epscor End-To-End Connectivity For Sustainability Science Collaboration, Michael Eckardt, Vicki Nemeth, Jeffrey Letourneau, Bruce E. Segee

University of Maine Office of Research Administration: Grant Reports

This NSF EPSCoR C2 project allowed Maine EPSCoR to continue the state’s momentum to enhance the connectivity of the state’s research, higher education, and K-12 institutions through Maine’s Research and Education Network (MaineREN). Over the last few years, multi-million dollar investments have built networking and computing power at the state level, including: 1) the installation of 1,100 miles of middle-mile fiber optic cable; 2) investments in shared computing resources for high performance computing and cloud computing; 3) the Maine School and Library Network; 4) the Maine Learning Technology Initiative (grade 6-12 laptops); and 5) investments in high-performance visualization and videoconferencing. …

What’S Motivation Got To Do With It? A Survey Of Recursion In The Computing Education Literature, Amber Settle

Technical Reports

One of the most challenging topics for both computing educators and students is recursion. Pedagogical approaches for teaching recursion have appeared in the computing education literature for over 30 years, and the topic has generated a significant body of work. Given its persistence, relatively little attention has been paid to student motivation. This article summarizes results on teaching and learning recursion explored by the computing education community, noting the relative lack of interest in motivation. It concludes by briefly discussing an approach to teaching recursion is appealing for students interested in web development.

On The Use Of Gaussian Approximation In Analyzing The Performance Of Optical Receivers, George El-Howayek, C. Zhang, Y. Li, J. S. Ng, J. P.R. David, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

The analytical calculation of the bit error rate (BER) of digital optical receivers that employ avalanche photodiodes (APDs) is challenging due to 1) the stochastic nature of the avalanche photodiode's impulse-response function and 2) the presence of intersymbol interference (ISI). At ultrafast transmission rates, ISI becomes a dominant component of the BER, and its effect on the BER should be carefully addressed. One solution to this problem, termed the bit-pattern-dependent (PD) approach, is to first calculate the conditional BER given a specific bit pattern and then average over all possible bit patterns. Alternatively, a simplifying method, termed the bit-pattern-independent (PI) …

Is Vehicle Characterization In Accordance With Standard Test Procedures A Necessary Prerequisite For Validating Computer Models Of A Test Vehicle?, Michael Hall

Masters

Vehicle characterization is the process by which a particular vehicle’s inherent dynamic behavior is classified by measuring its response to certain command inputs under standard test conditions. Such information is required when comparing its performance to that of other vehicles in response to the same test event and it is also used to authenticate computer models of the test vehicle. The aim of this research was to determine whether vehicle characterization is possible using data from non- standard tests and to judge whether such data can also be used for the purpose of validating a computer model of the test …

On Optimal Media/Video Distribution In Closed P2p-Based Iptv Networks, Hao Cui, Xiao Su, Weijia Shang

Faculty Publications

Video distribution over the Internet has become a popular service because of technological advances in internet (e.g., higher network bandwidth) and video coding (e.g., H.264/SVC). In this and other similar media distribution applications, a server or distribution center sends a media/video to a group peers with different bandwidth resources and display capacities. In one of the approaches, the peer-to-peer approach, the server sends only one copy of the media over Internet, and each peer receives one segment of the media and exchanges his/her segment with other peers to receive the complete media. A key design issue in this approach is …

Numerical Inversion And Assessment Of 2d Laplace Transforms Using The Brancik Algorithm And Its Use In 3d Holography, Monish Ranjan Chatterjee, Le Feng

Electrical and Computer Engineering Faculty Publications

An analytic examination of 3D holography under a 90° recording geometry was carried out earlier in which 2D spatial Laplace transforms were introduced in order to develop transfer functions for the scattered outputs under readout [1,2].

Thereby, the resulting reconstructed output was obtained in the 2D Laplace domain whence the spatial information would be found only by performing a 2D Laplace inversion. Laplace inversion in 2D was attempted by testing a prototype function for which the analytic result was known using two known inversion algorithms, viz., the Brancik and the Abate [2]. The results indicated notable differences in the 3D …

Investigation Of Profiled Beam Propagation Through A Turbulent Layer And Temporal Statistics Of Diffracted Output For A Modified Von Karman Phase Screen, Monish Ranjan Chatterjee, Fathi H.A. Mohamed

Electrical and Computer Engineering Faculty Publications

Gaussian beam propagation through a turbulent layer has been studied using a split-step methodology. A modified von Karman spectrum (MVKS) model is used to describe the random behavior of the turbulent media. Accordingly, the beam is alternately propagated (i) through a thin Fresnel layer, and hence subjected to diffraction; and (ii) across a thin modified von Karman phase screen which is generated using the power spectral density (PSD) of the random phase obtained via the corresponding PSD of the medium refractive index for MVKS turbulence.

The random phase screen in the transverse plane is generated from the phase PSD by …