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IEEE Conference on Decision and Control

作者： P. Krishnamurthy F. Khorrami Control/Robotics Research Laboratory (CRRL) Department of Electrical and Computer Engineering Polytechnic University Brooklyn NY USA

We propose an adaptive output-feedback control design technique for feedforward systems with Input-to-State Stable (ISS) appended dynamics and disturbance inputs. The design is based on our recent results on the application of dynamic high-gain scaling to state-feedback and output-feedback control of feedforward systems. Unlike previous approaches to the control of feedforward systems, the dynamic high-gain scaling technique provides robustness to additive disturbances and enabled the first output-feedback controller design for feedforward systems. In this paper, we further investigate the robustness properties of the dynamic high-gain scaling approach by introducing exogenous disturbance inputs and ISS appended dynamics coupled with all the system states and the input. The designed adaptive output-feedback controller achieves BIBS stability with respect to disturbance inputs and also provides a disturbance attenuation result. This provides the first results for feedforward systems with ISS appended dynamics and disturbance inputs.

关键词： Attenuation Feedforward systems Control systems Programmable control Adaptive control Control design Robust control Additives Robustness Stability

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Generalized state scaling-based robust control of nonlinear systems and applications to triangular systems

Generalized state scaling-based robust control of nonlinear ...

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American Control Conference (ACC)

作者： P. Krishnamurthy F. Khorrami Control/Robotics Research Laboratory(CRRL) Department of Electrical and Computer Engineering Six Metrotech Center Polytechnic University Brooklyn NY USA

In this paper, we propose a high-gain scaling based controller to achieve global state-feedback stabilization of a general class of nonlinear systems which are allowed to contain uncertain functions of all the states and the control input as long as polynomial bounds on ratios of some uncertain system terms are available. The design is based on a high-gain scaling involving appropriate powers of a high-gain scaling parameter which is a dynamic signal driven by the state. The designed controller has a very simple structure being essentially a dynamic extension and a linear feedback with state-dependent dynamic gains. The obtained results are applicable to both lower triangular (strict-feedback) and upper triangular (feedforward) structures and also to systems without any triangular structure as long as a set of inequalities involving powers of the polynomial bounds on the ratios of the uncertain system terms and scaling orders is solvable. The stability analysis is based on our recent results on uniform solvability of coupled state-dependent Lyapunov equations.

关键词： Robust control Nonlinear systems Nonlinear control systems Control systems Polynomials Uncertain systems Signal design Nonlinear dynamical systems Linear feedback control systems State feedback

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Transference of evolved unmanned aerial vehicle controllers to a wheeled mobile robot

Transference of evolved unmanned aerial vehicle controllers ...

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2005 IEEE International Conference on robotics and Automation

作者： Barlow, Gregory J. Mattos, Leonardo S. Grant, Edward Oh, Choong K. Center for Robotics and Intelligent Machines Department of Electrical and Computer Engineering North Carolina State University Raleigh NC 27695 U.S. Naval Research Laboratory 4555 Overlook Ave. S.W. Washington DC 20375 Robotics Institute Carnegie Mellon University 5000 Forbes Avenue Pittsburgh PA 15213

ISBN: (纸本)078038914X

Transference of controllers evolved in simulation to real vehicles is an important issue in evolutionary robotics (ER). We have previously evolved autonomous navigation controllers for fixed wing UAV applications using multi-objective genetic programming (GP). Controllers were evolved to locate a radar source, navigate the UAV to the source efficiently using on-board sensor measurements, and circle around the emitter. We successfully tested an evolved UAV controller on a wheeled mobile robot. A passive sonar system on the robot was used in place of the radar sensor, and a speaker emitting a tone was used as the target in place of a radar. Using the evolved navigation controller, the mobile robot moved to the speaker and circled around it. The results from this experiment demonstrate that our evolved controllers are capable of transference to real vehicles. Future research will include testing the best evolved controllers by using them to fly real UAVs. ©2005 IEEE.

关键词： Unmanned vehicles

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Adaptive output-feedback for nonlinear systems with no a priori bounds on parameters

Adaptive output-feedback for nonlinear systems with no a pri...

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American Control Conference (ACC)

作者： P. Krishnamurthy F. Khorrami Control/Robotics Research Laboratory(CRRL) Department of Electrical and Computer Engineering Six Metrotech Center Polytechnic University Brooklyn NY USA

In a result by P. Krishnamurthy and F. Khorrami (2004), we proposed a dynamic high-gain observer/controller architecture for nonlinear systems of the generalized output-feedback canonical form. The design of P. Krishnamurthy and F. Khorrami (2004) utilized the dual architecture of a high-gain observer and controller and incorporated a single dynamic scaling. The designed output-feedback controller was shown to be robust to functional and parametric uncertainties coupled with all states. However, a magnitude bound on the unknown parameters was required. In this paper, we propose a time-varying output-feedback controller that can handle time-varying nonlinear parametric uncertainty coupled with all states without requiring any a priori magnitude bounds on the unknown parameters. This is achieved using a novel time-varying dynamics of the high-gain scaling parameter. The proposed observer/controller structure provides a globally asymptotically stabilizing output-feedback solution for the benchmark open problem proposed in our earlier work with no magnitude bounds or sign information on the unknown parameter being necessary.

关键词： Nonlinear systems Control systems Observers Uncertainty Riccati equations Lyapunov method Nonlinear control systems Robust control Couplings Programmable control

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GODZILA: a low-resource algorithm for path planning in unknown environments

GODZILA: a low-resource algorithm for path planning in unkno...

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American Control Conference (ACC)

作者： P. Krishnamurthy F. Khorrami Control/Robotics Research Laboratory(CRRL) Department of Electrical and Computer Engineering Six Metrotech Center Polytechnic University Brooklyn NY USA

In this paper, we propose a novel path-planning and obstacle avoidance algorithm GODZILA for navigation in unknown environments. No prior knowledge of the environment is required. The path-planning algorithm follows a purely local approach using only the current range sensor measurements at each sampling instant and requiring only a small number of stored variables in memory. No map of the environment is built during navigation. This minimizes the memory and computational requirements for implementation of the algorithm, a feature that is especially attractive for small autonomous vehicles. The algorithm utilizes three components: an optimization algorithm, a local straight-line path planner to visible targets, and random navigation. It is proved, for navigation in any finite-dimensional space, that the path-planning algorithm converges in finite time with probability 1. The performance of the algorithm is demonstrated through simulations for path-planning in two-dimensional and three-dimensional spaces. It is seen that a relatively small number of range sensor measurements is sufficient even in complex unknown environments.

关键词： Path planning Navigation Remotely operated vehicles Mobile robots Current measurement Sampling methods Cost function Trajectory Robot sensing systems Orbital robotics

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A Robust Force Controller for an SRM Based Electromechanical Brake System

A Robust Force Controller for an SRM Based Electromechanical...

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IEEE Conference on Decision and Control

作者： P. Krishnamurthy W. Lu F. Khorrami A. Keyhani Department of Electrical and Computer Engineering Control/Robotics Research Laboratory (CRRL) Polytechnic University Brooklyn NY USA Department of Electrical Engineering Ohio State Uinversity Columbus OH USA

In this paper, we propose a robust nonlinear force controller for a switched reluctance motor (SRM) electromechanical brake system which is a promising replacement for hydraulic brakes in the automotive industry. A detailed model of the motor including current dependent inductance coefficients is used. The load exerted on the motor by the caliper may be modeled as a spring; however, the actual load model is taken to be an unknown nonlinear function of position to allow for uncertainties in the model. Hence, the developed controller works for a wide variety of loads including brake systems. The controller is designed using backstepping and incorporates a novel voltage commutation scheme. The controller does not require knowledge of the mechanical parameters of the motor and the functional forms of the relationships among the motor position, the brake force, and the motor load torque. Moreover, the controller provides significant robustness to uncertainty in the inductances. Furthermore, practical current and voltage constraints are addressed. The performance and robustness of the controller are demonstrated through simulation studies.

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COLLABORATING WITH HUMANOID ROBOTS IN SPACE

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International Journal of Humanoid robotics 2005年第2期2卷 181-201页

作者： SOFGE, DONALD BUGAJSKA, MAGDALENA TRAFTON, J. GREGORY PERZANOWSKI, DENNIS THOMAS, SCOTT SKUBIC, MARJORIE BLISARD, SAMUEL CASSIMATIS, NICHOLAS BROCK, DEREK ADAMS, WILLIAM SCHULTZ, ALAN Navy Center for Applied Research in Artificial Intelligence Naval Research Laboratory WashingtonDC20375 United States Electrical and Computer Engineering Department University of Missouri-Columbia ColumbiaMO65211 United States Cognitive Science Department Renssealer Polytechnic Institute Carnegie 108 110 8th Street TroyNY12180 United States

One of the great challenges of putting humanoid robots into space is developing cognitive capabilities for the robots with an interface that allows human astronauts to collaborate with the robots as naturally and efficiently as they would with other astronauts. In this joint effort with NASA and the entire Robonaut team, we are integrating natural language and gesture understanding, spatial reasoning incorporating such features as human–robot perspective taking, and cognitive model-based understanding to achieve a high level of human–robot interaction. Building greater autonomy into the robot frees the human operator(s) from focusing strictly on the demands of operating the robot, and instead allows the possibility of actively collaborating with the robot to focus on the task at hand. By using shared representations between the human and robot, and enabling the robot to assume the perspectives of the human, the humanoid robot may become a more effective collaborator with a human astronaut for achieving mission objectives in space. © 2005 World Scientific Publishing Company

关键词： Anthropomorphic robots

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Recognizing interaction from a robot's perspective

Recognizing interaction from a robot's perspective

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IEEE International Workshop on Robot and Human Communication (ROMAN)

作者： T. Salter F. Michaud K. Dautenhahn D. Letourneau S. Caron LABORIUS-Research Laboratory on Mobile Robotics and Intelligent Systems Department of Electrical Engineering and Computer Engineering Université de Sherbrook Sherbrooke QUE Canada Adaptive Systems Research Group School of Computer Science University of Herfordshire Hatfield UK

For meaningful interaction between a robot and a human, an autonomous robot must recognize whether the experienced situation is created by people or by the environment. Using only proprioceptive data from a mobile robotic platform, we discover that it is possible to distinguish sensory data patterns involving interaction. These patterns are obtained whilst navigating varying environments, both human populated and unpopulated. The paper reports the initial set of trials using Roball, a spherical mobile robot. Also described is the experimental methodology currently followed to validate the hypothesis that child interaction can be perceived directly from navigation sensors onboard a robotic platform.

关键词： Robot sensing systems Mobile robots Human robot interaction Navigation Intelligent robots Sensor phenomena and characterization Infrared sensors Educational institutions Plastics Mobile computing

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Optical flow-based tracking of deformable objects using a non-prior training active feature model 5th

Optical flow-based tracking of deformable objects using a no...

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5th Pacific Rim Conference on Multimedia, PCM 2004

作者： Kim, Sangjin Kang, Jinyoung Shin, Jeongho Lee, Seongwon Paik, Joonki Kang, Sangkyu Abidi, Besma Abidi, Mongi Image Processing and Intelligent Systems Laboratory Department of Image Engineering Graduate School of Advanced Imaging Science Multimedia and Film Chung-Ang University 221 Huksuk-Dong Tongjak-Ku Seoul156-756 Korea Republic of Imaging Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering The University of Tennessee KnoxvilleTN37996-2100 United States

ISBN: (纸本)9783540239857

This paper presents a feature point tracking algorithm using optical flow under the non-prior training active feature model (NPT-AFM) framework. The proposed algorithm mainly focuses on analysis of deformable objects, and provides real-time, robust tracking. The proposed object tracking procedure can be divided into two steps: (i) optical flow-based tracking of feature points and (ii) NPT-AFM for robust tracking. In order to handle occlusion problems in object tracking, feature points inside an object are estimated instead of its shape boundary of the conventional active contour model (ACM) or active shape model (ASM), and are updated as an element of the training set for the AFM. The proposed NPT-AFM framework enables the tracking of occluded objects in complicated background. Experimental results show that the proposed NPT-AFM-based algorithm can track deformable objects in real-time. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Optical flows

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A Modeling Framework for Six Degree-of-Freedom Control of Unmanned Sea Surface Vehicles

A Modeling Framework for Six Degree-of-Freedom Control of Un...

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IEEE Conference on Decision and Control

作者： P. Krishnamurthy F. Khorrami S. Fujikawa Control/Robotics Research Laboratory (CRRL) Department of Electrical and Computer Engineering Polytechnic University Brooklyn NY USA IntelliTech Microsystems Inc. Bowie MD USA

ISBN: (纸本)0780395670

A detailed six degree-of-freedom (DOF) nonlinear dynamic model of an Unmanned Sea Surface Vehicle (USSV) is developed. Models of the significant hydrodynamic effects including radiation-induced and damping forces and moments are incorporated. Disturbance models of forces and moments caused by ocean currents, waves, and wind are also included. Detailed models of the actuators including thrusters/propellers and control surfaces are included. To illustrate the importance of a six DOF modeling and the impact of disturbances, simulation results with two different controllers are presented. The detailed mathematical modeling in this paper is intended to provide the appropriate framework for a control design which explicitly addresses the six DOF USSV dynamics along with the disturbances.

关键词： Sea surface Vehicle dynamics Control design Kinematics Hydrodynamics Damping Oceans Actuators Propellers Mathematical model

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