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IEEE International Conference on robotics and Automation (ICRA)

作者： G.J. Hamlin A.C. Sanderson Electrical Computer and Systems Engineering Department Rensselaer Polytechnic InstituteNew York State Center for Advanced Technology in Automation and Robotics Rensselaer Polytechnic Institute RPI Troy NY USA

A modular system for the design, implementation, and control of a class of highly redundant parallel robotic mechanisms is described. The Tetrobot system features a novel concentric multilink spherical (CMS) joint which allows an arbitrary number of links to share a common center of rotation. The CMS joint facilitates the construction of a wide variety of variable geometry truss mechanisms using an integrated control and computational framework. A distributed control algorithm is based on an iterative virtual force based solution which propagates the goal positions of target nodes to determine systematic adjustments of actuators. Capabilities of the Tetrobot system have been demonstrated by the construction of several configurations of up to 18 nodes, 48 links, and 15 actuators. Implementations of a double Stewart platform and a six-legged walker, constructed from the same set of parts, are described in this paper.

关键词： Parallel robots Collision mitigation Actuators Concurrent computing Design engineering systems engineering and theory Electric variables control Control systems Computational geometry Centralized control

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Vision-based fuzzy controllers for navigation tasks

Vision-based fuzzy controllers for navigation tasks

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International Symposium on Computer Vision (ISCV)

作者： S.R. Kundur D. Raviv Robotics Center and Department of Electrical Engineering Florida Atlantic University Boca Raton FL USA Intelligent Systems Division National Institute for Standards and Technology MD USA

This paper deals with vision-based fuzzy closed-loop control schemes for collision avoidance as well as maintenance of clearance in a-priori unknown textured environments. These control schemes employ a visual motion cue, we call the visual threat cue (VTC) that provides some measure for a relative change in range as well as clearance between 3D surface and a fixated observer in motion. It is a collective measure obtained directly from the raw data of gray level images, is independent of the type of 3D surface texture. This motion cue is scale-independent, rotation independent, needs no 3D reconstruction and is measured in [time/sup -1/] units. Fuzzy control is closer in spirit to human thinking and can implement linguistically-expressed heuristic control policies directly without any knowledge about the dynamics of the complex process. The fuzzy controllers were implemented in real-time using a 486-based personal computer and a camera capable of undergoing 6-DOF motion. Results are highly encouraging.

关键词： Fuzzy control Navigation Motion control Motion measurement Surface reconstruction Collision avoidance Surface texture Image reconstruction Rotation measurement Time measurement

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Navigation, Guidance and Control of AUVs: An Application to the MARIUS Vehicle

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IFAC Proceedings Volumes 1995年第2期28卷 35-42页

作者： D. Fryxell P. Oliveira A. Pascoal C. Silvestre I. Kaminer Institute for Systems and Robotics and Department of Electrical Engineering Instituto Superior Técnico Av. Rovisco Pais 1096 Lisboa Codex Portugal Department of Aeronautics and Astronautics Naval Postgraduate School Monterey California 93943 USA

This paper addresses the problem of designing guidance, control and navigation systems for autonomous underwater vehicles (AUVs). Its contribution is twofold: i) it introduces a new methodology for integrated design of guidance and control, and ii) it describes a novel approach to the analysis and design of multi-rate complementary filters for navigation. The methodologies proposed lead to an efficient procedure for the design of controllers for AUVs to accurately track reference trajectories defined in an inertial reference frame. The paper ilustrates the application of this procedure to the design of a tracking controller for the AUV MARIUS. The design phase is summarized, and the performance of the resulting controller is assessed in simulation using dynamic models of the vehicle and its sensor suite.

关键词： AUVs Guidance Navigation Control Gain Scheduling

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An image-based visual threat cue for autonomous navigation

An image-based visual threat cue for autonomous navigation

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International Symposium on Computer Vision (ISCV)

The paper presents a new visual motion cue which we call the visual threat cue (VTC) that provides some measure for a relative change in range as well as clearance between a 3D surface and a fixated observer in motion. This cue is independent of the 3D environment, needs almost no a-priori knowledge about it, is rotation independent, and is measured in [time/sup -1/] units. A practical method to extract the VTC from a sequence of images of a 3D textured surface obtained by a fixated, fixed-focus monocular camera in motion is also presented. This approach of extracting the VTC is independent of the 3D surface texture and needs no optical flow information, 3D reconstruction, segmentation, feature tracking or pre-processing. It can be used in many textured environments and does not depend on the type of texture in the environment. This algorithm to extract the VTC was applied to several real indoor as well as outdoor textures, where we observed a similar behavior for all the textures.

关键词： Navigation Data mining Surface reconstruction Surface texture Motion measurement Rotation measurement Time measurement Cameras Image motion analysis Image reconstruction

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Preisach modeling of piezoceramic and shape memory alloy hysteresis

Preisach modeling of piezoceramic and shape memory alloy hys...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： D. Hughes J.T. Wen Control Laboratory for Mechanical Structures (CLaMS) Center for Advanced Technology in Automation Robotics & Manufacturing Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

Smart materials such as piezoceramics and shape memory alloys (SMAs) exhibit significant hysteresis and in order to estimate the effect on open and closed loop control a suitable model is needed. One promising candidate is the Preisach independent domain hysteresis model that is characterized by the congruent minor loop and wiping out properties. Comparable minor loop and decaying oscillation test data for a multi-sheet piezoceramic actuator (made of lead zirconate titanate) attached to a flexible beam are presented and are seen to be very consistent with the two Preisach model properties. The commanded parameter is the sheet transverse electric field while the measured parameter is an approximately colocated strain induced in the beam. Equivalent data for a Nitinol SMA wire muscle, attached to the same beam, are also presented. The input and output parameters are the SMA current and a beam strain respectfully. The minor loop and wiping out evidence is less strong than that of the piezoceramic case, but encouraging. In all experiments the quasi-steady state responses were generated in order to avoid exciting beam flexible modes which would complicate the analysis.

关键词： Piezoelectric materials Shape memory alloys Hysteresis Strain measurement Shape control Open loop systems Testing Actuators Titanium compounds Electric variables measurement

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A novel method to calculate looming cue for threat of collision

A novel method to calculate looming cue for threat of collis...

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International Symposium on Computer Vision (ISCV)

作者： K. Joarder D. Raviv The Electrical Engineering Department and The Robotics Center Florida Atlantic University Boca Raton FL USA Intelligent Systems Division National Institute for Standards and Technology Gaithersburg MD USA

Visual looming is related to an increased projected size of an object on a viewer's retina as the relative distance between the viewer and the object decreases. Psychologists have reported about subjects avoiding collision using this information by reacting defensively. In this paper we present a quantitative approach to visual looming and describe a novel method to measure this visual cue using visual fixation and studying the relative change in irradiance in the image. This visual cue can be used in the sense of a threat of collision for autonomous obstacle avoidance.

关键词： Retina Intelligent robots Psychology Intelligent systems Timing Acceleration Animals Nervous system Robot sensing systems Measurement units

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Synthesized passive feedback control of sensor-rich smart structures-experimental results

Synthesized passive feedback control of sensor-rich smart st...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： P. Akella J.T. Wen Control Laboratory for Mechanical Structures Department of Electrical Computer and Systems EngineeringCenter for Advanced Technology in Automation Robotics & Manufacturing Rensselaer Polytechnic Institute RPI Troy NY USA

Passivity based controllers are used in structural control due to their inherent robustness properties. These controllers require sensor/actuator collocation. In this paper, we consider the design of a "squaring down" matrix which renders a system passive by using a linear combination of all collocated and non-collocated sensor/actuator pairs. The design uses experimental transfer functions and does not require the knowledge of the system model. The problem of finding the squaring down matrix is cast as a solution to a set of linear matrix inequalities (LMIs) subject to some additional performance considerations. The design procedure of the squaring down matrix assumes that velocity information is available from the sensors which is not generally the case. We show that the squaring down matrix can be implemented without the use of such velocity information. We provide experimental results gathered from the single link flexible beam setup in the C/sub La/MS laboratory at RPI to show that implementation of passive loops without velocity measurements provides very good results.

关键词： Feedback control Linear matrix inequalities Intelligent sensors Control system synthesis Robust control Sensor systems Hydraulic actuators Transfer functions Laboratories Economic indicators

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Complete algorithms for reorienting polyhedral parts using a pivoting gripper

Complete algorithms for reorienting polyhedral parts using a...

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IEEE International Conference on robotics and Automation (ICRA)

作者： A. Rao D. Kriegman K. Goldberg Department of Computer Science Utrecht University Postbus Utrecht Netherlands Center for Systems Science Department of Electrical Engineering Yale University New Heaven CT USA University of Utrecht Netherlands Institute for Robotics and Intelligent Systems Department of Computer Science University of Southern California Los Angeles CA USA

To rapidly feed industrial parts on an assembly line, Carlisle et. al. (1994) proposed a flexible part feeding system that drops parts on a flat conveyor belt, determines the pose of parts with a vision system and manipulates them into a desired pose. A robot arm with 4-DOF is capable of moving parts through 6-DOF when equipped with a passive pivoting axis between the parallel jaws of its gripper. We refer to these actions as pivot grasps. This paper considers the planning problem. Given a polyhedral part shape, coefficient of friction and a pair of stable configurations as input, find pairs of grasp points that will cause the part to pivot from one stable configuration to the other. For some transitions, pivot grasps may not exist. For a part with n faces and m stable configurations, we give an O(m/sup 2/n log n) algorithm to generate the m/spl times/m matrix of pivot grasps. When the part is star shaped, this reduces to O(m/sup 2/n). We also study a generalization that considers "capture regions" around stable configurations. Both algorithms are complete in that they are guaranteed to find pivot grasps when they exist.

关键词： Grippers robotics and automation Service robots Feeds Belts Machine vision Computer science Intelligent robots Manipulators Robotic assembly

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FAULT-TOLERANT ASSOCIATE MEMORIES

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systems AND computers IN JAPAN 1995年第7期26卷 1-12页

作者： FUJIWARA, E TANAKA, T Member Faculty of Engineering Tokyo Institute of Technology Tokyo Japan 152 Eui Fujiwara:received his B.S. and M.S. degrees in Electronics Engineering in 1968 and 1970 respectively and his Dr. of Eng. degree in 1981 all from Tokyo Institute of Technology. In 1970 he joined the NTT Musashino Electrical Communication Laboratories and engaged in developing PIPS-1 and PIPS-11 computer systems. In 1988 he joined the Department of Computer Science Tokyo Institute of Technology as an Associate Professor. In 1990 he became a full Professor. He was a Visiting Professor at the Center for Advanced Computer Studies the University of Southwestern Louisiana from June 1985 to July 1986. His current research interests include coding theory for computers fault-tolerant memories VLSI defect-toleranceand WSI systems. He is a co-author ofError Control Coding for Computer Systems(Prentice-Hall1989) EssentiaLF of Error-Correcting Coding Techniques (Academic Press 1990) and other books. Dr. Fujiwara received the Young Engineer Award from the I.E.I.C.E. in 1978 and the Teshima Memorial Research Award in 1991. He is a senior member of the IEEE and a member of the Information Processing Society Japan. Associate Member

Because of its capability of high-speed search, the associative memory (CAM) is expected to be used in a variety of information processing systems. In this paper, novel fault-tolerant techniques which are effective for on-line use are proposed for TLB which is an example of the application of CAM. First, fault and error models of the TLB consisting of the CAM part and the SRAM part are clarified. Then, the fault-tolerant techniques for these faults and errors, such as distance separable technique, cod-ing technique, simplified 1-out-of-n check and graceful degradation, are proposed. The distance separable technique which encodes the data stored in the CAM part is the one which masks the faulty CAM part and prevents errors from propagating to the subsequent circuits. The coding technique checks the one-to-one correspondence between the data in the CAM and those in SRAM by using the SEC-DED code with byte error detection capability, i.e., SEC-DED-SbED code, and at the same time it detects and corrects errors in the data stored in SRAM. The simplified 1-out-of-n check processes association errors. The graceful degradation gives a flag in the faulty memory section and prevents it from being used. The methods proposed in this paper are evaluated from area augmentation and error detection capability perspectives. The results show that the fault-tolerant TLB with 32 virtual address bits, 32 physical address bits and 128 entries gives single fault detection probability of nearly 99 percent with 28 percent area increase.

关键词： CAM TLB DISTANCE SEPARABLE TECHNIQUE CODING TECHNIQUE SIMPLIFIED 1-OUT-OF-N CHECK GRACEFUL DEGRADATION

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PLACING REGISTRATION MARKS

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 1994年第1期41卷 51-59页

作者： RAO, AS GOLDBERG, KY Department of Computer Science University of Utrecht Utrecht Netherlands Departments of Computer Science and Electrical Engineering-Systems Institute of Robotics and Intelligent Systems University of Southern California Los Angeles CA USA

In industrial assembly, a registration mark can be placed on parts to aid a computer vision system in determining the position and orientation (pose) of parts. However, when sensor noise and limits on resolution introduce errors in the measured location of the registration mark, these errors can propagate into the measurement of part pose. In this paper, we define the registration mark problem: given an n-sided rigid planar polygonal part-and a set of k poses for the part, locate a point on the surface of the part that maximizes the minimum distance between transformed points. A registration mark at this point will be maximally robust to sensor imperfections. We give an 0(n log n + k4 log k log* k) time algorithm to solve this planar problem using a result from Schwartz and Sharir [21], and demonstrate the algorithm using a commercial vision system. Our results extend to classes of curved planar parts and polyhedral parts.

关键词： Computer vision Computer errors Noise measurement Manufacturing automation robotics and automation Computer science Intelligent robots Computer industry Assembly systems Robustness

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