bluuebunny/crossref_metadata_2025 huggingface dataset:
The roller‐coaster curve is in
Authors: Wong Kam L.
Published: July 2007

This is the second part of a three‐part article under the general heading of ‘Off the bathtub onto the roller‐coaster curve’, a short version1 of which was presented at the 1988 Annual Reliability and Maintainability Symposium in the U.S.A. The first part was entitled ‘The bathtub does not hold water any more’,2 and the last part, to be published in a later issue of this journal, is entitled ‘Physical basis for the roller‐coaster hazard rate curve’. This three‐part article provides detailed discussions of the findings leading to the conclusions on the roller‐coaster characteristics for the hazard rate curve for electronics. Part 1 discussed problems with the bathtub curve. This part explores the shape of the failure rate curve in view of some recent observations. For more than twenty years investigators studying semiconducting device burn‐in have subscribed to the concept of freak failures, which manifest themselves as a hump on the hazard rate curve. In addition to semiconducting device data several sets of screening data, as well as operational data dating all the way back to 1961, also showed that indeed one can expect electronic systems to have generally decreasing failure rate curves with failure humps on them. The author of this paper calls these curves the roller‐coaster curves.
Risk assessment and optimization of a safety system using the maros simulation package
Authors: Jardine I. J. A. , Jackson D.
Published: July 2007

The performance of a pressure‐surge relief system which acts as a safety mechanism within the export facility of an oil terminal is analysed in detail. Dynamic simulation methods are integrated with failure mode effects analysis to establish the risk of catastrophic failure of the terminal. An optimization procedure is presented which demonstrates the use of simulation to establish suitable inspection, testing and preventive maintenance schedules which maximize the effectiveness of the surge relief system over its design life. The importance of such activities is evident — left unattended the surge‐relief system will not meet minimum safety standards, whereas planned maintenance and testing is shown to improve safety standards above the minimum required.
Failure estimates with replacement/repair
Authors: Singhal S. C. , Amster S. J.
Published: July 2007

The expected number of circuit pack failures is an important input to the accurate planning of the inventory level of spares. The failure rate of a circuit pack depends on its age and is generally higher during the infant mortality period (frequently one year) as compared to the steady‐state period. In some of the existing models, it is assumed that all of the defective circuit packs are replaced with new circuit packs. On the other extreme, some models assume that each of the defective circuit packs is repaired and shipped back to the field. Depending on the modelling assumption, the estimates of expected number of failures can differ by as much as 15 per cent. The Markov process model described in this paper includes a parameter (fraction of non‐repairable circuit packs) which permits us to investigate cases where only a portion of the circuit packs are non‐repairable (i.e. need to be replaced with new circuit packs). The model estimates the expected number of failures based on the infant mortality rate, the steady‐state failure rate, age distribution of the installed circuit packs, growth potential and fraction of non‐repairable circuit packs.
The failure characteristics of mechanical equipment which receives comprehensive maintenance overhaul
Authors: De La Mare R. F.
Published: July 2007

Research into the failure and repair characteristics of such diverse mechanical equipment as centrifugal pumps and compressors, comminution machinery, electrical generators and offshore pipelines has shown that their repairs and overhauls seldom return their performance to a condition which is ‘as good as new’ in a reliability sense.

The research reported here was commissioned to test whether this conclusion applied to mining machinery, which was overhauled to exacting maintenance standards. The results showed that these machines eventually exhibited a similar deterioration, which was statistically, significant. Furthermore, the escalation in their real costs of overhaul was of such a magnitude as to justify their systematic and frequent replacement. The evidence suggested that this deterioration in life performance resulted from the wear out of machine components and the bodies of these machines, which could not be remedied properly by successive overhauls.
Load—strength simulation of a mechanical design
Authors: Loll Valter
Published: July 2007

The load—strength theory is used to simulate the movements of a mechanical mechanism consisting of a lever and a spring. The purpose of the mechanism is automatically to select the correct speed for a turntable depending on the size (weight) of the record. The procedure for the computation is given in detail.
Fault detection using parameter estimation
Authors: Pouliezos A. , Stavrakakis G. , Lefas C.
Published: July 2007

This paper presents a brief summary of fault‐detection methods using parameter estimation techniques. An overview of the fault‐detection system design methodology is first presented, followed by the principles of parameter‐estimation fault‐detection techniques. Applications from the field of industrial processes are given and finally a case study is described which applies the general techniques to the fault detection of D.C. motors using multiprocessor systems.
Reliability approach for vehicle safety components
Authors: Brunner Franz J.
Published: July 2007

Owing to ‘producer's liability for defective products’ the safety‐related components of vehicles have to be designed, tested and manufactured in an appropriate way. Some considerations are presented about useful procedures in design and testing of safety parts which may help to reach the required high reliability and minimize risks. Problem areas are indicated which need more research. In future the reliability approach in automotive industries will come closer to the standards in aeronautics. This trend is accelerated by the rapid use of electronics in automobiles.
A theoretical approach to a transformer reliability problem
Authors: Pollock J. R. , Hale P. W.
Published: July 2007

Product reliability testing of a video monitor, incorporating rapid thermal cycling, highlighted an interesting problem with failure of a small transformer on the analogue card, causing a severe shimmer of the display. A theoretical model describing this problem is presented, and shows how such an approach can assist in understanding the failure mechanism as well as assisting the resolution of certain dilemmas surrounding it.
DoD microcircuit qualification innovation–QML
Authors: Hakim Edward B.
Published: July 2007

The U.S. Department of Defence (DoD) has undertaken the task of modernizing the procedure for qualification of military high‐quality/high‐reliability microcircuits. This new approach, known as generic qualification, will develop a qualified manufacturers list (QML) which will permit certification of design, fabrication, assembly and packaging using an innovative approach. The objective is to have a single process flow on which both commercial and military product will be indistinguishable and only at qualification testing (which is revolutionary) will the differences be evident. The realization of this change is implementation of statistical process control (SPC) methodologies and total quality management (TQM).
Development and reduction of a fault tree for gearboxes of heavy commercial vehicles based on identification of critical components
Authors: Morello Marcelo Guimarães , Cavalca Katia Lucchesi , Silveira Zilda de Castro
Published: July 2007

This work deals with the development and reduction of a fault tree applied to gearboxes of heavy commercial vehicles. The improvement with respect to the classical failure tree analysis (FTA) is to reduce the number of FTA components based on the sensitivity of the system reliability to the statistical parameters of the components failure models during a certain lifetime. These parameters determine the shape and slope of the decreasing reliability curve. The lifetime plays an important role because it is the base for any decision about guarantee time and periodic inspection in vehicle maintenance. As the components are usually in series configuration in this kind of mechanical system, the proposal is to consider only the components to which the system presents a significant sensitivity. A factorial planning with two replicates is applied to identify the system sensitivity with respect to these parameters taking into account the confidence interval in each case, as the parameters are evaluated from a sample with a specific size, which has a significant influence on the confidence limits. Therefore, the lifetime is defined in terms of kilometers and it must be economically viable for the company with respect to guarantee period, vehicle stops and maintenance costs. Following this objective, it is important to highlight that the reliability function sensitivity of the system changes depending on the lifetime and the behavior of each FTA component's reliability (failure model parameters). Then, the fault tree is assembled and successively reduced considering the sensitivity to scale (α) and shape (β) factors for components with Weibull distribution, as well as mean (µ) and standard deviation (σ) for Gaussian and Lognormal distributions, in specific kilometer intervals. This methodology allows a reliability model conception for management of the actions focused on products' guarantee and provides design descriptions for the development areas and manufacturing. In this model, it is possible to obtain information about lifetime to assist in activities of performance studies and optimization in design engineering as well as the identification of problems related to design and manufacturing for several operation intervals. In the present case study, the methodology led to a 30% reduction on the number of components considered in the complete fault tree, contributing to guide future improvements to gearboxes reliability. Copyright © 2007 John Wiley & Sons, Ltd.
Nonlinear optimization of autonomous undersea vehicle sampling strategies for oceanographic data‐assimilation
Authors: Heaney Kevin D. , Gawarkiewicz Glen , Duda Timothy F. , Lermusiaux Pierre F. J.
Published: July 2007

The problem of how to optimally deploy a suite of sensors to estimate the oceanographic environment is addressed. An optimal way to estimate (nowcast) and predict (forecast) the ocean environment is to assimilate measurements from dynamic and uncertain regions into a dynamical ocean model. In order to determine the sensor deployment strategy that optimally samples the regions of uncertainty, a Genetic Algorithm (GA) approach is presented. The scalar cost function is defined as a weighted combination of a sensor suite's sampling of the ocean variability, ocean dynamics, transmission loss sensitivity, modeled temperature uncertainty (and others). The benefit of the GA approach is that the user can determine “optimal” via a weighting of constituent cost functions, which can include ocean dynamics, acoustics, cost, time, etc. A numerical example with three gliders, two powered AUVs, and three moorings is presented to illustrate the optimization approach in the complex shelfbreak region south of New England. © 2007 Wiley Periodicals, Inc.
An inverse kinematic solution for kinematically redundant robot manipulators
Authors: Oh Se‐Young , Orin David , Bach Michael
Published: July 2007

An inverse kinematic analysis addresses the problem of computing the sequence of joint motion from the Cartesian motion of an interested member, most often the end effector. Although the rates and accelerations are related linearly through the Jacobian, the positions go through a highly nonlinear transformation from one space to another. Hence, the closed‐form solution has been obtained only for rather simple manipulator configurations where joints intersect or where consecutive axes are parallel or perpendicular. For the case of redundant manipulators, the number of joint variables generally exceeds that of the constraints, so that in this case the problem is further complicated due to an infinite number of solutions. Previous approaches have been directed to minimize a criterion function, taking into account additional constraints, which often implies a time‐consuming optimization process. In this article, a different approach is taken to these problems. A Newton‐Raphson numerical procedure has been developed based on a composite Jacobian which now includes rows for all members under constraint. This procedure may be applied to solve the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive beforehand a closed‐form solution. The technique is applicable to redundant manipulators since additional constraints on other members as well as on the end effector may be imposed. Finally, this approach has been applied to a seven degree‐of‐freedom manipulator, and its ability to avoid obstacles is demonstrated.
Robot vision: An evaluation of imaging sensors
Authors: Pinson Lewis J.
Published: July 2007

Robot vision, robotics vision, and computer vision are terms that have evolved over the past few years to include two separate but related functions that provide visual sensing for computerdriven robots. These two functions are “electro‐optical imaging” and “image processing.” The purpose of electro‐optical imaging is to convert optical radiation to an appropriate electronic signal for input to the robot's computer; whereas, the purpose of image processing is to extract useful information from the electronic image provided by the sensor. This article deals with the electro‐optical sensing part of robot vision. It describes the operation and properties of electro‐optical imaging sensors. The fundamental concepts of optical radiation, optical radiation quantities and units, and photon energies are defined. The fundamental principles for detecting optical radiation and definitions for the primary performance measures for optical detectors are given. A relatively comprehensive overview of the parameters used to describe imaging sensors is presented. Factors affecting these parameters and obtainable sensor performance are compared. Example design analyses are presented to show the interaction of various performance measures.
Collision avoidance for industrial robots with arbitrary motion
Authors: Freund E. , Hoyer H.
Published: July 2007

For effective application of industrial robots in flexible manufacturing systems and in automatic assembly, guided automatic collision avoidance is an important and—in spite of many applications—so far unsolved problem. The basis is unconstrained path control of each robot controlled, for example, by optical sensors in connection with different priority levels assigned to the robots. Iterative, time‐consuming, hierarchical control methods are not applicable due to the complexity and the real‐time constraints of this task. As a new and successful approach the application of various hierarchical decision strategies in connection with extremely time‐efficient evaluation of decision tables is presented. This concept is based on a suitable description of the actual possible collision spaces.
Alternative methods for the analysis of robot arm dynamics
Authors: Driels M. R. , Yang Z. H.
Published: July 2007

Beginning with an outline of the accepted methods for kinematic analysis of robot manipulators, the structure of the dynamical system is provided using two complementary approaches. The first of these is based on Lagrangian techniques while the second is a modified version of Hollerbach's recursive formula. The results of both methods are demonstrated for the particular case of a PUMA robot, and the code for both algorithms is provided in the Appendix.
“BILDLIB:” the image analysis software at IPA
Authors: Rueff M. , Melchior K.
Published: July 2007

The image analysis software for visual inspection purposes developed at IPA, the Fraunhofer‐Institute for Manufacturing Engineering and Automation, is described. Its basic mathematical framework, its organization scheme, some of its contents, as well as some examples are given. Current research and future developments are discussed.
Adjustment of robot joint gears using encoder velocity and position information
Authors: Dagalakis Nicholas G. , Myers Donald R.
Published: July 2007

A new technique for the adjustment of joint gears in industrial robots is presented. Band‐limited random excitation signals were injected into the drive system of the joint under test, and both the actuator shaft velocity and position were monitored. The coherence functions between the voltage at the terminals of the electric actuator and the position and velocity signals were determined. The change in the coherence functions was studied for various joint gear settings. An algorithm is proposed for determining the gear setting which results in the most linear operation of the joint drive system. This algorithm was tested on the adjustment of the gears of the wrist rotation joint of a PUMA 560 robot arm.
TL‐10: A programming language for assembly robots
Authors: Nakano Masaru , Hasegawa Junzo , Kuno Toshitaka , Moribe Hiroshi , Ikeda Toshiaki , Koide Mitsuo , Shiroshita Osamu , Sukigara Kazutoshi
Published: July 2007

TL‐10, Toyoto Robot Language‐10, is a BASIC‐like robot language. It has functions that define locations and subroutine parameters, which are useful in the accumulation and the transference of robot applied technology. It also has functions to communicate with other computers such as those for vision systems. The important features are described and illustrated by examples.
Robust robot control with bounded input torques
Authors: Slotine Jean‐Jacques E. , Spong Mark W.
Published: July 2007

A new scheme is presented to achieve effective on‐line tracking control of robot manipulators in the presence of model uncertainty and torque limitations. Pointwise optimization techniques are incorporated into a “slow” feedback loop in order to generate feasible desired trajectories, optimally close to the original desired trajectories. A suction controller is used in the “fast” main feedback loop, allowing to combine robust tracking with simple controller design. Simulations show very significant performance improvement over standard techniques. The algorithm is computationally cheap and can easily be implemented on‐line.
Semiautomatic calibration of robot manipulator for visual inspection task
Authors: Lin Wei‐Chung , Ross Joseph B. , Ziegler Michelle H.
Published: July 2007

A semiautomatic procedure to calibrate a robot manipulator for improving positioning accuracy is proposed. An error‐correcting transformation is estimated using the point‐pairs in the theoretical and actual coordinate frames. The theoretical points are obtained using a 3D model of the inspected part, whereas the actual points are derived with image processing and analytic geometry techniques. The estimation of the error‐correcting transformation is based on a leastsquare method. Experimental results are described to illustrate the calibration procedure.
On certain aspects of the zero reference position method and its applications to an industrial manipulator
Authors: Gupta K. C. , Carlson G. J.
Published: July 2007

The zero reference position method, proposed by Gupta in 1981, is based upon an arbitrary choice of the zero reference position, the principle of displacement similarity, and the hand‐to‐the‐base sequence of changing the joint variables in a serial manipulator. Its applications in performing recursive computations, formulating explicit governing equations, and obtaining closed form solutions for serial manipulators are presented in this paper. A Bendix‐type of industrial robot is used for illustrating the closed form solution procedure.
Technology and corporate culture of industrial robots in Japan
Authors: Aida Shuhei , Hasegawa Mitsuhiko , Ueda Taizo
Published: July 2007

This paper describes with examples of some typical industrial robots developed in Japan the process of development, which industrial robots in Japan took. It also describes citing the differences of cultural basis between Japan and western countries the influences of automation to man, culture and society, and survey the future industrial robots.
Three‐dimensional shape recognition method using ultrasonics for manipulator control system
Authors: Tsujimura Takeshi , Yabuta Tetsuro , Morimitsu Takenori
Published: July 2007

This article describes a three‐dimensional shape recognition method that employs an ultrasonic distance sensor mounted on a manipulator, and its application to a manipulator control system. The principle of the method is to reconstruct an object surface numerically using both distance and orientation informations of an object. The method makes it possible to control the manipulator, to set the sensor in any position and orientation employing freedom of the manipulator, and to measure the object. The method is available for manipulator control because it can precisely assess the distance from the manipulator to the object, as well as reconstruct the object shape. Experimental results show that the newly developed method make object shape recognition easy and inexpensive. Application experiment proved that the method is effective for manipulator work due to its provision of distance information.
Robot navigation in an unexplored terrain
Authors: Rao Nageswara S. V. , Iyengar S. S. , Jorgensen C. C. , Weisbin C. R.
Published: July 2007

Navigation planning is one of the most vital aspects of an autonomous mobile robot. Robot navigation for completely known terrain has been solved in many cases. Comparatively less research dealing with robot navigation in unexplored obstacle terrain has been reported in the literature. In recent times this problem has been addressed by adding learning capability to a robot. The robot explores terrain using sensors as it navigates, and builds a terrain model in an incremental manner. In this article we present concurrent algorithms for robot navigation in unexplored terrain. The performance of the concurrent algorithms is analyzed in terms of planning time, travel time, scanning time, and update time. The analysis reveals the need for an efficient data structure to store an obstacle terrain model in order to reduce traversal time, and also to incorporate learning. A modified adjacency list is proposed as a data structure for storing a spatial graph that represents an obstacle terrain. The time complexities of the algorithms that access, maintain, and update the spatial graph are estimated, and the effectiveness of the implementation is illustrated.
A modeling approach to aid in designing robotized manufacturing cells
Authors: Wilhelm Wilbert E. , Kalkunte Mohan , Cash Charles
Published: July 2007

This article describes an approach for modeling the work cycle of robotized manufacturing cells. The approach incorporates the logic of GERT networks and the computational techniques of recursion models, but extends these fundamental concepts to provide a resource‐based model of cell operations. Since the approach gives approximate estimates of performance, accuracy is evaluated in comparison with simulation results. A comprehensive, but hypothetical, example is given to describe use of the model as an aid in cell design. Typical applications involve “what if” studies to evaluate end‐of‐arm effectors, cell layout, a limited supply of tooling, equipment capabilities (e.g., speeds), and sequence of operations in cells employing one or more robots.
Application of a dynamic programming algorithm for trajectory planning of finger‐like manipulators
Authors: Thakor Nitish V. , McNeela Martin A.
Published: July 2007

Dextrous hand designs require planning and coordination of multijointed fingers. This communication presents a dynamic programming algorithm to optimize the trajectory of a finger or a fingerlike manipulator. The algorithm generates a minimum cost trajectory for a specified cost function (such as accuracy or time of travel) and a set of constraints (such as obstacles along the trajectory). We present simulations demonstrating the trajectory planning for simplified fingerlike manipulator configurations. This approach is potentially applicable to several additional situations faced by multijointed fingers employed in dextrous hand designs, such as complex trajectory planning, obstacle avoidance, and fault tolerance. We illustrate some results obtained by computer simulations of these problems.
Off‐line programming motion and process commands for robotic welding of space shuttle main engines
Authors: Ruokangas C. C. , Guthmiller W. A. , Pierson B. L. , Sliwinski K. E. , Lee J. M. F.
Published: July 2007

An intelligent, adaptive robotic system is being developed for a low‐volume, high precision process: the welding of the Space Shuttle Main Engines (SSMEs). The overall system goals include the development of a workstation‐based system to provide flexible, efficient off‐line programming of both motion and welding process commands for the robotic workcell. This offline programming system includes: implementation of a user interface for weld engineers, generation of both geometric and process commands for the workcell, development of a weld parameter database system, and display of both run‐time and archived data. This article presents details of the off‐line programming system, including interfaces, implementation, and limitations. The system will be implemented on the SSME production floor, and will be benchmarked in effectiveness and productivity against commercially available robotic welding systems presently in use. The overall system development is a joint effort between NASA's Marshall Space Flight Center and two divisions of Rockwell International: Rocketdyne and the Science Center.
A multi‐purpose dynamic and tactile sensor for robot manipulators
Authors: Tzou H. S. , Pandita S.
Published: July 2007

In this article, a multi‐purpose tactile/acceleration sensor system made of newly developed thick polymeric piezoelectric material and capable of sensing acceleration, contact force and pressure is developed and evaluated using analytical and experimental techniques, The sensor system is discretized and modeled by a single degree of freedom second order system from which equations of electromechanical dynamics are formulated to evaluate its performance. Analytical solutions are compared favorably with experimental results.
Position control of two‐arm manipulators for coordinated point‐to‐point motion
Authors: Benhabib B. , Zak G. , Tabarah E.
Published: July 2007

A trajectory planning and motion control algorithm is; presented for the point‐to‐point (PTP) motion of two‐arm manipulators cooperating on a task. The proposed method considers the multi‐arm manipulator as a system when formulating its kinematic model and obtains a global solution to the system, as opposed to individual arm solutions. For PTP motion control between two arm configurations, a simple trajectory is first assumed by defining joint velocity profiles and maximum allowable task space errors between the two end effectors of the manipulator. The task space errors during the motion are then continuously monitored to take corrective action when necessary to prevent those errors from exceeding the given tolerance limits. The main objective of this method is to reduce the number of inverse kinematics solutions during the real‐time control of the two‐arm system. The algorithm is illustrated by a numerical example for an eight degree‐of‐freedom kinematically redundant planar two‐arm system.
The application of newton‐euler recursive methods to the derivation of closed form dynamic equations
Authors: Driels M. R. , Fan U. J. , Pathre U. S.
Published: July 2007

The article presents, in tutorial format, a development of the Newton‐Euler (NE) approach to the analysis of robot dynamics. Beginning with fundamental concepts drawn from vector calculus and mechanics, a set of recursive equations are developed which allow the calculation of the dynamics of a manipulator in closed form. An example based on conventional manipulator design is evaluated in some detail and shows that, for kinematic models of some complexity, the NE approach is as fast as other techniques based on Lagrangian methods for deriving closed form dynamical equations.
Direct adaptive control of a one‐link flexible arm with tracking
Authors: Yuan Bau‐San , Book Wayne J. , Siciliano Bruno
Published: July 2007

A robust tracking controller for a one‐link flexible arm based on a model reference adaptive control approach is proposed. In order to satisfy the model matching conditions, the reference model is chosen to be the optimally controlled linearized model of the system. The resulting controller overcomes the fundamental limitation in previously published research on direct adaptive control of flexible robots that required additional actuators solely to control the flexible degrees of freedom. The nominal trajectory is commanded by means of a tracking control. Simulation results for the prototype in the laboratory show improvements obtained with the outer adaptive feedback loop compared to a pure optimal regulator control. Robustness is tested by varying the payload mass.
A forward displacement analysis of a class of stewart platforms
Authors: Griffis M. , Duffy J.
Published: July 2007

A closed‐form forward displacement analysis is performed for a Stewart Platform‐type of parallel mechanism, whose six legs meet in a pair‐wise fashion at three points in the top and base platforms. The six legs and two platforms of this mechanism together form an octahedron. An eighth‐degree polynomial in the square of the tan‐half‐angle that measures the elevation of a triangular face of the octahedron relative to the base triangle is derived. Each of three vertices of the base triangle of the octahedron is modeled by a spherical four‐bar mechanism, and the polynomial is obtained by eliminating a pair of tan‐half‐angular displacements from the displacement equations of the three spherical four‐bar mechanisms. The result are verified numerically by performing a reverse displacement analysis and displaying real solutions on a graphic system. It is clear that there are a maximum of eight reflected pairs of real assembly configurations of the octahedral form of the Stewart Platform.
An efficient algorithm for computation of manipulator inertia matrix
Authors: Fijany Amir , Bejczy Antal K.
Published: July 2007

In this article an efficient algorithm for computation of the manipulator inertia matrix is presented. The algorithm is derived based on Newton's and Euler's laws governing the motion of rigid bodies. Using spatial notations, the algorithm leads to the definition of the composite rigid‐body spatial inertia which is a spatial representation of the notion of augmented body. The equations resulting from this algorithm are derived in a coordinate‐free form. The choice of the coordinate frame for projection of the coordinate‐free equations, that is, the intrinsic equations, is discussed by analyzing the vectors and the tensors involved in the final equations. Previously proposed algorithms, the physical interpretations leading to their derivation, and the redundancy in their computations are analyzed. The developed algorithm achieves a greater efficiency by eliminating the redundancy in the intrinsic equations as well as by a suitable choice of coordinate frame for projection of the intrinsic equations.
A comparative study of inverse dynamics of manipulators with closed‐chain geometry
Authors: Lin Yueh‐Jaw , Song Shin‐Min
Published: July 2007

The dynamics of closed‐chain manipulators was not studied as extensively as that of open‐chain manipulators. In this article, the inverse dynamics of two types of closedchain manipulators, namely, a pantograph manipulator and a five‐bar manipulator, are studied. The recently developed computationally efficient method1 is applied to both manipulators. The computational efficiency of inverse dynamics is evaluated in terms of both formulating methods (the method in reference 1 vs. the Lagrange method), and geometric structures (the pantograph vs. the five‐bar). The inverse kinematics computation of pantogaph manipulators is expected to be simpler than that of five‐bar manipulators simply because of the decoupling nature of the pantogaph mechanisms. On the contrary, the inverse kinetics of the pantograph is less efficient than the five‐bar because more links are involved during motion. It is also found that the overall inverse dynamics which includes both the inverse kinematics and kinetics of the pantograph manipulators, is more computationally efficient than that of the five‐bar, mainly due to the simple kinematics of the pantograph.
A nominal adaptive controller for a robot manipulator
Authors: Dawson D. M. , Lewis F. L. , Dorsey J. F.
Published: July 2007

This article derives an adaptive controller to achieve trajectory following for a robot manipulator. Lyapunov's second method is used for the design. The parameter, position, and velocity errors are shown to be uniformly bounded in the presence of an unknown bounded disturbance. To obtain insight for selecting the various control parameters for maintaining small tracking and parameter errors, we derive an error bound in terms of the system disturbances.
Inverse kinematics of variable‐geometry truss manipulators
Authors: Naccarato Frank , Hughes Peter
Published: July 2007

A new class of robotic arm consists of a periodic sequence of truss substructures, each of which has several variable‐length members. Such variable‐geometry truss manipulators (VGTMs) are inherently highly redundant and promise a significant increase in dexterity over conventional anthropomorphic manipulators. This dexterity may be exploited for both obstacle avoidance and controlled deployment in complex workspaces. The inverse kinematics problem for such unorthodox manipulators, however, becomes complex because of the large number of degrees of freedom, and conventional solutions to the inverse kinematics problem become inefficient because of the high degree of redundancy. This paper presents a solution to this problem based on a spline‐like reference curve for the manipulator's shape. Such an approach has a number of advantages: (1) direct, intuitive manipulation of shape; (2) reduced calculation time; and (3) direct control over the effective degree of redundancy of the manipulator. Furthermore, although the algorithm has been developed primarily for variable‐geometry‐truss manipulators, it is general enough for application to other manipulator designs.
Undersea optical stationkeeping: Improved methods
Authors: Negahdaripour Shahriar , Fox Joel
Published: July 2007

Submersibles require the capability to accurately maintain their position when they are observing, photographing, or working at a site. The most direct way for an ROV or AUV to maintain position in the near bottom environment is to track or lock onto stationary objects on the ocean floor. A particular advantage of an optical stationkeeping system is its ability to use natural rather than manmade beacons. Several improvements to our previously reported optical flow methods for the detection of vehicle motion have been investigated. Experimental results indicate that an adaptation of Newton‐Raphson search combined with the use of a low‐noise, high accuracy camera can drastically reduce the number of image points at which computations need be made. Other experiments with an algorithm, which accounts for illumination variations that one may encounter in undersea environments, show significant improvement in the estimation of optical flow and vehicle motion.
Design and performance evaluation of an actively compliant underwater manipulator for full‐ocean depth
Authors: Yoerger Dana R. , Schempf Hagen , Dipietro David M.
Published: July 2007

An underwater manipulator is described that can exhibit a wide range of compliance through a combination of mechanical design and software control and its performance characterized. The manipulator has been used in conjunction with the JASON Remotely Operated Vehicle at full‐ocean depth. The major goal of the design was to produce a manipulator that can actively control the interaction forces with the work task in the hostile deep‐ocean environment. The manipulator's performance has been characterized in the lab and its overall operational utility has been confirmed during tests to depths of approximately 4000 meters, including an archaeological excavation at 700 meters depth in the Mediterranean. The manipulator uses high performance brushless DC servomotors driving the joints though low‐friction, zero‐backlash reductions of moderate ratio consisting of cables and pulleys. Each joint is highly backdriveable and has a large range of rotation. This approach permits a variety of force control schemes such as impedance control to be implemented with no sensors other than the displacement sensors integrated with the brushless motor. It also permits high‐quality torque servomechanisms to be directly implemented. This article outlines the design and illustrates the performance of a single joint in terms of friction, stiffness, and in implementing variable compliance and as a closed‐loop torque servo.
Obstacle avoidance via articulation
Authors: Choi Yong J. , Crane Carl D. , Matthew Gary K.
Published: July 2007

This article presents a practical implementation of the theory for articulation of spatial robots such as the PUMA and TRS type robots. The “Blueprint Algorithm” is introduced as a simple rule‐based planning algorithm in which the geometry of interference takes on the role of a basis in a collision‐free path planning process amongst obstacles. This implementation presents a novel idea of “Machine Intelligence Via Robot Geometry” which utilizes robot attributes such as workspace and dexterity.
Collision avoidance by a modified least‐mean‐square‐error classification scheme for indoor autonomous land vehicle navigation
Authors: Wang Ling‐Ling , Tsai Wen‐Hsiang
Published: July 2007

In this article, a new collision‐avoidance scheme is proposed for autonomous land vehicle (ALV) navigation in indoor corridors. The goal is to conduct indoor collisionfree navigation of a three‐wheel ALV among static obstacles with no a priori position information as well as moving obstacles with unknown trajectories. Based on the predicted positions of obstacles, a local collision‐free path is computed by the use of a modified version of the least‐mean‐square‐error (LMSE) classifier in pattern recognition. Wall and obstacle boundaries are sampled as a set of 2D coordinates, which are then viewed as feature points. Different weights are assigned to different feature points according to the distances of the feature points to the ALV location to reflect the locality of path planning. The trajectory of each obstacle is predicted by a real‐time LMSE estimation method. And the maneuvering board technique used for nautical navigation is employed to determine the speed of the ALV for each navigation cycle. Smooth collision‐free paths found in the simulation results are presented to show the feasibility of the proposed approach.
Fast parallel robots
Authors: Pierrot F. , Dauchez P. , Fournier A.
Published: July 2007

This paper presents two parallel robots that have been recently designed. The first one is a 3‐degree‐of‐freedom lightweight robot called DELTA and designed in Switzerland by EPFL. We give here the equations corresponding to different models of this robot: forward and inverse kinematics as well as inverse dynamics. The important feature of our method in deriving these models is to use a “good” set of parameters in order to simplify the equations. Based upon these considerations of simplicity, we have tried to extend the principle of the DELTA mechanical structure to a 6‐degree‐of‐freedom parallel robot. We came up with a new design we called the HEXA. We present this robot and show that it should have the same dynamic capabilities as the DELTA, because, like this one, it can be built with light material and it can be easily modeled.
Modeling and adaptive coordination control of a two‐Robot system
Authors: Huang Han‐Pang , Chen Ruey‐Sheng
Published: July 2007

Multiple robots are usually required in a flexible manufacturing system or a complex working environment. In particular, when an object under processing is too big or too heavy, a single robot is insufficient to handle it. Two robots are applicable in such case. This article aims to develop a complete mathematical model and an adaptive controller for two robots carrying a common load. It will be shown that the dynamic model of the two‐robot system turns out to be a singular system, taking into account the object dynamics. The condition for which the system model holds is also discussed. The adaptive controller will be used to overcome uncertainties in the object dynamics and robots. The distributed forces in the robot end effectors are determined by an optimal criterion. It will be shown that the adaptive controller surpasses the conventional computed torque controller.
Robot manipulator control for hazardous waste‐handling applications
Authors: Colbaugh R. , Jamshidi M.
Published: July 2007

The U.S. Department of Energy has identified robotics as a major technology to be utilized in its program of environmental restoration and waste management, and in particular has targeted robotic handling of hazardous waste to be an essential element in this program. Successful performance of waste‐handling operations will require a robot to perform complex tasks involving both accurate positioning of its end effector and compliant contact between the end effector and the environment, and will demand that these tasks be completed in uncertain surroundings. This article focuses on the development of a robot control system capable of meeting the requirements of hazardous‐waste‐handling applications and presents as a solution an adaptive scheme for controlling the mechanical impedance of kinematically redundant manipulators. The proposed controller is capable of accurate end effector impedance control and effective redundancy utilization, does not require knowledge of the complex robot dynamic model or parameter values for the robot or the environment, and is implemented without calculation of the robot inverse kinematic transformation. Computer simulation results are given for a 4 degree of freedom redundant robot under adaptive impedance control. These results indicate that the proposed controller is capable of successfully performing tasks of importance in robotic waste‐handling applications.
Power grasp force distribution control using artificial neural networks
Authors: Hanes Mark D. , Ahalt Stanley C. , Mirza Khalid , Orin David E.
Published: July 2007

In this article, methods for force distribution control of power grasp are developed. A power grasp is characterized by multiple points of contact between the object grasped and the surfaces of the fingers and palm. The grasp is highly stable because of form closure. However, modeling power grasps is difficult because of the resulting closed kinematic structure and the complexity of multiple contacts. The first method used to obtain the desired force distribution is based on linear programming. In particular, a model of the DIGITS grasping system, under development at The Ohio State University, is used, and constraint equations are formulated for force balance and actuator torque limits. Supervisory control of the desired forces at the contacts is achieved by prescribing a desired clinch level. The objective function is designed to achieve the desired clinch level, except in cases where the specified force is inadequate to stably hold the object. Although this method yields the desired force distribution, a second method based on artificial neural networks (ANNs) is developed to achieve constant‐time solutions. Linear programming solutions are used to generate training data for a set of ANNs. Two techniques, modular networks and adaptive slopes, are also developed and employed in the training to improve the training time and accuracy of the ANNs. The results show that the ANNs learn the appropriate nonlinear mapping for the force distribution and provide stable grasp over a wide range of object sizes and clinch levels.
Is visual reconstruction necessary? obstacle avoidance without passive ranging
Authors: Aloimonos Yiannis
Published: July 2007

Is it possible to perform nontrivial visual tasks without using passive ranging? Is it necessary to create, using vision, an accurate 3‐D description of the outside world to recognize, navigate, and manipulate? Could a visual system perform obstacle avoidance without reconstructing the depth of the scene in view, but through the recognition of a collision in some amount of time that is quite small and not far into the future? In this article, it is shown that it is possible to avoid obstacles without recovering depth and a detailed algorithm is provided for obstacle avoidance using the spatiotemporal derivatives of the image intensity function as input. © 1992 John Wiley & Sons, Inc.
Application of robust control techniques to a mobile robot system
Authors: Liu Kai , Lewis Frank L.
Published: July 2007

This article deals with the stabilization problem of a class of nonlinear second‐order multivariable dynamical systems with bounded uncertainties. A robust discontinuous controller is proposed to guarantee asymptotic stability of this class of systems. Then, to guarantee the continuity of the control, aquasi‐saturation function is introduced into the control law. Guaranteed eventual stability‐in‐the‐large (ESL) of the dynamical systems is proved with the continuous, robust controller, which is much different from the standard “computed‐torque control.” The controller requires known bounding functions that are easier to determine as well as more general than the bounds needed in other approaches. An application is given to trajectory‐following control for a two‐link mobile robot. © 1992 John Wiley & Sons Inc.
A fast procedure for manipulator inverse kinematics computation and singularities prevention
Authors: Mayorga R. V. , Milano N. , Wong A. K. C.
Published: July 2007

In this article, a fast procedure for numerical manipulator inverse kinematics computation and singularities prevention is presented. The approach is based upon solving a linear system and automatically calculating some parameters. These parameters are properly used in either one of two original schemes that are also proposed to induce robustness to the pseudoinverse. Furthermore, here it is also shown how to properly implement one of these schemes in conjunction with a recently developed approach for the singularities prevention of redundant manipulators. The resultant algorithms are tested on the simulation of a planar redundant manipulator. From the results obtained, it is observed that the proposed approach compares favorably with the approaches using a Gaussian elimination procedure and with pseudoinverse robustness based on a manipulability measure.
Existence and uniqueness of solutions of the inverse dynamics of multilink flexible arms: Convergence of a numerical scheme
Authors: Moulin Hervé C. , Bayo Eduardo , Paden Bradley
Published: July 2007

The inverse dynamics of flexible manipulators consists in finding the joint torques that drive the end effector of a manipulator along a given trajectory. A proof of the existence and uniqueness of solutions of the inverse dynamics of planar open‐chain multilink flexible manipulators and the convergence of an algorithm previously proposed by the second author for the numerical solution of the problem are presented in this article. Higher‐order strain terms leading to the geometric stiffness matrix in finite element models are included in the formulation and their influence on the inverse dynamics solution is studied.