bluuebunny/crossref_metadata_2025_split huggingface dataset:
Undersea optical stationkeeping: Improved methods
Authors: Negahdaripour Shahriar , Fox Joel 
Published: July 2007

AbstractSubmersibles 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

AbstractAn 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

AbstractThis 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

AbstractIn 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

AbstractThis 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

AbstractMultiple 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

AbstractThe 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

AbstractIn 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

AbstractIs 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

AbstractThis 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

AbstractIn 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

AbstractThe 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.
Measurement and analysis of structural dynamics properties of robotic joint transmission system
Authors: Huang Shiuh‐Jer , Chen Chin‐Yih 
Published: July 2007

AbstractThe flexibility of a robotic manipulator is considered an important factor, especially the joint compliance for improving the accuracy and operating speed of a robot application. In this article, two methods are employed to identify the structural dynamic characteristics of each joint transmission system of an ITRI‐U type robot. The driving system of each joint is modeled as a mass‐spring‐damper mechanism that has a second‐order dynamic mathematical equation. Then, the response experiments of hammer impact excitation and motor driving actuation are done and the difference between them compared. Those are used to simulate two different operation situations, the robot colliding with the environment and the discontinuing dynamic operation impacts. The system's parameters of each joint axis are obtained by the system identification technique. From the experimental results, the angular error of the motor shaft can be compensated by the control gain of the motor controller. However, the small damping ratio of the robotic mechanism limits the magnitude of servo gain. If the servo gain increases, the robot arm has oscillation phenomenon during dynamic operation. In addition, the error due to joint elasticity cannot be overcome by the current industrial robotic controller. Therefore, a suitable controller should be designed to compensate the dynamic effects of joint compliance with the identified parameters.
Direct adaptive impedance control of robot manipulators
Authors: Colbaugh R. , Seraji H. , Glass K. 
Published: July 2007

AbstractThis article presents an adaptive scheme for controlling the end‐effector impedance of robot manipulators. The proposed control system consists of three subsystems: a simple “filter” that characterizes the desired dynamic relationship between the end‐effector position error and the end‐effector/environment contact force, an adaptive controller that produces the Cartesian‐space control input required to provide this desired dynamic relationship, and an algorithm for mapping the Cartesian‐space control input to a physically realizable joint‐space control torque. The controller does not require knowledge of either the structure or the parameter values of the robot dynamics and is implemented without calculation of the robot inverse kinematic transformation. As a result, the scheme represents a general and computationally efficient approach to controlling the impedance of both nonredundant and redundant manipulators. Furthermore, the method can be applied directly to trajectory tracking in free‐space motion by removing the impedance filter. Computer simulation results are given for a planar four degree‐of‐freedom redundant robot under adaptive impedance control. These results demonstrate that accurate end‐effector impedance control and effective redundancy utilization can be achieved simultaneously by using the proposed controller.
Experimental two‐axis vibration suppression and control of a flexible robot arm
Authors: Yim Woosoon , Zuang Jichun , Singh Sahjendra N. 
Published: July 2007

AbstractThis article focuses on the implementation of a dual‐mode controller for the maneuver of a two‐axis flexible robotic arm. The joint angle trajectory tracking is accomplished by proportional and derivative and feedforward controllers. Based on the pole placement technique, a linear stabilizer is designed for elastic mode stabilization in the plane perpendicular to each joint axis. The stabilizer is switched on when the trajectory reaches the vicinity of the terminal state. The effect of switching time of the stabilizer and varying payload on arm vibration are investigated. With the proposed control system, accurate joint angle tracking and elastic mode stabilization can be accomplished. © 1993 John Wiley & Sons, Inc.
An efficient method for inverse dynamics of manipulators based on the virtual work principle
Authors: Zhang Chang‐De , Song Shin‐Min 
Published: July 2007

AbstractThe computational efficiency of inverse dynamics of a manipulator is important to the real‐time control of the system. For serial manipulators, the recursive Newton‐Euler method has been proven to be the most efficient. However, for more general manipulators, such as serial manipulators with closed kinematic loops or parallel manipulators, it must be modified accordingly and the resultant computational efficiency is degraded. This article presents a computationally efficient scheme based on the virtual work principle for inverse dynamics of general manipulators. The present method uses a forward recursive scheme to compute velocities and accelerations, the Newton‐Euler equation to calculate inertia forces/torque, and the virtual work principle to formulate the dynamic equations of motion. This method is equally effective for serial and parallel manipulators. For serial manipulators, its computational efficiency is comparable to the recursive Newton‐Euler method. For parallel manipulators or serial manipulators with closed kinematic loops, it is more efficient than the existing methods. As an example, the computations of inverse dynamics (including inverse kinematics) of a general Stewart platform require only 842 multiplications, 511 additions, and 12 square roots.
Direct digital design of computed torque controllers
Authors: Ishihara Tadashi 
Published: July 2007

AbstractDirect digital design of computed torque controllers for a robot manipulator is discussed in this article. A simple discrete‐time model of the robot manipulator obtained by Euler's method is used for the design. Taking account of computation delay in the digital processor, we propose predictor‐based designs of the PD and PID type controllers. The PID‐type controller is designed based on a modified version of the discrete‐time integral controller proposed by Mita. For both controllers, the feedback gains can be determined easily by using simple formulas. A simulation example is presented to illustrate the relevance of the proposed designs and the robustness of PID‐type controller against physical parameter variations. © 1994 John Wiley & Sons, Inc.
Definition of a kinematic metric for robot manipulators
Authors: Tchoń Krzysztof , Dulȩba Ignacy 
Published: July 2007

AbstractUsing a Riemannian metric in the special Euclidean group we define a kinematic metric on the space of kinematics of robot manipulators. Prospective applications of the metric in kinematic design and performance evaluation of robot manipulators are indicated. For exemplary kinematics, including the PUMA 600, explicit formulas are provided describing the dependence of the metric on manipulator's geometric parameters. © 1994 John Wiley & Sons, Inc.
On the velocity and acceleration snalyses of general parallel robotic manipulators
Authors: Wans Li‐Chun T. , Chen Chih Cheng 
Published: July 2007

AbstractThis article presents a unified method for the velocity and acceleration analyses of general parallel robotic manipulators. In this method, the governing velocity and acceleration equations of the robot are formulated in the joint space by considering it as a tree‐type mechanism subjected to Cartesian velocity and acceleration constraints. The procedures for solving the direct and the inverse analysis problems are established based on the generalized coordinate partitioning technique and the full pivoting Gaussian elimination method. These procedures take into account the overconstrained kinematic loops and redundant joints, and are applicable to either fully parallel robots or hybrid series‐parallel robots without any modifications. In addition, a set of generalized recursive formulas for computing the forward Cartesian velocity and acceleration transformations are developed. These formulas are also useful for efficient evaluating the complex nonlinear terms of the governing acceleration equations. © 1995 John Wiley & Sons, Inc.
Geometric phases and robotic locomotion
Authors: Kelly Scott D. , Murray Richard M. 
Published: July 2007

AbstractRobotic locomotion is based in a variety of instances upon cyclic changes in the shape of a robot mechanism. Certain variations in shape exploit the constrained nature of a robot's interaction with its environment to generate net motion. This is true for legged robots, snakelike robots, and wheeled mobile robots undertaking maneuvers such as parallel parking. In this article we explore the use of tools from differential geometry to model and analyze this class of locomotion mechanisms in a unified way. In particular, we describe locomotion in terms of the geometric phase associated with a connection on a principal bundle, and address issues such as controllability and choice of gait. We also provide an introduction to the basic mathematical concepts that we require and apply the theory to numerous example systems. © 1995 John Wiley & Sons, Inc.
Analtical‐ form direct kinematicefor the second scheme of a 5–5 general‐geometry fully parallel manipulator
Authors: Innocenti Carlo 
Published: July 2007

AbstractThis article presents the direct kinematics of a 6 degrees of freedom fully parallel manipulator that features five connection points on both base and platform. The considered leg arrangement is one of the two possible, the other having been referred to in a previous paper. The base and platform have a general geometry, i.e., the connection points are not bound to lie on planes. The direct kinematics is solved in analytical form, which allows determination of every possible solution. After a suitable set of five equations in five unknowns has been laid down, and an original elimination procedure applied, a final polynomial equation of the 24th order is found whose 24 solutions correspond to as many assembly configurations for the considered fully parallel manipulator. A case study is reported. © 1995 John Wiley & Sons, Inc.