bluuebunny/crossref_metadata_2025_split huggingface dataset:
Position control of robot manipulators with elastic joints using force feedback
Authors: Kircanski Nenad , Timcenko Aleksandar , Vukobratovic Miomir 
Published: July 2007

AbstractTransmission flexibility, as a predominant source of mechanical resonance, often results in inaccurate tracking of prescribed robot trajectories. Thus, the control algorithm must compensate not only for nonlinear dynamics of the arm and payload variations, but also for resonant effects in joints. The compensation for all of these effects results in a very complicated control algorithms which are difficult to apply in practice. In this article we suggest the measurement of torque/force on the output shaft of elastic reducer in order to compensate for elastic effects. The torque measurement can be replaced by the simultaneous measurement of the joint and the motor‐shaft angle. Then, we introduce a dynamic compensator with two zeros and two poles to filtrate the torque signal. It appears that the obtained control law is very simple and compensates for nonlinear system dynamics, variable payload parameters and resonant effects in joints. The proposed control scheme is illustrated by computer simulation of a six‐degree‐of‐freedom robot.
A quadtree‐based path‐planning algorithm for a mobile robot
Authors: Noborio Hiroshi , Naniwa Tomohide , Arimoto Suguru 
Published: July 2007

AbstractTo enable a mobile robot to select automatically a collision‐free path in a given workspace, design of a path‐planning algorithm which must work efficiently in real‐time is crucial. This article proposes a path‐planning algorithm that selects a reasonable collision‐free path tying start and goal points out of a quadtree representation of the robot workspace. The quadtree is obtained from fast conversion of a real image taken through a camera on the ceiling. It represents obstacles and their allocation in the workspace in good time and hence the algorithm is able to find a collision‐free path while following the change of obstacles and their allocation. The algorithm is designed on the basis of “small‐is‐quick” principle. That is, the smaller a search space of the algorithm is, the faster the algorithm selects the shortest path out of the search space. To put the principle in practice, the algorithm investigates a path graph instead of the quadtree while spreading the path graph on the quadtree as small as possible, and selects fast the shortest collision‐free path out of the path graph as a reasonable collision‐free path. Thus the algorithm fulfils its function fast even in a workspace that has a number of obstacles with complicated shape. In comparison with several conventional path‐planning algorithms presented so far, it is shown from experimental results that the proposed algorithm selects faster a reasonable collision‐free robot path than others.
Optimal control of robotic manipulators in the presence of obstacles
Authors: Chen Yao‐Chon , Vidyasagar Mathukumalli 
Published: July 2007

AbstractIn this article, the optimal control problem for (rigid) robotic manipulators in the presence of obstacles is considered. First, two methods for the modeling of obstacles are considered. Through these methods, closed‐form approximations of obstacles in terms of the generalized coordinates of the manipulator are obtained. These expressions are then used to formulate an optimal control problem with state space constraints. The resulting optimal control problem is then solved numerically.
Control of the Utah/MIT dextrous hand: Hardware and software hierarchy
Authors: Speeter Thomas H. 
Published: July 2007

AbstractThis article describes a hardware and software hierarchy for the control of manipulation with the Utah/MIT Dextrous Hand (UMDH). Control algorithms execute within a multiprocessing, shared memory computer environment partitioned into a three tiered hierarchy. Joint level servo algorithms are executed at the lowest level, trajectory generation and communication at the middle level and at the highest level, a new programming language called HPL (Hand Programming Language) is implemented. A functional approach to the control of manipulation is described and the functional philosophy is embedded within HPL. Tasks are specified by the concatenation and linear combination of small functional units called motor primitives. HPL provides an abstraction of the process of manipulation through its use of motor primitives. Hand control programs can be written and easily refined within the HPL programming environment and the resulting programs act as a conveniently annotated description of manipulation tasks.
The local calibration method for robot inaccuracy compensation
Authors: Davies Brady R. , Red W. Edward , Lawson John S. 
Published: July 2007

AbstractThis article presents a local calibration method that is philosophically different from the more contemporary global calibration methods. Local methods seek models of robot performance at the robot distal link measured relative to parts in localized part regions. In contrast, global methods seek to model various sources of robot inaccuracy internal to the robot. For example, a significant global research area is the determination of the actual robot arm structural parameters. Given more accurate estimates of these parameters, global compensation methods propose perturbation techniques or improved kinematic models that can be used to control the as‐manufactured robot. To implement local calibration methods, calibration procedures have been developed to locate tool and sensor tool control frames (TCF's) and to measure robot inaccuracy in localized regions. Using the measured position and orientation (pose) data obtained by hardware sensors, the components of operational inaccuracy are integrated into compensation models. This article discusses compensating model effectiveness and considers the interactions between hardware sensors and part features necessary to extract robot pose measurements automatically and effectively. Applying the relative calibration methodologies presented in this article to a GMF S‐200 six‐axis robot, robot repeatability was reduced by 39% and average localized robot inaccuracy was reduced from 3.4 mm (0.134 inch) to less than 0.86 mm (0.034 inch). The compensated robot inaccuracy is near the unstructured robot repeatability.
Improved configuration control for redundant robots
Authors: Seraji H. , Colbaugh R. 
Published: July 2007

AbstractThis article presents a singularity‐robust task‐prioritized reformulation of the configuration control scheme for redundant robot manipulators. This reformulation suppresses large joint velocities near singularities, at the expense of small task trajectory errors. This is achieved by optimally reducing the joint velocities to induce minimal errors in the task performance by modifying the task trajectories. Furthermore, the same framework provides a means for assignment of priorities between the basic task of end‐effector motion and the user‐defined additional task for utilizing redundancy. This allows automatic relaxation of the additional task constraints in favor of the desired end‐effector motion, when both cannot be achieved exactly. The improved configuration control scheme is illustrated for a variety of additional tasks, and extensive simulation results are presented.
A new solid model HSM and its application to interference detection between moving objects
Authors: Liu Yun‐Hui , Arimoto Suguru , Noborio Hiroshi 
Published: July 2007

AbstractIn order to realize collision‐free coordination of multiple robots, it is crucial to model the robots in a computer adequately and to detect existence or nonexistence of an interference between them on the basis of data structure of the robot models. Motivated by this observation, this article proposes a new solid model named “Hierarchical Sphere Model” (HSM) for modeling moving objects (robots) and presents a feasible algorithm for checking an interference between them on the basis of HSM. HSM arranges region informations in a hierarchical tree structure whose nodes correspond to spherical regions. On the basis of hierarchy of HSM, the algorithm checks only intersections between HSMs' nodes which are close to each other, and hence it works efficiently even if the objects have complicated shape. Furthermore, because a node of HSM represents a spherical region, intersection between, two nodes can be easily found just by calculating the distance between two spheres corresponding to them no matter how the objects move. Finally, the efficiency of the algorithm is demonstrated by several experiments.
A new composite body method for manipulator dynamics
Authors: Lin Shir‐Kuan 
Published: July 2007

AbstractThis article presents a new composite body method for numerically forming the inertia matrix and the bias vector of manipulators, which is more efficient than the other two existing types of composite body methods. The main discrepancy of this one from the existing ones is that all points in a manipulator are observed from the origin of the base frame and the distances are all measured from this origin. The required computations of the present method for the inertia matrix and the bias vector of a manipulator withnrotational joints are (10.5n2+ 38.5n‐ 85)M + (6n2+ 39n‐ 70)A and (12.5n2+ 5.5n+ 3)M + (9n2+n)A, respectively, where “M” denotes multiplications, “A” does additions. In numerically forming the inertia matrix, the present method is more efficient than other methods in the literature for a manipulator with five or more joints; whereas this method is also superior to the recursive Newton‐Euler formulation in computing the bias vector for a manipulator with six or less joints.
Trajectory optimization for kinematically redundant arms
Authors: Carignan Craig R. 
Published: July 2007

AbstractA review of local optimization methods for resolving joint configurations in underconstrained manipulation tasks is conducted. A new approach is developed for observing joint limits and avoiding obstacles during the trajectory planning. The methodology is used in a four‐link arm example to avoid a workspace singularity and is compared with results using the extended Moore‐Penrose technique. An alternative measure of arm “manipulability” based directly on the rank of the Jacobian is also introduced.
Modeling methods for underwater robotic vehicle dynamics
Authors: Goheen K. R. 
Published: July 2007

AbstractModels of the open‐loop dynamics for prototype Remotely Operated Underwater Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs) are required for performance prediction and autopilot design. This article describes techniques which can be used to derive these models. The methods may be conveniently grouped into predictive techniques i.e., those which require only vehicle design data and which predict dynamics before the prototype is built and testing techniques i.e., methods which measure open‐loop dynamics from the trials performance of a prototype ROV. The relative benefits and drawbacks of the various methods are examined.
A kinematic analysis of the space station remote manipulator system (SSRMS)
Authors: Crane Carl D. , Duffy Joseph , Carnahan Tim 
Published: July 2007

AbstractAn efficient reverse analysis of three 6‐degree‐of‐freedom (dof) subchains of the 7‐dof SSRMS is presented. The first subchain is formed by locking the seventh joint. The second subchain is formed by locking the second joint, while the third subchain is formed by locking the first joint (the grounded joint is counted as the first joint in the chain). There are a maximum of eight different arm configurations in each of the three subchains, and these were determined by employing a computer‐efficient algorithm, which required the rooting of only at most quadratic polynomials. The algorithms were implemented, and the SSRMS was employed in an animated environment to perform and practice a number of useful tasks for space station servicing. The locking of the second joint has the advantage in that an operator could, at the outset, choose the orientation of the plane that contains the two longest links (the upper arm and forearm) so as to avoid collisions with obstacles. However, it has the disadvantage that when the second joint angle equals 0° or 180°, the manipulator is in a singularity configuration (a singularity analysis of the SSRMS is presented in a second article). It is interesting to note that this plane can also be oriented by specifying the first joint angle. This has the distinct advantage that the plane can be oriented arbitrarily and, in this way, the singularity is avoided.
Dynamic steering control of conventionally steered mobile robots
Authors: Feng Dai , Krogh Bruce H. 
Published: July 2007

AbstractThis article presents an algorithm for dynamically steering an autonomous mobile robot (AMR) along a collision‐free path to a goal using local feedback information. A twolevel navigation algorithm is presented in which a subgoal selection algorithm (SSA) generates visible subgoals to be pursued by the steering control algorithm (SCA). An earlier article presented the SSA in detail, demonstrating how subgoals can be updated while the AMR is moving so that a continuous motion is achieved without stopping to replan the path when new sensor data become available. This study focuses on the SCA. In particular, a general feedback scheme is developed for dynamically steering an AMR to a visible goal in the local obstacle‐free space identified by the SSA. We present the detailed implementation of the SCA for a conventionally steered AMR (CAMR). Simulation results are presented that demonstrate the effectiveness of the combined SSA‐SCA feedback scheme. The algorithm has been successfully implemented on the NavLab at CMU.
Kinematics of a parallel‐serial (Hybrid) manipulator
Authors: Shahinpoor M. 
Published: July 2007

AbstractHybrid manipulators are parallel‐serial connection robots that give rise to a multitude of highly articulate robotic manipulators. These manipulators are modular and can be extended by additional modules over large distances. Every module has a hemispherical work space and collective modules give rise to highly dexterous symmetrical work space. In this article, some basic designs and kinematical structures of these robot manipulators are discussed, the associated direct and the inverse kinematics formulations are presented, and solutions to the inverse kinematic problem are obtained explicitly and elaborated upon. These robot manipulators are shown to have a strength‐to‐weight ratio many times larger than the value currently available with industrial or research manipulators. This is due to the fact that these hybrid manipulators are stress compensated and have an ultralight weight, yet are extremely stiff due to the fact that the force distribution in their structure is mostly axial. The means of actuation in these manipulators are entirely prismatic and can be provided by ball‐screws with antibacklash nuts or linear induction motors for maximum precision.
Multiplexed piezoelectric polymer tactile sensor
Authors: Kolesar Edward S. , Reston Rocky R. , Ford Douglas G. , Fitch Robert C. 
Published: July 2007

AbstractAn electrically multiplexed robotic tactile sensor has been realized using a monolithic silicon‐integrated circuit coupled to a piezoelectric polyvinylidene fluoride (PVDF) film. The integrated circuit incorporates 25 sensor electrodes arranged in a symmetrical 5 × 5 matrix. Each electrode occupies a 600 × 600 m̈m square area, and they are separated from each other by 600 m̈m. A 25‐m̈m thick PVDF film was experimentally determined to be compatible with the fabrication process, and also yielded very favorable tactile sensing performance characteristics. The response of the tactile sensor is essentially linear for loads spanning 0.8 to 60 g force (gmf). The response bandwidth is 33 Hz, the hysteresis level is very small, and crosstalk is not a significant problem. A novel precharge bias scheme has been implemented to stabilize the pre‐ and postload sensor response. A rudimentary tactile object image measurement process was evaluated to recognize the shapes of circular, rectangular, toroidal, and hexagonal loads.
Model‐based, sensor‐directed remediation of underground storage tanks
Authors: Christensen B. , Drotning W. , Thunborg S. 
Published: July 2007

AbstractSensor‐rich, intelligent robots that function with respect to models of their environment have significant potential to reduce the time and cost for the cleanup of hazardous waste while increasing operator safety. Sandia National Laboratories is performing experimental investigations into the application of intelligent robot control technology to the problem of removing waste stored in tanks. This article describes the experimental environment employed at Sandia with particular attention to the computing and software control environment. Intelligent system control is achieved through the integration of extensive geometric and kinematic world models with real‐time sensor‐based control. All operator interactions with the system are through fully animated, graphical representations that validate all operator commands before execution to provide for safe operation. Sensing is used to add information to the robot system's world model and to allow sensor‐based servo control during selected operations. The results of a first critical features test are reported and the potential for applying advanced intelligent control concepts to the removal of waste in storage tanks is discussed.
A kinematic analysis of the modified flight telerobotic servicer manipulator system
Authors: Crane Carl , Carnahan Tim , Duffy Joseph 
Published: July 2007

AbstractA reverse analysis of a 6 degree of freedom (dof) subchain of a modified 7 dof flight telerobotic servicer (FTS) manipulator system is presented. The 6 dof subchain is designated as a TR‐RT* chain. At the outset, it was considered that the reverse analysis would be similar to a TTT manipulator analyzed previously for which the third and fourth joints intersect at a finite point. This was not, however, the case and a sixteenth‐degree tan‐half‐angle polynomial was derived for the TR‐RT manipulator. The elimination procedure is interesting and much simpler than the procedures for the general case.
Vision‐based obstacle detection for rotorcraft flight
Authors: Sridhar Banavar , Suorsa Ray , Smith Phillip , Hussien Bassam 
Published: July 2007

AbstractThe ability of rotorcraft to fly at low altitude is hindered by the high pilot workload required to avoid obstacles. The development of automation tools that can detect obstacles in the rotorcraft flight path, warn the crew, and interact with the guidance system to avoid detected obstacles would significantly reduce pilot workload and increase safety. This article describes an obstacle detection approach based on feature tracking and recursive range estimation that takes into account the characteristics of rotorcraft flight. The merits and weaknesses of the approach are discussed using image sequences from the laboratory and from flight. © 1992 John Wiley & Sons, Inc.
The reachability and dexterity of elbow and dual‐elbow robot manipulators
Authors: Emiris Dimitrios M. , Tourassis Vassilios D. 
Published: July 2007

AbstractThe objective of this article is to highlight the reachability and dexterity of dual‐elbow manipulators and provide a comparative evaluation of their capabilities. By necessity, dual‐elbow robots are compared to elbow manipulators, the de facto standard of industrial applications. Although it is well established that the ideal elbow and dual elbow geometries are comparable in terms of workspace optimization, it is shown that the corresponding realistic geometries exhibit distinct properties. Realistic dual‐elbow and elbow manipulators are investigated and the effects of manufacturing distortions on the flexibility and workspace utilization of the two geometries are quantified and contrasted. Realistic dual‐elbow geometries are shown to provide, in general, better reachability and dexterity, especially for manipulators with a large structural frame, and to be less sensitive to parallelism errors. © 1992 John Wiley & Sons, Inc.
An efficient technique for finding the desired global optimum of robotic joint displacement
Authors: Lin Paul P. , Yang An‐Jen 
Published: July 2007

AbstractFor an industrial robot on a daily operation basis such as pick and place, it is desired to minimize the robotic joint displacements when moving the robot from one location to another. The objective of the optimization here is to simultaneously minimize a robot end effector's positional error and the robotic joint displacements. By modifying the searching algorithm in the existing complex optimization method, this article presents a technique for finding the desired global optimum solution more efficiently. To compare the optimum searching capability between the proposed and existing searching algorithms, a modified Himmelblau's function is used as an objective function. The presented technique is then applied to a spatial three‐link robot manipulator for global minimization of the joint displacements. © 1992 John Wiley & Sons, Inc.
Kinematics of an infinitely flexible robot arm
Authors: Choi P. J. , Rice J. A. , Cesarone J. C. 
Published: July 2007

AbstractThis article describes a research effort to develop a command and control algorithm for a proposed flexible robot arm. This robot arm, unlike previous arms, is assumed to be extremely flexible, possessing a large number of degrees of freedom and functioning as a “tentacle.” Algorithms for commanding smooth motion of this arm in the presence of obstacles are developed, including both forward and inverse kinematics. The approach is based on the use of Catmull‐Rom splines and local radius of curvature commands to discrete actuators along the arm's length. Several example trajectories are presented and explained. According to the proposed method, a spline curve algorithm is successfully applied for the configuration of the flexible robot and the accuracy and the collision avoidability of the flexible arm are verified through simulation.
Nonlinear control with end‐point acceleration feedback for a two‐link flexible manipulator: Experimental results
Authors: Khorrami Farshad , Jain Sandeep 
Published: July 2007

AbstractExperimental results for end‐point positioning of multi‐link flexible manipulators through end‐point acceleration feedback are presented in this article. The advocated controllers are implemented on a two‐link flexible arm developed at the Control/Robotics Research Laboratory at Polytechnic University. The advocated approach in this article is based on a two‐stage control design. The first stage is a nonlinear (1) feedback linearizing controller corresponding to the rigid body motion of the manipulator. Because this scheme does not utilize any feedback from the end‐point motion, significant vibrations are induced at the end effector. To this effect, and to enhance the robustness of the closed‐loop dynamics to parameter variations, the inner loop is augmented with an outer loop based on a linear output LQR design that utilizes an end‐point acceleration feedback. The forearm of the manipulator is significantly more flexible as compared with the upper arm. Experimental and simulation results validate the fact that the end‐effector performance is significantly better with the proposed (1) feedback linearizing control as compared with the linear independent joint PD control. In addition, the nonlinear control offers other advantages in terms of smaller and smoother actuator torques and reducing the effects of nonlinearities. Close conformation between simulation and experimental results validates the accuracy of the model.