waashk/dblp huggingface dataset:
fuzzy control of robot manipulator with a flexible tool. in some tasks, a rigid robot manipulator handles a long, slender, and flexible tool, which usually has not been equipped with vibration measuring devices. this situation makes a different tool tip position control problem. in this paper, a new method will be presented for simultaneous tip position and vibration suppression control of a flexible tool on a rigid-link 3-dof robot. this approach uses fuzzy logic rule-based controllers without using any sensors and actuators on the tool or a priori knowledge about the tool. numerical simulation of robot and tool set has been accomplished and results support the fact that designed fuzzy controllers perform remarkably well in reducing vibrations and precision guidance of robot tool tip for tracking various trajectories. &copy; 2005 wiley periodicals, inc.
kinematic path-tracking of mobile robot using iterative learning control. this paper develops a kinematic path-tracking algorithm for a nonholonomic mobile robot using an iterative learning control (ilc) technique. the proposed algorithm produces a robot velocity command, which is to be executed by the proper dynamic controller of the robot. the difference between the velocity command and the actual velocity acts as state disturbances in the kinematic model of the mobile robot. given the kinematic model with state disturbances, we present an ilc-based path-tracking algorithm. an iterative learning rule with both predictive and current learning terms is used to overcome uncertainties and the disturbances in the system. it shows that the system states, outputs, and control inputs are guaranteed to converge to the desired trajectories with or without state disturbances, output disturbances, or initial state errors. simulations and experiments using an actual mobile robot verify the feasibility and validity of the proposed learning algorithm. &copy; 2005 wiley periodicals, inc.
compliant grasping with passive forces. because friction is central to robotic grasp, developing an accurate and tractable model of contact compliance, particularly in the tangential direction, and predicting the passive force closure are crucial to robotic grasping and contact analysis. this paper analyzes the existence of the uncontrollable grasping forces (i.e., passive contact forces) in enveloping grasp or fixturing, and formulates a physical model of compliant enveloping grasp. first, we develop a locally elastic contact model to describe the nonlinear coupling between the contact force with friction and elastic deformation at the individual contact. further, a set of &ldquo;compatibility&rdquo; equations is given so that the elastic deformations among all contacts in the grasping system result in a consistent set of displacements of the object. then, combining the force equilibrium, the locally elastic contact model, and the &ldquo;compatibility&rdquo; conditions, we formulate the natural compliant model of the enveloping grasp system where the passive compliance in joints of fingers is considered, and investigate the stability of the compliant grasp system. the crux of judging passive force closure is to predict the passive contact forces in the grasping system, which is formulated into a nonlinear least square in this paper. using the globally convergent levenberg-marquardt method, we predict contact forces and estimate the passive force closure in the enveloping grasps. finally, a numerical example is given to verify the proposed compliant enveloping grasp model and the prediction method of passive force closure. &copy; 2005 wiley periodicals, inc.
sensory-motor control mechanism for reaching movements of a redundant musculo-skeletal arm. this paper studies the human arm's sensory-motor control mechanism in reaching movements. first, we formulate both the kinematics and dynamics of a two-link planar arm model with six redundant muscles. the nonlinear muscle dynamics is modeled based on several biological understandings. we then show the stability of the overall system and perform some numerical simulations. by considering the internal forces induced by the redundant muscles, we show that the damping factors in each joint can be regulated, and as the result, it can realize humanlike quasistraight line reaching movements. in addition, we also propose the gravity compensation method at the muscle input level and present the result of numerical simulation to verify the usefulness of this method. &copy; 2005 wiley periodicals, inc.
geometrical conditions for the design of partial or full isotropic hexapods. this paper presents a methodology for the design of pkms (parallel kinematic machines) with defined isotropy and stiffness. partial isotropy or full isotropy can be achieved by suitable design choices. the former is useful for five axis applications, while the latter for six axis manipulators. the paper summarizes the concept of full and partial isotropy, and for a wide class of hexapods defines in analytical form the conditions to achieve it exactly. these conditions can be used to design isotropic parallel manipulators. the methodology requires that the six legs have to be divided into two groups (terns). the legs belonging to one tern are mutually identical and are positioned with radial symmetry with respect to the tcp (tool center point). the paper shows that the manipulator structure can be defined in term of 13 design parameters, the value of six of them are chosen in order to achieve the required isotropy and stiffness properties, while the remaining seven parameters can be used to optimize the structure. the design criterion here presented assures that stiffness isotropy, force, and velocity isotropy are all achieved contemporarily. this methodology can be practically applied to a large family of hexapods. &copy; 2005 wiley periodicals, inc.
telerobotic systems design based on real-time corba. a new class of telerobotic applications is making its way into research laboratories, fine arts or science museums, and industrial installations. virtual laboratories and remote equipment maintenance are examples of these applications, which are built exploiting distributed computing systems and internet technologies. distributed computing technologies provide several advantages to telerobotic applications, such as dynamic and multiuser access to remote resources and arbitrary user locations. nonetheless, building these applications remains a substantial endeavor, especially when performance requirements must be met. the aim of this paper is to investigate how mainstream and advanced features of the corba object-oriented middleware can be put to work to meet the requirements of novel telerobotic applications. we show that real-time corba extensions and asynchronous method invocation of corba services can be relied upon to meet performance and functional requirements, thereby enabling teleoperation on local area networks. furthermore, corba services for concurrency control and large-scale data distribution enable geographic-scale access for robot teleprogramming. limitations in the currently available implementations of the corba standard are also discussed, along with their implications. the effectiveness and suitability for telerobotic applications of several corba mechanisms are tested first individually and then by means of a software framework exploiting corba services and ensuring component-based development, software reuse, low development cost, fully portable real-time and communication support. a comprehensive telerobotic application built based on the framework is described in the paper and evaluated on both local and wide area networks. the application includes a robot manipulator and several sensory subsystems under concurrent access by multiple competing or collaborating operators, one of which is equipped with a multimodal user interface acting as the master device. &copy; 2005 wiley periodicals, inc.
a bio-inspired approach for regulating and measuring visco-elastic properties of a robot arm. this work focuses on interaction control of robot manipulators in unstructured environments, with special regard for situations of unpredictable contact&#x002f;noncontact transitions. it is basically addressed to those environments where a high level of robot adaptability is required and no information on the geometry of the environment is available. by pointing out the main limitations of standard interaction control schemes in managing situations of contact&#x002f;noncontact transitions, this paper proposes a new control solution that is inspired by the biological model of motor control in voluntary movements. it consists of a combination of a feedforward loop and a proportional-derivative plus gravity compensation control in the feedback loop. the control law is named coactivation-based compliance control in the joint space since a unique function, called coactivation function, is evaluated for regulating robot visco-elasticity in an unpredictably variable environment. it resumes the mechanism of adjustable visco-elastic properties acting on the agonist and antagonist muscles of a human arm. the work also proposes a methodology for evaluating performance of interaction control schemes that is based on stiffness graphical representation through ellipses. the method replicates the experimental setup used in neuroscience to measure stiffness in human limbs. it is regarded as a powerful tool for evaluating robot behavior over space and time, since it allows both a visual representation of stiffness variation during motion and a quantitative measure of robot performance. it is shown how the method can be used to evaluate a control scheme and how it can provide indications to improve a control law. in this paper, an application to the standard compliance control in the joint space and the coactivation-based compliance control is presented. &copy; 2005 wiley periodicals, inc.
stereoscopic video images for telerobotic applications. this article addresses the use of stereoscopic images in teleoperated tasks. depth perception is a key point in the ability to skillfully manipulate in remote environments. displaying three-dimensional images is a complex process but it is possible to design a teleoperation interface that displays stereoscopic images to assist in manipulation tasks. the appropriate interface for image viewing must be chosen and the stereoscopic video cameras must be calibrated so that the image disparity is natural for the observer. attention is given to the calculation of stereoscopic image disparity, and suggestions are made as to the limits within which adequate stereoscopic image perception takes place. the authors have designed equipment for image visualization in teleoperated systems. these devices are described and their performance evaluated. finally, an architecture for the transmission of stereoscopic video images via network is proposed, which in the future will substitute for current image processing devices. &copy; 2005 wiley periodicals, inc.
case study: a novel surface scanning system. this paper presents the design and development of a novel surface scanning system that employs an array of 144 equal spaced probing pins for capturing the surface coordinates of an object simultaneously. operation of the system is computer driven. the captured surface data is saved in a point-cloud data file, which can be postprocessed by a cad system to construct a surface model of the scanned object. the created cad model can be used to facilitate the design and making of thermoforming moulds. the thermoforming moulds are to be used for forming plastic sheets for packaging consumer products for retail selling. a prototype of the system has been built. test results demonstrate that the developed system can satisfy the technical and economical requirements of the packaging industry. &copy; 2005 wiley periodicals, inc.
formulation of dynamics, actuation, and inversion of a three-dimensional two-link rigid body system. in this paper, three issues related to three-dimensional multilink rigid body systems are considered: dynamics, actuation, and inversion. based on the newton-euler equations, a state space formulation of the dynamics is discussed that renders itself to inclusion of actuators, and allows systematic ways of stabilization and construction of inverse systems. the development here is relevant to robotic systems, biological modeling, humanoid studies, and collaborating man-machine systems. the recursive dynamic formulation involves a method for sequential measurement and estimation of joint forces and couples for an open chain system. the sequence can start from top downwards or from the ground upwards. three-dimensional actuators that produce couples at the joints are included in the dynamics. inverse methods that allow estimation of these couples from the kinematic trajectories and physical parameters of the system are developed. the formulation and derivations are carried out for a two-link system. digital computer simulations of a two-rigid body system are presented to demonstrate the feasibility and effectiveness of the methods. &copy; 2005 wiley periodicals, inc.
kinetostatic modeling of the clearance-affected prismatic pair. the presence of clearance in the kinematic pairs of mechanisms has a strong influence on the mechanism performances. where positioning tasks are concerned, clearance can be considered as one of the most relevant error sources, since it affects both accuracy and repeatability. the development of predictive models then becomes relevant, suitable for assessing in advance the influence of clearance and for correcting unacceptable effects. several deterministic techniques assessing the accuracy of clearance-affected mechanisms have been proposed in the literature; these techniques require the development of kinetostatic models for clearance-affected pairs. this paper presents a modeling for clearance-affected prismatic pairs. such a model determines the three-dimensional displacement between the pairing elements in the prismatic pair, and relates it to the load acting on the pair. since the displacement depends strongly on the actual pair design, the model is described in detail for a particular pair geometry; in principle, however, this approach could be used for any geometry. the proposed model may be implemented in kinematic, kinetostatic, or dynamic analyses as well, with the purpose of computing the influence of clearance on the position and orientation error of any link of a mechanism. &copy; 2005 wiley periodicals, inc.
generation of natural motions for redundant multi-joint systems: a differential-geometric approach based upon the principle of least actions. this article challenges bernstein's problem of redundant degrees of freedom (dof) that remains unsolved from both the standpoints of physiology and robotics. a rather simpler but difficult control problem of movements of human-like multi-joint reaching with excess dof is analyzed from newtonian mechanics and differential geometry. it is shown that, regardless of ill-posedness of inverse kinematics for such a redundant system, a simpler control signal composed of a well-tuned (synergistic) combination of task-space position feedback (corresponding to spring-like forces) and joint velocity feedback (viscous-like forces) leads to a skilled motion of reaching in a natural way without solving inverse kinematics or dynamics. fundamental characteristics of human skilled multi-joint movements such as (1) generation of a quasi-straight line trajectory of the endpoint and (2) a little &ldquo;variability&rdquo; in task space but notable &ldquo;variability&rdquo; in joint space are analyzed from the concepts of &ldquo;stability on an ep (equilibrium-point) manifold&rdquo; and &ldquo;transferability to an ep submanifold.&rdquo; it is claimed that the control signal exerts torques on joints of the whole arm just like a single virtual-spring drawing the endpoint of the arm to the target while giving a specified viscosity to each joint. this leads to an interpretation that skilled reaching movements emerge through formation of a set of neuro-motor signals exerting relevant group of muscles to generate a total potential energy equivalent to that of the spring. discussions are presented on how such control signals in case of human reaching can be generated in a feedforward manner with capability of anticipatory adjustments of stiffness. &copy; 2005 wiley periodicals, inc.
reliable computation of minimum-time motions for manipulators moving in obstacle fields using a successive search for minimum-overload trajectories. in this paper we present a practical method for finding obstacle-free minimum-time motions for manipulators subject to the limits of velocity-dependent actuator forces. an optimal motion-planning problem is converted into a finite-dimensional nonlinear programming problem by means of parameter optimization with quintic b-splines. we introduce the concept of the minimum-overload trajectory in which the motion time is specified to be faster than the actuators can handle, and the actuator overloads are minimized with the motion time fixed. by successive searches for minimum-overload trajectories, minimum-time motions are determined for three example manipulators without simplifying any of the kinematic, dynamic or geometric properties of the manipulators or the obstacles. in the resultant minimum-time motions, almost all of the joint actuators are close to saturation during the motions. &copy; 2005 wiley periodicals, inc.
from task parameters to motor synergies: a hierarchical framework for approximately optimal control of redundant manipulators. we present a hierarchical framework for approximately optimal control of redundant manipulators. the plant is augmented with a low-level feedback controller, designed to yield input-output behavior that captures the task-relevant aspects of plant dynamics but has reduced dimensionality. this makes it possible to reformulate the optimal control problem in terms of the augmented dynamics, and optimize a high-level feedback controller without running into the curse of dimensionality. the resulting control hierarchy compares favorably to existing methods in robotics. furthermore, we demonstrate a number of similarities to (nonhierarchical) optimal feedback control. besides its engineering applications, the new framework addresses a key unresolved problem in the neural control of movement. it has long been hypothesized that coordination involves selective control of task parameters via muscle synergies, but the link between these parameters and the synergies capable of controlling them has remained elusive. our framework provides this missing link. &copy; 2005 wiley periodicals, inc.
type synthesis of 5-dof parallel manipulators based on screw theory. with the introduction of virtual chains to represent the motion patterns of 5-dof motions, a classification of 5-dof pms (parallel manipulators) is proposed at first. a general method for the type synthesis of 5-dof pms is then proposed based on screw theory and using the concept of virtual chains. the type synthesis of us-equivalent pms is presented in detail to show the application of the proposed approach. us-equivalent pms are the parallel counterparts of the 5-dof us serial manipulators. for a us-equivalent pm, the moving platform can rotate arbitrarily about a point moving along a spherical surface. the type synthesis of legs for us-equivalent pkcs (parallel kinematic chains), the type synthesis of us-equivalent pkcs, as well as the selection of actuated joints of us-equivalent pms are dealt with in sequence. us-equivalent pkcs with and without inactive joints are synthesized. several us-equivalent pms as well as other classes of 5-dof pms with identical type of legs are obtained. &copy; 2005 wiley periodicals, inc.
bio-mimetic trajectory generation using a neural time-base generator. this paper presents a neural time-base generator (tbg) that can generate a family of neural control signals with a controllable finite duration and bell-shaped velocity profile. then, a bio-mimetic trajectory generation method using the neural tbg model is explained. using the proposed model, the generation ability of human-like trajectories is examined through comparisons between computer simulations and human arm trajectories during reaching movements according to the curvature of constrained trajectories. &copy; 2005 wiley periodicals, inc.
grasping determination experiments within the uji robotics telelab. as a result of new technology becoming available it is increasingly possible to develop more natural human-robot interfaces. in particular, interaction channels based on both voice and synthesis recognition, and combined with other sensors, mainly computer vision, are now implemented in current robots. these capabilities enable a more natural face-to-face dialogue in the human-robot interaction. currently, they are demonstrating their potential in many service robot applications, such as museums, hospitals, and so on. one area where these new forms of interaction have been extensively tested recently is within the educational robotics context. this article addresses a novel user-interface implemented in such a system developed in our lab, namely &ldquo;the uji robotics telelab&rdquo;, where the word uji is the acronym for the name of our university. in order to develop this kind of complex system, several years of intensive research have been necessary in both multimedia tutoring systems and robotics. the principal motive for the project was the experimentation and validation of a complete telelaboratory, including an internet-based robot system, with off-line and on-line control possibilities, and other different facilities (e.g., multimedia tutorial, chat channel, etc.) aimed at teaching undergraduate students in the robotics subject in our university campus. finally, taking into account experience gained from using this system for regular undergraduate courses in robotics, new facilities have been implemented, and results showing the user performance, usability, and reliability of this novel contribution are discussed, including its advantages and limitations. &copy; 2005 wiley periodicals, inc.
potential-based path planning for robot manipulators. in this paper, a potential-based path-planning algorithm for a high dof robot manipulator is proposed. unlike some c-space-based approaches, which often require expensive preprocessing for the construction of the c-space, the proposed approach uses the workspace information directly. the approach computes, similar to that done in electrostatics, repulsive force and torque between objects in the workspace. a collision-free path of a manipulator will then be obtained by locally adjusting the manipulator configuration to search for minimum potential configurations using that force and torque. the proposed approach is efficient because these potential gradients are analytically tractable. simulation results show that the proposed algorithm works well, in terms of computation time and collision avoidance, for manipulators up to 9 degrees of freedom (dof). &copy; 2005 wiley periodicals, inc.
adaptive position and orientation regulation for the camera-in-hand problem. this paper considers the camera-space position and orientation regulation problem for the camera-in-hand problem via visual serving in the presence of parametric uncertainty associated with the robot dynamics and the camera system. specifically, an adaptive robot controller is developed that forces the end-effector of a robot manipulator to move such that the position and orientation of an object are regulated to a desired position and orientation in the camera-space, despite parametric uncertainty throughout the entire robot-camera system. an extension is also provided that illustrates how slight modifications can be made to the camera-in-hand control law to achieve adaptive position and orientation tracking of the end-effector in the camera-space for a fixed-camera configuration. simulation results are provided to illustrate the performance of the adaptive, camera-in-hand controller. &copy; 2005 wiley periodicals, inc.