bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experiments with a mobile robot operating in a cluttered unknown environment
Authors: Skewis T. , Lumelsky V. 
Published: July 2007

AbstractMotion planning for mobile robots has been an active area of research in recent years. One reason for this is the increasing importance of applications that take place in unstructured and time‐varying environments—such as outdoor waste management or delivery of food and medicines in a hospital. One of the main difficulties in automating such tasks is combining on‐line sensing with “on the fly” intelligent motion planning. On the other hand, the theoretical work in this area has matured enough to warrant active hardware and experimentation work. Discussed below is an attempt to implement a class of strategies for motion planning with incomplete information. We address the following experimental issues: the robot's ability to cope with limited information available from typical sensors while operating in a cluttered environment with unknown obstacles; handling the registration problem to assess the robot's current location; performing necessary data processing and planning fast enough to assure acceptable motion speeds; and handling situations that require the robot to make loops, retreat, and visit some areas of its path more than once. The results are encouraging; they indicate the feasibility of practical systems capable of operating in a highly complex uncertain environment. © 1994 John Wiley & Sons, Inc.
Calibration of an smt robot assembly cell
Authors: Zupančič Jure 
Published: July 2007

AbstractA new calibration method for an assembly robot cell is described. The proposed method is a combination of a model‐free, numerical, relative robot calibration procedure and a procedure for the robot periphery calibration. Two important simplifications based on the study of an assembly process are introduced into the calibration strategy. A robot is calibrated in a task (Cartesian) space. The robot workspace and the number of calibrated degrees of freedom (dof) in the task space are reduced in accordance with thedifficulty measureof the task. An automatic measurement system for measuring the relative robot accuracy was developed. An original principle of transforming the robot endpoint approach distance into the one‐dimensional position displacement error is introduced. The accuracy errors of each particular calibrated dof in the task space is measured separately. The error tables are used in a direct robot calibration procedure that is based on the linear interpolation of the discrete position‐error functions. An iterative inverse calibration algorithm used in a particular robot cell is described. An efficient sensor‐based system for an additional simultaneous robot periphery calibration is presented. The implementation of the proposed calibration methodology in the pick‐and‐place robot cell for Surface Mount Technology (SMT) is presented. © 1994 John Wiley & Sons, Inc.
Inverse dynamics of spatial open‐chain flexible manipulators with lumped and distributed actuators
Authors: Ledesma Ragnar , Devasia Santosh , Bayo Eduardo 
Published: July 2007

AbstractThis article addresses the problem of inverse dynamics for three‐dimensional flexible manipulators with both lumped and distributed actuators. A recursive procedure is presented for computing the lumped inverse dynamic torques and the distributed piezoelectric actuator inputs for simultaneously tracking a prescribed end‐point trajectory and reducing induced vibrations in the manipulator. The procedure sequentially solves for the non‐causal inverse dynamic torques and piezoelectric voltages applied to each link in the manipulator, starting from the last element in the chain and proceeding to the base element. The method allows trajectory tracking wherein controllability of the structural vibrations is assured in all possible configurations through the use of only one motor at each intermediate joint and three motors at the ground. Numerical simulation shows that the elastic vibrations can be reduced significantly through the use of distributed actuators while at the same time satisfying the trajectory tracking requirement through the use of inverse dynamics. © 1994 John Wiley & Sons, Inc.
Dynamic hybrid position/force control of a two degree‐of‐freedom flexible manipulator
Authors: Matsuno Fumitoshi , Yamamoto Kazuo 
Published: July 2007

AbstractIn this article, a method is proposed whereby both contact force exerted by a flexible manipulator and position of end‐effector while in contact with a surface are controlled. We approximate elastic deformations by means of B‐spline functions and derive dynamic equations of joint angles, vibration of the flexible link, and constraint force. A controller for the hybrid position/force control of the flexible manipulator is designed on the basis of the singular perturbation method. Simulation results confirm that the controller performs remarkably well. © 3994 John Wiley & Sons, Inc.
Enhanced measurement and estimation methodology for flexible link arm control
Authors: Lin J. , Lewis F. L. 
Published: July 2007

AbstractThe two objectives of this article are (1) to study the effects of truncation of the infinite series in the assumed mode shapes approach for flexible‐link robot arms, and (2) to design an improved Kalman filter for estimation of the rigid and flexible modes for controls purposes. A singular perturbation approach is used to derive an improved reduced‐order model that does not correspond simply to truncating the finite series, but includes some additional information about the neglected residual modes. Then, a second time‐scale separation is used to design a slow/fast Kalman filter with improved performance for flexible‐link arms. © 1994 John Wiley & Sons, Inc.
Design concept and prototype development of a flexible integrated vision system
Authors: Lee Kok‐Meng , Blenis Robert 
Published: July 2007

AbstractMany industrial tasks require sophisticated vision interpretation, yet demand low cost, high speed, accuracy, and flexibility. To be fully effective, future machine vision systems must be able to handle complex industrial parts. This includes verifying or recognizing incoming parts, and determining the location and orientation of the part within a short cycle time. It is generally required that the cycle time required by the part‐feeding system be less than that of the subsequent processes where parts are fed. To achieve this goal, a Flexible Integrated Vision System (FIVS) has been developed. FIVS offers performance and cost advantages by integrating the imaging sensor, control, illumination, direct digitization, computation, and data communication in a single unit. © 1994 John Wiley & Sons, Inc.
Estimation model for kinematic calibration of manipulators with a parallel structure
Authors: Kugiumtzis Dimitris , Lillekjendlic BjØRn 
Published: July 2007

AbstractThis article provides an estimation model for calibrating the kinematics of manipulators with a parallel geometrical structure. Parameter estimation for serial link manipulators is well developed, but fail for most structures with parallel actuators, because the forward kinematics is usually not analytically available for these. We extend parameter estimation to such parallel structures by developing an estimation method where errors in kinematical parameters are linearly related to errors in the tool pose, expressed through the inverse kinematics, which is usually well known. The method is based on the work done to calibrate the MultiCraft robot. This robot has five linear actuators built in parallel around a passive serial arm, thus making up a two‐layered parallel‐serial manipulator, and the unique MultiCraft construction is reviewed. Due to the passive serial arm, for this robot conventional serial calibration must be combined with estimation of the parameters in the parallel actuator structure. The developed kinematic calibration method is verified through simulations with realistic data and real robot kinematics, taking the MultiCraft manipulator as the case. © 1994 John Wiley & Sons, Inc.
Complete forward displacement solutions for a class of three‐branch parallel manipulators
Authors: And Leila Notash , Podhorodeski Ron P. 
Published: July 2007

AbstractForward displacement solutions are presented for a class of spatial parallel manipulators. In particular, considered are manipulators consisting of a platform supported through passive spherical joints by three branches, each branch having three‐revolute joints forming its main arm. Solutions are described for arbitrary main‐arm layouts and for all possible cases of redundant (nine, eight, and seven sensors) and non‐redundant (six sensors) sensing of branch main‐arm joint displacements. It is demonstrated that closed‐form forward displacement solutions can be found for all cases of redundant sensing. Furthermore, it is shown that a closed‐form solution can be obtained for one of the two possible cases of non‐redundant sensing of the main‐arm joint displacements. The only case of joint displacement sensing not allowing a closed‐form forward displacement solution is two joints sensed per branch, a case that can be expressed as a 16th‐order polynomial of a single variable. Due to the importance of having efficient and failure‐safe solutions for the forward displacement problem, it is suggested that appropriate redundancy in displacement sensing should be an important consideration in the design of parallel manipulation devices. © 1994 John Wiley & Sons, Inc.
External force control of an industrial puma 560 robot
Authors: And Eric Dégoulange , Dauchez Pierre 
Published: July 2007

AbstractDeformations occurring in a robot working in contact with a rigid environment is a real problem in the industrial world. This problem can be solved by taking into account forces undergone by the robot at the end‐effector level. The first part of this article is aimed at determining a force control scheme that satisfies this constraint and that can be implemented on a non‐modified industrial robot controller. Various existing force control schemes are investigated and the reasons for discarding them are given. Then, the emphasis is put on a so‐called external force control scheme, which seems to be a solution to our problem. The control law appearing in such a scheme is determined by means of a realistic robot simulator developed on a SUN workstation. A simple integral term on the force error gives acceptable results in various robot configurations. This is illustrated in the form of graphs. In a second part, the implementation of this external control scheme in a real PUMA 560 robot's UNIMATE controller is presented. Certain software issues and implementation solutions are pointed out. Several experiments are described. Once again, graphs are used to show the experimental results. © 1994 John Wiley & Sons, Inc.
Dynamic control and coupling of a free‐flying space robot system
Authors: Xu Yangsheng , Shum Heung‐Yeung 
Published: July 2007

AbstractIn this article we discuss the problem of dynamic coupling and control of a space robot with a free‐flying base, which could be a spacecraft, space station, or satellite. We formulate the dynamics of the system systematically and demonstrate nonlinearity of parameterization of the dynamics structure. We study the dynamic coupling of the robot and base system, and propose a concept, i.e., coupling factor, to illustrate the motion and force dependencies. Based on the coupling factor, we define a measure to characterize the degree of the dynamic coupling. The measure can be considered as a performance index in planning robot motion, or in evaluating robot trajectory for minimizing base motion, or in optimizing the robot configuration design and selecting the robot base location. Based on the dynamics analysis, we propose control schemes for position regulation and trajectory tracking problems. The regulation controller is simple to implement and will be useful in regular material transporting tasks. The tracking controller uses a dynamic model and provides more accurate and faster motion, and will be feasible for tracking moving objects or structural inspection tasks. A simulation study is shown at the end of the article. © 1994 John Wiley & Sons, Inc.
Flexible‐link robot arm control by a feedback linearization/singular perturbation approach
Authors: Vandegrift M. W. , Lewis F. L. , Zhu S. Q. 
Published: July 2007

AbstractA nonlinear tracking controller for the link‐tip positions and velocities of a multi‐link flexible robot arm is designed that gives guaranteed performance. The controller has three parts: a model‐based trajectory generator, an inner loop based on input‐output feedback linearization, and an outer loop that stabilizes the internal dynamics (e.g., the flexible modes) using a singular perturbation design. We show how to stabilize the internal dynamics by selecting a physically meaningful modified performance output for tracking; this output is the slow portion of the link‐tip motions. That is, the tracking requirement is relaxed so that the internal dynamics are stabilizable through a boundary layer correction that attenuates the flexible mode vibrations. © 1994 John Wiley & Sons, Inc.
An approach to the identifiable parameters of a manipulator
Authors: Lin Shir‐Kuan 
Published: July 2007

AbstractThis article deals with the minimal parameters of a manipulator in the least squares sense, so that the minimal parameters are equivalent to the identifiable parameters. The least squares concept is used to introduce terminology for the minimal linear combinations (MLCs) of the system parameters that define a set of linear combinations of the system parameters. The number of elements of the set is minimal, yet the set still completely determines the system. Furthermore, it is shown that the problem of finding a set of MLCs of a manipulator can be simplified to that of finding two individual sets of MLCs that determine the entries of the inertia matrix and the gravity load. Although the approach is applied to the inertia constants of composite bodies to obtain a set of MLCs identical to an earlier one, the result is newly interpreted in the least squares sense. The approach itself is a new method for finding the identifiable parameters of a manipulator, and it yields some new insight into the manipulator dynamics. The crucial feature is that a set of MLCs found by using the present approach is guaranteed to be identifiable. The earlier approaches always require an identification method to verify the results. An equivalence theorem is also presented that rigorously states the equivalence between the different sets of minimal parameters. © 1994 John Wiley & Sons, Inc.
A new notation for transform matrix and definitions of related operations
Authors: Wang Rongdong 
Published: July 2007

AbstractNew transform matrices and their multiplications and inversion are defined. Properties of these matrices and operations are derived. The new notation is suitable for both conceptual formula derivation and actual computation. An example of using the new notation for computation of kinematics of robotic manipulators is given. © 1994 John Wiley & Sons, Inc.
A new class of adaptive controllers for robot trajectory tracking
Authors: Colbaugh Richard , Seraji Homayoun , Glass Kristin 
Published: July 2007

AbstractThis article presents a new class of adaptive schemes for the motion control of robot manipulators. The proposed controllers are very general and computationally efficient because they do not require knowledge of either the mathematical model or the parameter values of the manipulator dynamics, and are implemented without calculation of the robot inverse dynamics or inverse kinematic transformations. It is shown that the control strategies are globally uniformly bounded in the presence of bounded disturbances, and that in the absence of disturbances the ultimate bound on the size of the tracking errors can be made arbitrarily small. Computer simulation results are given for a PUMA 560 manipulator, and demonstrate that accurate and robust trajectory tracking can be achieved by using the proposed controllers. © 1994 John Wiley & Sons, Inc.
Real‐ time geometric modeling using models in an actuator space and cartesian space
Authors: Sanders David A 
Published: July 2007

AbstractIn this article, three models in two different spaces are compared for use with an image processing system working in real time. A static geometric model of a robot work‐cell is held in computer memory as several solid polyhedra. This model is updated as new objects enter or leave the workplace. Similar 2‐D slices in joint space, spheres, and simple polyhedra are used to model these objects. The three models are compared for their ability to be updated with new information and for the efficiency of the whole system in accessing data concerning new objects. The system supplies data to a “Path Planner.” The path planner contains a geometric model of the static environment and a robot. The robot machinery structure is modeled as connected cylinders and spheres and the range of motion is quantized. © 1995 John Wiley & Sons, Inc.
Reachability analysis for base placement in mobile manipulators
Authors: Seraji Homayoun 
Published: July 2007

AbstractThis article addresses the problem of base placement for mobile robots using a reachability analysis. A simple geometric solution is proposed to determine the appropriate base locations from which the robot can reach a stationary or moving target point. This leads to a simple criterion for automated base placement, thus relieving the operator from the tedious and repetitive procedure for continuously positioning the robot base manually during the execution of the end‐effector task. For robots with one degree‐of‐mobility such as tracked robots, the feasible base locations consists of a region on the translational axis, the boundaries of which are derived in this article. The results are used to obtain the base locations so that the robot can reach a vertical line, a square surface, and a cubic volume. Using the proposed method, two experimental studies at the JPL Surface Inspection Laboratory are described: scanning a surface and reaching inside an opening. The results of the article are extended to mobile robots with two and three degrees‐of‐mobility such as rover‐mounted arms and gantry robots, and a simple numerical example is given for illustration. ©1995 John Wiley & Sons, Inc.
Control strategies for rodotic contact tasks: An experimental study
Authors: Mandal Nitish , Payandeh Shahram 
Published: July 2007

AbstractIn this article, we study the contact instability problem encountered in robotic manipulators while trying to make contact with an environment, such as grasping or pushing against objects, and propose a unified control strategy capable of achieving a stable contact against both stiff and compliant environments. The problem has three distinct stages of the contact task. In the first stage, free‐space motion, the robot is approaching the environment; in the second stage, post‐contact force regulation; in the third, impact stage, the transition from the first stage to the second. We make an experimental comparison of the control schemes that may be used for the three stages. For example, during impact, the manipulator should not lose contact with the environment, nor exert high impulsive forces on the environment, and in the post‐impact phase, the robot should have a fast force trajectory tracking. The best strategies for the above stages are experimentally determined and then combined into a single unified controller that can achieve stable contact as well as a fast force trajectory tracking response for surfaces of variable stiffnesses. This control scheme does not require a priori knowledge of the stiffness of the environment, and is able to estimate the environmental stiffness and tune gains accordingly so as to achieve the best response. Also experimentally compared is the use of such a scheme with impedance control, another method proposed in the literature for robotic contact task control. ©1995 John Wiley & Sons, Inc.
Toward efficient path‐planning for articulated robots
Authors: Gini G. , Massa R. , Negretti R. 
Published: July 2007

AbstractReal‐time issues are becoming more and more important in robot programming. When a 6‐dof manipulator is used, planning obstacle‐avoiding paths is a time‐consuming activity, usually done in simulation. We present the geometric models and the reasoning techniques we have implemented while realizing a gross motion planner for a manipulator with six revolute joints. First, construction of a problem‐oriented representation of the robot working space is explained. Then, the actual trajectory research carried out in our C‐space representation is described. The whole C‐space is not calculated; instead, a sequential strategy is used to determine the C‐space only for the first two links. Our approximation of the obstacles, which occupy fixed and known positions, greatly speeds the computation, allowing us to reduce the problem to planar geometric reasoning. The work is not limited to theoretical studies or simulations; experiments have been run very thoroughly, with various tests, on a PUMA robot to assess the real efficiency and usability of our software. The method applies to robots in a fixed and known environment. © 3995 John Wiley & Sons, Inc.
Sensor‐based self‐localization for wheeled mobile robots
Authors: Curran A. , Kyriakopoulos K. J. 
Published: July 2007

AbstractIn this article, we demonstrate a reliable, robust, and computationally efficient algorithm that uses inexpensive hardware to localize a mobile robot in a rather structured environment that is relatively consistent to an a priori map. Furthermore, the incorporation of thresholding makes possible the localization of the robot even in the presence of objects not depicted in the a priori map. An Extended Kalman Filter is used to combine dead‐reckoning, ultrasonic, and infrared sensor data to estimate current position and orientation. Implementation issues and experimental results from experience with a mobile robot, Nomad 200, are also presented. ©1995 John Wiley & Sons, Inc.