bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse kinematics of planar redundant manipulators via virtual links with configuration index
Authors: Chung W. J. , Youm Y. , Chung W. K.
Published: July 2007

This article presents a new method for generating inverse kinematic solutions for planar manipulators with large redundancy (hyper‐redundant manipulators). The proposed method starts by decomposing a planar redundant manipulator into a series of local planar arms that are either 2‐link or 3‐link manipulator modules, and connecting the conjunction points between them with virtual links. The manipulator then can be handled by a simple virtual link system, which may be conveniently divided into non‐singular and singular cases depending on its configuration. When the virtual link system is no longer effective due to a singular configuration, the displacement of the end‐effector is then allocated to virtual links according to a displacement distribution criterion. A dexterity index called the “configuration index” distinguishes the non‐singular and singular cases. The concept of virtual link is shown by computer simulations to be simple and effective for the inverse kinematics of a planar hyper‐redundant manipulator with a discrete model. In particular, it can be applied to solving the inverse kinematics of a SCARA‐type spatial redundant manipulator whose redundancy is included in its planar mechanism. © 1994 John Wiley & Sons, Inc.
Mobile manipulator path planning by a genetic algorithm
Authors: Zhao Min , Ansari Nirwan , Hou Edwin S. H.
Published: July 2007

This article addresses the path‐planning problem for a mobile manipulator system that is used to perform a sequence of tasks specified by locations and minimum oriented force capabilities. The problem is to find an optimal sequence of base positions and manipulator configurations for performing a sequence of tasks given a series of task specifications. The formulation of the problem is nonlinear. The feasible regions for the problem are nonconvex and unconnected. Genetic algorithms applied to such problems appear to be very promising while traditional optimization methods cause difficulties. Computer simulations are carried out on a three‐degrees‐of‐freedom manipulator mounted on a two‐degrees‐of‐freedom mobile base to search for the near optimal path‐planning solution for performing the sequence of tasks. © 1994 John Wiley & Sons, Inc.
Navigation control for a mobile robot
Authors: Han Min‐Hong , Rhee Sang‐Yong Rhee
Published: July 2007

This article describes a navigation method of a mobile robot which uses a single camera and a guide mark. A travel path is instructed to the robot by means of path drawn on a monitor screen. The image of the guide mark provides information regarding the robot's position and heading direction. The heading direction is adjusted while moving if any deviation from the specified path is detected. The proposed method has been implemented in a mobile robot which runs at the average speed of 2.5 ft/s. without deviating more than one foot from the specified path in an indoor environment. © 1994 John Wiley & Sons, Inc.
Model‐based location of automated guided vehicles in the navigation sessions by 3d computer vision
Authors: Lee Pai‐Shih , Shen Yuh‐Erl , Wang Ling‐Ling
Published: July 2007

A model‐based approach to determining the location of an automated guided vehicle (AGV) in the navigation session is proposed. Significant scenes along the navigation path are taken and stored as model images. Also, specific templates of each model image are chosen in advance for matching. When the AGV approaches one significant scene in the navigation session, an input image is taken and the corresponding model image is fetched. Each template in the model image is matched with the input image through the use of the three‐step method. The templates are directly used for matching; therefore, no special image processing techniques are required for the input image in the navigation session. In addition, several templates in a model image are used for matching instead of the model image itself. This promotes the robustness of the matching results and saves the computation cost. Furthermore, the 2D string method is used as a post‐verifier to discard erroneous matching results. The remaining correct matching results then can be used to determine the vehicle location on the navigation path. Simulated experiments are implemented and the results confirm the feasibility of the proposed approach. © 1994 John Wiley & Sons, Inc.
Convergence and robustness of a discrete‐time learning control scheme for constrained manipulators
Authors: Cheah C. C. , Wang Danwei , Soh Y. C.
Published: July 2007

The constrained motion control is one of the most common control tasks found in many industrial robot applications. The nonlinear and nonclassical nature of the dynamic model of constrained robots make designing a controller for accurate tracking of both motion and force a difficult problem. In this article, a discrete‐time learning control problem for precise path tracking of motion and force for constrained robots is formulated and solved. The control system is able to reduce the tracking error iteratively in the presence of external disturbances and errors in initial condition as the robot repeats its action. Computer simulation result is presented to demonstrate the performance of the proposed learning controller. © 1994 John Wiley & Sons, Inc.
Experiments with a mobile robot operating in a cluttered unknown environment
Authors: Skewis T. , Lumelsky V.
Published: July 2007

Motion 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

A 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

This 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

In 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

The 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

Many 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

This 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

Forward 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

Deformations 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

In 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

A 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

This 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

New 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

This 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

In 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

This 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

In 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

Real‐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

In 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.
Intemal correction of dead‐reckoning errors with a dual‐drive compliant linkage mobil robot
Authors: Borenstein Johann
Published: July 2007

This paper presents internalposition error correction(IPEC)—a new method for accurate and reliable dead‐reckoning with mobile robots. The IPEC method has been implemented on our recently developedmulti‐degree‐of‐freedom(MDOF) mobile platform, a vehicle in which two differential‐drive mobile robots (called trucks) are physically connected through acompliant linkage.In addition to its four wheel encoders, the MDOF platform has one linear and two rotaryinternalencoders, which allow measurement of the relative distance and bearing between the two trucks. During operation, both trucks perform conventional dead‐reckoning with their wheel encoders. But, in addition, the IPEC method uses information from the internal encoders to detect and correct dead‐reckoning errors as soon as they occur.

Our system, calledcompliant linkage autonomous platform with position error recovery(CLAPPER), requires neither external references (such as navigation beacons, artificial landmarks, known floorplans, or satellite signals), nor inertial navigation aids (such as accelerometers or gyros). Nonetheless, the experimental results included in this article show one to two orders of magnitude better positioning accuracy than systems based on conventional dead‐reckoning. The CLAPPER corrects not only systematic errors, such as different wheel diameters, but also non‐systematic errors, such as those caused by floor roughness, bumps, or cracks in the floor.

These features are made possible by exploiting the newgrowth‐rate conceptfor dead‐reckoning errors that is introduced in this article for the first time. The growth‐rate concept distinguishes between certain dead‐reckoning errors that develop slowly and other dead‐reckoning errors that develop quickly. Based on this concept, truck A frequently measures a property withslow‐growingerror characteristics on reference truck B (thus admitting a small error) to detect afast‐growingerror on truck A (thus correcting a large error), and vice versa. ©1995 John Wiley & Sons, Inc.
Sliding mode force, motion control, and stabilization of elastic manipulator in the presence of uncertainties
Authors: Vim Woosoon , Singh Sahjendra N.
Published: July 2007

This article considers the question of position and force control of three‐link elastic robotic systems on a constraint surface in the presence of robot parameter and environmental constraint geometry uncertainties. The approach of this article is applicable to any multi‐link elastic robot. A sliding mode control law is derived for the position and force trajectory control of manipulator. Unlike the rigid robots, sliding mode control of an end point gives rise to unstable zero dynamics. Instability of the zero dynamics is avoided by Controlling a point that lies in the neighborhood of the actual end point position. The sliding mode controller accomplishes tracking of the end‐effector and force trajectories on the constrained surface; however, the maneuver of the arm causes elastic mode excitation. For point‐to‐point control on the constraint surface, a stabilizer is designed for the final capture of the terminal state and vibration suppression. Numerical results are presented to show that in the closed‐loop system position and force control is accomplished in spite of payload and constraint surface geometry uncertainty. © 1995 John Wiley & Sons, Inc.
Vibration‐free handing of deformable beams by robot end‐effectors
Authors: Chen Ming Z. , Zheng Yuan F.
Published: July 2007

Passive approaches for vibration‐free handling of deformable beams are investigated in this article. Dynamic equations of a flexible beam handled by robot end‐effectors are formulated and analyzed first. From the analysis, it is revealed that the inertia forces caused by the beam motion may affect the vibration of the beam in certain motion patterns. Motion trajectories of the end‐effector that lead to a small or no vibration of the beam in these motion patterns are then specified. Because vibrations cannot be totally eliminated even if the vibration‐free motion trajectory is employed, another passive approach is further suggested. The approach employs a rubber pad in parallel with a spring installed on the fingers of the end‐effector. To understand the effectiveness of this passive approach, damped vibration and optimal damping are investigated. Experiments and simulations are conducted to verify the above two methods. The experiments display the vibration‐free motion of the beam using the proposed motion planning strategy. The simulation results demonstrate the effects of the vibration‐free trajectory and the passive damping. © 1995 John Wiley & Sons, Inc.
Collision detection for multiple robot manipulatyors by using orthogonal neural networks
Authors: Tsens Ching‐Shiow , Wu Chen‐Chun
Published: July 2007

This article discusses the application of orthogonal neural networks to detect collisions between multiple robot manipulators that work in an overlapped space. By applying an expansion/shrinkage algorithm, the problem of collision detection between arms is transformed into that among cylinders (or rectangular solids) and line segments. This mapping simplifies the collision detection problem and thus neural networks can be applied to solve it. The property of parallel processing enables neural networks to detect collisions rapidly. A single‐layer orthogonal neural network is developed to avert the problems of conventional multilayer feedforward neural networks such as initial weights and the number of layers and processing elements. This orthogonal neural network can approximate various functions and is used to calculate forward solution and to detect collisions. An efficient neural network system for collision detection is also developed. © 1995 John Wiley & Sons, Inc.
Optimal trajectory planning for a space robot docking with a moving target via homotopy algorithms
Authors: Chen Y. , Watson L. T.
Published: July 2007

The mathematical formulation of optimal trajectory planning for a space robot docking with a moving target is derived. The calculus of variations is applied to the problem so that the optimal robot trajectory can be obtained directly from the target information without first planning the trajectory of the end‐effector. The nonlinear two‐point boundary value problem resulting from the problem formulation is solved numerically by a globally convergent homotopy algorithm. The algorithm guarantees convergence to a solution for an arbitrarily chosen initial guess. Numerical simulation for three examples demonstrates the approach. © 3995 John Wiley & Sons, Inc.
Inverse dynamics of redundant manipulators using a minimum number of control forces
Authors: Ider S. Kemal
Published: July 2007

The number of the control actuators used by the inverse kinematics and dynamics algorithms that have been developed in the literature for generating redundant robot joint trajectories is equal to the number of the degrees of freedom of the manipulator. In this article, an inverse dynamics algorithm that performs the tasks using only a minimum number of actuators is proposed. The number of actuators is equal to the dimension of the task space, and the control forces are solved simultaneously with the corresponding system motion. It is shown that because all degrees of freedom are not actuated, the control forces may lose the ability to make an instantaneous effect on the end‐effector acceleration at certain configurations, yielding the dynamical equation set of the system to be singular. The dynamical equations are modified in the neighborhood of the singular configurations by utilizing higher‐order derivative information, so that the singularities in the numerical procedure are avoided. Asymptotically stable inverse dynamics closed‐loop control in the presence of perturbations is also discussed. The algorithm is further generalized to closed chain manipulators. Three‐link and two‐link redundant planar manipulators are analyzed to illustrate the validity of the approach. © 2995 John Wiley & Sons, Inc.
Task reliability assessment in robotic systems
Authors: Musto Joseph C. , Saridis George N.
Published: July 2007

A new method for assessing the performance of a robotic system performing a high‐precision task has been developed. The method utilizes an entropy‐based formulation to provide a measure of the reliability of a robotic system with respect to a task specification. The derivation of the proposed technique is presented, including two alternative formulations that differ in terms of their complexity and level of approximation. Methods for combining these measures for complex robotic tasks are detailed. The new method is demonstrated in a case study involving a robotic assembly system, in which the entropy formulation is used to select an optimal system design from a set of alternatives. (c)1995 John Wiley & Sons, Inc.
A smart robot's geometric model inverting system
Authors: Zhou J. , Coiffet P.
Published: July 2007

This article deals with a real‐time model inverting system. The mathematical inverting problem is no longer solved with a mathematical algorithm but through the design of the system control itself. The control algorithm is issued from human knowledge. The stability of this system is proved, and the properties are discussed. This system can be used where a geometric model should be inverted in real time, especially for redundant robots. (c)1995 John Wiley & Sons, Inc.
Dynamic control of a robot manipulator for high‐performance conveyor tracking
Authors: Park Tae Hyoung , Lee Beom Hee
Published: July 2007

A new robot control scheme for the specific application to conveyor tracking is presented. To improve the performance of conveyor tracking, the robot arm dynamics is incorporated into the control scheme. The tracking problem for the workpiece on a variable‐speed conveyor is formulated as a stochastic optimal tracking problem with specified criteria. Dividing the conveyor speed into the nominal term and the perturbed term, a two‐stage control strategy is employed to cope with the nonlinearity and uncertainty of the robot‐conveyor system. Simulation results are given to verify the good tracking performance with fast cycle time and high accuracy obtained in a robotic workcell. ©1995 John Wiley & Sons, Inc.
The jacodian matrix for a flexble manipulator
Authors: Piedboeuf Jean‐Claude
Published: July 2007

This article develops the exact first‐order endpoint Jacobian matrix for a general n‐degrees of freedom tree‐like robot with flexible links. The Jacobian is developed in terms of the joint axes, the link deformations, and the relative position vectors using cross products. To have the correct first‐order endpoint Jacobian matrix, the second‐order kinematics is used to describe a flexible link. Using two local Jacobian matrices enables to write the endpoint Jacobian sub‐matrix associated to a flexible link, which is similar to the column of the Jacobian associated to a joint. An example with a one‐link flexible arm rotating in a vertical plane illustrates the usefulness of the endpoint Jacobian in calculating the torque required to apply an endpoint force and the link deformation resulting from this force. An experimental verification proves the validity of the developed Jacobian and suggests that using only first‐order kinematics results in serious errors in the prediction of the beam's curvatures and deformations © 1995John Wiley & Sons, Inc.
A partial state feedback controller for tajectory tracking of rigid‐link fiexible‐joint robot using an observed backstepping approach
Authors: Urn S. Y. , Hu J. , Dawson D. M. , Queiroz M.
Published: July 2007

This article presents a partial state feedback controller for a rigid‐link flexible‐joint (RLFJ) robot using an observed integrator backstepping approach. The robot controller requires only link position and actuator position measurements, and eliminates the need for measuring link velocity and actuator velocity. The controller uses two exact knowledge, second‐order nonlinear observers to estimate the link and actuator velocities. The overall control system achieves a semiglobal exponential stability result for the link position and velocity tracking errors as well as the velocity observation errors. A stability proof and simulation results for the proposed partial state feedback controller are included in the article. © 1995John Wiley & Sons, Inc.
A Study of Reactional Force Compensation Based on Three‐Degree‐of Freedom Parallel Platforms
Authors: Song Shin‐Min , Zhang Ming‐Dons
Published: July 2007

Reaction compensation is necessary for space robot applications because reactional forces/torques will cause undesired movement of the spacecraft. Because the reactional torques can be compensated by the existing torque balancing device in the spacecraft, an additional reaction compensating device is necessary to compensate the reactional forces. In this article we study two types of reactional force compensating devices based on three‐degree‐of freedom, parallel platforms. The first type has three R‐P‐S legs while the second type has three R‐R‐P‐S leg and a passive R‐R‐P leg. A three‐degree of freedom serial manipulator is used to generate reactional forces, which are to be compensated by the paralle platforms. The kinematics and dynamics of both platforms are analyzed and closed form inverse kinematics solutions are derived. We then design a reactional force compensating device that satisfies the strict volume constraint in a spacecraft. The first type of parallel platform is found to require very long legs due to large orientational motion at certain positions. The second type has smooth motion in both position and orientation, and therefore its size can be very compact. It is concluded that the second type of parallel platform has great potential to be used as a compact reactional force compensating device. © 1995 John Wiley & Sons, Inc.
Real‐time direct kinematics of general six‐degree‐of‐freedom parallel manipulators with minimum‐sensor data
Authors: Etemadi‐zanganeh Kourosh , Angeles Jorge
Published: July 2007

We present a formulation of the direct kinematics of a general six‐degree‐of‐freedom parallel manipulator, sometimes referred to as the generalized Steward platform, whereby the positioning and orientation problems are decoupled by introducing two auxiliary coordinates in the forms of either two angles or two lengths. This is in accordance with the type of extra sensors, i.e., rotary or translational, that are collocated on a leg of the manipulator. Moreover, a real‐time implementation of extra‐sensor data, with a unique direct kinematics solution, is proposed by resorting to an eigenvalue problem. The parallelism in the proposed formulation enables the user to benefit from a parallel computing environment. Hence, we introduce a parallel computing algorithm that highly increases the robustness of the computational algorithm. © 1995 John Wiley & Sons, Inc.
On the stiffnes of a novel six‐degree‐freedom parallel minimanipulator
Authors: Tahmasebi Farhad , Tsai Lung‐Wen
Published: July 2007

The dimensionally uniform Jacobian matrix of a novel three‐limbed, six degree‐of‐freedom (DOF) minimanipulator is used to derive its dimensionally uniform stiffness matrix. The minimanipulator limbs are inextensible and its actuators are base‐mounted. The lower ends of the limbs are connected to bidirectional linear stepper motors that are constrained to move on a base plane. The minimanipulator is capable of providing high positional resolution and high stiffness. It is shown that, at a central configuration, the stiffness matrix of the minimanipulator can be decoupled (diagona‐lized), if proper design parameters are chosen. It is also shown that the stiffness of the minimanipulator is higher than that of the Stewart platform. Guidelines for obtaining large minimanipulator stiffness values are established. © 1995 John Wiley & Sons, Inc.
Simulation and computer‐aided kinematic design of three‐degree‐of‐freedom spherical parallel manipulators
Authors: Gosselin Clement M.
Published: July 2007

Parallel robotic manipulators are complex mechanical systems that lead to involved kinematic and dynamic equations. Hence, the design of such systems is in general not intuitive, and advanced simulation and design tools specialized for this type of architecture are highly desirable. This article discusses the kinematic simulation and computer‐aided design of three‐degree‐of‐freedom spherical parallel manipulators with either prismatic or revolute actuators. The kinematic analysis of spherical parallel manipulators is first reviewed. Solutions for the direct and inverse kinematic problems are given, and the expressions for the singularity loci are then introduced. The determination of the workspace of this type of manipulator is also addressed. Finally, a computer package developed specifically for the CAD of spherical parallel manipulators is presented. This package allows the interactive analysis of manipulators of arbitrary architecture including the representation of the workspace, the representation of singularities, and the graphic animation of trajectories specified either by the direct or the inverse kinematic module. It can be used for the design of any spherical parallel three‐degree‐of‐freedom actuated mechanism, which can find many applications in high‐performance robotic systems. © 3995 John Wiley & Sons, Inc.
A robotically assisted munition loading system
Authors: Nguyen Charles C. , Zhou Zhen‐Lei , Bryfogle Mark D.
Published: July 2007

Due to the reliance upon manual operations, conventional loading of munitions on tactical arcraft has several deficiencies including inefficient manpower and time utilization; accident potential; exposure of crew members to chemical, biological, and nuclear agents; and visual obstruction. This article reports on the research and development of a full‐scale prototype robotic system called Robotically Assisted Munition Loading System (RAMLS) comprising a fine motion mechanism (FIMOM), a pose acquisition device (PAD), a manual controller, and a data acquisition and computing system. The FIMOM is a six‐degree‐of‐freedom (DOF) parallel mechanism driven by six hydraulic actuators and the PAD is a passive open kinematic chain mechanism having 6 DOF. The article describes the design and functions of the RAMLS components and presents results of experiments conducted to evaluate the RAMLS's performance. © 3995 John Wiley & Sons, Inc.
Low earth orbit satellite systems for communications
Authors: Maral Gérard , de Ridder Jean‐Jacques , Evans Barry G. , Richharia Madhavendra
Published: July 2007

It may be that we are now entering the era of LEO constellation satellite communications after thirty years of domination by the GEO systems. This paper heralds the coming of the new era with a tutorial approach to the system design and trade‐offs of LEO constellation system design. It discusses orbital configurations, network topologies and routeing considerations, multiple access schemes and link performance design. In so doing it brings out the major design parameters and how they interact with each other. Also considered are the service applications for the LEO constellation systems, and the important difference between real‐time and delayed communication systems is highlighted. Examples of single and multi‐beam (cellular) coverage system link designs are presented for L‐Ka frequency bands. Future papers will consider aspects of the LEO spacecraft and launchers.
A promising application for broadband ISDN: Hypermedia teleconference
Authors: Shimamura Kazunori , Masaki Shigeki , Tanigawa Hiroya
Published: July 2007

The optimum BISDN teleconference service for business, calledhypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high‐speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable‐bit‐rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services.