bluuebunny/crossref_metadata_2025_split huggingface dataset:
A technique for the detection of robot joint gear tightness
Authors: Dagalakis Nicholas G. , Myers Donald R. 
Published: July 2007

AbstractA new technique for the examination of gear tightness in robot joint drive systems is presented. A single robot joint is subjected to random excitation while the rest of the joints are constrained. The corresponding link motion is monitored by two accelerometers mounted on the link. The transfer function of the translational component of link acceleration is then obtained. From the half peak magnitude bandwidth of the first resonant frequency it is possible to determine whether the joint gears under testing have a tight or loose meshing. Tests were performed on the wrist rotation joint of an industrial robot in two steady state positions with the end effector loaded and unloaded.
Computational robot dynamics: Foundations and applications
Authors: Neuman Charles P. , Murray John J. 
Published: July 2007

AbstractIn 1984, the authors unveiled the computer program Algebraic Robot Modeler (ARM) for the symbolic generation of complete closed‐form dynamic robot models. In this paper, we introduce computational robot dynamics as the synthesis of classical mechanics and computer software for the symbolic and numeric modeling of robotic mechanisms, and branch‐out in three directions. First, we outline the foundations of computational robot dynamics. From its inception (in 1973), we review chronologically the contributions of prominent roboticists, tracing the parallel development of robot dynamics formulations and computational robot dynamics. We then highlight our research activities, the current capabilities of ARM, and our plans for the continuing development and application of ARM and computational robot dynamics. Finally, we focus on practical applications of computational robot dynamics. We apply ARM to produce examples illustrating the comparative computational requirements of robot dynamics formulations for symbolic processing and customized algorithms for numeric processing.
Adaptation of the IBM 7535 robot for use as a slave in a hierarchical master/slave relationship
Authors: Ward M. , Eberhardt Allen C. 
Published: July 2007

AbstractA new programming environment for the IBM 7535 robot is introduced. AML/E is replaced by a hierarchical control scheme involving a host and a subservient robot. Application programs are developed on the host, an IBM‐PC XT, in an extended version of the “C” programming language. These extensions allow an application program to be composed of several concurrent processes, one of which is responsible for commanding the robot. To configure the robot as a slave in this relationship, a new operating system was developed for its controller. Written in the same language employed at the host level, it is structured as four concurrent processes managing the robot's resources. An interprocess message‐passing scheme provides a path for master/slave communication. The resultant environment is believed to be superior to the original language AML/E for the following reasons: Concurrency, along with the data and control structures of “C,” is made available to the application programmer. Communication is well structured. The robot's operating system is documented, written in a high‐level language, and open to the user for modification. Due to the significance of integrating the robot into more complex applications involving sensors, these characteristics are felt to be essential in future robots.
A finite‐element approach to control the end‐point motion of a single‐link flexible robot
Authors: Bayo Eduardo 
Published: July 2007

AbstractA structural finite‐element technique based on Bernoulli‐Euler beam theory is presented which will permit the finding of the torques (or forces) that are necessary to apply at one end of a flexible link to produce a desired motion at the other end. This technique is suitable for the open loop control of the tip motion. It may also provide a good control law for feedback control. The finite‐element method is used to discretize the equations of motion. This method has a major advantage in the fact that different material properties and boundary conditions like hubs, tip loads, changes in cross sections, etc., can be handled in a very simple and straightforward manner. The resulting differential equations are integrated via the frequency domain. This allows for the expansion of the desired end motion into its harmonic components and helps to visualize the complex wave propagation nature of the problem. The performance of the proposed technique is illustrated in the solution of a practical example. Results point out the potential that this technique has in the study of the dynamics and control not only of flexible robots, but also of any other flexible mechanisms like those used in biomechanics, where high precision at the tip of very light flexible arms is required.
Generalized joint model for robot manipulator kinematic calibration and compensation
Authors: Driels Morris R. , Pathre Uday S. 
Published: July 2007

AbstractA generalized model that goes beyond the usual assumption of “ideal” joint behavior is proposed. The “real” joint has five ancillary degrees of freedom besides the dominant motion. The resulting manipulator transformation with its greater degree of sophistication is expected to help in calibration and compensation of the various kinematic contributions to robot inaccuracy. The procedure to compute this generalized manipulator transformation is presented. The generalized model also results in manipulator differential relationships and these are discussed.
Direct adaptive control of manipulators in cartesian space
Authors: Seraji H. 
Published: July 2007

AbstractA new adaptive‐control scheme for direct control of manipulator end effector to achieve trajectory tracking in Cartesian space is developed in this article. The control structure is obtained from linear multivariable theory and is composed of simple feedforward and feedback controllers and an auxiliary input. The direct adaptation laws are derived from model reference adaptive control theory and are not based on parameter estimation of the robot model. The utilization of adaptive feedforward control and the inclusion of auxiliary input are novel features of the present scheme and result in improved dynamic performance over existing adaptive control schemes. The adaptive controller does not require the complex mathematical model of the robot dynamics or any knowledge of the robot parameters or the payload, and is computationally fast for on‐line implementation with high sampling rates. The control scheme is applied to a two‐link manipulator for illustration.
Singularities in motion and displacement functions for a 7 degree‐of‐freedom manipulator
Authors: Litvin F. L. , Castelli V. Parenti , Shaheen M. 
Published: July 2007

AbstractThe authors propose a method for the determination of singularities in motion and displacement functions for a seven degree‐of‐freedom manipulator. The manipulator is considered, hereby, as a set of six degree‐of‐freedom manipulators. It is proven that two types of singularities in motion can occur at link positions that are independent and dependent with respect to the trajectory to be executed. The relations between the structure of singularity equations and displacement equations are discussed. The derivation of displacement equations for a manipulator with singularities of the second type is based on the idea of modeling of a manipulator by two open kinematic chains and invariants that may be found for these chains. The inverse kinematic equations and the equations of singularities in motion have been derived using a symbolic computer program which can handle manipulators of general structure (with five, six, and seven degrees‐of‐freedom). This program is written in the Symbolic Computation Language REDUCE.
A systematic formulation of dynamic equations for robot manipulators with elastic links
Authors: Lowl K. H. 
Published: July 2007

AbstractAlthough a variety of formulation schemes for the dynamic equations of robot manipulators with rigid links can be found in the literature, an efficient method of the formulation for robot manipulators with elastic links is not well known. Accordingly, this work presents the derivation of the equations of motion for application to mechanical manipulators with elastic links. The formulation is conducted analytically using Hamilton's principle. The resultant equations consist of the terms of inertial, Coriolis, centrifugal, gravitational, and exerted forces. They are expressed in terms of a set of independent generalized coordinates. In contrast to conventional variational approaches, the present method provides an efficient and systematic way for obtaining the compact symbolic equations of flexible manipulator systems. Two examples are presented to illustrate the proposed methodology. Firstly, a three‐link flexible manipulator with three revolute joints is studied. A flexible manipulator consisting of a prismatic joint and a discrete mass is the second model.
A strictly convergent real‐time solution for inverse kinematics of robot manipulators
Authors: Tsai Yusheng T. , Orin David E. 
Published: July 2007

AbstractInverse Kinematics has been recognized as an important problem in robotics applications. A robot independent solution can only be obtained through numerical methods, but most solutions which use this approach have problems with convergence especially near singularity points. This article develops a strictly convergent algorithm and a special‐purpose Inverse Kinematics Processor (IKP) to obtain the solution in real time. While the algorithm is based on open‐loop integration of rates, the absolute position deviation is used as a criterion to control the iteration, and a feedback mechanism has been especially designed to eliminate problems with long‐term drift or with initial errors in the solution. The architecture of the IKP is based on a high‐speed floating‐point arithmetic processor and is designed to perform the common matrix‐vector operations efficiently with a minimum processor cycle time. The algorithm has been simulated on the proposed architecture, and the results show its robustness and real‐time capability. For a six degree‐of‐freedom robot manipulator (for which no closed‐form solution exist), the Inverse Kinematics solution may be obtained at an approximate 2 khz rate with an error which is within standard repeatability limits.
Customized computational robot dynamics
Authors: Neuman Charles P. , Murray John J. 
Published: July 2007

AbstractIn 1983 the authors implemented the computer program Algebraic Robot Modeler (ARM) to generate symbolically complete closed‐form and recursive dynamic robot models.1–3Then, in 1985, we incorporated in ARM heuristic rules for the systematic organization of dynamic robot models to reduce the computational requirements of customized forward and inverse dynamics calculations. We resolve the issue of numerical efficiency of customized closed‐form and recursive forward and inverse dynamics algorithms for kinematically and dynamically structured manipulators. We find that ARM‐generated customized closed‐form algorithms are the most computationally efficient calculators of forward and inverse dynamics of three degree‐of‐freedom manipulators. For six DOF predominantly rotational manipulators, ARM‐generated customized recursive algorithms are the most computationally efficient foward and inverse dynamics algorithms; inverse dynamics can be computed in less than one millisecond on commercially‐available processors (in software, without special‐purpose hardware). In our companion article,4we compare the symbolic efficiencies of six robot dynamics formulations for generating closed‐form and recursive models.
Two robot arms in assembly by using impulsive information
Authors: Zheng Yuan F. 
Published: July 2007

AbstractWhen two robot arms execute coordinated motions in assembly, collision between the two end‐effectors cannot be avoided. The collision effects on the two coordinating robots include two aspects: abrupt velocity changes of the robot joints and impulsive forces exerting on the contact point as well as on robot joints. Since the direction of the impulsive force exerting on the contact point is related to the relative position and orientation of the two mating parts, the impulsive force can be used to detect the alignment errors of the two end‐effectors. Thus a new assembly method is proposed in this article. The new method uses impulsive information to adjust the position and orientation errors of the two robot arms in assembly, rather than employing a compliance mechanism. The advantage of the new method is that the jamming problem, which is usually associated with compliance methods, never takes place. To make the method practically useful, wrist force sensors are suggested to installed at the wrist of each robot. Dynamic relations between the sensed information and the impulsive force at the contact point are then established. The sensed information thus becomes useful in analyzing the alignment situation. Finally, practical cases are studied to illustrate the use of the new assembly method.
Symbolically efficient formulations for computational robot dynamics
Authors: Neuman Charles P. , Murray John J. 
Published: July 2007

AbstractIn 1983, the authors implemented the computer program Algebraic Robot Modeler (ARM) to generatesymbolicallycomplete closed‐form and recursive dynamic robot models.1–4Then, in 1985, we incorporated in ARM heuristic rules for the systematic organization of dynamic robot models to reduce the computational requirements ofcustomizedforward and inverse dynamics calculations. We compare the symbolic efficiencies of six robot dynamics formulations for generating closed‐form and recursive models. We find that our Lagrange‐Christoffel formulation is the most symbolically efficient generator of closed‐form dynamic robot models. In our companion paper,3we resolve the issue of numerical efficiency of customized closed‐form and recursive algorithms for computing the forward and inverse dynamics of kinematically and dynamically structured manipulators.
Region filling operations with random obstacle avoidance for mobile robots
Authors: Cao Zuo Llang , Huang Yuyu , Hall Ernest L. 
Published: July 2007

AbstractThe article presents a new topic in path planning for mobile robots, region filling. which involves a sweeping operation to fill a whole region with random obstacle avoidance. The approaches for global strip filling and local path searching driven by sensory data procedures are developed. A computer graphic simulation is used to verify the filling strategy available. The research was developed from the program for the design of a robot lawn mower. However, the solution appears generic. The significance is that a problem of wide application and generic solutions for general autonomous mobile robots have been developed.
Collision avoidance for Robot manipulators: Application to Catia/IBM 7565 interface
Authors: Fletcher R. W. , Goldenberg A. A. 
Published: July 2007

AbstractA collision avoidance algorithm has been developed to augment the capability of an automatic (off‐line) robot path planning (programming) tool. The use of off‐line programming tools for robot task programming is becoming increasingly important, but the advantages to be gained by off‐line programming may be lost if collision‐free path planning capabilities are not included. This article addressed the problem of collision‐free path planning in the context of a gantry type robot. The collision avoidance algorithm described here uses the <heuristic approach> to collision‐free path planning. The manipulator and obstacles are modeled as spheres to simplify tests for collision. An important feature of this algorithm is that it permits the manipulation of objects in the robot's environment. When compared against an algorithm from the literature, given a lightly cluttered environment modelled by spheres, the new algorithm finds a collision‐free path much faster. This new algorithm has been implemented as part of the CATIA/IBM 7565 interface which forms an automatic off‐line programming system for the IBM 7565 robot. It has also been implemented as a supervisory collision filter to allow collision‐free control of the robot from the operator's console. In both cases the algorithm has been demonstrated to provide efficient and effective collision avoidance for the IBM 7565 robot.
Inverse dynamic analysis and simulation of a platform type of robot
Authors: Do W. Q. D. , Yang D. C. H. 
Published: July 2007

AbstractThis article presents an algorithm to solve the inverse dynamics for platform type of manipulators using Newton‐Euler equations of motion. We found that the inverse dynamics of the system is governed by thirty‐six linear equations. The number of these simultaneous equations can be reduced to six, if a proper sequence is taken. The relationships between the actuating forces and the shape of the structure are analyzed. Based on the algorithm, computer code for simulation was developed. Three cases were studied. As a result, configurations which minimize the actuating forces are suggested. It is also found that the fluctuation of the driving forces is lesser when the path is closer to the center of the base. These results are believed to be useful in the design and control of this type of manipulating devices.
Numerical filtering for the operation of robotic manipulators through kinematically singular configurations
Authors: Maciejewski Anthony A. , Klein Charles A. 
Published: July 2007

AbstractThe loss of independent degrees of freedom at singular configurations is an inherent characteristic of robotic manipulators. Due to the unavoidable singularity of mechanical wrists, singular configurations cannot be avoided by simply restricting the bounds of the workspace. Techniques for operating at singular configurations without inducing unacceptably high joint velocities or end effector tracking errors are presented. Extensions to the damped least‐squares formulation which incorporate estimates of the proximity to singularities and selective filtering of singular components are illustrated. The generality of the technique presented is illustrated in a computer simulation of a commercially available manipulator operating through singular configurations.
Adaptive gait control for a walking robot
Authors: Kumar Vijay R. , Waldron Kenneth J. 
Published: July 2007

AbstractWalking vehicles have the potential to emulate the superior off‐road mobility of biological systems. However, it is important to make the walking machine terrain adaptive and versatile, and to minimize man's role as an operator in order to realize this potential. Terrain adaptive locomotion involves intelligent foothold selection and the control of gait to produce the desired motion. This requires a departure from the idealized, structured stepping patterns for statically stable gaits which have been the object of considerable research. A modifiedwave gaitis used to demonstrate that it is possible for the vehicle velocity to be varied continuously in accordance with higher level commands even with irregular, asymmetric, and changing support patterns, A varying duty factor is employed to enable optimal leg cycling frequencies. Implementation of gait control algorithms and results from a computer simulation are also presented.
Dynamic control of redundant manipulators
Authors: Hsu Ping , Mauser John , Sastry Shankar 
Published: July 2007

AbstractRedundant manipulators provide increased flexibility for the execution of complex tasks. Redundancy is often required to maintain manipulability and avoid obstacles while completing the required task. Self‐motion is the internal (joint) motion of the manipulator that does not contribute to the end effector motion. In this article we provide a dynamic feedback control law that guarantees the tracking of a desired end effector trajectory and provides redundancy resolution by making the self‐motion of the manipulator flow along the projection of a given arbitrary vector field. By choosing this vector field to be the gradient of a cost function, for example, the manipulator can be made to seek an optimum configuration. The effectiveness of the control law is illustrated with simulation results.
Six‐axis force sensor evaluation and a new type of optimal frame truss design for robotic applications
Authors: Bayo E. , Stubbe J. R. 
Published: July 2007

AbstractThe different means currently available for six‐axis wrist force sensor evaluation are discussed, and a unified criteria is proposed that is based on the condition number, the overall static and dynamic stiffness of the sensor, and the strain gauge sensitivity. In this light a new frame/truss type of sensor body design is introduced. The uniqueness of the design lies in the elastic members that exhibit truss (axial deformation), as opposed to the commonly used beam (bending) behavior. Several improvements over previous designs result, including: increased force sensitivity with a consistently low condition number, increased rigidity, and improved design flexibility. In addition, a design methodology is presented that uses optimization theory in combination with finite element analysis, to yield the best possible frame/truss force sensor design for a given set of specified principal forces.
On controller tuning for a flexible‐link manipulator with varying payload
Authors: Yurkovich Stephen , Pacheco Fernando E. 
Published: July 2007

AbstractIn this article experimental results are presented for system identification and control of a single‐link flexible manipulator carrying an unknown, varying payload. The control objective is to maintain endpoint position accuracy in the presence of flexure effects after rapid movement due to a rigid body slew‐angle commanded position. Various time‐domain parameter estimation techniques are used to identify ARMA model representations to be employed in controller tuning schemes for vibration compensation. Only endpoint acceleration measurements and motor shaft angle measurements are utilized in relatively simple PID control schemes, which are tuned as dictated by a varying, unknown payload.
Criteria optimization using self‐motion of a 9‐R redundant robot
Authors: Lam K. P. 
Published: July 2007

AbstractUsing inverse kinematic solutions forself‐motionof a class of 9‐R redundant robots, a conjugate‐gradient based constrained optimization scheme for incremental trajectory planning is formulated. The proposed scheme has been evaluated and proved to be an efficient optimization method for redundancy utilization. It can also be used for studying 7‐R and 8‐R manipulators by simply restricting to one‐variable and two‐variable optimization, respectively. In contrast with other approaches which are based on the Jacobian, our scheme exploits the availability ofclosed‐forminverse kinematic solutions to give more effective and accurate results.